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Sample records for liquid liquid microextraction

  1. Gas flow headspace liquid phase microextraction.

    Science.gov (United States)

    Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

    2009-11-06

    There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

  2. Extensible automated dispersive liquid–liquid microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Li, Songqing; Hu, Lu; Chen, Ketao; Gao, Haixiang, E-mail: hxgao@cau.edu.cn

    2015-05-04

    Highlights: • An extensible automated dispersive liquid–liquid microextraction was developed. • A fully automatic SPE workstation with a modified operation program was used. • Ionic liquid-based in situ DLLME was used as model method. • SPE columns packed with nonwoven polypropylene fiber was used for phase separation. • The approach was applied to the determination of benzoylurea insecticides in water. - Abstract: In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid–liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C{sub 8}MIM]NTf{sub 2}) is formed through the reaction between [C{sub 8}MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf{sub 2}) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16–0.45 ng mL{sup −1}. The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r > 0.9986) was obtained over the calibration range from 2 to 500 ng mL{sup −1}. The proposed

  3. Extensible automated dispersive liquid–liquid microextraction

    International Nuclear Information System (INIS)

    Li, Songqing; Hu, Lu; Chen, Ketao; Gao, Haixiang

    2015-01-01

    Highlights: • An extensible automated dispersive liquid–liquid microextraction was developed. • A fully automatic SPE workstation with a modified operation program was used. • Ionic liquid-based in situ DLLME was used as model method. • SPE columns packed with nonwoven polypropylene fiber was used for phase separation. • The approach was applied to the determination of benzoylurea insecticides in water. - Abstract: In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid–liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C 8 MIM]NTf 2 ) is formed through the reaction between [C 8 MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf 2 ) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16–0.45 ng mL −1 . The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r > 0.9986) was obtained over the calibration range from 2 to 500 ng mL −1 . The proposed method opens a new avenue

  4. Liquid phase microextraction of pesticides: a review on current methods

    International Nuclear Information System (INIS)

    Farajzadeh, Mir Ali; Sorouraddin, Saeed Mohammad; Mogaddam, Mohammad Reza Afshar

    2014-01-01

    Liquid phase microextraction (LPME) enables analytes to be extracted with a few microliters of an organic solvent. LPME is a technique for sample preparation that is extremely simple, affordable and virtually a solvent-free. It can provide a high degree of selectivity and enrichment by eliminating carry-over between single runs. A variety of solvents are known for the extraction of the various analytes. These features have led to the development of techniques such as single drop microextraction, hollow fiber LPME, dispersive liquid-liquid microextraction, and others. LPME techniques have been applied to the analysis of pharmaceuticals, food, beverages, and pesticides. This review covers the history of LPME methods, and then gives a comprehensive collection of their application to the preconcentration and determination of pesticides in various matrices. Specific sections cover (a) sample treatment techniques in general, (b) single-drop microextraction, (c) extraction based on the use of ionic liquids, (d) solidified floating organic drop microextraction, and various other techniques. (author)

  5. A comparison of various modes of liquid-liquid based microextraction techniques: determination of picric acid.

    Science.gov (United States)

    Burdel, Martin; Šandrejová, Jana; Balogh, Ioseph S; Vishnikin, Andriy; Andruch, Vasil

    2013-03-01

    Three modes of liquid-liquid based microextraction techniques--namely auxiliary solvent-assisted dispersive liquid-liquid microextraction, auxiliary solvent-assisted dispersive liquid-liquid microextraction with low-solvent consumption, and ultrasound-assisted emulsification microextraction--were compared. Picric acid was used as the model analyte. The determination is based on the reaction of picric acid with Astra Phloxine reagent to produce an ion associate easily extractable by various organic solvents, followed by spectrophotometric detection at 558 nm. Each of the compared procedures has both advantages and disadvantages. The main benefit of ultrasound-assisted emulsification microextraction is that no hazardous chlorinated extraction solvents and no dispersive solvent are necessary. Therefore, this procedure was selected for validation. Under optimized experimental conditions (pH 3, 7 × 10(-5) mol/L of Astra Phloxine, and 100 μL of toluene), the calibration plot was linear in the range of 0.02-0.14 mg/L and the LOD was 7 μg/L of picric acid. The developed procedure was applied to the analysis of spiked water samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup

    Science.gov (United States)

    A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally de...

  7. Pesticide extraction from table grapes and plums using ionic liquid based dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Herrera-Herrera, Antonio V; Rodríguez-Delgado, Miguel Angel

    2009-12-01

    Room temperature ionic liquids (RTILs) have been used as extraction solvents in dispersive liquid-liquid microextraction (DLLME) for the determination of eight multi-class pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox, and fenazaquin) in table grapes and plums. The developed method involves the combination of DLLME and high-performance liquid chromatography with diode array detection. Samples were first homogenized and extracted with acetonitrile. After evaporation and reconstitution of the extract in water containing sodium chloride, a quick DLLME procedure that used the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) and methanol was developed. The RTIL dissolved in a very small volume of acetonitrile was directed injected in the chromatographic system. The comparison between the calibration curves obtained from standards and from spiked sample extracts (matrix-matched calibration) showed the existence of a strong matrix effect for most of the analyzed pesticides. A recovery study was also developed with five consecutive extractions of the two types of fruits spiked at three concentration levels. Mean recovery values were in the range of 72-100% for table grapes and 66-105% for plum samples (except for thiophanate-methyl and carbofuran, which were 64-75% and 58-66%, respectively). Limits of detection (LODs) were in the range 0.651-5.44 microg/kg for table grapes and 0.902-6.33 microg/kg for plums, representing LODs below the maximum residue limits (MRLs) established by the European Union in these fruits. The potential of the method was demonstrated by analyzing 12 commercial fruit samples (six of each type).

  8. Ionic liquid based dispersive liquid-liquid microextraction for the extraction of pesticides from bananas.

    Science.gov (United States)

    Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Asensio-Ramos, María; Rodríguez-Delgado, Miguel Angel

    2009-10-23

    This paper describes a dispersive liquid-liquid microextraction (DLLME) procedure using room temperature ionic liquids (RTILs) coupled to high-performance liquid chromatography with diode array detection capable of quantifying trace amounts of eight pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox and fenazaquin) in bananas. Fruit samples were first homogenized and extracted (1g) with acetonitrile and after suitable evaporation and reconstitution of the extract in 10 mL of water, a DLLME procedure using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) as extraction solvent was used. Experimental conditions affecting the DLLME procedure (sample pH, sodium chloride percentage, ionic liquid amount and volume of disperser solvent) were optimized by means of an experimental design. In order to determine the presence of a matrix effect, calibration curves for standards and fortified banana extracts (matrix matched calibration) were studied. Mean recovery values of the extraction of the pesticides from banana samples were in the range of 69-97% (except for thiophanate-methyl and carbofuran, which were 53-63%) with a relative standard deviation lower than 8.7% in all cases. Limits of detection achieved (0.320-4.66 microg/kg) were below the harmonized maximum residue limits established by the European Union (EU). The proposed method, was also applied to the analysis of this group of pesticides in nine banana samples taken from the local markets of the Canary Islands (Spain). To the best of our knowledge, this is the first application of RTILs as extraction solvents for DLLME of pesticides from samples different than water.

  9. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

    Science.gov (United States)

    Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

    2017-08-29

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction

    International Nuclear Information System (INIS)

    Chisvert, Alberto; Benedé, Juan L.; Anderson, Jared L.; Pierson, Stephen A.; Salvador, Amparo

    2017-01-01

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67–791), limits of detection (low ng L −1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87–113%, 91–117% and 89–115% for river, sea and swimming pool water samples, respectively). - Highlights: • A new microextraction method combining the

  11. Non-conventional solvents in liquid phase microextraction and aqueous biphasic systems.

    Science.gov (United States)

    An, Jiwoo; Trujillo-Rodríguez, María J; Pino, Verónica; Anderson, Jared L

    2017-06-02

    The development of rapid, convenient, and high throughput sample preparation approaches such as liquid phase microextraction techniques have been continuously developed over the last decade. More recently, significant attention has been given to the replacement of conventional organic solvents used in liquid phase microextraction techniques in order to reduce toxic waste and to improve selectivity and/or extraction efficiency. With these objectives, non-conventional solvents have been explored in liquid phase microextraction and aqueous biphasic systems. The utilized non-conventional solvents include ionic liquids, magnetic ionic liquids, and deep eutectic solvents. They have been widely used as extraction solvents or additives in various liquid phase microextraction modes including dispersive liquid-liquid microextraction, single-drop microextraction, hollow fiber-liquid phase microextraction, as well as in aqueous biphasic systems. This review provides an overview into the use of non-conventional solvents in these microextraction techniques in the past 5 years (2012-2016). Analytical applications of the techniques are also discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Determination of Trace Amounts of Lead with ETAAS After Single Drop Microextraction and Dispersive Liquid Liquid Microextraction Methods

    Directory of Open Access Journals (Sweden)

    Efeçınar M.

    2013-04-01

    Full Text Available Two liquid-phase microextraction procedures, single-drop microextraction (SDME and dispersive liquid–liquid microextraction (DLLME, have been developed for the determination of lead by electrothermal atomic absorption spectrometry (ETAAS. Both methods were based on the formation of lead iodide-Rhodamine B complex which is in phosphoric acid medium. In the presence of KI, anionic lead iodide was complexed with Rhodamine B as an ion-association complex. Several factors that may be affected on the SDME and DLLME methods were optimized. In the optimum experimental conditions, the limit of detection (3s and the enhancement factor were 0.008 μgL−1 and 152 for SDME and 0.0129 μgL−1 and 89 for DLLME respectively. The relative standard deviation (RSD for eight replicate determinations of 0.25 μgL−1 Pb was 4.6% for SDME and 0.5 μgL−1 Pb was 2.9% for DLLME. The developed methods were validated by the analysis of certified reference materials, and applied successfully to the determination of lead in several water and food samples.

  13. Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

    Science.gov (United States)

    Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-01-01

    A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

  14. Determination of triazine herbicides in juice samples by microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography.

    Science.gov (United States)

    Su, Rui; Li, Dan; Wu, Lijie; Han, Jing; Lian, Wenhui; Wang, Keren; Yang, Hongmei

    2017-07-01

    A novel microextraction method, termed microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high-performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1-hexyl-3-methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1-butyl-3-methylimidazolium tetrafluoroborate. In addition, an ion-pairing agent (NH 4 PF 6 ) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00-250.00 μg/L, with the correlation coefficients of 0.9982-0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7-105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Pre-concentration of uranium from water samples by dispersive liquid-liquid micro-extraction

    Energy Technology Data Exchange (ETDEWEB)

    Khajeh, Mostafa; Nemch, Tabandeh Karimi [Zabol Univ. (Iran, Islamic Republic of). Dept. of Chemistry

    2014-07-01

    In this study, a simple and rapid dispersive liquid-liquid microextraction (DLLME) was developed for the determination of uranium in water samples prior to high performance liquid chromatography with diode array detection. 1-(2-pyridylazo)-2-naphthol (PAN) was used as complexing agent. The effect of various parameters on the extraction step including type and volume of extraction and dispersive solvents, pH of solution, concentration of PAN, extraction time, sample volume and ionic strength were studied and optimized. Under the optimum conditions, the limit of detection (LOD) and preconcentration factor were 0.3 μg L{sup -1} and 194, respectively. Furthermore, the relative standard deviation of the ten replicate was <2.6%. The developed procedure was then applied to the extraction and determination of uranium in the water samples.

  16. Pre-concentration of uranium from water samples by dispersive liquid-liquid micro-extraction

    International Nuclear Information System (INIS)

    Khajeh, Mostafa; Nemch, Tabandeh Karimi

    2014-01-01

    In this study, a simple and rapid dispersive liquid-liquid microextraction (DLLME) was developed for the determination of uranium in water samples prior to high performance liquid chromatography with diode array detection. 1-(2-pyridylazo)-2-naphthol (PAN) was used as complexing agent. The effect of various parameters on the extraction step including type and volume of extraction and dispersive solvents, pH of solution, concentration of PAN, extraction time, sample volume and ionic strength were studied and optimized. Under the optimum conditions, the limit of detection (LOD) and preconcentration factor were 0.3 μg L -1 and 194, respectively. Furthermore, the relative standard deviation of the ten replicate was <2.6%. The developed procedure was then applied to the extraction and determination of uranium in the water samples.

  17. Rapid screening of oxytetracycline residue in catfish muscle by dispersive liquid-liquid microextraction and europium-sensitized luminescence

    Science.gov (United States)

    Oxytetracycline (OTC) residue in catfish muscle was screened by dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). After extraction in EDTA, HCl, and acetonitrile, cleanup was carried out by DLLME, and ESL was measured at microgram = 385 nm and wavelength = ...

  18. Comparison of dispersive liquid-liquid microextraction and hollow fiber liquid-liquid-liquid microextraction for the determination of fentanyl, alfentanil, and sufentanil in water and biological fluids by high-performance liquid chromatography.

    Science.gov (United States)

    Saraji, Mohammad; Khalili Boroujeni, Malihe; Hajialiakbari Bidgoli, Ali Akbar

    2011-06-01

    Dispersive liquid-liquid microextraction (DLLME) and hollow fiber liquid-liquid-liquid microextraction (HF-LLLME) combined with HPLC-DAD have been applied for the determination of three narcotic drugs (alfentanil, fentanyl, and sufentanil) in biological samples (human plasma and urine). Different DLLME parameters influencing the extraction efficiency such as type and volume of the extraction solvent and the disperser solvent, concentration of NaOH, and salt addition were investigated. In the HF-LLLME, the effects of important parameters including organic solvent type, concentration of NaOH as donor solution, concentration of H(2)SO(4) as acceptor phase, salt addition, stirring rate, temperature, and extraction time were investigated and optimized. The results showed that both extraction methods exhibited good linearity, precision, enrichment factor, and detection limit. Under optimal condition, the limits of detection ranged from 0.4 to 1.9 μg/L and from 1.1 to 2.3 μg/L for DLLME and HF-LLLME, respectively. For DLLME, the intra- and inter-day precisions were 1.7-6.4% and 14.2-15.9%, respectively; and for HF-LLLME were 0.7-5.2% and 3.3-10.1%, respectively. The enrichment factors were from 275 to 325 and 190 to 237 for DLLME and HF-LLLME, respectively. The applicability of the proposed methods was investigated by analyzing biological samples. For analysis of human plasma and urine samples, HF-LLLME showed higher precision, more effective sample clean-up, higher extraction efficiency, lower organic solvent consumption than DLLME.

  19. Kinetic aspects of hollow fiber liquid-phase microextraction and electromembrane extraction

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Jensen, Henrik; Rasmussen, Knut Einar

    2012-01-01

    In this paper, extraction kinetics was investigated experimentally and theoretically in hollow fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) with the basic drugs droperidol, haloperidol, nortriptyline, clomipramine, and clemastine as model analytes. In HF...

  20. Use of dispersive liquid-liquid microextraction for simultaneous preconcentration of samarium, europium, gadolinium and dysprosium

    International Nuclear Information System (INIS)

    Mallah, M.H.; Atomic Energy Organization of Iran, Tehran; Shemirani, F.; Ghannadi Maragheh, M.

    2008-01-01

    A new preconcentration method of dispersive liquid-liquid microextraction (DLLME) was developed for simultaneous preconcentration of samarium, europium, gadolinium and dysprosium. DLLME technique was successfully used as a sample preparation method. In this preconcentration method, an appropriate mixture of extraction solvent, disperser solvent was injected rapidly into an aqueous solution containing Sm, Eu, Gd and Dy after complex formation using chelating reagent of the 1-(2-pyridylazo)-2-naphthol (PAN). After phase separation, 0.5 mL of the settled phase containing enriched analytes was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The main factors affected the preconcentration of Sm, Eu, Gd and Dy were extraction and dispersive solvent type and their volume, extraction time, volume of chelating agent (PAN), centrifuge speed and drying temperature of the samples. Under the best operating condition simultaneous preconcentration factors of 80, 100, 103 and 78 were obtained for Sm, Eu, Gd and Dy, respectively. (author)

  1. Analysis of chlorpheniramine in human urine samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Mehdi Maham

    2014-09-01

    Full Text Available A simple and environmentally friendly microextraction technique was used for determination of chlorpheniramine (CPM, an antihistamine drug, in human urine samples using dispersive liquid-liquid microextraction (DLLME followed by high performance liquid chromatography with diode array detection (HPLC-DAD. In this extraction technique, an appropriate mixture of acetonitrile (disperser solvent and carbon tetrachloride (extraction solvent was rapidly injected into the urine sample containing the target analyte. Tiny droplets of extractant were formed and dispersed into the sample solution and then sedimented at the bottom of the conical test tube by centrifugation. Under optimal conditions, the calibration curve was linear in the range of 0.055-5.5 µg mL-1, with a detection limit of 16.5 ng mL-1. This proposed method was successfully applied to the analysis of real urine samples. Low consumption of toxic organic solvents, simplicity of operation, low cost and acceptable figures of merit are the main advantages of the proposed technique.

  2. Determination of Trichloroethylene in Water by Liquid–Liquid Microextraction Assisted Solid Phase Microextraction

    Directory of Open Access Journals (Sweden)

    Mengliang Zhang

    2015-02-01

    Full Text Available A method for the determination of trichloroethylene (TCE in water using portable gas chromatography/mass spectrometry (GC/MS was developed. A novel sample preparation method, liquid–liquid microextraction assisted solid phase microextraction (LLME–SPME, is introduced. In this method, 20 µL of hexane was added to 10 mL of TCE contaminated aqueous samples to assist headspace SPME. The extraction efficiency of SPME was significantly improved with the addition of minute amounts of organic solvents (i.e., 20 µL hexane. The absolute recoveries of TCE at different concentrations were increased from 11%–17% for the samples extracted by SPME to 29%–41% for the samples extracted by LLME–SPME. The method was demonstrated to be linear from 10 to 1000 ng mL−1 for TCE in water. The improvements on extraction efficiencies were also observed for toluene and 1, 2, 4-trichlorobenzene in water by using LLME–SPME method. The LLME–SPME method was optimized by using response surface modeling (RSM.

  3. Detection of Organophosphorus Pesticides in Wheat by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with HPLC

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2018-01-01

    Full Text Available Food safety issues closely related to human health have always received widespread attention from the world society. As a basic food source, wheat is the fundamental support of human survival; therefore, the detection of pesticide residues in wheat is very necessary. In this work, the ultrasonic-assisted ionic liquid-dispersive liquid-liquid microextraction (DLLME method was firstly proposed, and the extraction and analysis of three organophosphorus pesticides were carried out by combining high-performance liquid chromatography (HPLC. The extraction efficiencies of three ionic liquids with bis(trifluoromethylsulfonylimide (Tf2N anion were compared by extracting organophosphorus in wheat samples. It was found that the use of 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonylimide ([OMIM][Tf2N] had both high enrichment efficiency and appropriate extraction recovery. Finally, the method was used for the determination of three wheat samples, and the recoveries of them were 74.8–112.5%, 71.8–104.5%, and 83.8–115.5%, respectively. The results show that the method proposed is simple, fast, and efficient, which can be applied to the extraction of organic matters in wheat samples.

  4. Magnetomotive room temperature dicationic ionic liquid: a new concept toward centrifuge-less dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Beiraghi, Asadollah; Shokri, Masood; Seidi, Shahram; Godajdar, Bijan Mombani

    2015-01-09

    A new centrifuge-less dispersive liquid-liquid microextraction technique based on application of magnetomotive room temperature dicationic ionic liquid followed by electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of trace amount of gold and silver in water and ore samples, for the first time. Magnetic ionic liquids not only have the excellent properties of ionic liquids but also exhibit strong response to an external magnetic field. These properties provide more advantages and potential application prospects for magnetic ionic liquids than conventional ones in the fields of extraction processes. In this work, thio-Michler's ketone (TMK) was used as chelating agent to form Ag/Au-TMK complexes. Several important factors affecting extraction efficiency including extraction time, rate of vortex agitator, pH of sample solution, concentration of the chelating agent, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) were 3.2 and 7.3ngL(-1) with the preconcentration factors of 245 and 240 for Au and Ag, respectively. The precision values (RSD%, n=7) were 5.3% and 5.8% at the concentration level of 0.05μgL(-1) for Au and Ag, respectively. The relative recoveries for the spiked samples were in the acceptable range of 96-104.5%. The results demonstrated that except Hg(2+), no remarkable interferences are created by other various ions in the determination of Au and Ag, so that the tolerance limits (WIon/WAu or Ag) of major cations and anions were in the range of 250-1000. The validated method was successfully applied for the analysis of Au and Ag in some water and ore samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.

    Science.gov (United States)

    Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria

    2014-02-21

    Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ∼0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Multimycotoxin LC-MS/MS Analysis in Tea Beverages after Dispersive Liquid-Liquid Microextraction (DLLME).

    Science.gov (United States)

    Pallarés, Noelia; Font, Guillermina; Mañes, Jordi; Ferrer, Emilia

    2017-11-29

    The aim of the present study was to develop a multimycotoxin liquid chromatography tandem mass spectrometry (LC-MS/MS) method with a dispersive liquid-liquid microextraction procedure (DLLME) for the analysis of AFs, 3aDON, 15aDON, NIV, HT-2, T-2, ZEA, OTA, ENNs, and BEA in tea beverages and to evaluate their mycotoxin contents. The proposed method was characterized in terms of linearity, limits of detection (LODs), limits of quantification (LOQs), recoveries, repeatability (intraday precision), reproducibility (interday precision), and matrix effects to check suitability. The results show LODs in the range of 0.05-10 μg/L, LOQs in the range of 0.2-33 μg/L, and recoveries in the range of 65-127% (RSD tea, red tea, green tea, and green mint tea. The results show that, of the analyzed mycotoxins, AFB2, AFG2, 15aDON, AFG1, and ENB were detected in the samples. AFB2 (14.4-32.2 μg/L) and 15aDON (60.5-61 μg/L) presented the highest levels. Green mint tea contained the highest concentration of mycotoxins. The risk assessment study shows that the population is not much exposed to mycotoxins through the consumption of tea beverages.

  8. Dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Zeini Jahromi, Elham; Bidari, Araz; Assadi, Yaghoub; Milani Hosseini, Mohammad Reza; Jamali, Mohammad Reza

    2007-01-01

    Dispersive liquid-liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 μL methanol (disperser solvent) containing 34 μL carbon tetrachloride (extraction solvent) and 0.00010 g ammonium pyrrolidine dithiocarbamate (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with ammonium pyrrolidine dithiocarbamate, and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25 ± 1 μL). Then a 20 μL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 125 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the rage of 2-20 ng L -1 with detection limit of 0.6 ng L -1 . The relative standard deviation (R.S.D.s) for ten replicate measurements of 20 ng L -1 of cadmium was 3.5%. The relative recoveries of cadmium in tap, sea and rivers water samples at spiking level of 5 and 10 ng L -1 are 108, 95, 87 and 98%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on-line liquid-liquid extraction, single drop microextraction (SDME), on-line solid phase extraction (SPE) and co-precipitation based on bibliographic data. Therefore, DLLME combined with

  9. Vortex-assisted liquid-liquid microextraction for the rapid screening of short-chain chlorinated paraffins in water.

    Science.gov (United States)

    Chang, Chia-Yu; Chung, Wu-Hsun; Ding, Wang-Hsien

    2016-01-01

    The rapid screening of trace levels of short-chain chlorinated paraffins in various aqueous samples was performed by a simple and reliable procedure based on vortex-assisted liquid-liquid microextraction combined with gas chromatography and electron capture negative ionization mass spectrometry. The optimal vortex-assisted liquid-liquid microextraction conditions for 20 mL water sample were as follows: extractant 400 μL of dichloromethane; vortex extraction time of 1 min at 2500 × g; centrifugation of 3 min at 5000 × g; and no ionic strength adjustment. Under the optimum conditions, the limit of quantitation was 0.05 μg/L. Precision, as indicated by relative standard deviations, was less than 9% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was above 91%. The vortex-assisted liquid-liquid microextraction with gas chromatography and electron capture negative ionization mass spectrometry method was successfully applied to quantitatively extract short-chain chlorinated paraffins from samples of river water and the effluent of a wastewater treatment plant, and the concentrations ranged from 0.8 to 1.6 μg/L. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Applications of liquid-phase microextraction in the sample preparation of environmental solid samples.

    Science.gov (United States)

    Prosen, Helena

    2014-05-23

    Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

  11. Applications of Liquid-Phase Microextraction in the Sample Preparation of Environmental Solid Samples

    Directory of Open Access Journals (Sweden)

    Helena Prosen

    2014-05-01

    Full Text Available Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc. published in the last decade. Several innovative liquid-phase microextraction (LPME techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME, hollow fiber-liquid phase microextraction (HF-LPME, dispersive liquid-liquid microextraction (DLLME. Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

  12. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. In-syringe dispersive liquid-liquid microextraction with liquid chromatographic determination of synthetic pyrethroids in surface water

    Directory of Open Access Journals (Sweden)

    Saeed S. Albaseer

    2012-03-01

    Full Text Available An indigenously fabricated in laboratory glass syringe was used for in-syringe dispersive liquid-liquid microextraction (is-DLLME and preconcentration of synthetic pyrethroids (SPs from surface waters suitable for their determination by high performance liquid chromatography. In contrast to classical DLLME, is-DLLME allows the use of lighter-than-water organic solvents and the analysis of environmental contaminants’ samples without prior filtration, which is of great importance due to the high affinity of pyrethroids to adsorb to solid particulates present in environmental samples. The effects of various parameters on the extraction efficiency were evaluated and optimized systemically using one-factor-at-a-time method (OFAT and statistically using full factorial design (24. Three SPs (viz.; cypermethrin, resmethrin and permethrin were analyzed. The method showed good accuracy with RSD% in the range of of 4.8–6.9%. The method detection limits of the three pesticides ranged from 0.14 to 0.16 ng mL-1. The proposed method was applied for the determination of synthetic pyrethroids in lake water

  14. Spectrophotometric determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Lemos, Valfredo Azevedo; dos Santos, Liz Oliveira; Silva, Eldevan dos Santos; Vieira, Emanuel Vitor dos Santos

    2012-01-01

    A simple method for the determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction is described. The procedure is based on the extraction of mercury in the form of a complex and its subsequent determination by spectrophotometry. The complex is formed between Hg(II) and 2-(2-benzothiazolylazo)-p-cresol. The detection at 650 nm is performed directly in the metal-rich phase, which is spread on a triacetylcellulose membrane. The method eliminates the need to use a cuvet or large quantities of samples and reagents. The parameters that influence the preconcentration were studied, and the analytical characteristics were determined. The enrichment factor and the consumptive index for this method were 64 and 0.16 mL, respectively. The LOD (3.3 microg/L) and LOQ (11.1 microg/L) were also determined. The accuracy of the method was tested by the determination of mercury in certified reference materials BCR 397 (Human Hair) and SRM 2781 (Domestic Sludge). The method was applied to the determination of mercury in samples of drinking water, sea water, and river water.

  15. Dispersive liquid-liquid microextraction coupled with magnetic nanoparticles for extraction of zearalenone in wheat samples

    Directory of Open Access Journals (Sweden)

    Mitra Amoli-Diva

    2017-01-01

    Full Text Available A new, sensitive and fast dispersive liquid-liquid microextraction (DLLME coupled with micro-solid phase extraction (μ-SPE was developed for determination of zearalenone (ZEN in wheat samples. The DLLME was performed using acetonitrile/water (80:20 v/v as the disperser solvent and 1-octanol as the extracting solvent.  The acetonitrile/water (80:20 v/v solvent was also used to extract ZEN from solid wheat matrix, and was directly applied as the disperser solvent for DLLME process. Additionally, hydrophobic oleic-acid-modified magnetic nanoparticles were used in μ-SPE approach to retrieve the analyte from the DLLME step. So, the method uses high surface area and strong magnetism properties of these nanoparticles to avoid time-consuming column-passing processes in traditional SPE. Main parameters affecting the extraction efficiency and signal enhancement were investigated and optimized. Under the optimum conditions, the calibration curve showed a good linearity in the range of 0.1-500 μg kg−1 (R2=0.9996 with low detection limit of 83 ng g−1. The intra-day and inter-day precisions (as RSD % in the range of 2.6-4.3 % and high recoveries ranging from 91.6 to 99.1 % were obtained. The pre-concentration factor was 3. The method is simple, inexpensive, accurate and remarkably free from interference effects.

  16. Dispersive liquid-liquid microextraction of copper ions as neocuproine complex in environmental aqueous samples.

    Science.gov (United States)

    Shariati, Shahab; Golshekan, Mostafa

    2011-06-01

    In the present study, a simple and efficient extraction method based on dispersive liquid-liquid microextraction prior to UV-Vis spectrophotometry was developed for the preconcentration and determination of copper ions in environmental samples. Briefly, cupric ions (Cu II) were reduced to cuprous (Cu I) with addition of hydroxyl amine hydrochloride and formed hydrophobic chelates with neocuproine. Then, a proper mixture of acetonitrile (as dispersive solvent) and choloroform (as extraction solvent) was rapidly injected into the solution and a cloudy solution was formed. After centrifuging, choloroform was sedimented at the bottom of a conical tube and diluted with 100 µL of methanol for further UV-Vis spectrophotometry measurement. An orthogonal array design (OAD) was employed to study the effects of different parameters on the extraction efficiency. Under the optimum experimental conditions, a preconcentration factor up to 63.6 was achieved for extraction from 5.0 mL of sample solution. The limit of detection (LOD) based on S/N = 3 was 0.33 µg L-1 and the calibration curve was linear in the range of 1-200 µg L-1 with reasonable linearity (r2 > 0.997). Finally, the accuracy of the proposed method was successfully evaluated by determination of trace amounts of copper ions in different water samples and satisfactory results were obtained.

  17. Ligandless-dispersive liquid-liquid microextraction of trace amount of copper ions

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Sayed Zia, E-mail: szmohammadi@yahoo.com [Department of Chemistry, Payame Noor University (PNU), Kerman (Iran, Islamic Republic of); Afzali, Daryoush [Environment Department, Institute Research of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Baghelani, Yar Mohammad [Department of Chemistry, Payame Noor University (PNU), Kerman (Iran, Islamic Republic of)

    2009-10-27

    In the present work, a new ligandless-dispersive liquid-liquid microextraction (LL-DLLME) method has been developed for preconcentration trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing on the extraction efficiency of copper and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of sample solution, extraction time and salting out effect. Under the optimal conditions, the calibration curve was linear in the range of 1.0 ng mL{sup -1}-0.6 {mu}g mL{sup -1} of copper with R{sup 2} = 0.9985. Detection limit was 0.5 ng mL{sup -1} in original solution (3S{sub b}/m) and the relative standard deviation for seven replicate determination of 0.2 {mu}g mL{sup -1} copper was {+-}1.4%. The proposed method has been applied for determination of copper in standard and water samples with satisfactory results.

  18. Ligandless-dispersive liquid-liquid microextraction of trace amount of copper ions

    International Nuclear Information System (INIS)

    Mohammadi, Sayed Zia; Afzali, Daryoush; Baghelani, Yar Mohammad

    2009-01-01

    In the present work, a new ligandless-dispersive liquid-liquid microextraction (LL-DLLME) method has been developed for preconcentration trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing on the extraction efficiency of copper and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of sample solution, extraction time and salting out effect. Under the optimal conditions, the calibration curve was linear in the range of 1.0 ng mL -1 -0.6 μg mL -1 of copper with R 2 = 0.9985. Detection limit was 0.5 ng mL -1 in original solution (3S b /m) and the relative standard deviation for seven replicate determination of 0.2 μg mL -1 copper was ±1.4%. The proposed method has been applied for determination of copper in standard and water samples with satisfactory results.

  19. Rapid determination of 226Ra in drinking water samples using dispersive liquid-liquid microextraction coupled with liquid scintillation counting

    International Nuclear Information System (INIS)

    Sadi, B.K.; Chunsheng Li; Kramer, G.H.; Johnson, C.L.; Queenie Ko; Lai, E.P.C.

    2011-01-01

    A new radioanalytical method was developed for rapid determination of 226 Ra in drinking water samples. The method is based on extraction and preconcentration of 226 Ra from a water sample to an organic solvent using a dispersive liquid-liquid microextraction (DLLME) technique followed by radiometric measurement using liquid scintillation counting. In DLLME for 226 Ra, a mixture of an organic extractant (toluene doped with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone) and a disperser solvent (acetonitrile) is rapidly injected into the water sample resulting in the formation of an emulsion. Within the emulsion, 226 Ra reacts with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone and partitions into the fine droplets of toluene. The water/toluene phases were separated by addition of acetonitrile as a de-emulsifier solvent. The toluene phase containing 226 Ra was then measured by liquid scintillation counting. Several parameters were studied to optimize the extraction efficiency of 226 Ra, including water immiscible organic solvent, disperser and de-emulsifier solvent type and their volume, chelating ligands for 226 Ra and their concentrations, inorganic salt additive and its concentration, and equilibrium pH. With the optimized DLLME conditions, the accuracy (expressed as relative bias, B r ) and method repeatability (expressed as relative precision, S B ) were determined by spiking 226 Ra at the maximum acceptable concentration level (0.5 Bq L -1 ) according to the Guidelines for Canadian Drinking Water Quality. Accuracy and repeatability were found to be less than -5% (B r ) and less than 6% (S B ), respectively, for both tap water and bottled natural spring water samples. The minimum detectable activity and sample turnaround time for determination of 226 Ra was 33 mBq L -1 and less than 3 h, respectively. The DLLME technique is selective for extraction of 226 Ra from its decay progenies. (author)

  20. Simultaneous determination of several phytohormones in natural coconut juice by hollow fiber-based liquid-liquid-liquid microextraction-high performance liquid chromatography.

    Science.gov (United States)

    Wu, Yunli; Hu, Bin

    2009-11-06

    A simple, selective, sensitive and inexpensive method of hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV) detection was developed for the determination of four acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), (+/-) abscisic acid (ABA) and (+/-) jasmonic acid (JA)) in natural coconut juice. To the best of our knowledge, this is the first report on the use of liquid phase microextraction (LPME) as a sample pretreatment technique for the simultaneous analysis of several phytohormones. Using phenetole to fill the pores of hollow fiber as the organic phase, 0.1molL(-1) NaOH solution in the lumen of hollow fiber as the acceptor phase and 1molL(-1) HCl as the donor phase, a simultaneous preconcentration of four target phytohormones was realized. The acceptor phase was finally withdrawn into the microsyringe and directly injected into HPLC for the separation and quantification of the target phytohormones. The factors affecting the extraction efficiency of four phytohormones by HF-LLLME were optimized with orthogonal design experiment, and the data was analyzed by Statistical Product and Service Solutions (SPSS) software. Under the optimized conditions, the enrichment factors for SA, IAA, ABA and JA were 243, 215, 52 and 48, with the detection limits (S/N=3) of 4.6, 1.3, 0.9ngmL(-1) and 8.8 microg mL(-1), respectively. The relative standard deviations (RSDs, n=7) were 7.9, 4.9, 6.8% at 50ngmL(-1) level for SA, IAA, ABA and 8.4% at 500 microg mL(-1) for JA, respectively. To evaluate the accuracy of the method, the developed method was applied for the simultaneous analysis of several phytohormones in five natural coconut juice samples, and the recoveries for the spiked samples were in the range of 88.3-119.1%.

  1. Determination of five antiarrhythmic drugs in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Jouyban, Abolghasem; Sorouraddin, Mohammad Hossein; Farajzadeh, Mir Ali; Somi, Mohammad Hossein; Fazeli-Bakhtiyari, Rana

    2015-03-01

    A fast and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed and validated for the simultaneous quantitation of five antiarrhythmic drugs (metoprolol, propranolol, carvedilol, diltiazem, and verapamil) in human plasma samples. It involves dispersive liquid-liquid microextraction (DLLME) of the desired drugs from 660 µL plasma and separation using isocratic elution with UV detection at 200 nm. The complete separation of all analytes was achieved within 7 min. Acetonitrile (as disperser solvent) resulting from the protein precipitation procedure was mixed with 100 µL dichloromethane (as an extraction solvent) and rapidly injected into 5 mL aqueous solution (pH 11.5) containing 1% (w/v), NaCl. After centrifugation, the sedimented phase containing enriched analytes was collected and evaporated to dryness. The residue was re-dissolved in 50 µL de-ionized water (acidified to pH 3) and injected into the HPLC system for analysis. Under the optimal conditions, the enrichment factors and extraction recoveries ranged between 4.4-10.8 and 33-82%, respectively. The suggested method was linear (r(2) ≥0.997) over a dynamic range of 0.02-0.80 µg mL(-1) in plasma. The intra- and inter-days relative standard deviation (RSD%) and relative error (RE%) values of the method were below 20%, which shows good precision and accuracy. Finally, this method was applied to the analysis of real plasma samples obtained from the patients treated with these drugs. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Analysis of drugs of abuse in human plasma by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Fernández, P; Regenjo, M; Bermejo, A M; Fernández, A M; Lorenzo, R A; Carro, A M

    2015-04-01

    Opioids and cocaine are widely used at present, both for recreational purposes and as drugs of abuse. This raises the need to develop new analytical methods specifically designed for the simultaneous detection of several drugs of abuse in biological samples. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a new sample treatment for the simultaneous extraction of morphine (MOR), 6-acetylmorphine (6AM), cocaine (COC), benzoylecgonine (BZE) and methadone (MET) from human plasma. Preliminary assays were done before developing an experimental design based on a Uniform Network Doehlert which allowed the optimum extraction conditions to be identified, namely: a volume of extractant solvent (chloroform) and dispersant solvent (acetonitrile) of 220 µl and 3.2 ml, respectively; 0.2 g of NaCl as a salting-out additive; pH 10.6 and ultrasound stirring for 3.5 min. The resulting extracts were analyzed by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), using an XBridge® RP18 column (250 × 4.6 mm i.d., 5 µm particle size). Calibration graphs were linear over the concentration range 0.1-10 µg ml⁻¹, and detection limits ranged from 13.9 to 28.5 ng ml⁻¹. Precision calculated at three different concentration levels in plasma was included in the range 0.1-6.8% RSD. Recoveries of the five drugs were all higher than 84% on average. Finally the proposed method was successfully applied to 22 plasma samples from heroin, cocaine and/or methadone users, and the most frequently detected drug was benzoylecgonine, followed by methadone, cocaine and morphine. Copyright © 2014 John Wiley & Sons, Ltd.

  3. Selective extraction of emerging contaminants from water samples by dispersive liquid-liquid microextraction using functionalized ionic liquids.

    Science.gov (United States)

    Yao, Cong; Li, Tianhao; Twu, Pamela; Pitner, William R; Anderson, Jared L

    2011-03-25

    Functionalized ionic liquids containing the tris(pentafluoroethyl)trifluorophosphate (FAP) anion were used as extraction solvents in dispersive liquid-liquid microextraction (DLLME) for the extraction of 14 emerging contaminants from water samples. The extraction efficiencies and selectivities were compared to those of an in situ IL DLLME method which uses an in situ metathesis reaction to exchange 1-butyl-3-methylimidazolium chloride (BMIM-Cl) to 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BMIM-NTf(2)). Compounds containing tertiary amine functionality were extracted with high selectivity and sensitivity by the 1-(6-amino-hexyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (HNH(2)MPL-FAP) IL compared to other FAP-based ILs and the BMIM-NTf(2) IL. On the other hand, polar or acidic compounds without amine groups exhibited higher enrichment factors using the BMIM-NTf(2) IL. The detection limits for the studied analytes varied from 0.1 to 55.1 μg/L using the traditional IL DLLME method with the HNH(2)MPL-FAP IL as extraction solvent, and from 0.1 to 55.8 μg/L using in situ IL DLLME method with BMIM-Cl+LiNTf(2) as extraction solvent. A 93-fold decrease in the detection limit of caffeine was observed when using the HNH(2)MPL-FAP IL compared to that obtained using in situ IL DLLME method. Real water samples including tap water and creek water were analyzed with both IL DLLME methods and yielded recoveries ranging from 91% to 110%. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Determination of statin drugs in hospital effluent with dispersive liquid-liquid microextraction and quantification by liquid chromatography.

    Science.gov (United States)

    Martins, Ayrton F; Frank, Carla da S; Altissimo, Joseline; de Oliveira, Júlia A; da Silva, Daiane S; Reichert, Jaqueline F; Souza, Darliana M

    2017-08-24

    Statins are classified as being amongst the most prescribed agents for treating hypercholesterolaemia and preventing vascular diseases. In this study, a rapid and effective liquid chromatography method, assisted by diode array detection, was designed and validated for the simultaneous quantification of atorvastatin (ATO) and simvastatin (SIM) in hospital effluent samples. The solid phase extraction (SPE) of the analytes was optimized regarding sorbent material and pH, and the dispersive liquid-liquid microextraction (DLLME), in terms of pH, ionic strength, type and volume of extractor/dispersor solvents. The performance of both extraction procedures was evaluated in terms of linearity, quantification limits, accuracy (recovery %), precision and matrix effects for each analyte. The methods proved to be linear in the concentration range considered; the quantification limits were 0.45 µg L -1 for ATO and 0.75 µg L -1 for SIM; the matrix effect was almost absent in both methods and the average recoveries remained between 81.5-90.0%; and the RSD values were <20%. The validated methods were applied to the quantification of the statins in real samples of hospital effluent; the concentrations ranged from 18.8 µg L -1 to 35.3 µg L -1 for ATO, and from 30.3 µg L -1 to 38.5 µg L -1 for SIM. Since the calculated risk quotient was ≤192, the occurrence of ATO and SIM in hospital effluent poses a potential serious risk to human health and the aquatic ecosystem.

  5. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    Science.gov (United States)

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Ionic liquid-based air-assisted liquid-liquid microextraction followed by high performance liquid chromatography for the determination of five fungicides in juice samples.

    Science.gov (United States)

    You, Xiangwei; Chen, Xiaochu; Liu, Fengmao; Hou, Fan; Li, Yiqiang

    2018-01-15

    A novel and simple ionic liquid-based air-assisted liquid-liquid microextraction technique combined with high performance liquid chromatography was developed to analyze five fungicides in juice samples. In this method, ionic liquid was used instead of a volatile organic solvent as the extraction solvent. The emulsion was formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent repeatedly using a 10mL glass syringe. No organic dispersive solvent was required. Under the optimized conditions, the limits of detection (LODs) were 0.4-1.8μgL -1 at a signal-to-noise ratio of 3. The limits of quantification (LOQs) set as the lowest spiking levels with acceptable recovery in juices were 10μgL -1 , except for fludioxonil whose LOQ was 20μgL -1 . The proposed method was applied to determine the target fungicides in juice samples, and acceptable recoveries ranging from 74.9% to 115.4% were achieved. Copyright © 2017. Published by Elsevier Ltd.

  7. Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L.

    Science.gov (United States)

    Wang, Zhibing; Hu, Jianxue; Du, Hongxia; He, Shuang; Li, Qing; Zhang, Hanqi

    2016-06-05

    The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Liquid phase microextraction for the analysis of trace elements and their speciation

    International Nuclear Information System (INIS)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-01-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated. - Highlights: • The state of art of LPME for trace elements and their speciation analysis is updated. • Different extraction formats of LPME are described. • The application potential and future

  9. Overcoming the challenges of conventional dispersive liquid-liquid microextraction: analysis of THMs in chlorinated swimming pools.

    Science.gov (United States)

    Faraji, Hakim; Helalizadeh, Masoumeh; Kordi, Mohammad Reza

    2018-01-01

    A rapid, simple, and sensitive approach to the analysis of trihalomethanes (THMs) in swimming pool water samples has been developed. The main goal of this study was to overcome or to improve the shortcomings of conventional dispersive liquid-liquid microextraction (DLLME) and to maximize the realization of green analytical chemistry principles. The method involves a simple vortex-assisted microextraction step, in the absence of the dispersive solvent, followed by salting-out effect for the elimination of the centrifugation step. A bell-shaped device and a solidifiable solvent were used to simplify the extraction solvent collection after phase separation. Optimization of the independent variables was performed by using chemometric methods in three steps. The method was statistically validated based on authentic guidance documents. The completion time for extraction was less than 8 min, and the limits of detection were in the range between 4 and 72 ng L -1 . Using this method, good linearity and precision were achieved. The results of THMs determination in different real samples showed that in some cases the concentration of total THMs was more than threshold values of THMs determined by accredited healthcare organizations. This method indicated satisfactory analytical figures of merit. Graphical Abstract A novel green microextraction technique for overcoming the challenges of conventional DLLME. The proposed procedure complies with the principles of green/sustainable analytical chemistry, comprising decreasing the sample size, making easy automation of the process, reducing organic waste, diminishing energy consumption, replacing toxic reagents with safer reagents, and enhancing operator safety.

  10. Development of a dispersive liquid-liquid microextraction method for the determination of polychlorinated biphenyls in water

    International Nuclear Information System (INIS)

    Rezaei, Fatemeh; Bidari, Araz; Birjandi, Afsoon Pajand; Milani Hosseini, Mohammad Reza; Assadi, Yaghoub

    2008-01-01

    A very simple and powerful microextraction procedure, the dispersive liquid-liquid microextraction (DLLME), was used for the determination of the content of 10 polychlorinated biphenyls (PCBs) in water samples, using gas chromatography coupled with electron-capture detection (GC-ECD). The appropriate amount of acetone (disperser solvent) and chlorobenzene (extraction solvent) at the microlevel volume was used for this procedure. The conditions for the microextraction performance were investigated and optimized. The optimized method exhibited a good linearity (R 2 > 0.996) over the studied range (0.005-2 μg L -1 ), illustrating a satisfactory precision level with R.S.D. values between 4.1% and 11.0%. The values of the detection limit (S/N = 3) were found to be lower than 0.002 μg L -1 . Furthermore, a large enrichment factor for the analytes (up to a 540-fold) was achieved in a very short time for only a 5.00-mL water sample. The effectiveness of the method towards real samples was tested by analyzing well, river and seawater samples. The relative recoveries of the well, river and seawater samples, which had been spiked with different levels of PCBs were equal to 92.0-114.0%, 97.0-102.0% and 96.0-103.0%, respectively. The attained results demonstrated that DLLME combined with GC-ECD was a fast and inexpensive technique for the PCBs determination in water samples

  11. Use of Dispersive Liquid-Liquid Microextraction and UV-Vis Spectrophotometry for the Determination of Cadmium in Water Samples

    Directory of Open Access Journals (Sweden)

    J. Pérez-Outeiral

    2014-01-01

    Full Text Available A simple and inexpensive method for cadmium determination in water using dispersive liquid-liquid microextraction and ultraviolet-visible spectrophotometry was developed. In order to obtain the best experimental conditions, experimental design was applied. Calibration was made in the range of 10–100 μg/L, obtaining good linearity (R2 = 0.9947. The obtained limit of detection based on calibration curve was 8.5 μg/L. Intra- and interday repeatability were checked at two levels, obtaining relative standard deviation values from 9.0 to 13.3%. The enrichment factor had a value of 73. Metal interferences were also checked and tolerable limits were evaluated. Finally, the method was applied to cadmium determination in real spiked water samples. Therefore, the method showed potential applicability for cadmium determination in highly contaminated liquid samples.

  12. Ionic liquid ultrasound assisted dispersive liquid-liquid microextraction method for preconcentration of trace amounts of rhodium prior to flame atomic absorption spectrometry determination

    Energy Technology Data Exchange (ETDEWEB)

    Molaakbari, Elaheh [Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Young Research Society, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mostafavi, Ali, E-mail: mostafavi.ali@gmail.com [Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Afzali, Daryoush [Environment and Nanochemistry Department, Research Institute of Environmental Science, International Center for Science, High Technology and Environmental Science, Kerman (Iran, Islamic Republic of); Mineral Industries Research Center, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2011-01-30

    In this article, we consider ionic liquid based ultrasound-assisted dispersive liquid-liquid microextraction of trace amounts of rhodium from aqueous samples and show that this is a fast and reliable sample pre-treatment for the determination of rhodium ions by flame atomic absorption spectrometry. The Rh(III) was transferred into its complex with 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol as a chelating agent, and an ultrasonic bath with the ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide at room temperature was used to extract the analyte. The centrifuged rhodium complex was then enriched in the form of ionic liquid droplets and prior to its analysis by flame atomic absorption spectrometry, 300 {mu}L ethanol was added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh(III) was optimized. Under optimum conditions, the calibration graph was linear in the range of 4.0-500.0 ng mL{sup -1}, the detection limit was 0.37 ng mL{sup -1} (3S{sub b}/m, n = 7) and the relative standard deviation was {+-}1.63% (n = 7, C = 200 ng mL{sup -1}). The results show that ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction, combined with flame atomic absorption spectrometry, is a rapid, simple, sensitive and efficient analytical method for the separation and determination of trace amounts of Rh(III) ions with minimum organic solvent consumption.

  13. Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

    Science.gov (United States)

    Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

    2016-08-01

    A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Fully-automated in-syringe dispersive liquid-liquid microextraction for the determination of caffeine in coffee beverages.

    Science.gov (United States)

    Frizzarin, Rejane M; Maya, Fernando; Estela, José M; Cerdà, Víctor

    2016-12-01

    A novel fully-automated magnetic stirring-assisted lab-in-syringe analytical procedure has been developed for the fast and efficient dispersive liquid-liquid microextraction (DLLME) of caffeine in coffee beverages. The procedure is based on the microextraction of caffeine with a minute amount of dichloromethane, isolating caffeine from the sample matrix with no further sample pretreatment. Selection of the relevant extraction parameters such as the dispersive solvent, proportion of aqueous/organic phase, pH and flow rates have been carefully evaluated. Caffeine quantification was linear from 2 to 75mgL(-1), with detection and quantification limits of 0.46mgL(-1) and 1.54mgL(-1), respectively. A coefficient of variation (n=8; 5mgL(-1)) of a 2.1% and a sampling rate of 16h(-1), were obtained. The procedure was satisfactorily applied to the determination of caffeine in brewed, instant and decaf coffee samples, being the results for the sample analysis validated using high-performance liquid chromatography. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design.

    Science.gov (United States)

    Razmi, Rasoul; Shahpari, Behrouz; Pourbasheer, Eslam; Boustanifar, Mohammad Hasan; Azari, Zhila; Ebadi, Amin

    2016-11-01

    A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

    Science.gov (United States)

    Asghari, Alireza; Fahimi, Ebrahim; Bazregar, Mohammad; Rajabi, Maryam; Boutorabi, Leila

    2017-05-01

    Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100μL of CCl 4 (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL -1 for the three psychotropic drugs with the correlation of determinations (R 2 s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL -1 and 1.0-1.5ngmL -1 , respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Determination of organochlorine pesticides in water using dynamic hook-type liquid-phase microextraction

    International Nuclear Information System (INIS)

    Chen, Pai-Shan; Huang, Shih-Pin; Fuh, Ming-Ren; Huang, Shang-Da

    2009-01-01

    We developed a simple and efficient headspace liquid-phase microextraction (LPME) technique named dynamic hook-type liquid-phase microextraction (DHT-LPME) and used it in combination with gas chromatography-mass spectrometry (GC-MS) and an electron capture detector (ECD). Aqueous specimens of organochlorine pesticides (OCPs) were used as model compounds to demonstrate the effectiveness of the technique. In the present study, the calibration curves were linear over at least 2 orders of magnitude with R 2 values of 0.997. The method detection limits (MDLs) varied from 2 to 44.0 ng L -1 . The precision of DHT-LPME ranged from 6.5 to 14.4%. The relative recoveries of OCPs in rainwater were more than 84.2%. Enrichment factors (EF) in the range 275-1127 were obtained using DHT-LPME.

  18. Determination of organochlorine pesticides in water using dynamic hook-type liquid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pai-Shan; Huang, Shih-Pin [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Fuh, Ming-Ren, E-mail: msfuh@mail.scu.edu.tw [Department of Chemistry, Soochow University, Taipei, Taiwan (China); Huang, Shang-Da, E-mail: sdhuang@mx.nthu.edu.tw [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2009-08-11

    We developed a simple and efficient headspace liquid-phase microextraction (LPME) technique named dynamic hook-type liquid-phase microextraction (DHT-LPME) and used it in combination with gas chromatography-mass spectrometry (GC-MS) and an electron capture detector (ECD). Aqueous specimens of organochlorine pesticides (OCPs) were used as model compounds to demonstrate the effectiveness of the technique. In the present study, the calibration curves were linear over at least 2 orders of magnitude with R{sup 2} values of 0.997. The method detection limits (MDLs) varied from 2 to 44.0 ng L{sup -1}. The precision of DHT-LPME ranged from 6.5 to 14.4%. The relative recoveries of OCPs in rainwater were more than 84.2%. Enrichment factors (EF) in the range 275-1127 were obtained using DHT-LPME.

  19. Liquid-phase microextraction approaches combined with atomic detection: A critical review

    International Nuclear Information System (INIS)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2010-01-01

    Liquid-phase microextraction (LPME) displays unique characteristics such as excellent preconcentration capability, simplicity, low cost, sample cleanup and integration of steps. Even though LPME approaches have the potential to be combined with almost every analytical technique, their use in combination with atomic detection techniques has not been exploited until recently. A comprehensive review dealing with the applications of liquid-phase microextraction combined with atomic detection techniques is presented. Theoretical features, possible strategies for these combinations as well as the effect of key experimental parameters influencing method development are addressed. Finally, a critical comparison of the different LPME approaches in terms of enrichment factors achieved, extraction efficiency, precision, selectivity and simplicity of operation is provided.

  20. Analysis of aromatic amines in water samples by liquid-liquid-liquid microextraction with hollow fibers and high-performance liquid chromatography.

    Science.gov (United States)

    Zhao, Limian; Zhu, Lingyan; Lee, Hian Kee

    2002-07-19

    Liquid-liquid-liquid microextraction (LLLME) with hollow fibers in high-performance liquid chromatography (HPLC) has been applied as a rapid and sensitive quantitative method for the detection of four aromatic amines (3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline) in environmental water samples. The preconcentration procedure was induced by the pH difference inside and outside the hollow fiber. The target compounds were extracted from 4-ml aqueous sample (donor solution, pH approximately 13) through a microfilm of organic solvent (di-n-hexyl ether), immobilized in the pores of a hollow fiber (1.5 cm length x 0.6 mm I.D.), and finally into 4 microl of acid acceptor solution inside the fiber. After a prescribed period of time, the acceptor solution inside the fiber was withdrawn into the microsyringe and directly injected into the HPLC system for analysis. Factors relevant to the extraction procedure were studied. Up to 500-fold enrichment of analytes could be obtained under the optimized conditions (donor solution: 0.1 M sodium hydroxide solution with 20% sodium chloride and 2% acetone; organic phase: di-n-hexyl ether; acceptor solution: 0.5 M hydrochloric acid and 500 mM 18-crown-6 ether; extraction time of 30 min; stirring at 1,000 rev./min). The procedure also served as a sample clean-up step. The influence of humic acid on the extraction efficiency was also investigated, and more than 85% relative recoveries of the analytes at two different concentrations (20 and 100 microg/l) were achieved at various concentration of humic acid. This technique is a low cost, simple and fast approach to the analysis of polar compounds in aqueous samples.

  1. Determination of ten pyrethroids in various fruit juices: comparison of dispersive liquid-liquid microextraction sample preparation and QuEChERS method combined with dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Zhang, Yaohai; Zhang, Xuelian; Jiao, Bining

    2014-09-15

    Dispersive liquid-liquid microextraction (DLLME) sample preparation and the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with DLLME were developed and compared for the analysis of ten pyrethroids in various fruit juices using gas chromatography-electron capture detection (GC-ECD). QuEChERS-DLLME method has found its widespread applications to all the fruit juices including those samples with more complex matrices (orange, lemon, kiwi and mango) while DLLME was confined to the fruit juices with simpler matrices (apple, pear, grape and peach). The two methods provided acceptable recoveries and repeatability. In addition, the applicabilities of two methods were demonstrated with the real samples and further confirmed by gas chromatography-mass spectrometry (GC-MS). Copyright © 2014. Published by Elsevier Ltd.

  2. Liquid-phase microextraction for simultaneous chromatographic analysis of three antidepressant drugs in plasma

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Dobrovolskni Porto

    2012-01-01

    Full Text Available A method using Liquid Phase Microextraction for simultaneous detection of citalopram (CIT, paroxetine (PAR and fluoxetine (FLU, using venlafaxine as internal standard, in plasma by high performance liquid chromatography with fluorescence detection was developed. The linearity was evaluated between 5.0 and 500 ng mL-1 (r > 0.99 and the limit of quantification was 2.0, 3.0 and 5.0 ng mL-1 for CIT, PAR and FLU, respectively. Therefore, it can be applied to therapeutic drug monitoring, pharmacokinetics or bioavailability studies and its advantages are that it necessary relatively inexpensive equipment and sample preparation techniques.

  3. Binary Solvents Dispersive Liquid-Liquid Microextraction (BS-DLLME) Method for Determination of Tramadol in Urine Using High-Performance Liquid Chromatography.

    Science.gov (United States)

    Kiarostami, Vahid; Rouini, Mohamad-Reza; Mohammadian, Razieh; Lavasani, Hoda; Ghazaghi, Mehri

    2014-02-03

    Tramadol is an opioid, synthetic analog of codeine and has been used for the treatment of acute or chronic pain may be abused. In this work, a developed Dispersive liquid liquid microextraction (DLLME) as binary solvents-based dispersive liquid-liquid microextraction (BS-DLLME) combined with high performance liquid chromatography (HPLC) with fluorescence detection (FD) was employed for determination of tramadol in the urine samples. This procedure involves the use of an appropriate mixture of binary extraction solvents (70 μL CHCl3 and 30 μL ethyl acetate) and disperser solvent (600 μL acetone) for the formation of cloudy solution in 5 ml urine sample comprising tramadol and NaCl (7.5%, w/v). After centrifuging, the small droplets of extraction solvents were precipitated. In the final step, the HPLC with fluorescence detection was used for determination of tramadol in the precipitated phase. Various factors on the efficiency of the proposed procedure were investigated and optimized. The detection limit (S/N = 3) and quantification limit (S/N = 10) were found 0.2 and 0.9 μg/L, respectively. The relative standard deviations (RSD) for the extraction of 30 μg L of tramadol was found 4.1% (n = 6). The relative recoveries of tramadol from urine samples at spiking levels of 10, 30 and 60 μg/L were in the range of 95.6 - 99.6%. Compared with other methods, this method provides good figures of merit such as good repeatability, high extraction efficiency, short analysis time, simple procedure and can be used as microextraction technique for routine analysis in clinical laboratories.

  4. Rapid determination of some beta-blockers in complicated matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

    Science.gov (United States)

    Hemmati, Maryam; Asghari, Alireza; Bazregar, Mohammad; Rajabi, Maryam

    2016-11-01

    In this research work, an efficient tandem dispersive liquid-liquid microextraction (TDLLME) procedure coupled with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was successfully applied for the determination of beta-blockers in human plasma and pharmaceutical wastewater samples. High clean-up and preconcentration factor are easily and rapidly feasible via this novel, cheap, and safe microextraction method, leading to high quality experimental data. It consists of two sequential dispersive liquid-liquid microextraction methods, accomplished via air/ultrasonic agitation and air agitation, respectively. In order to enrich the optimal values for the mentioned procedures, the Box-Behnken design (BBD) combined with the desirability function (DF) was used. The optimum values were found to be 11.0 % (w/v) of the salt amount, an initial pH value of 12.0, 103 μL of organic extractant phase, and 45 μL of aqueous extractant phase with pH value of 2.0, resulted in reasonable recovery percentages with a logical desirability. Under optimal experimental conditions, good linear ranges (3-2000 ng mL -1 for metoprolol and 2.5-2500 ng mL -1 for propranolol with the correlation of determinations (R 2 s) higher than 0.99) and low limits of detection (0.8 and 1.0 ng mL -1 for propranolol and metoprolol, respectively) were obtainable. Also, TDLLME-HPLC-UV provided good proper repeatabilities (relative standard deviations (RSDs) below 5.7 %, n = 3) and high enrichment factors (EFs) of 75-100. Graphical abstract TDLLME of beta-blockers from complicated matrices.

  5. The recent developments in dispersive liquid–liquid microextraction for preconcentration and determination of inorganic analytes

    Directory of Open Access Journals (Sweden)

    H.M. Al-Saidi

    2014-12-01

    Full Text Available Recently, increasing interest on the use of dispersive liquid–liquid microextraction (DLLME developed in 2006 by Rezaee has been found in the field of separation science. DLLME is miniaturized format of liquid–liquid extraction in which acceptor-to-donor phase ratio is greatly reduced compared with other methods. In the present review, the combination of DLLME with different analytical techniques such as atomic absorption spectrometry (AAS, inductively coupled plasma-optical emission spectrometry (ICP-OES, gas chromatography (GC, and high-performance liquid chromatography (HPLC for preconcentration and determination of inorganic analytes in different types of samples will be discussed. Recent developments in DLLME, e.g., displacement-DLLME, the use of an auxiliary solvent for adjustment of density of extraction mixture, and the application of ionic liquid-based DLLME in determination of inorganic species even in the presence of high content of salts are presented in the present review. Finally, comparison of DLLME with the other liquid-phase microextraction approaches and limitations of this technique are provided.

  6. Modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction followed by atomic absorption spectrometry for trace determination of zinc in water and food samples

    International Nuclear Information System (INIS)

    Zeeb, M.; Sadeghi, M.

    2011-01-01

    We report on a new method for the microextraction and determination of zinc (II). The ion is accumulated via ionic-liquid cold-induced aggregation dispersive liquid-liquid microextraction (IL-CIA-DLLME) followed by flame atomic absorption spectrometry (FAAS). The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate is dispersed into a heated sample solution containing sodium hexafluorophosphate as a common ion source. The solution is then placed in an ice-water bath upon which a cloudy solution forms due to the decrease of the solubility of the IL. Zinc is complexed with 8-hydroxyquinoline and extracted into the IL. The enriched phase is dissolved in a diluting agent and introduced to the FAAS. The method is not influenced by variations in the ionic strength of the sample solution. Factors affecting the performance were evaluated and optimized. At optimum conditions, the limit of detection is 0.18 μg L -1 , and the relative standard deviation is 3.0% (at n=5). The method was validated by recovery experiments and by analyzing a certified reference material and successfully applied to the determination of Zn (II) in water and food samples. (author)

  7. Quantitation of tetrabromobisphenol-A from dust sampled on consumer electronics by dispersed liquid-liquid microextraction

    International Nuclear Information System (INIS)

    Di Napoli-Davis, Gina; Owens, Janel E.

    2013-01-01

    Tetrabromobisphenol-A (TBBPA) is a brominated flame retardant used worldwide. Despite its widespread use, there are few data concerning environmental concentrations of TBBPA. Thus, the objective of this work was to optimize an ultrasound-assisted dispersed liquid-liquid microextraction (DLLME) method to analyze swabbed surfaces of consumer electronics to determine TBBPA concentrations. Upon sample preparation with DLLME, TBBPA was derivatized with acetic anhydride and then analyzed by gas chromatography–mass spectrometry (GC/MS). Using a 13 C 12 -TBBPA internal standard to improve precision and quantitation, a recovery study was performed. At concentrations of 250–1000 ng/mL, recoveries were 104–106%. Sample preparation with solid phase extraction had comparable recoveries, although overall, improved analyte recovery and precision were achieved with DLLME. In a small survey study, TBBPA concentrations in dust collected from 100 cm 2 areas on electronic surfaces (monitor, microwave, refrigerator, and TV) were determined to range from less than the LOQ to 523 ng/mL. -- Highlights: •Tetrabromobisphenol-A (TBBPA) concentrations in dust samples were determined. •Dust samples were collected from surfaces of consumer electronics. •Dispersed liquid-liquid microextraction was used to prepare samples for GC/MS. •A 13 C 12 -labeled internal standard was used to improve precision and quantitation. •TBBPA was found in dust samples at levels below LOQ to 523 ng/mL. -- This work describes the analysis of the brominated flame retardant, tetrabromobisphenol-A (TBBPA), from dust sampled on surfaces of consumer electronics

  8. Microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid for the determination of sulfonamides in environmental water samples.

    Science.gov (United States)

    Song, Ying; Wu, Lijie; Lu, Chunmei; Li, Na; Hu, Mingzhu; Wang, Ziming

    2014-12-01

    An easy, quick, and green method, microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1-Ethy-3-methylimidazolium hexafluorophosphate, which is a solid-state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid-state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00-400.00 μg/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 μg/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Low Density Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Synthetic Antioxidants in Beverages by High-Performance Liquid Chromatography

    Science.gov (United States)

    Çabuk, Hasan; Köktürk, Mustafa

    2013-01-01

    A simple and efficient method was established for the determination of synthetic antioxidants in beverages by using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection. Butylated hydroxy toluene, butylated hydroxy anisole, and tert-butylhydroquinone were the antioxidants evaluated. Experimental parameters including extraction solvent, dispersive solvent, pH of sample solution, salt concentration, and extraction time were optimized. Under optimal conditions, the extraction recoveries ranged from 53 to 96%. Good linearity was observed by the square of correlation coefficients ranging from 0.9975 to 0.9997. The relative standard deviations ranged from 1.0 to 5.2% for all of the analytes. Limits of detection ranged from 0.85 to 2.73 ng mL−1. The method was successfully applied for determination of synthetic antioxidants in undiluted beverage samples with satisfactory recoveries. PMID:23853535

  10. Low Density Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Synthetic Antioxidants in Beverages by High-Performance Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Hasan Çabuk

    2013-01-01

    Full Text Available A simple and efficient method was established for the determination of synthetic antioxidants in beverages by using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection. Butylated hydroxy toluene, butylated hydroxy anisole, and tert-butylhydroquinone were the antioxidants evaluated. Experimental parameters including extraction solvent, dispersive solvent, pH of sample solution, salt concentration, and extraction time were optimized. Under optimal conditions, the extraction recoveries ranged from 53 to 96%. Good linearity was observed by the square of correlation coefficients ranging from 0.9975 to 0.9997. The relative standard deviations ranged from 1.0 to 5.2% for all of the analytes. Limits of detection ranged from 0.85 to 2.73 ng mL−1. The method was successfully applied for determination of synthetic antioxidants in undiluted beverage samples with satisfactory recoveries.

  11. Salting-out homogenous extraction followed by ionic liquid/ionic liquid liquid-liquid micro-extraction for determination of sulfonamides in blood by high performance liquid chromatography.

    Science.gov (United States)

    Liu, Zhongling; Yu, Wei; Zhang, Hanqi; Gu, Fanbin; Jin, Xiangqun

    2016-12-01

    Salting-out homogenous extraction followed by ionic liquid/ionic liquid dispersive liquid-liquid micro-extraction system was developed and applied to the extraction of sulfonamides in blood. High-performance liquid chromatography was applied to the determination of the analytes. The blood sample was centrifuged to obtain the serum. After the proteins in the serum were removed in the presence of acetonitrile, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, dipotassium hydrogen phosphate, ionic liquid 1-Hexyl-3-methylimidazolium hexafluorophosphate were added into the resulting solution. After the resulting mixture was ultrasonically shaken and centrifuged, the precipitate was separated. The acetonitrile was added in the precipitate and the analytes were extracted into the acetonitrile phase. The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of dipotassium hydrogen phosphate, volume of dispersant, extraction time and temperature were investigated. The limits of detection of sulfamethizole (STZ), sulfachlorpyridazine (SCP), sulfamethoxazole (SMX) and Sulfisoxazole (SSZ) were 4.78, 3.99, 5.21 and 3.77μgL -1 , respectively. When the present method was applied to the analysis of real blood samples, the recoveries of analytes ranged from 90.0% to 113.0% and relative standard deviations were lower than 7.2%. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. An evaporation-assisted dispersive liquid-liquid microextraction technique as a simple tool for high performance liquid chromatography tandem-mass spectrometry determination of insecticides in wine.

    Science.gov (United States)

    Timofeeva, Irina; Kanashina, Daria; Moskvin, Leonid; Bulatov, Andrey

    2017-08-25

    A sample pre-treatment technique based on evaporation-assisted dispersive liquid-liquid microextraction (EVA-DLLME), followed by HPLC-MS/MS has been developed for the determination of organophosphate insecticides (malathion, diazinon, phosalone) in wine samples. The procedure includes the addition of mixture of organic solvents (with density higher than water), consisting of the extraction (low density) and volatile (high density) solvents, to aqueous sample followed by heating of the mixture obtained, what promotes the volatile solvent evaporation and moving extraction solvent droplets from down to top of the aqueous sample and, as a consequence, microextraction of target analytes. To initiate the evaporation process an initiator is required. It was established that hexanol (extraction solvent) and dichloromethane (volatile solvent) mixture (1:1, v/v) provides effective microextraction of the insecticides from wine samples with recovery from 92 to 103%. The conditions of insecticides' microextraction such as selection of extraction solvent, ratio of hexanol/dichloromethane and hexanol/sample, type and concentration of initiator, and effect of ethanol as one of the main components of wine have been studied. Under optimal experimental conditions the linear detection ranges were found to be 10 -7 -10 -3 gL -1 for malathion, 10 -9 -10 -4 gL -1 for diazinon, and 10 -6 -10 -2 gL -1 for phosalone. The LODs, calculated from a blank test, based on 3σ, found to be 3×10 -8 gL -1 for malathion, 3×10 -10 gL -1 for diazinon and 3×10 -7 gL -1 for phosalone. The advantages of EVA-DLLME are the rapidity, simplicity, high sample throughput and low cost. As an outcome, the analytical results agreed fairly well with the results obtained by a reference GC-MS method. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid-phase microextraction coupled with ultra-high performance liquid chromatography and ultraviolet detection.

    Science.gov (United States)

    Jiang, Yuehuang; Tang, Tingting; Cao, Zhen; Shi, Guoyue; Zhou, Tianshu

    2015-06-01

    A hydroxyl-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid-phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H-bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0-1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0-1000 μg/L for estriol. The detection limits were in the range of 1.7-3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Development of an ionic-liquid-based dispersive liquid-liquid microextraction method for the determination of antichagasic drugs in human breast milk: Optimization by central composite design.

    Science.gov (United States)

    Padró, Juan M; Pellegrino Vidal, Rocío B; Echevarria, Romina N; Califano, Alicia N; Reta, Mario R

    2015-05-01

    Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which extent a neonate may be exposed to a drug during lactation. In this work, we developed an analytical technique to quantify benznidazole and nifurtimox (the two antichagasic drugs currently available for medical treatment) in human breast milk, with a simple sample pretreatment followed by an ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and UV detection. For this technique, the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate has been used as the "extraction solvent." A central composite design was used to find the optimum values for the significant variables affecting the extraction process: volume of ionic liquid, volume of dispersant solvent, ionic strength, and pH. At the optimum working conditions, the average recoveries were 77.5 and 89.7%, the limits of detection were 0.06 and 0.09 μg/mL and the interday reproducibilities were 6.25 and 5.77% for benznidazole and nifurtimox, respectively. The proposed methodology can be considered sensitive, simple, robust, accurate, and green. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma.

    Science.gov (United States)

    Xu, Xu; Su, Rui; Zhao, Xin; Liu, Zhuang; Zhang, Yupu; Li, Dan; Li, Xueyuan; Zhang, Hanqi; Wang, Ziming

    2011-11-30

    The ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0-110.8, 95.4-106.3, 95.0-108.3, and 95.7-107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n=5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination of SAs in liquid samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. A new chiral residue analysis method for triazole fungicides in water using dispersive liquid-liquid microextraction (DLLME).

    Science.gov (United States)

    Luo, Mai; Liu, Donghui; Zhou, Zhiqiang; Wang, Peng

    2013-09-01

    A rapid, simple, reliable, and environment-friendly method for the residue analysis of the enantiomers of four chiral fungicides including hexaconazole, triadimefon, tebuconazole, and penconazole in water samples was developed by dispersive liquid-liquid microextraction (DLLME) pretreatment followed by chiral high-performance liquid chromatography (HPLC)-DAD detection. The enantiomers were separated on a Chiralpak IC column by HPLC applying n-hexane or petroleum ether as mobile phase and ethanol or isopropanol as modifier. The influences of mobile phase composition and temperature on the resolution were investigated and most of the enantiomers could be completely separated in 20 min under optimized conditions. The thermodynamic parameters indicated that the separation was enthalpy-driven. The elution orders were detected by both circular dichroism detector (CD) and optical rotatory dispersion detector (ORD). Parameters affecting the DLLME performance for pretreatment of the chiral fungicides residue in water samples, such as the extraction and dispersive solvents and their volume, were studied and optimized. Under the optimum microextraction condition the enrichment factors were over 121 and the linearities were 30-1500 µg L(-1) with the correlation coefficients (R(2)) over 0.9988 and the recoveries were between 88.7% and 103.7% at the spiking levels of 0.5, 0.25, and 0.05 mg L(-1) (for each enantiomer) with relative standard deviations varying from 1.38% to 6.70% (n = 6) The limits of detection (LODs) ranged from 8.5 to 29.0 µg L(-1) (S/N = 3). © 2013 Wiley Periodicals, Inc.

  17. Sensitive determination of melamine in milk and powdered infant formula samples by high-performance liquid chromatography using dabsyl chloride derivatization followed by dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Faraji, M; Adeli, M

    2017-04-15

    A new and sensitive pre-column derivatization with dabsyl chloride followed by dispersive liquid-liquid microextraction was developed for the analysis of melamine (MEL) in raw milk and powdered infant formula samples by high performance liquid chromatography (HPLC) with visible detection. Derivatization with dabsyl chloride leads to improving sensitivity and hydrophobicity of MEL. Under optimum conditions of derivatization and microextraction steps, the method yielded a linear calibration curve ranging from 1.0 to 500μgL -1 with a determination coefficient (R 2 ) of 0.9995. Limit of detection and limit of quantification were 0.1 and 0.3μgL -1 , respectively. The relative standard deviation (RSD%) for intra-day (repeatability) and inter-day (reproducibility) at 25 and 100μgL -1 levels of MEL was less than 7.0% (n=6). Finally, the proposed method was successfully applied for the preconcentration and determination of MEL in different raw milk and powdered infant formula, and satisfactory results were obtained (relative recovery ⩾94%). Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review.

    Science.gov (United States)

    de la Calle, Inmaculada; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2016-09-14

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Speciation of chromium by dispersive liquid–liquid microextraction followed by laser-induced breakdown spectrometry detection (DLLME–LIBS)

    OpenAIRE

    Gaubeur, Ivanise; Aguirre Pastor, Miguel Ángel; Kovachev, Nikolay; Hidalgo Núñez, Montserrat; Canals Hernández, Antonio

    2015-01-01

    In this study, an analytical methodology based on a combination of dispersive liquid–liquid microextraction with laser-induced breakdown spectrometry was evaluated for simultaneous pre-concentration, speciation and detection of Cr. The microextraction procedure was based on the injection of appropriated quantities of 1-undecanol and ethanol into a sample solution containing the complexes formed between Cr(VI) and diethyldithiocarbamate (DDTC). The main experimental factors affecting the compl...

  20. Ionic Liquid Dispersive Liquid-Liquid Microextraction Method for the Determination of Irinotecan, an Anticancer Drug, in Water and Urine Samples Using UV-Vis Spectrophotometry.

    Science.gov (United States)

    Uysal, Deniz; Karadaş, Cennet; Kara, Derya

    2017-05-01

    A new, simple, efficient, and environmentally friendly ionic liquid dispersive liquid-liquid microextraction method was developed for the determination of irinotecan, an anticancer drug, in water and urine samples using UV-Vis spectrophotometry. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate was used as the extraction solvent, and ethanol was used as the disperser solvent. The main parameters affecting the extraction efficiency, including sample pH, volume of the ionic liquid, choice of the dispersive solvent and its volume, concentration of NaCl, and extraction and centrifugation times, were investigated and optimized. The effect of interfering species on the recovery of irinotecan was also examined. Under optimal conditions, the LOD (3σ) was 48.7 μg/L without any preconcentration. Because the urine sample was diluted 10-fold, the LOD for urine would be 487 μg/L. However, this could be improved 16-fold if preconcentration using a 40 mL aliquot of the sample is used. The proposed method was successfully applied to the determination of irinotecan in tap water, river water, and urine samples spiked with 10.20 mg/L for the water samples and 8.32 mg/L for the urine sample. The average recovery values of irinotecan determined were 99.1% for tap water, 109.4% for river water, and 96.1% for urine.

  1. Dispersive liquid-liquid microextraction for metals enrichment: a useful strategy for improving sensitivity of laser-induced breakdown spectroscopy in liquid samples analysis.

    Science.gov (United States)

    Aguirre, M A; Selva, E J; Hidalgo, M; Canals, A

    2015-01-01

    A rapid and efficient Dispersive Liquid-Liquid Microextraction (DLLME) followed by Laser-Induced Breakdown Spectroscopy detection (LIBS) was evaluated for simultaneous determination of Cr, Cu, Mn, Ni and Zn in water samples. Metals in the samples were extracted with tetrachloromethane as pyrrolidinedithiocarbamate (APDC) complexes, using vortex agitation to achieve dispersion of the extractant solvent. Several DLLME experimental factors affecting extraction efficiency were optimized with a multivariate approach. Under optimum DLLME conditions, DLLME-LIBS method was found to be of about 4.0-5.5 times more sensitive than LIBS, achieving limits of detection of about 3.7-5.6 times lower. To assess accuracy of the proposed DLLME-LIBS procedure, a certified reference material of estuarine water was analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry for a sensitive determination of cadmium in water samples

    International Nuclear Information System (INIS)

    Li Shengqing; Cai Shun; Hu Wei; Chen Hao; Liu Hanlan

    2009-01-01

    A new method was developed for the determination of cadmium in water samples using ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-based USA-DLLME) followed by electrothermal atomic absorption spectrometry (ETAAS). The IL-based USA-DLLME procedure is free of volatile organic solvents, and there is no need for a dispersive solvent, in contrast to conventional DLLME. The ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6 ), was quickly disrupted by an ultrasonic probe for 1 min and dispersed in water samples like a cloud. At this stage, a hydrophobic cadmium-DDTC complex was formed and extracted into the fine droplets of HMIMPF 6 . After centrifugation, the concentration of the enriched cadmium in the sedimented phase was determined by ETAAS. Some effective parameters of the complex formation and microextraction, such as the concentration of the chelating agent, the pH, the volume of the extraction solvent, the extraction time, and the salt effect, have been optimized. Under optimal conditions, a high extraction efficiency and selectivity were reached for the extraction of 1.0 ng of cadmium in 10.0 mL of water solution employing 73 μL of HMIMPF 6 as the extraction solvent. The enrichment factor of the method is 67. The detection limit was 7.4 ng L - 1 , and the characteristic mass (m 0 , 0.0044 absorbance) of the proposed method was 0.02 pg for cadmium (Cd). The relative standard deviation (RSD) for 11 replicates of 50 ng L - 1 Cd was 3.3%. The method was applied to the analysis of tap, well, river, and lake water samples and the Environmental Water Reference Material GSBZ 50009-88 (200921). The recoveries of spiked samples were in the range of 87.2-106%.

  3. Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

    2016-06-01

    An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop

    International Nuclear Information System (INIS)

    He Yi; Vargas, Angelica; Kang, Youn-Jung

    2007-01-01

    This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H 3 PO 4 drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 μg L -1 , repeatability of the extraction (R.S.D. -1 for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples

  5. Determination of antimony and tin in beverages using inductively coupled plasma-optical emission spectrometry after ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction.

    Science.gov (United States)

    Biata, N Raphael; Nyaba, Luthando; Ramontja, James; Mketo, Nomvano; Nomngongo, Philiswa N

    2017-12-15

    The aim of this study was to develop a simple and fast ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction (UA-IL-DLLME) method for preconcetration of trace antimony and tin in beverage samples. The novelty of this study was based on the application of ligandless UA-IL-DLLME using low-density ionic liquid and organic solvents for preconcentration of Sb and Sn. The concentration of Sb and Sn were quantified using ICP-OES. Under the optimum conditions, the calibration graph was found to be LOQ-250µgL -1 (r 2 =0.9987) for Sb and LOQ-350µgL -1 for Sn. The LOD and LOQ of Sb and Sn ranged from 1.2to 2.5ngL -1 and 4.0 to 8.3ngL -1 , respectively, with high preconcentration factors. The precisions (%RSD) of the proposed method ranged from 2.1% to 2.5% and 3.9% to 4.7% for Sb and Sn, respectively. The proposed method was successfully applied for determination of Sb and Sn in beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Determination of Bisphenol A and Bisphenol AF in Vinegar samples by two-component mixed ionic liquid dispersive liquid-phase microextraction coupled with high performance liquid chromatography

    International Nuclear Information System (INIS)

    Tai, Z.; Liu, M.; Hu, X.; Yang, Y.

    2014-01-01

    This paper describes a sensitive and simple method for the determination of bisphenol A (BPA) and bisphenol AF (BPAF) in vinegar samples using two-component mixed ionic liquid dispersive liquid-phase microextraction coupled with high performance liquid chromatography. In this work, BPA and BPAF were selected as the model analytes, and two-component mixed ionic liquid included 1-butyl-3-methylimidazolium hexafluorophosphate ((C4Mim)PF6) and 1-hexyl-3-methyl-imidazolium hexafluorophosphate ((C6Mim)PF6) was used as the extraction solvent for the first time here. Parameters that affect the extraction efficiency were investigated. Under the optimum conditions, good linear relationships were discovered in the range of 1.0-100 micro g/L for BPA and 2.0-150 micro g/L for BPAF, respectively. Detection limits of proposed method based on the signal-to-noise ratio (S/N=3) were in the range of 0.15-0.38 micro g/L. The efficiencies of proposed method have also been demonstrated with spiked real vinegar samples. The result show this method/ procedure to be a more efficient approach for the determination of BPA and BPAF in real vinegar, presenting average recovery rate of 89.3-112 % and precision values of 0.9-13.5% (RSDs, n = 6). In comparison with traditional solid phase extraction procedures this method results in lower solvent consumption, low pollution levels, and faster sample preparation. (author)

  7. Ionic Liquid-Assisted Liquid-Liquid Microextraction based on the Solidification of Floating Organic Droplet in Sample Preparation for Simultaneous Determination of Herbicide Residues in Fruits.

    Science.gov (United States)

    Vichapong, Jitlada; Santaladchaiyakit, Yanawath; Burakham, Rodjana; Srijaranai, Supalax

    2017-09-01

    An ionic liquid-assisted liquid-liquid microextraction based on the solidification of floating organic droplet (ILSFODLLME) was investigated for analysis of four herbicide residues (i.e. simazine, atrazine, propazine, and linuron) by high performance liquid chromatography. For ILSFOD-LLME, the optimal extraction conditions were 5% w/v Na2SO4, 30 μL [C4MIM][PF6]RTIL, 100 μL of 1-octanol, ultrasonication time 30 s and centrifugation at 5000 rpm for 5 min. Under the optimal conditions, linearity was obtained within the range of 0.1-1000 μg kg-1, with the correlation coefficients greater than 0.999. The high enrichment factors of the target analytes were in the range of 64.5-139.9 and low limit of detection could be obtained. A modified QuEChERS was applied for fruit sample preparation before analysis. Matrix effects were also investigated using matrix matched standards for construction of the calibration graph. The proposed method has been successfully applied for extraction and preconcentration of herbicide residues in fruit samples, and good recoveries in the range of 87.32% to 99.93% were obtained.

  8. Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometric for selenium speciation in foods and beverages.

    Science.gov (United States)

    Tuzen, Mustafa; Pekiner, Ozlem Zeynep

    2015-12-01

    A rapid and environmentally friendly ultrasound assisted ionic liquid dispersive liquid liquid microextraction (USA-IL-DLLME) was developed for the speciation of inorganic selenium in beverages and total selenium in food samples by using graphite furnace atomic absorption spectrometry. Some analytical parameters including pH, amount of complexing agent, extraction time, volume of ionic liquid, sample volume, etc. were optimized. Matrix effects were also investigated. Enhancement factor (EF) and limit of detection (LOD) for Se(IV) were found to be 150 and 12 ng L(-1), respectively. The relative standard deviation (RSD) was found 4.2%. The accuracy of the method was confirmed with analysis of LGC 6010 Hard drinking water and NIST SRM 1573a Tomato leaves standard reference materials. Optimized method was applied to ice tea, soda and mineral water for the speciation of Se(IV) and Se(VI) and some food samples including beer, cow's milk, red wine, mixed fruit juice, date, apple, orange, grapefruit, egg and honey for the determination of total selenium. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Combination of solvent extractants for dispersive liquid-liquid microextraction of fungicides from water and fruit samples by liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José

    2017-10-15

    A multiresidue method was developed to determine twenty-five fungicides belonging to three different chemical families, oxazoles, strobilurins and triazoles, in water and fruit samples, using dispersive liquid-liquid microextraction (DLLME) and liquid chromatography/tandem mass spectrometry (LC-MS 2 ). Solid-liquid extraction with acetonitrile was used for the analysis in fruits, the extract being used as dispersant solvent in DLLME. Since some of the analytes showed high affinity for chloroform and the others were more efficiently extracted with undecanol, a mixture of both solvents was used as extractant in DLLME. After evaporation of CHCl 3 , the enriched phase was analyzed. Enrichment factors in the 23-119 and 12-60 ranges were obtained for waters and fruits, respectively. The approach was most sensitive for metominostrobin with limits of quantification of 1ngL -1 and 5ngkg -1 in waters and fruits, respectively, while a similar sensitivity was attained for tebuconazole in fruits. Recoveries of the fungicides varied between 86 and 116%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xu; Su Rui; Zhao Xin; Liu Zhuang; Zhang Yupu; Li Dan; Li Xueyuan; Zhang Hanqi [College of Chemistry, Jilin University, Changchun 130012 (China); Wang Ziming, E-mail: analchem@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

    2011-11-30

    Graphical abstract: The extraction and derivatization efficiency of SAs is dependent on type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of derivatization reagent, pH of sample solution as well as ionic strength. Highlights: Black-Right-Pointing-Pointer A new, rapid and sensitive method for determining sulfonamides (SAs) was proposed. Black-Right-Pointing-Pointer Derivatization, extraction and preconcentration of SAs were performed in one step. Black-Right-Pointing-Pointer IL-based MADLLME and derivatization were first applied for the determination of SAs. Black-Right-Pointing-Pointer Trace SAs in river water, honey, milk, and pig plasma were determined. - Abstract: The ionic liquid-based microwave-assisted dispersive liquid-liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0-110.8, 95.4-106.3, 95.0-108.3, and 95.7-107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n = 5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination

  11. Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

    Science.gov (United States)

    2016-01-01

    Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 μL; dispersing solvent: isopropyl alcohol, 400 μL; no salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 μL of organic solvent. PMID:27830105

  12. Feasibility of corona discharge ion mobility spectrometry for direct analysis of samples extracted by dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Jafari, Mohammad T; Riahi, Farhad

    2014-05-23

    The capability of corona discharge ionization ion mobility spectrometry (CD-IMS) for direct analysis of the samples extracted by dispersive liquid-liquid microextraction (DLLME) was investigated and evaluated, for the first time. To that end, an appropriate new injection port was designed and constructed, resulting in possibility of direct injection of the known sample volume, without tedious sample preparation steps (e.g. derivatization, solvent evaporation, and re-solving in another solvent…). Malathion as a test compound was extracted from different matrices by a rapid and convenient DLLME method. The positive ion mobility spectra of the extracted malathion were obtained after direct injection of carbon tetrachloride or methanol solutions. The analyte responses were compared and the statistical results revealed the feasibility of direct analysis of the extracted samples in carbon tetrachloride, resulting in a convenient methodology. The coupled method of DLLME-CD-IMS was exhaustively validated in terms of sensitivity, dynamic range, recovery, and enrichment factor. Finally, various real samples of apple, river and underground water were analyzed, all verifying the feasibility and success of the proposed method for the easy extraction of the analyte using DLLME separation before the direct analysis by CD-IMS. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Hollow fiber liquid-phase microextraction of cadmium(II) using an ionic liquid as the extractant

    International Nuclear Information System (INIS)

    Chen, Hui; Wang, Yun; Hu, Yutao; Ni, Liang; Liu, Yingying; Kang, Wenbing; Liu, Yan; Han, Juan

    2014-01-01

    A method is presented for hollow fiber liquid-phase microextraction (HF-LPME) of cadmium(II), which is chelated with 1-(2-pyridylazo)-2-naphthol (PAN) to obtain a hydrophobic complex which then is extracted into a polypropylene hollow fiber containing an ionic liquid in its pores which acts as the membrane phase. EDTA is then injected into the lumen of the membrane as an acceptor phase to trap the analyte. The extraction time (20 min), agitation (400 rpm at 25 °C), pH value (10.0), and the concentrations of PAN (2.5 ng mL −1 ) and EDTA (250 ng mL −1 ) were optimized. With a sample volume of 50 mL and a stripping volume of 15 μL, the enrichment factor is 162. Cadmium(II) was then quantified by graphite furnace AAS. The limit of detection is 0.12 pg mL −1 , the relative standard deviation is 5.2 %, and the linear working range extends from 4 to 45 pg mL −1 . The method was successfully applied to the determination of Cd(II) in environmental and food samples. (author)

  14. Determination of thiobencarb in water samples by gas chromatography using a homogeneous liquid-liquid microextraction via flotation assistance procedure

    Directory of Open Access Journals (Sweden)

    H.A. Mashayekhi

    2013-09-01

    Full Text Available Homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA coupled with gas chromatography-flame ionization detection (GC-FID was applied for the extraction and determination of thiobencarb in water samples. In this study, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added into the extraction cell which contained an appropriate mixture of toluene (as an extraction solvent and acetone (as a homogeneous solvent. By using air flotation, the organic solvent was collected at the conical part of the designed cell. The effect of the different parameters on the efficiency of extraction such as type and volume of extraction and homogeneous solvents, ionic strength and extraction time were studied and optimized. Under the optimal conditions, linearity of the method was in the range of 1.0-200 µg L-1. The relative standard deviations in the real samples varied from 7.8-11.7 % (n = 3. The proposed method was successfully applied to analysis of thiobencarb in the water samples and satisfactory results were obtained.DOI: http://dx.doi.org/10.4314/bcse.v27i3.4

  15. Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Greyce Kelly Steinhorst Alcantara

    2016-01-01

    Full Text Available Levetiracetam (LEV is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 μL; dispersing solvent: isopropyl alcohol, 400 μL; no salt addition and no vortex agitation time, the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient’s plasma sample using less than 550 μL of organic solvent.

  16. Synthesis and application of magnetic deep eutectic solvents: Novel solvents for ultrasound assisted liquid-liquid microextraction of thiophene.

    Science.gov (United States)

    Khezeli, Tahere; Daneshfar, Ali

    2017-09-01

    Two novel magnetic deep eutectic solvents (MDESs), comprised of cheap and simple components named [choline chloride/phenol] [FeCl 4 ] and [choline chloride/ethylene glycol] [FeCl 4 ] were prepared and characterized by CHN elemental analysis, proton nuclear magnetic resonance ( 1 H NMR), vibrating sample magnetometery (VSM), Raman, Fourier transform-infrared (FT-IR) and UV-Vis spectrometery. The extraction efficiency of the prepared MDESs has been investigated in ultrasound assisted liquid-liquid microextraction based MDES (UALLME-MDES). Briefly, MDESs were added to n-heptan containing thiophene. Then, MDESs were dispersed in n-heptane by sonication. After that, microdroplets of MDESs were collected by a magnet and the remained concentration of thiophene in n-heptane phase was analyzed by GC-FID. The results indicated that [choline chloride/phenol] [FeCl 4 ] has higher extraction efficiency than [choline chloride/ethylene glycol] [FeCl 4 ]. This work opens a new way to the application of MDESs. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Determination of lead in environmental waters with dispersive liquid-liquid microextraction prior to atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    Zhou, Qingxiang; Zhao, Na; Xie, Guohong

    2011-01-01

    This paper established a new, rapid and sensitive method for the determination of lead in water samples preconcentrated by dispersive liquid-liquid microextraction (DLLME) prior to atomic fluorescence spectrometry. Dithizone was used as the chelating agent. In the DLLME procedure, lead formed lead-dithizone complex and migrated into the carbon tetrachloride micro-droplets. Important factors that would affect the extraction efficiency had been investigated including the kind and volume of extraction solvent and dispersive solvent, sample pH, the amount of chelating agent, extraction time and centrifugation time. The results showed that the coexisting ions containing in water samples had no obvious negative effect on the determination of lead. The experimental results indicated that the proposed method had a good linear range of 0.01-100 ng mL -1 (r 2 = 0.9990). The precision was 2.12% (RSD, n = 7) and the detection limit was 0.95 ng L -1 . Proposed method was validated with four real environmental samples and the results indicated that the proposed method was excellent for the future use and satisfied spiked recoveries were in the range of 92.9-97.4%.

  18. Surfactant-enhanced liquid-liquid microextraction coupled to micro-solid phase extraction onto highly hydrophobic magnetic nanoparticles

    International Nuclear Information System (INIS)

    Giannoulis, Kiriakos M.; Giokas, Dimosthenis L.; Tsogas, George Z.; Vlessidis, Athanasios G.; Zhu, Qing; Pan, Qinmin

    2013-01-01

    We are presenting a simplified alternative method for dispersive liquid-liquid microextraction (DLLME) by resorting to the use of surfactants as emulsifiers and micro solid-phase extraction (μ-SPE). In this combined procedure, DLLME of hydrophobic components is initially accomplished in a mixed micellar/microemulsion extractant phase that is prepared by rapidly mixing a non-ionic surfactant and 1-octanol in aqueous medium. Then, and in contrast to classic DLLME, the extractant phase is collected by highly hydrophobic polysiloxane-coated core-shell Fe 2 O 3 (at)C magnetic nanoparticles. Hence, the sample components are the target analyte in the DLLME which, in turn, becomes the target analyte of the μ-SPE step. This 2-step approach represents a new and simple DLLME procedure that lacks tedious steps such as centrifugation, thawing, or delicate collection of the extractant phase. As a result, the analytical process is accelerated and the volume of the collected phase does not depend on the volume of the extraction solvent. The method was applied to extract cadmium in the form of its pyrrolidine dithiocarbamate chelate from spiked water samples prior to its determination by FAAS. Detection limits were brought down to the low μg L −1 levels by preconcentrating 10 mL samples with satisfactory recoveries (96.0–108.0 %). (author)

  19. Determination of chlorophenols in honey samples using in-situ ionic liquid-dispersive liquid-liquid microextraction as a pretreatment method followed by high-performance liquid chromatography.

    Science.gov (United States)

    Fan, Chen; Li, Nai; Cao, Xueli

    2015-05-01

    In-situ ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40 μL of 0.14 M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8-3.2 μg/L and high enrichment factor, 34-65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. Determination of benzimidazoles in meat samples by capillary zone electrophoresis tandem mass spectrometry following dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Tejada-Casado, Carmen; Moreno-González, David; Lara, Francisco J; García-Campaña, Ana M; Del Olmo-Iruela, Monsalud

    2017-03-24

    A novel method based on capillary zone electrophoresis-tandem mass spectrometry has been proposed and validated for the identification and simultaneous quantification of twelve benzimidazoles in meat samples. Electrophoretic separation was carried out using 500mM formic acid (pH 2.2) as background electrolyte and applying a voltage of 25kV at 25°C. In order to improve the sensitivity, stacking mode injection was applied, using as injection solvent a mixture of 30:70 acetonitrile/water at 50mbar for 75s. Sensitivity enhancement factors from 74 to 317 were obtained under these conditions. Detection using an ion trap as analyzer, operating in multiple reactions monitoring mode was employed. The main MS/MS parameters as well as the composition of the sheath liquid and other electrospray variables were optimized in order to obtain the highest sensitivity and precision in conjunction with an unequivocal identification. The method was applied to poultry and pork muscle samples. The deproteinization of samples and extraction of benzimidazoles was carried out with acetonitrile. MgSO 4 and NaCl were added as salting-out agents. Subsequently, dispersive liquid-liquid microextraction was applied as clean up procedure. The organic layer (acetonitrile, used as dispersant) containing the benzimidazoles was mixed with the extractant (chloroform) and both were injected in water, producing a cloudy solution. Recoveries for fortified samples were higher than 70%, with relative standard deviations lower than 16% were obtained in all cases. The limits of detection were below 3μgkg -1 , demonstrating the applicability of this fast, simple, and environmentally friendly method. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Direct solid-phase microextraction combined with gas and liquid chromatography for the determination of lidocaine in human urine

    NARCIS (Netherlands)

    Koster, E.H M; Hofman, N.S K; de Jong, G.J.

    Solid-phase microextraction (SPME) has been combined with gas chromatography (GC) and liquid chromatography (LC) for the determination of lidocaine in human urine. A polydimethylsiloxane (PDMS) coated fibre was directly immersed into buffered urine. Extraction conditions such as time, pH, ionic

  2. A new dispersive liquid-liquid microextraction using ionic liquid based microemulsion coupled with cloud point extraction for determination of copper in serum and water samples.

    Science.gov (United States)

    Arain, Salma Aslam; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Mariam Shahzadi; Panhwar, Abdul Haleem; Khan, Naeemullah; Baig, Jameel Ahmed; Shah, Faheem

    2016-04-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on ionic liquid assisted microemulsion (IL-µE-DLLME) combined with cloud point extraction has been developed for preconcentration copper (Cu(2+)) in drinking water and serum samples of adolescent female hepatitits C (HCV) patients. In this method a ternary system was developed to form microemulsion (µE) by phase inversion method (PIM), using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and nonionic surfactant, TX-100 (as a stabilizer in aqueous media). The Ionic liquid microemulsion (IL-µE) was evaluated through visual assessment, optical light microscope and spectrophotometrically. The Cu(2+) in real water and aqueous acid digested serum samples were complexed with 8-hydroxyquinoline (oxine) and extracted into IL-µE medium. The phase separation of stable IL-µE was carried out by the micellar cloud point extraction approach. The influence of of different parameters such as pH, oxine concentration, centrifugation time and rate were investigated. At optimized experimental conditions, the limit of detection and enhancement factor were found to be 0.132 µg/L and 70 respectively, with relative standard deviation <5%. In order to validate the developed method, certified reference materials (SLRS-4 Riverine water) and human serum (Sero-M10181) were analyzed. The resulting data indicated a non-significant difference in obtained and certified values of Cu(2+). The developed procedure was successfully applied for the preconcentration and determination of trace levels of Cu(2+) in environmental and biological samples. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Combination of saponification and dispersive liquid-liquid microextraction for the determination of tocopherols and tocotrienols in cereals by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Shammugasamy, Balakrishnan; Ramakrishnan, Yogeshini; Ghazali, Hasanah M; Muhammad, Kharidah

    2013-07-26

    A simple sample preparation technique coupled with reversed-phase high-performance liquid chromatography was developed for the determination of tocopherols and tocotrienols in cereals. The sample preparation procedure involved a small-scale hydrolysis of 0.5g cereal sample by saponification, followed by the extraction and concentration of tocopherols and tocotrienols from saponified extract using dispersive liquid-liquid microextraction (DLLME). Parameters affecting the DLLME performance were optimized to achieve the highest extraction efficiency and the performance of the developed DLLME method was evaluated. Good linearity was observed over the range assayed (0.031-4.0μg/mL) with regression coefficients greater than 0.9989 for all tocopherols and tocotrienols. Limits of detection and enrichment factors ranged from 0.01 to 0.11μg/mL and 50 to 73, respectively. Intra- and inter-day precision were lower than 8.9% and the recoveries were around 85.5-116.6% for all tocopherols and tocotrienols. The developed DLLME method was successfully applied to cereals: rice, barley, oat, wheat, corn and millet. This new sample preparation approach represents an inexpensive, rapid, simple and precise sample cleanup and concentration method for the determination of tocopherols and tocotrienols in cereals. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Salt-assisted liquid-liquid microextraction of Cr(VI) ion using an ionic liquid for preconcentration prior to its determination by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Majidi, B.; Shemirani, F.

    2012-01-01

    We report on the salt-assisted liquid-liquid microextraction of cationic complexes of Cr(VI) ion using the hydrophilic ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoraborate and potassium hydrogen phosphate. This is a novel, simple, non-toxic and effective technique for sample pretreatment technique that displays large extraction efficiency and represents a new platform where Cr(VI) is complexed with 1,5-diphenylcarbazide (DPC) in sulfuric acid medium. It was applied to the extraction of Cr(VI) in the form of the Cr(VI)-DPC complex prior to its determination by flame atomic absorption spectrometry. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). Extraction is mainly affected by the amount of water-soluble IL, the kind and quantity of inorganic salts, by pH and the concentration of DPC. Calibration plots are linear in the range from 3 to 150 μg L -1 of Cr(VI), and the limit of detection is 1. 25 μg L -1 . The method was successfully applied to the speciation and determination of trace levels of Cr(III) and Cr(VI) in environmental water samples containing high levels of dissolved salts or food grade salts. (author)

  5. Determination of spirocyclic tetronic/tetramic acid derivatives and neonicotinoid insecticides in fruits and vegetables by liquid chromatography and mass spectrometry after dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José

    2016-07-01

    Dispersive liquid-liquid microextraction was used to preconcentrate three spirocyclic tetronic/tetramic acid derivatives (spirotetramat, spiromesifen and spirodiclofen) and five neonicotinoid (thiamethoxam, chlotianidin, imidacloprid, acetamiprid and thiacloprid) insecticides previously extracted from fruit and vegetable matrices with acetonitrile. The organic enriched phase was evaporated, reconstituted in 25μL acetonitrile and analyzed by reversed-phase liquid chromatography with tandem mass spectrometry using a triple quadrupole in selected reaction monitoring mode. Enrichment factors in the 15-100 range were obtained. A matrix effect was observed, the detection limits varying between 0.025 and 0.5ngg(-1), depending on the compound and the sample matrix. The developed method was applied to the analysis of 25 samples corresponding to five different fruit and vegetable matrices. Only thiamethoxam was detected in a lemon sample at a concentration close to the quantification limit, and spiromesifen and spirotetramat at concentrations between 11.6 and 54.5ngg(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Speciation of mercury in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jia Xiaoyu; Han Yi; Liu Xinli [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Duan Taicheng, E-mail: tcduan@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun 130022 (China); Chen Hangting, E-mail: htchen@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun 130022 (China)

    2011-01-15

    The dispersive liquid-liquid microextraction (DLLME) combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry for the speciation of mercury in water samples was described. Firstly methylmercury (MeHg{sup +}) and mercury (Hg{sup 2+}) were complexed with sodium diethyldithiocarbamate, and then the complexes were extracted into carbon tetrachloride by using DLLME. Under the optimized conditions, the enrichment factors of 138 and 350 for MeHg{sup +} and Hg{sup 2+} were obtained from only 5.00 mL sample solution. The detection limits of the analytes (as Hg) were 0.0076 ng mL{sup -1} for MeHg{sup +} and 0.0014 ng mL{sup -1} for Hg{sup 2+}, respectively. The relative standard deviations for ten replicate measurements of 0.5 ng mL{sup -1} MeHg{sup +} and Hg{sup 2+} were 6.9% and 4.4%, respectively. Standard reference material of seawater (GBW(E)080042) was analyzed to verify the accuracy of the method and the results were in good agreement with the certified values. Finally, the developed method was successfully applied for the speciation of mercury in three environmental water samples.

  7. Determination of carbohydrates in tobacco by pressurized liquid extraction combined with a novel ultrasound-assisted dispersive liquid-liquid microextraction method.

    Science.gov (United States)

    Cai, Kai; Hu, Deyu; Lei, Bo; Zhao, Huina; Pan, Wenjie; Song, Baoan

    2015-07-02

    A novel derivatization-ultrasonic assisted-dispersive liquid-liquid microextraction (UA-DLLME) method for the simultaneous determination of 11 main carbohydrates in tobacco has been developed. The combined method involves pressurized liquid extraction (PLE), derivatization, and UA-DLLME, followed by the analysis of the main carbohydrates with a gas chromatography-flame ionization detector (GC-FID). First, the PLE conditions were optimized using a univariate approach. Then, the derivatization methods were properly compared and optimized. The aldononitrile acetate method combined with the O-methoxyoxime-trimethylsilyl method was used for derivatization. Finally, the critical variables affecting the UA-DLLME extraction efficiency were searched using fractional factorial design (FFD) and further optimized using Doehlert design (DD) of the response surface methodology. The optimum conditions were found to be 44 μL for CHCl3, 2.3 mL for H2O, 11% w/v for NaCl, 5 min for the extraction time and 5 min for the centrifugation time. Under the optimized experimental conditions, the detection limit of the method (LODs) and linear correlation coefficient were found to be in the range of 0.06-0.90 μg mL(-1) and 0.9987-0.9999. The proposed method was successfully employed to analyze three flue-cured tobacco cultivars, among which the main carbohydrate concentrations were found to be very different. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Dispersive Liquid-Liquid Microextraction Combined with Ultrahigh Performance Liquid Chromatography/Tandem Mass Spectrometry for Determination of Organophosphate Esters in Aqueous Samples

    Directory of Open Access Journals (Sweden)

    Haiying Luo

    2014-01-01

    Full Text Available A new technique was established to identify eight organophosphate esters (OPEs in this work. It utilised dispersive liquid-liquid microextraction in combination with ultrahigh performance liquid chromatography/tandem mass spectrometry. The type and volume of extraction solvents, dispersion agent, and amount of NaCl were optimized. The target analytes were detected in the range of 1.0–200 µg/L with correlation coefficients ranging from 0.9982 to 0.9998, and the detection limits of the analytes were ranged from 0.02 to 0.07 µg/L (S/N=3. The feasibility of this method was demonstrated by identifying OPEs in aqueous samples that exhibited spiked recoveries, which ranged between 48.7% and 58.3% for triethyl phosphate (TEP as well as between 85.9% and 113% for the other OPEs. The precision was ranged from 3.2% to 9.3% (n=6, and the interprecision was ranged from 2.6% to 12.3% (n=5. Only 2 of the 12 selected samples were tested to be positive for OPEs, and the total concentrations of OPEs in them were 1.1 and 1.6 µg/L, respectively. This method was confirmed to be simple, fast, and accurate for identifying OPEs in aqueous samples.

  9. Determination of desipramine in biological samples using liquid-liquid-liquid microextraction combined with in-syringe derivatization, gas chromatography, and nitrogen/phosphorus detection.

    Science.gov (United States)

    Saraji, Mohammad; Mehrafza, Narges; Bidgoli, Ali Akbar Hajialiakbari; Jafari, Mohammad Taghi

    2012-10-01

    A method was established for the determination of desipramine in biological samples using liquid-liquid-liquid microextraction followed by in-syringe derivatization and gas chromatography-nitrogen phosphorus detection. The extraction method was based on the use of two immiscible organic solvents. n-Dodecane was impregnated in the pores of the hollow fiber and methanol was placed inside the lumen of the fiber as the acceptor phase. Acetic anhydride was used as the reagent for the derivatization of the analyte inside the syringe barrel. Parameters that affect the extraction efficiency (composition of donor and acceptor phase, ionic strength, sample temperature, and extraction time) as well as derivatization efficiency (amount of acetic anhydride and reaction time and temperature) were investigated. The limit of detection was 0.02 μg/L with intra and interday RSDs of 2.6 and 7.7%, respectively. The linearity of the method was in the range of 0.2-20 μg/L (r(2) = 0.9986). The method was successfully applied to determine desipramine in human plasma and urine. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Facile and sensitive determination of N-nitrosamines in food samples by high-performance liquid chromatography via combining fluorescent labeling with dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Lu, Shuaimin; Wu, Di; Li, Guoliang; Lv, Zhengxian; Gong, Peiwei; Xia, Lian; Sun, Zhiwei; Chen, Guang; Chen, Xuefeng; You, Jinmao; Wu, Yongning

    2017-11-01

    The intake of N-nitrosamines (NAs) from foodstuffs is considered to be an important influence factor for several cancers. But the rapid and sensitive screening of NAs remains a challenge in the field of food safety. Inspired by that, a sensitive and rapid method was demonstrated for determination of five NAs (Nitrosopyrrolidine, Nitrosodimethylamine, Nitrosodiethylamine, Nitrosodipropylamine and Nitrosodibutylamine) using dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The NAs were firstly denitrosated and labeled by 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and finally enriched by DLLME. Furthermore, the main DLLME conditions were optimized systematically. Under the optimal conditions, satisfactory limits of detection (LODs) were obtained with a range of 0.01-0.07ngg -1 , which were significantly lower than the reported methods. The developed method showed many merits including rapidity, simplicity, high sensitivity and excellent selectivity, which shows a broad prospect in food safety analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Speciation of mercury in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Jia Xiaoyu; Han Yi; Liu Xinli; Duan Taicheng; Chen Hangting

    2011-01-01

    The dispersive liquid-liquid microextraction (DLLME) combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry for the speciation of mercury in water samples was described. Firstly methylmercury (MeHg + ) and mercury (Hg 2+ ) were complexed with sodium diethyldithiocarbamate, and then the complexes were extracted into carbon tetrachloride by using DLLME. Under the optimized conditions, the enrichment factors of 138 and 350 for MeHg + and Hg 2+ were obtained from only 5.00 mL sample solution. The detection limits of the analytes (as Hg) were 0.0076 ng mL -1 for MeHg + and 0.0014 ng mL -1 for Hg 2+ , respectively. The relative standard deviations for ten replicate measurements of 0.5 ng mL -1 MeHg + and Hg 2+ were 6.9% and 4.4%, respectively. Standard reference material of seawater (GBW(E)080042) was analyzed to verify the accuracy of the method and the results were in good agreement with the certified values. Finally, the developed method was successfully applied for the speciation of mercury in three environmental water samples.

  12. Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples.

    Science.gov (United States)

    Liu, Yao-Min; Zhang, Feng-Ping; Jiao, Bao-Yu; Rao, Jin-Yu; Leng, Geng

    2017-04-14

    An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg + ), ethylmercury (EtHg + ) and inorganic mercury (Hg 2+ ) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10-1200ngL -1 for EtHg + and 5-450ngL -1 for MeHg + and Hg 2+ . Limits of detection were 3.0ngL -1 for EtHg + and 1.5ngL -1 for MeHg + and Hg 2+ . Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4-96.1%, and relative standard deviations <5.1%. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

    2014-10-01

    A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Vortex-assisted magnetic β-cyclodextrin/attapulgite-linked ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the fast determination of four fungicides in water samples.

    Science.gov (United States)

    Yang, Miyi; Xi, Xuefei; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2015-02-13

    A novel microextraction technique combining magnetic solid-phase microextraction (MSPME) with ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) to determine four fungicides is presented in this work for the first time. The main factors affecting the extraction efficiency were optimized by the one-factor-at-a-time approach and the impacts of these factors were studied by an orthogonal design. Without tedious clean-up procedure, analytes were extracted from the sample to the adsorbent and organic solvent and then desorbed in acetonitrile prior to chromatographic analysis. Under the optimum conditions, good linearity and high enrichment factors were obtained for all analytes, with correlation coefficients ranging from 0.9998 to 1.0000 and enrichment factors ranging 135 and 159 folds. The recoveries for proposed approach were between 98% and 115%, the limits of detection were between 0.02 and 0.04 μg L(-1) and the RSDs changed from 2.96 to 4.16. The method was successfully applied in the analysis of four fungicides (azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin) in environmental water samples. The recoveries for the real water samples ranged between 81% and 109%. The procedure proved to be a time-saving, environmentally friendly, and efficient analytical technique. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Liquid phase micro-extraction: Towards the green methodology for ultratrace metals determination in aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    López-López J. A.

    2013-04-01

    Full Text Available Heavy metals are normally found, in natural waters, in very low concentrations. Some of them are essential for life in low level; however, in higher level they are toxic. Therefore, analyzing their bio-available fraction is of main interest. Standard methodology is based in the collection of a number of samples from a water body. Collected samples must be stored, pre-treated and then analyzed. Pre-treatment usually involves pre-concentrating the metal, with the corresponding risk of contamination or loss of analyte. This way, punctual information is obtained from every sampling campaign. As an alternative, passive sampling techniques allow the continuous and coupled sampling-pre-treatment for heavy metals analysis, giving a better approach in the characterization of the studied water body. Liquid phase micro-extraction (LPME is a green analytical alternative for liquid-liquid extraction that promotes a reduction of sample volume, solvent needed and waste generation. Using these systems, polypropylene hollow fibers (HF with pores in their walls can be used. A few micro-liters of organic solvent are supported in the pores. The sample is placed in the outer part of the fiber and a receiving phase is placed in its inner part, allowing continuous liquid extraction of the metal from the sample. Several fibers with different physical features have been employed to analyzed total concentration and bio-availability of some heavy metals (Ag, Ni, Cu in natural water samples. Thanks to fibers configuration, devices for passive sampling based in HF-LPME could be designed. Advantages of this methodology over existing ones are supported because the receiving phase is liquid. As a consequence, retained metals do not need to be eluted from the acceptor prior to instrumental analysis.

  16. Ion-pair vortex assisted liquid-liquid microextraction with back extraction coupled with high performance liquid chromatography-UV for the determination of metformin in plasma.

    Science.gov (United States)

    Alshishani, Anas; Makahleh, Ahmad; Yap, Hui Fang; Gubartallah, Elbaleeq Adam; Salhimi, Salizawati Muhamad; Saad, Bahruddin

    2016-12-01

    A new sample preparation method, ion-pair vortex assisted liquid-liquid microextraction (VALLME-BE), for the determination of a highly polar anti-diabetic drug (metformin) in plasma sample was developed. The VALLME-BE was performed by diluting the plasma in borate buffer and extracted to 150µL 1-octanol containing 0.2M di-(2-ethylhexyl)phosphoric acid as intermediate phase. The drug was next back-extracted into 20µL of 0.075M HCl solution. The effects of pH, ion-pair concentration, type of organic solvent, volume of extraction phases, ionic strength, vortexing and centrifugation times on the extraction efficiency were investigated. The optimum conditions were at pH 9.3, 60s vortexing and 2min centrifugation. The microextract, contained metformin and buformin (internal standard), was directly injected into a HPLC unit using C1 column (250mm×4.6mm×10µm) and detected at 235nm. The method was validated and calibration curve was linear with r 2 >0.99 over the range of 20-2000µgL -1 . The limits of detection and quantitation were 1.4 and 4.1µgL -1 , respectively. The accuracy was within 94.8-108% of the nominal concentration. The relative standard deviation for inter- and intra-day precision was less than 10.8%. The method was conveniently applied for the determination of metformin in plasma samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection.

    Science.gov (United States)

    Chen, Chen-Wen; Hsu, Wen-Chan; Lu, Ya-Chen; Weng, Jing-Ru; Feng, Chia-Hsien

    2018-02-15

    Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r 2 =0.998, 0.1-10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Ionic liquid-based dispersive microextraction of nitro toluenes in water samples

    International Nuclear Information System (INIS)

    Berton, Paula; Regmi, Bishnu P.; Spivak, David A.; Warner, Isiah M.

    2014-01-01

    We describe a method for dispersive liquid-liquid microextraction of nitrotoluene-based compounds. This method is based on use of the room temperature ionic liquid (RTIL) 1-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide as the accepting phase, and is shown to work well for extraction of 4-nitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene. Separation and subsequent detection of analytes were accomplished via HPLC with UV detection. Several parameters that influence the efficiency of the extraction were optimized using experimental design. In this regard, a Plackett–Burman design was used for initial screening, followed by a central composite design to further optimize the influencing variables. For a 5-mL water sample, the optimized IL-DLLME procedure requires 26 mg of the RTIL as extraction solvent and 680 μL of methanol as the dispersant. Under optimum conditions, limits of detection (LODs) are lower than 1.05 μg L −1 . Relative standard deviations for 6 replicate determinations at a 4 μg L −1 analyte level are <4.3 % (calculated using peak areas). Correlation coefficients of >0.998 were achieved. This method was successfully applied to extraction and determination of nitrotoluene-based compounds in spiked tap and lake water samples. (author)

  19. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Calle, Inmaculada de la; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos, E-mail: bendicho@uvigo.es

    2016-09-14

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. - Highlights: • We review the LPME-GFAAS combination in a comprehensive way. • A brief description of main LPME modes is included. • Effect of experimental parameters in the performance of LPME-GFAAS is discussed. • Main applications for trace element analysis and speciation are reviewed.

  20. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review

    International Nuclear Information System (INIS)

    Calle, Inmaculada de la; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2016-01-01

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. - Highlights: • We review the LPME-GFAAS combination in a comprehensive way. • A brief description of main LPME modes is included. • Effect of experimental parameters in the performance of LPME-GFAAS is discussed. • Main applications for trace element analysis and speciation are reviewed.

  1. Hollow fiber-based liquid-liquid-liquid micro-extraction with osmosis: II. Application to quantification of endogenous gibberellins in rice plant.

    Science.gov (United States)

    Wu, Qian; Wu, Dapeng; Duan, Chunfeng; Shen, Zheng; Guan, Yafeng

    2012-11-23

    The phenomenon and benefits of osmosis in hollow fiber-based liquid-liquid-liquid micro-extraction (HF-LLLME) were theoretically discussed in part I of this study. In this work, HF-LLLME with osmosis was coupled with high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-triple quadrupole MS/MS) to analyze eight gibberellins (gibberellin A(1), gibberellin A(3), gibberellin A(4), gibberellin A(7), gibberellin A(8), gibberellin A(9), gibberellin A(19) and gibberellin A(20)) in rice plant samples. According to the theory of HF-LLLME with osmosis, single factor experiments, orthogonal design experiments and mass transfer simulation of extraction process were carried out to select the optimal conditions. Cyclohexanol - n-octanol (1:3, v/v) was selected as organic membrane. Donor phase of 12 mL was adjusted to pH 2 and 20% NaCl (w/v) was added. Acceptor phase with an initial volume of 20 μL was the solution of 0.12 mol L(-1) Na(2)CO(3)-NaHCO(3) buffer (pH 9). Temperature was chosen to be 30 °C and extraction time was selected to be 90 min. Under optimized conditions, this method provided good linearity (r, 0.99552-0.99991) and low limits of detection (0.0016-0.061 ng mL(-1)). Finally, this method was applied to the analysis of endogenous gibberellins from plant extract which was obtained with traditional solvent extraction of rice plant tissues, and the relative recoveries were from 62% to 166%. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

    Science.gov (United States)

    Sadeghi, Susan; Ashoori, Vahid

    2017-10-01

    The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  3. Application of dispersive liquid-liquid microextraction for the preconcentration of eight parabens in real samples and their determination by high-performance liquid chromatography.

    Science.gov (United States)

    Shen, Xiong; Liang, Jian; Zheng, Luxia; Lv, Qianzhou; Wang, Hong

    2017-11-01

    A simple and sensitive method for the simultaneous determination of eight parabens in human plasma and urine samples was developed. The samples were preconcentrated using dispersive liquid-liquid microextraction based on the solidification of floating organic drops and determined by high-performance liquid chromatography with ultraviolet detection. The influence of variables affecting the extraction efficiency was investigated and optimized using Placket-Burman design and Box-Behnken design. The optimized values were: 58 μL of 1-decanol (as extraction solvent), 0.65 mL methanol (as disperser solvent), 1.5% w/v NaCl in 5.0 mL of sample solution, pH 10.6, and 4.0 min centrifugation at 4000 rpm. The extract was injected into the high-performance liquid chromatography system for analysis. Under the optimum conditions, the linear ranges for eight parabens in plasma and urine were 1.0-1000 ng/mL, with correlation coefficients above 0.994. The limit of detection was 0.2-0.4 and 0.1-0.4 ng/mL for plasma and urine samples, respectively. Relative recoveries were between 80.3 and 110.7%, while relative standard deviations were less than 5.4%. Finally, the method was applied to analyze the parabens in 98 patients of primary breast cancer. Results showed that parabens existed widely, at least one paraben detected in 96.9% (95/98) of plasma samples and 98.0% (96/98) of urine samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. In-vial liquid-liquid microextraction-capillary electrophoresis method for the determination of phenolic acids in vegetable oils.

    Science.gov (United States)

    Abu Bakar, Nur Bahiyah; Makahleh, Ahmad; Saad, Bahruddin

    2012-09-12

    An in-vial liquid-liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20 g sample were: volume of diluent (n-hexane), 2 mL; extractant, methanol: 5 mM sodium hydroxide (60:40; v/v); volume of extractant, 300 μL (twice); vortex, 1 min; centrifugation, 5 min. Recoveries for the studied phenolic acids were 80.1-119.5%. The simultaneous determination of the phenolic acid extracts was investigated by capillary electrophoresis (CE). Separations were carried out on a bare fused-silica capillary (50 μm i.d.× 40 cm length) involving 25 mM sodium tetraborate (pH 9.15) and 5% methanol as CE background electrolyte in the normal polarity mode, voltage of 30 kV, temperature of 25°C, injection time of 4s (50 mbar) and electropherograms were recorded at 200 nm. The phenolic acids were successfully separated in less than 10 min. The validated in-vial LLME-CE method was applied to the determination of phenolic acids in vegetable oil samples (extra virgin olive oil, virgin olive oil, pure olive oil, walnut oil and grapeseed oil). The developed method shows significant advantages over the current methods as lengthy evaporation step is not required. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Selective determination of inorganic cobalt in nutritional supplements by ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction and electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Berton, Paula; Martinis, Estefanía M.; Martinez, Luis D.; Wuilloud, Rodolfo G.

    2012-01-01

    Highlights: ► Synergy of ultrasound energy and TILDLME technique for improved metal extraction. ► Highly selective determination of inorganic Co species at trace levels. ► Speciation analysis of Co in several nutritional supplements with highly complex matrices. ► Development of an environmentally friendly microextraction technique with minimal waste production and sample consumption. - Abstract: In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C 6 mim][PF 6 ] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L −1 , while the relative standard deviation (RSD) was 4.7% (at 0.5 μg L −1 Co level and n = 10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements.

  6. Selective determination of inorganic cobalt in nutritional supplements by ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction and electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Paula; Martinis, Estefania M. [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN-CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Martinez, Luis D. [INQUISAL-CONICET, Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, San Luis (Argentina); Wuilloud, Rodolfo G., E-mail: rwuilloud@mendoza-conicet.gob.ar [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN-CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer Synergy of ultrasound energy and TILDLME technique for improved metal extraction. Black-Right-Pointing-Pointer Highly selective determination of inorganic Co species at trace levels. Black-Right-Pointing-Pointer Speciation analysis of Co in several nutritional supplements with highly complex matrices. Black-Right-Pointing-Pointer Development of an environmentally friendly microextraction technique with minimal waste production and sample consumption. - Abstract: In the present work, a simple and rapid analytical method based on application of ionic liquids (ILs) for inorganic Co(II) species (iCo) microextraction in a variety of nutrient supplements was developed. Inorganic Co was initially chelated with 1-nitroso-2-naphtol (1N2N) reagent followed by a modern technique named ultrasound-assisted temperature-controlled ionic liquid dispersive liquid phase microextraction (USA-TILDLME). The extraction was performed with 1-hexyl-3-methylimidazolium hexafluorophosphate [C{sub 6}mim][PF{sub 6}] with the aid of ultrasound to improve iCo recovery. Finally, the iCo-enriched IL phase was solubilized in methanol and directly injected into an electrothermal atomic absorption spectrometer (ETAAS). Several parameters that could influence iCo microextraction and detection were carefully studied. Since the main difficulty in these samples is caused by high concentrations of potential interfering ions, different approaches were evaluated to eliminate interferences. The limit of detection (LOD) was 5.4 ng L{sup -1}, while the relative standard deviation (RSD) was 4.7% (at 0.5 {mu}g L{sup -1} Co level and n = 10), calculated from the peak height of absorbance signals. Selective microextraction of iCo species was achieved only by controlling the pH value during the procedure. The method was thus successfully applied for determination of iCo species in nutritional supplements.

  7. Dispersive liquid-liquid microextraction (DLLME combined with graphite furnace atomic absorption spectrometry (GFAAS for determination of trace Cu and Zn in water Samples

    Directory of Open Access Journals (Sweden)

    Ghorbani A.

    2014-07-01

    Full Text Available Dispersive liquid-liquid microextraction (DLLME combined with graphite furnace atomic absorption spectrometry (GFAAS was proposed for the determination of trace amounts of Copper and Zinc ions using 8-hydroxyquinoline (8-HQ as chelating agent. Several factors influencing the microextraction efficiency of Cu and Zn and their subsequent determinations, such as pH, extraction and disperser solvent type and their volume, concentration of the chelating agent and extraction time were studied, and the optimized experimental conditions were established. After extraction, the enrichment factors were 25 and 26 for Cu and Zn, respectively. The detection limits of the method were 0.025 and 0.0033 μg/L for Cu and Zn, and the relative standard deviations (R.S.D for five determinations of 1 ng/ml Cu and Zn were 8.51% and 7.41%, respectively.

  8. Extraction and Determination of Crocin in Saffron Samples by Dispersive Liquid-Liquid Microextraction

    Directory of Open Access Journals (Sweden)

    Somayeh Heydari

    2016-11-01

    Full Text Available The main component responsible for color in saffron is crocin with the chemical formula of C44H64O24. Crocin is one of several carotenoids in nature that is soluble in water. This solubility is one of the reasons for its widespread usage as a colorant in food and medicine compared to other carotenoids. The coloring strength of saffron is one of the major factors that determine the quality of the saffron stigma. It will be evaluated with measuring of crocin. Microextraction is the newest and easiest method that can be successfully applied for the preconcentration and separation of crocin in saffron samples. The advantages of this method are faster, cheaper and easier analysis by UV-Vis spectrophotometry in measurement of crocin compared to the chromatographic analysis methods. The studies showed that the type and volume of disperser and extractant solvent have a significant effect on the efficiency of crocin extraction. In this work, acetone as the disperser solvent and dichlorometane as the extractant solvent were found to be suitable combinations. Under the optimal conditions, the calibration curve was linear in the range of 0.15-0.00001 μg mL-1 and the limit of detection (LOD was calculated based on 3 Sb/m (where, Sb and m are the standard deviation of the blank and slop ratio of the calibration curve respectively was 0.000008 μg mL-1. The procedure was applied to saffron samples and the good recovery percent for the saffron samples was obtained.

  9. Centrifugeless dispersive liquid-liquid microextraction based on salting-out phenomenon followed by high performance liquid chromatography for determination of Sudan dyes in different species.

    Science.gov (United States)

    Bazregar, Mohammad; Rajabi, Maryam; Yamini, Yadollah; Arghavani-Beydokhti, Somayeh; Asghari, Alireza

    2018-04-01

    In this work, a novel method, namely centrifugeless dispersive liquid-liquid microextraction, is introduced for the efficient extraction of banned Sudan dyes from foodstuff and water samples. In this method, which is based upon the salting-out phenomenon, in order to accelerate the extraction process, the extraction solvent (1-undecanol, 75 μL) is dispersed into the sample solution. Then the mixture is passed through a small column filled with 5 g sodium chloride, used as a separating reagent. In this condition, fine droplets of the extraction solvent are floated on the mixture, and the phase separation is simply achieved. This method is environmentally friendly, simple, and very fast, so that the overall extraction time is only 7 min. Under the optimal experimental conditions, the preconcentration factors in the range of 90-121 were obtained for the analytes. Also good linearities were obtained in the range of 2.5-1200 ng mL -1 (r 2  ≥ 0.993). Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Maghemite nanoparticle-decorated hollow fiber electromembrane extraction combined with dispersive liquid-liquid microextraction for the determination of thymol from Carum copticum

    DEFF Research Database (Denmark)

    Khajeh, Mostafa; Pedersen-Bjergaard, Stig; Bohlooli, Mousa

    2017-01-01

    BACKGROUND A novel technique using maghemite nanoparticle-decorated hollow fibers to assist electromembrane extraction is proposed. Electromembrane extraction combined with dispersive liquid–liquid microextraction (EME-DLLME) was applied for the extraction of thymol from Carum copticum, followed...... by gas chromatography with flame ionization detection (GC-FID). RESULTS The use of maghemite nanoparticle-decorated hollow fibers was found to improve the extraction efficiency of thymol significantly. Important operational parameters, including pH of acceptor phase, extraction time, voltage...

  11. Guanidinium ionic liquid-based surfactants as low cytotoxic extractants: Analytical performance in an in-situ dispersive liquid-liquid microextraction method for determining personal care products.

    Science.gov (United States)

    Pacheco-Fernández, Idaira; Pino, Verónica; Ayala, Juan H; Afonso, Ana M

    2017-05-01

    The IL-based surfactant octylguanidinium chloride (C 8 Gu-Cl) was designed and synthetized with the purpose of obtaining a less harmful surfactant: containing guanidinium as core cation and a relatively short alkyl chain. Its interfacial and aggregation behavior was evaluated through conductivity and fluorescence measurements, presenting a critical micelle concentration value of 42.5 and 44.6mmolL -1 , respectively. Cytotoxicity studies were carried out with C 8 Gu-Cl and other IL-based and conventional surfactants, specifically the analogue 1-octyl-3-methylimidazolium chloride (C 8 MIm-Cl), and other imidazolium- (C 16 MIm-Br) and pyridinium- (C 16 Py-Cl) based surfactants, together with the conventional cationic CTAB and the conventional anionic SDS. From these studies, C 8 Gu-Cl was the only one to achieve the classification of low cytotoxicity. An in situ dispersive liquid-liquid microextraction (DLLME) method based on transforming the water-soluble C 8 Gu-Cl IL-based surfactant into a water-insoluble IL microdroplet via a simple metathesis reaction was then selected as the extraction/preconcentration method for a group of 6 personal care products (PCPs) present in cosmetic samples. The method was carried out in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The method was properly optimized, requiring the use of only 30μL of C 8 Gu-Cl for 10mL of aqueous sample with a NaCl content of 8% (w/v) to adjust the ionic strength and pH value of 5. The metathesis reaction required the addition of the anion exchange reagent (bis[(trifluoromethyl)sulfonyl]imide - 1:1 molar ratio), followed by vortex and centrifugation, and dilution of the final microdroplet up to 60μL with acetonitrile before the injection in the HPLC-DAD system. The optimum in situ DLLME-HPLC-DAD method takes ∼10min for the extraction step and ∼22min for the chromatographic separation, with analytical features of low detection limits: down to 0.4

  12. Matrix solid-phase dispersion coupled with homogeneous ionic liquid microextraction for the determination of sulfonamides in animal tissues using high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Zhibing; He, Mengyu; Jiang, Chunzhu; Zhang, Fengqing; Du, Shanshan; Feng, Wennan; Zhang, Hanqi

    2015-12-01

    Matrix solid-phase dispersion coupled with homogeneous ionic liquid microextraction was developed and applied to the extraction of some sulfonamides, including sulfamerazine, sulfamethazine, sulfathiazole, sulfachloropyridazine, sulfadoxine, sulfisoxazole, and sulfaphenazole, in animal tissues. High-performance liquid chromatography was applied to the separation and determination of the target analytes. The solid sample was directly treated by matrix solid-phase dispersion and the eluate obtained was treated by homogeneous ionic liquid microextraction. The ionic liquid was used as the extraction solvent in this method, which may result in the improvement of the recoveries of the target analytes. To avoid using organic solvent and reduce environmental pollution, water was used as the elution solvent of matrix solid-phase dispersion. The effects of the experimental parameters on recoveries, including the type and volume of ionic liquid, type of dispersant, ratio of sample to dispersant, pH value of elution solvent, volume of elution solvent, amount of salt in eluate, amount of ion-pairing agent (NH4 PF6 ), and centrifuging time, were evaluated. When the present method was applied to the analysis of animal tissues, the recoveries of the analytes ranged from 85.4 to 118.0%, and the relative standard deviations were lower than 9.30%. The detection limits for the analytes were 4.3-13.4 μg/kg. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Quantitative Analysis of Piroxicam Using Temperature-Controlled Ionic Liquid Dispersive Liquid Phase Microextraction Followed By Stopped-Flow Injection Spectrofluorimetry

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Ganjali

    2013-07-01

    Full Text Available Background:Piroxicam (PXM belongs to the wide class of non-steroidal anti-inflammatory drugs (NSAIDs. PXM has been widely applied in the treatment of rheumatoid arthritis, gonarthrosis, osteoarthritis, backaches, neuralgia, mialgia. In the presented work, a green and benign sample pretreatment method called temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME was followed with stopped-flow injection spectrofluorimetry (SFIS for quantitation of PXM in pharmaceutical formulations and biological samples.Methods:Temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME was applied as an environmentally friendly sample enrichment method to extract and isolate PXM prior to quantitation. Dispersion of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6] ionic liquid (IL through the sample aqueous solution was performed by applying a relatively high temperature. PXM was extracted into the extractor, and after phase separation, PXM in the final solution was determined by stopped-flow injection spectrofluorimetry (SFIS.Results and Major Conclusion:Different factors affecting the designed method such as IL amount, diluting agent, pH and temperature were investigated in details and optimized. The method provided a linear dynamic range of 0.2-150 μg l-1, a limit of detection (LOD of 0.046 μg l-1 and a relative standard deviation (RSD of 3.1%. Furthermore, in order to demonstrate the analytical applicability of the recommended method, it was applied for quantitation of PXM in real samples.

  14. Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection to determination of opium alkaloids in human plasma.

    Science.gov (United States)

    Ahmadi-Jouibari, Toraj; Fattahi, Nazir; Shamsipur, Mojtaba; Pirsaheb, Meghdad

    2013-11-01

    A novel, simple, rapid and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine opium alkaloids in human plasma. During the extraction procedure, plasma protein was precipitated by using a mixture of zinc sulfate solution and acetonitrile. Some effective parameters on extraction were studied and optimized. Under the optimum conditions (extraction solvent: 30.0 μl 1-undecanol; disperser solvent: 470 μl acetone; pH: 9; salt addition: 1%(w/v) NaCl and extraction time: 0.5 min), calibration curves are linear in the range of 1.5-1000 μgl(-1) and limit of detections (LODs) are in the range of 0.5-5 μgl(-1). The relative standard deviations (RSDs) for 100 μgl(-1) of morphine and codeine, 10.0 μgl(-1) of papaverine and 20.0 μgl(-1) of noscapine in diluted human plasma are in the range of 4.3-7.4% (n=5). Finally, the method was successfully applied in the determination of opium alkaloids in the actual human plasma samples. The relative recoveries of plasma samples spiked with alkaloids are 88-110.5%. The obtained results show that DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of opium alkaloids in human plasma. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. [Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization].

    Science.gov (United States)

    Wang, Xiaoyan; Qi, Weimei; Zhao, Xian'en; Lü, Tao; Wang, Xiya; Zheng, Longfang; Yan, Yehao; You, Jinmao

    2014-06-01

    To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 microL chloroform as extraction solvent, 400 microL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na2CO3-NaHCO3 buffer/acetonitrile at 50 degrees C for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc.

  16. Simultaneous determination of pyrethroids and pyrethrins by dispersive liquid-liquid microextraction and liquid chromatography triple quadrupole mass spectrometry in environmental samples.

    Science.gov (United States)

    Ccanccapa-Cartagena, Alexander; Masiá, Ana; Picó, Yolanda

    2017-08-01

    A simple and environmentally friendly dispersive liquid-liquid microextraction (DLLME) method coupled with electrospray ionization liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) was developed for the simultaneous determination of 17 synthetic and natural pyrethroids. A comparison of solid-phase extraction (SPE) versus DLLME for water samples and only "dilute and shoot" versus the additional extract cleanup by DLLME for sediment samples is reported. Chloroform was the extracting solvent in the DLLME technique for both water and sediment samples. Ultrasonic energy was applied to fully extract the analytes into fine droplets, providing high recoveries in short times. Method detection limits (MDLs) ranged from 0.12 to 0.62 ng L -1 and recoveries from 70 to 119% with RSD values 2-15% (n = 5) for water samples. In sediment samples, MDLs ranged from 0.50 to 2.50 ng g -1 and recoveries from 71 to 112% with RSDs 2-16% (n = 5). The proposed method showed a good linearity within the range of 10-500 ng mL -1 , with coefficients of determination (R 2 ) higher than 0.99. Matrix effects were observed for most compounds in water and sediment (ME% Albufera wetland and Turia River. Acrinathrin (48 ng g -1 ) and etofenprox (16 ng g -1 ) were detected in sediment samples. Graphical abstract Pyrethrins and pyrethroid determination in water and sediments by DLLME and LC-MS/MS.

  17. Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples

    Directory of Open Access Journals (Sweden)

    Jan Åke Jönsson

    2011-10-01

    Full Text Available Hollow fiber liquid phase micro-extraction (LPME of linear alkylbenzene sulfonates (LAS from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM. Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 µg L−1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ~15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sample volume. Secondly, the enrichment depended on LAS sample concentration with 35–150 times enrichment below ~150 µg L−1 and 1850–4400 times enrichment at 1 mg L−1. Thirdly, lower homologues were enriched more than higher homologues at low sample concentrations, with reversed conditions at higher concentrations. These observations may be due to the fact that LAS and the amine counter ion themselves influence the mass transfer at the water-SLM interface. The observations on LPME of LAS may aid in LPME application to other compounds with surfactant properties or in surfactant enhanced membrane extraction of other compounds.

  18. Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop

    Energy Technology Data Exchange (ETDEWEB)

    He Yi [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)]. E-mail: yhe@jjay.cuny.edu; Vargas, Angelica [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States); Kang, Youn-Jung [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)

    2007-04-25

    This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H{sub 3}PO{sub 4} drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 {mu}g L{sup -1}, repeatability of the extraction (R.S.D. < 5%, n = 6), and low detection limits (0.3 {mu}g L{sup -1} for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples.

  19. Binary Solvents Dispersive Liquid—Liquid Microextraction (BS-DLLME) Method for Determination of Tramadol in Urine Using High-Performance Liquid Chromatography

    Science.gov (United States)

    2014-01-01

    Background Tramadol is an opioid, synthetic analog of codeine and has been used for the treatment of acute or chronic pain may be abused. In this work, a developed Dispersive liquid liquid microextraction (DLLME) as binary solvents-based dispersive liquid-liquid microextraction (BS-DLLME) combined with high performance liquid chromatography (HPLC) with fluorescence detection (FD) was employed for determination of tramadol in the urine samples. This procedure involves the use of an appropriate mixture of binary extraction solvents (70 μL CHCl3 and 30 μL ethyl acetate) and disperser solvent (600 μL acetone) for the formation of cloudy solution in 5 ml urine sample comprising tramadol and NaCl (7.5%, w/v). After centrifuging, the small droplets of extraction solvents were precipitated. In the final step, the HPLC with fluorescence detection was used for determination of tramadol in the precipitated phase. Results Various factors on the efficiency of the proposed procedure were investigated and optimized. The detection limit (S/N = 3) and quantification limit (S/N = 10) were found 0.2 and 0.9 μg/L, respectively. The relative standard deviations (RSD) for the extraction of 30 μg L of tramadol was found 4.1% (n = 6). The relative recoveries of tramadol from urine samples at spiking levels of 10, 30 and 60 μg/L were in the range of 95.6 – 99.6%. Conclusions Compared with other methods, this method provides good figures of merit such as good repeatability, high extraction efficiency, short analysis time, simple procedure and can be used as microextraction technique for routine analysis in clinical laboratories. PMID:24495475

  20. Microextraction Techniques Coupled to Liquid Chromatography with Mass Spectrometry for the Determination of Organic Micropollutants in Environmental Water Samples

    Directory of Open Access Journals (Sweden)

    Mª Esther Torres Padrón

    2014-07-01

    Full Text Available Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE, that use large volumes of organic solvents. Solid-phase extraction (SPE uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS and time-of-flight mass spectrometric (TOF/MS techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME, stir bar sorptive extraction (SBSE and liquid-phase microextraction (LPME. Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These

  1. Trace determination of volatile polycyclic aromatic hydrocarbons in natural waters by magnetic ionic liquid-based stir bar dispersive liquid microextraction.

    Science.gov (United States)

    Benedé, Juan L; Anderson, Jared L; Chisvert, Alberto

    2018-01-01

    In this work, a novel hybrid approach called stir bar dispersive liquid microextraction (SBDLME) that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) has been employed for the accurate and sensitive determination of ten polycyclic aromatic hydrocarbons (PAHs) in natural water samples. The extraction is carried out using a neodymium stir bar magnetically coated with a magnetic ionic liquid (MIL) as extraction device, in such a way that the MIL is dispersed into the solution at high stirring rates. Once the stirring is ceased, the MIL is magnetically retrieved onto the stir bar, and subsequently subjected to thermal desorption (TD) coupled to a gas chromatography-mass spectrometry (GC-MS) system. The main parameters involved in TD, as well as in the extraction step affecting the extraction efficiency (i.e., MIL amount, extraction time and ionic strength) were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ng L -1 level, good intra- and inter-day repeatability (RSD < 13%) and good enrichment factors (18 - 717). This sensitive analytical method was applied to the determination of trace amounts of PAHs in three natural water samples (river, tap and rainwater) with satisfactory relative recovery values (84-115%), highlighting that the matrices under consideration do not affect the extraction process. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Air-assisted dispersive liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent for the preconcentration of benzophenone-type UV filters from aqueous samples.

    Science.gov (United States)

    Ge, Dandan; Zhang, Yi; Dai, Yixiu; Yang, Shumin

    2018-04-01

    Deep eutectic solvents are considered as new and green solvents that can be widely used in analytical chemistry such as microextraction. In the present work, a new dl-menthol-based hydrophobic deep eutectic solvent was synthesized and used as extraction solvents in an air-assisted dispersive liquid-liquid microextraction method for preconcentration and extraction of benzophenone-type UV filters from aqueous samples followed by high-performance liquid chromatography with diode array detection. In an experiment, the deep eutectic solvent formed by dl-menthol and decanoic acid was added to an aqueous solution containing the UV filters, and then the mixture was sucked up and injected five times by using a glass syringe, and a cloudy state was achieved. After extraction, the solution was centrifuged and the upper phase was subjected to high-performance liquid chromatography for analysis. Various parameters such as the type and volume of the deep eutectic solvent, number of pulling, and pushing cycles, solution pH and salt concentration were investigated and optimized. Under the optimum conditions, the developed method exhibited low limits of detection and limits of quantitation, good linearity, and precision. Finally, the proposed method was successfully applied to determine the benzophenone-type filters in environmental water samples with relative recoveries of 88.8-105.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. One-step displacement dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry for the selective determination of methylmercury in environmental samples.

    Science.gov (United States)

    Liang, Pei; Kang, Caiyan; Mo, Yajun

    2016-01-01

    A novel method for the selective determination of methylmercury (MeHg) was developed by one-step displacement dispersive liquid-liquid microextraction (D-DLLME) coupled with graphite furnace atomic absorption spectrometry. In the proposed method, Cu(II) reacted with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which was used as the chelating agent instead of DDTC for the dispersive liquid-liquid microextraction (DLLME) of MeHg. Because the stability of MeHg-DDTC is higher than that of Cu-DDTC, MeHg can displace Cu from the Cu-DDTC complex and be preconcentrated in a single DLLME procedure. MeHg could be extracted into the extraction solvent phase at pH 6 while Hg(II) remained in the sample solution. Potential interference from co-existing metal ions with lower DDTC complex stability was largely eliminated without the need of any masking reagent. Under the optimal conditions, the limit of detection of this method was 13.6ngL(-1) (as Hg), and an enhancement factor of 81 was achieved with a sample volume of 5.0mL. The proposed method was successfully applied for the determination of trace MeHg in some environmental samples with satisfactory results. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Development of a robust ionic liquid-based dispersive liquid-liquid microextraction against high concentration of salt for preconcentration of trace metals in saline aqueous samples: Application to the determination of Pb and Cd

    International Nuclear Information System (INIS)

    Yousefi, Seyed Reza; Shemirani, Farzaneh

    2010-01-01

    A new ionic liquid-based dispersive liquid-liquid microextraction method was developed for preconcentration and determination of compounds in aqueous samples containing very high salt concentrations. This method can solve the problems associated with the limited application of the conventional IL-based DLLME in these samples. This is believed to arise from dissolving of the ionic liquids in aqueous samples with high salt content. In this method, the robustness of microextraction system against high salt concentration (up to 40%, w/v) is increased by introducing a common ion of the ionic liquid into the sample solution. The proposed method was applied satisfactorily to the preconcentration of lead and cadmium in saline samples. After preconcentration, the settled IL-phase was dissolved in 100 μL ethanol and aspirated into the flame atomic absorption spectrometer (FAAS) using a home-made microsample introduction system. Several variables affecting the microextraction efficiency were investigated and optimized. Under the optimized conditions and preconcentration of only 10 mL of sample, the enhancement factors of 273 and 311 and the detection limits of 0.6 μg L -1 and 0.03 μg L -1 were obtained for lead and cadmium, respectively. Validation of the method was performed by both an analysis of a certified reference material (CRM) and comparison of results with those obtained by ISO standard method.

  5. Ultrasound assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography designated for bioavailability studies of felodipine combinations in rat plasma.

    Science.gov (United States)

    Ahmed, Sameh; Atia, Noha N; Bakr Ali, Marwa Fathy

    2017-03-01

    Felodipine (FLD), a calcium channel antagonist, is commonly prescribed for the treatment of hypertension either with Metoprolol (MET) or Ramipril (RAM) in two different drug combinations. FLD has high plasma protein binding ability affecting its extraction recoveries from plasma samples. Hence, a specific ultrasound assisted dispersive liquid-liquid microextraction (UA-DLLME) method coupled with HPLC using photodiode array detector was developed and validated for the simultaneous determination of FLD, MET and RAM in rat plasma after oral administration of these combinations. The factors affecting UA-DLLME were carefully optimized. In this study, UA-DLLME method could provide simple and efficient plasma extraction procedures with superior recovery results. Under optimum condition, all target drugs were separated within 13min. The validation procedures was carried out in agreement with US-FDA guidelines and shown to be suitable for anticipated purposes. Linear calibration ranges were obtained in the range 0.05-2.0μgmL -1 for FLD and MET and 0.1-2.0μgmL -1 for RAM with detection limits of 0.013-0.031μgmL -1 for all the studied drug combinations. The%RSD for inter-day and intra-day precisions was in range of 0.63-3.85% and the accuracy results were in the range of 92.13-100.5%. The validated UA-DLLME-HPLC method was successfully applied for the bioavailability studies of FLD, MET and RAM. The pharmacokinetic parameters were calculated for all the investigated drugs in rats after single-dose administrations of two different drug combinations. Although FLD was bioequivalent in the two formulations, a small increase in plasma levels of MET and RAM was found in the presence of FLD. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Ultrasound-air-assisted demulsified liquid-liquid microextraction by solidification of a floating organic droplet for determination of three antifungal drugs in water and biological samples.

    Science.gov (United States)

    Ezoddin, Maryam; Shojaie, Mehran; Abdi, Khosrou; Karimi, Mohammad Ali

    2017-03-01

    A novel ultrasound-air-assisted demulsified liquid-liquid microextraction by solidification of a floating organic droplet (UAAD-LLM-SFO) followed by HPLC-UV detection was developed for the analysis of three antifungal drugs in water and biological samples. In this method, 1-dodecanol was used as the extraction solvent. The emulsion was rapidly formed by pulling in and pushing out the mixture of sample solution and extraction solvent for 5 times repeatedly using a 10-mL glass syringe while sonication was performed. Therefore, an organic dispersive solvent required in common microextraction methods was not used in the proposed method. After dispersing, an aliquot of acetonitrile was introduced as a demulsifier solvent into the sample solution to separate two phases. Therefore, some additional steps, such as the centrifugation, ultrasonication, or agitation of the sample solution, are not needed. Parameters influencing the extraction recovery were investigated. The proposed method showed a good linearity for the three antifungal drugs studied with the correlation coefficients (R 2  > 0.9995). The limits of detection (LODs) and the limits of the quantification (LOQs) were between 0.01-0.03 μg L -1 and 0.03-0.08 μg L -1 , respectively. The preconcentration factors (PFs) were in the range of 107-116, respectively. The precisions, as the relative standard deviations (RSDs) (n = 5), for inter-day and intra-day analysis were in the range of 2.1-4.5% and 6.5-8.5%, respectively. This method was successfully applied to determine the three antifungal drugs in tap water and biological samples. The recoveries of antifungal drugs in these samples were 92.4-98.5%. Graphical abstract Ultrasound-air-assisted demulsified liquid-liquid microextraction by solidification of a floating organic droplet for the analysis of three antifungal drugs prior HPLC-UV.

  7. Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

    Science.gov (United States)

    Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

    2015-05-22

    Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Ionic Liquid-Bonded Fused Silica as a New Solid-Phase Microextraction Fiber for the Liquid Chromatographic Determination of Bisphenol A as an Endocrine Disruptor.

    Science.gov (United States)

    Mohammadnezhad, Nasim; Matin, Amir Abbas; Samadi, Naser; Shomali, Ashkan; Valizadeh, Hassan

    2017-01-01

    Linear ionic liquid bonded to fused silica and its application as a solid-phase microextraction fiber for the extraction of bisphenol A (BPA) from water samples were studied. After optimization of microextraction conditions (15 mL sample volume, extraction time of 40 min, extraction temperature of 30 ± 1°C, 300 μL acetonitrile as the desorption solvent, and desorption time of 7 min), the fiber was used to extract BPA from packed mineral water, followed by HPLC-UV on an XDB-C18 column (150 × 4.6 mm id, 3.5 μm particle) with a mobile phase of acetonitrile-water (45 + 55%, v/v) and flow rate of 1 mL . min-1). A low LOD (0.20 μg . L-1) and good linearity (0.9977) in the calibration graph indicated that the proposed method was suitable for the determination of BPA.

  9. Determination of free formaldehyde in cosmetics containing formaldehyde-releasing preservatives by reversed-phase dispersive liquid-liquid microextraction and liquid chromatography with post-column derivatization.

    Science.gov (United States)

    Miralles, Pablo; Chisvert, Alberto; Alonso, M José; Hernandorena, Sandra; Salvador, Amparo

    2018-03-30

    An analytical method for the determination of traces of formaldehyde in cosmetic products containing formaldehyde-releasing preservatives has been developed. The method is based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME), that allows the extraction of highly polar compounds, followed by liquid chromatography-ultraviolet/visible (LC-UV/vis) determination with post-column derivatization. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the selected conditions, a mixture of 500 μL of acetonitrile (disperser solvent) and 50 μL of water (extraction solvent) was rapidly injected into 5 mL of toluene sample solution. The extracts were injected into the LC-UV/vis system using phosphate buffer 6 mmol L -1 at pH 2 as mobile phase. After chromatographic separation, the eluate merged with a flow stream of pentane-2,4-dione in ammonium acetate solution as derivatizing reagent and passed throughout a post-column reactor at 85 °C in order to derivatize formaldehyde into 3,5-diacetyl-1,4-dihydrolutidine, according to Hantzsch reaction, which was finally measured spectrophotometrically at 407 nm. The method was successfully validated showing good linearity, an enrichment factor of 86 ± 2, limits of detection and quantification of 0.7 and 2.3 ng mL -1 , respectively, and good repeatability (RSD < 9.2%). Finally, the proposed analytical method was applied to the determination of formaldehyde in different commercial cosmetic samples containing formaldehyde-releasing preservatives, such as bronopol, diazolidinyl urea, imidazolidinyl urea, and DMDM hydantoin, with good relative recovery values (91-113%) thus showing that matrix effects were negligible. The good analytical features of the proposed method besides of its simplicity and affordability, make it useful to carry out the quality control of cosmetic products containing formaldehyde-releasing preservatives. Copyright

  10. Expanding the Applicability of Poly(Ionic Liquids in Solid Phase Microextraction: Pyrrolidinium Coatings

    Directory of Open Access Journals (Sweden)

    David J. S. Patinha

    2017-09-01

    Full Text Available Crosslinked pyrrolidinium-based poly(ionic liquids (Pyrr-PILs were synthesized through a fast, simple, and solventless photopolymerization scheme, and tested as solid phase microextraction (SPME sorbents. A series of Pyrr-PILs bearing three different alkyl side chain lengths with two, eight, and fourteen carbons was prepared, characterized, and homogeneously coated on a steel wire by using a very simple procedure. The resulting coatings showed a high thermal stability, with decomposition temperatures above 350 °C, excellent film stability, and lifetime of over 100 injections. The performance of these PIL-based SPME fibers was evaluated using a mixture of eleven organic compounds with different molar volumes and chemical functionalities (alcohols, ketones, and monoterpenes. The Pyrr-PIL fibers were obtained as dense film coatings, with 67 μm thickness, with an overall sorption increase of 90% and 55% as compared to commercial fibers of Polyacrylate (85 μm (PA85 and Polydimethylsiloxane (7 μm (PDMS7 coatings, respectively. A urine sample doped with the sample mixture was used to study the matrix effect and establish relative recoveries, which ranged from 60.2% to 104.1%.

  11. [Detecting Thallium in Water Samples using Dispersive Liquid Phase Microextraction-Graphite Furnace Atomic Absorption Spectroscopy].

    Science.gov (United States)

    Zhu, Jing; Li, Yan; Zheng, Bo; Tang, Wei; Chen, Xiao; Zou, Xiao-li

    2015-11-01

    To develope a method of solvent demulsification dispersive liquid phase microextraction (SD-DLPME) based on ion association reaction coupled with graphite furnace atomic absorption spectroscopy (GFAAS) for detecting thallium in water samples. Methods Thallium ion in water samples was oxidized to Tl(III) with bromine water, which reacted with Cl- to form TlCl4-. The ionic associated compound with trioctylamine was obtained and extracted. DLPME was completed with ethanol as dispersive solvent. The separation of aqueous and organic phase was achieved by injecting into demulsification solvent without centrifugation. The extractant was collected and injected into GFAAS for analysis. With palladium colloid as matrix modifier, a two step drying and ashing temperature programming process was applied for high precision and sensitivity. The linear range was 0.05-2.0 microg/L, with a detection limit of 0.011 microg/L. The relative standard derivation (RSD) for detecting Tl in spiked water sample was 9.9%. The spiked recoveries of water samples ranged from 94.0% to 103.0%. The method is simple, sensitive and suitable for batch analysis of Tl in water samples.

  12. Combination of flame atomic absorption spectrometry with ligandless-dispersive liquid- liquid microextraction for preconcentration and determination of trace amount of lead in water samples

    Directory of Open Access Journals (Sweden)

    Y.M. Baghelani

    2013-05-01

    Full Text Available A new ligandless-dispersive liquid–liquid microextraction method has been developed for the separation and flame atomic absorption spectrometry determination of trace amount of lead(II ion. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents. Factors influencing the extraction efficiency of lead, including the extraction and dispersive solvent type and volume, pH of sample solution, concentration of chloride and extraction time were studied. Under the optimal conditions, the calibration curve was linear in the range of 7.0–6000 ng mL−1 of lead with R2 = 0.9992 (n = 10 and detection limit based on three times the standard deviation of the blank (3Sb was 0.5 ng mL−1 in original solution. The relative standard deviation for eight replicate determinations of 1.0 mg mL-1 lead was ±1.6%. The high efficiency of dispersive liquid-liquid microextraction to carry out the determination of trace amounts of lead in complex matrices was demonstrated. The proposed method has been applied for determination of trace amounts of lead in water samples and satisfactory results were obtained. The accuracy was checked by analyzing a certified reference material from the National Institute of Standard and Technology, Trace elements in water (NIST CRM 1643e.

  13. In-situ ionic liquid dispersive liquid-liquid microextraction using a new anion-exchange reagent combined Fe3O4 magnetic nanoparticles for determination of pyrethroid pesticides in water samples.

    Science.gov (United States)

    Fan, Chen; Liang, You; Dong, Hongqiang; Ding, Guanglong; Zhang, Wenbing; Tang, Gang; Yang, Jiale; Kong, Dandan; Wang, Deng; Cao, Yongsong

    2017-07-04

    In this work, in-situ ionic liquid dispersive liquid-liquid microextraction combined ultrasmall Fe 3 O 4 magnetic nanoparticles was developed as a kind of pretreatment method to detect pyrethroid pesticides in water samples. New anion-exchange reagents including Na[DDTC] and Na[N(CN) 2 ] were optimized for in-situ extraction pyrethroids, which showed enhanced microextraction performance. Pyrethroids were enriched by hydrophilic ionic liquid [P 4448 ][Br] (aqueous solution, 200 μL, 0.2 mmol mL -1 ) reaction in-situ with anion-exchange reagent Na[N(CN) 2 ] (aqueous solution, 300 μL, 0.2 mmol mL -1 ) forming hydrophobic ionic liquid as extraction agent in water sample (10 mL). Ultrasmall superparamagnetic iron oxide nanoparticles (30 mg) were used to collect the mixture of ionic liquid and pyrethroids followed by elution with acetonitrile. The extraction of ionic liquid strategies was unique and efficiently fulfilled with high enrichment factors (176-213) and good recoveries (80.20-117.31%). The method was successively applied to the determination of pyrethroid pesticides in different kinds of water samples with the limits of detection ranged from 0.16 to 0.21 μg L -1 . The proposed method is actually nanometer-level microextraction (average size 80 nm) with the advantages of simplicity, rapidity, and sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

    International Nuclear Information System (INIS)

    Berton, Paula; Wuilloud, Rodolfo G.

    2010-01-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C 6 mim][PF 6 ] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L -1 , while the relative standard deviation (RSD) was 3.4% (at 1 μg L -1 Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

  15. A novel extraction technique based on carbon nanotubes reinforced hollow fiber solid/liquid microextraction for the measurement of piroxicam and diclofenac combined with high performance liquid chromatography.

    Science.gov (United States)

    Song, Xin-Yue; Shi, Yan-Ping; Chen, Juan

    2012-10-15

    A novel design of carbon nanotubes reinforced hollow fiber solid/liquid phase microextraction (CNTs-HF-SLPME) was developed to determine piroxicam and diclofenac in different real water samples. Functionalized multi-walled carbon nanotubes (MWCNTs) were held in the pores of hollow fiber with sol-gel technology. The pores and lumen of carbon nanotubes reinforced hollow fiber were subsequently filled with a μL volume of organic solvent (1-octanol), and then the whole assembly was used for the extraction of the target analytes in direct immersion sampling mode. The target analytes were extracted from the sample by two extractants, one of which is organic solvent placed inside the pores and lumen of hollow fiber and the other one is CNTs held in the pores of hollow fiber. After extraction, the analytes were desorbed in acetonitrile and analyzed using high performance liquid chromatography. This novel extraction mode showed more excellent extraction performance in comparison with conventional hollow fiber liquid microextraction (without adding CNTs) and carbon nanotubes reinforced hollow fiber solid microextraction (CNTs held in the pores of hollow fiber, but no organic solvents placed inside the lumen of hollow fiber) under the respective optimum conditions. This method provided 47- and 184-fold enrichment factors for piroxicam and diclofenac, respectively, good inter-fiber repeatability and batch-to-batch reproducibility. Linearity was observed in the range of 20-960 μg L(-1) for piroxicam, and 10-2560 μg L(-1) for diclofenac, with correlation coefficients of 0.9985 and 0.9989, respectively. The limits of detection were 4.58 μg L(-1) for piroxicam and 0.40 μg L(-1) for diclofenac. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Ionic liquid based vortex assisted liquid-liquid microextraction combined with liquid chromatography mass spectrometry for the determination of bisphenols in thermal papers with the aid of response surface methodology.

    Science.gov (United States)

    Asati, Ankita; Satyanarayana, G N V; Panchal, Smita; Thakur, Ravindra Singh; Ansari, Nasreen G; Patel, Devendra K

    2017-08-04

    A sensitive, rapid and efficient ionic liquid-based vortex assisted liquid-liquid microextraction (IL-VALLME) with Liquid Chromatography Mass spectrometry (LC-MS/MS) method is proposed for the determination of bisphenols in thermal paper. Extraction factors were systematically optimized by response surface methodology. Experimental factors showing significant effects on the analytical responses were evaluated using design of experiment. The limit of detection for Bisphenol-A (BPA) and Bisphenol-S (BPS) in thermal paper were 1.25 and 0.93μgkg -1 respectively. The dynamic linearity range for BPA was between 4 and 100μgkg -1 and the determination of coefficient (R 2 ) was 0.996. The values of the same parameters were 3-100μgkg -1 and 0.998 for BPS. The extraction recoveries of BPA and BPS in thermal paper were 101% and 99%. Percent relative standard deviation (% RSD) for matrix effect and matrix match effects were not more than 10%, for both bisphenols. The proposed method uses a statistical approach for the analysis of bisphenols in environmental samples, and is easy, rapid, requires minimum organic solvents and efficient. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Ceria nanocubic-ultrasonication assisted dispersive liquid-liquid microextraction coupled with matrix assisted laser desorption/ionization mass spectrometry for pathogenic bacteria analysis.

    Science.gov (United States)

    Abdelhamid, Hani Nasser; Bhaisare, Mukesh L; Wu, Hui-Fen

    2014-03-01

    A new ceria (CeO2) nanocubic modified surfactant is used as the basis of a novel nano-based microextraction technique for highly sensitive detection of pathogenic bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). The technique uses ultrasound enhanced surfactant-assisted dispersive liquid-liquid microextraction (UESA-DLLME) with and without ceria (CeO2) followed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). In order to achieve high separation efficiency, we investigated the influential parameters, including extraction time of ultrasonication, type and volume of the extraction solvent and surfactant. Among various surfactants, the cationic surfactants can selectively offer better extraction efficiency on bacteria analysis than that of the anionic surfactants due to the negative charges of bacteria cell membranes. Extractions of the bacteria lysate from aqueous samples via UESA-DLLME-MALDI-MS were successfully achieved by using cetyltrimethyl ammonium bromide (CTAB, 10.0 µL, 1.0×10(-3) M) as surfactants in chlorobenzene (10.0 µL) and chloroform (10.0 µL) as the optimal extracting solvent for P. aeruginosa and S. aureus, respectively. Ceria nanocubic was synthesized, and functionalized with CTAB (CeO2@CTAB) and then characterized using transmission electron microscopy (TEM) and optical spectroscopy (UV and FTIR). CeO2@CTAB demonstrates high extraction efficiency, improve peaks ionization, and enhance resolution. The prime reasons for these improvements are due to the large surface area of nanoparticles, and its absorption that coincides with the wavelength of MALDI laser (337 nm, N2 laser). CeO2@CTAB-based microextraction offers lowest detectable concentrations tenfold lower than that of without nanoceria. The present approach has been successfully applied to detect pathogenic bacteria at low concentrations of 10(4)-10(5) cfu/mL (without ceria) and at 10(3)-10(4) cfu/mL (with ceria) from bacteria suspensions. Finally, the

  18. Modified dispersive liquid-liquid microextraction for pre-concentration of benzene, toluene, ethylbenzene and xylenes prior to their determination by GC

    International Nuclear Information System (INIS)

    Faraji, Hakim; Feizbakhsh, Alireza; Helalizadeh, Masoumeh

    2013-01-01

    We have developed a modified method for the extraction and preconcentration of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples. It based on dispersive liquid-liquid microextraction along with solidification of floating organic microdrops. The dispersion of microvolumes of an extracting solvent into the aqueous occurs without dispersive solvent. Various parameters have been optimized. BTEX were quantified via GC with FID detection. Under optimized conditions, the preconcentration factors range from 301 to 514, extraction efficiencies from 60 to 103 %, repeatabilities from 2.2 to 4.1 %, and intermediate precisions from 3.5 to 7.0 %. The relative recovery for each analyte in water samples at three spiking levels is >85.6 %, with a relative standard deviation of <7.4 %. (author)

  19. Preconcentration procedure using vortex-assisted liquid-liquid microextraction for the fast determination of trace levels of thorium in water samples

    International Nuclear Information System (INIS)

    Ehsan Zolfonoun; Maryam Salahinejad

    2013-01-01

    A new simple and rapid vortex-assisted liquid-liquid microextraction method was applied for the determination of thorium in water samples. In this method, chloroform used as extraction solvent was directly injected into the water sample solution. The extraction solvent was dispersed into the aqueous phase under vigorously shaking with the vortex. After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom centrifuge tube. The effect of different experimental parameters on the performance of the method were studied and discussed. Under the optimum conditions, the detection limit for Th(IV) was 7.5 ng mL -1 . The precision of the method, evaluated as the relative standard deviation obtained by analyzing of 10 replicates, was 2.8 %. The practical applicability of the developed method was examined using natural water and monazite sand samples. (author)

  20. Headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE): comparison of the performance in classification of ecstasy tablets. Part 2.

    Science.gov (United States)

    Bonadio, Federica; Margot, Pierre; Delémont, Olivier; Esseiva, Pierre

    2008-11-20

    Headspace solid-phase microextraction (HS-SPME) is assessed as an alternative to liquid-liquid extraction (LLE) currently used for 3,4-methylenedioxymethampethamine (MDMA) profiling. Both methods were compared evaluating their performance in discriminating and classifying samples. For this purpose 62 different seizures were analysed using both extraction techniques followed by gas chromatography-mass spectroscopy (GC-MS). A previously validated method provided data for HS-SPME, whereas LLE data were collected applying a harmonized methodology developed and used in the European project CHAMP. After suitable pre-treatment, similarities between sample pairs were studied using the Pearson correlation. Both methods enable to distinguish between samples coming from the same pre-tabletting batches and samples coming from different pre-tabletting batches. This finding emphasizes the use of HS-SPME as an effective alternative to LLE, with additional advantages such as sample preparation and a solvent-free process.

  1. 2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography.

    Science.gov (United States)

    Faraji, Mohammad; Hamdamali, Mohammadrezza; Aryanasab, Fezzeh; Shabanian, Meisam

    2018-07-13

    In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L -1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L -1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L -1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). Copyright © 2018. Published by Elsevier B.V.

  2. Ionic-liquid-based dispersive liquid-liquid microextraction combined with magnetic solid-phase extraction for the determination of aflatoxins B1 , B2 , G1 , and G2 in animal feeds by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Zhao, Jiao; Zhu, Yan; Jiao, Yang; Ning, Jinyan; Yang, Yaling

    2016-10-01

    A novel two-step extraction technique combining ionic-liquid-based dispersive liquid-liquid microextraction with magnetic solid-phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high-performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid-liquid microextraction, and hydrophobic pelargonic acid modified Fe 3 O 4 magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins-containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid-liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid-liquid microextraction and magnetic solid-phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3-103.7% with relative standard deviations of 3.2-6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B 1 , B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Optimization of two different dispersive liquid-liquid microextraction methods followed by gas chromatography-mass spectrometry determination for polycyclic aromatic hydrocarbons (PAHs) analysis in water.

    Science.gov (United States)

    Tseng, Wan-Chi; Chen, Pai-Shan; Huang, Shang-Da

    2014-03-01

    Novel sample preparation methods termed "up-and-down shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME)" and "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)" coupled with gas chromatography-mass spectrometry (GC-MS) have been developed for the analysis of 11 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. For UDSA-DLLME, an up-and-down shaker-assisted emulsification was employed. Extraction was complete in 3min. Only 14 μL of 1-heptanol was required, without a dispersive solvent. Under the optimum conditions, the linear range was 0.08-100 µg L(-1), and the LODs were in the range 0.022-0.060 µg L(-1). The enrichment factors (EFs) ranged from 392 to 766. Relative recoveries were between 84% and 113% for river, lake, and field water. In WLSEME, 9 μL of 1-nonanol as extraction solvent and 240 μL of 1 mg L(-1) Triton X-100 as surfactant were mixed in a microsyringe to form a cloudy emulsified solution, which was then injected into the samples. Compared with other surfactant-assisted emulsion methods, WLSEME uses much less surfactant. The linear range was 0.08-100 µg L(-1), and the LODs were 0.022-0.13 µg L(-1). The EFs ranged from 388 to 649. The relative recoveries were 86-114% for all three water specimens. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Air-assisted liquid-liquid microextraction using floating organic droplet solidification for simultaneous extraction and spectrophotometric determination of some drugs in biological samples through chemometrics methods

    Science.gov (United States)

    Farahmand, Farnaz; Ghasemzadeh, Bahar; Naseri, Abdolhossein

    2018-01-01

    An air assisted liquid-liquid microextraction by applying the solidification of a floating organic droplet method (AALLME-SFOD) coupled with a multivariate calibration method, namely partial least squares (PLS), was introduced for the fast and easy determination of Atenolol (ATE), Propanolol (PRO) and Carvedilol (CAR) in biological samples via a spectrophotometric approach. The analytes would be extracted from neutral aqueous solution into 1-dodecanol as an organic solvent, using AALLME. In this approach a low-density solvent with a melting point close to room temperature was applied as the extraction solvent. The emulsion was immediately formed by repeatedly pulling in and pushing out the aqueous sample solution and extraction solvent mixture via a 10-mL glass syringe for ten times. After centrifugation, the extractant droplet could be simply collected from the aqueous samples by solidifying the emulsion at a lower than the melting point temperature. In the next step, analytes were back extracted simultaneously into the acidic aqueous solution. Derringer and Suich multi-response optimization were utilized for simultaneous optimizing the parameters of three analytes. This method incorporates the benefits of AALLME and dispersive liquid-liquid microextraction considering the solidification of floating organic droplets (DLLME-SFOD). Calibration graphs under optimized conditions were linear in the range of 0.30-6.00, 0.32-2.00 and 0.30-1.40 μg mL- 1 for ATE, CAR and PRO, respectively. Other analytical parameters were obtained as follows: enrichment factors (EFs) were found to be 11.24, 16.55 and 14.90, and limits of detection (LODs) were determined to be 0.09, 0.10 and 0.08 μg mL- 1 for ATE, CAR and PRO, respectively. The proposed method will require neither a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

  5. Glyoxal and methylglyoxal as urinary markers of diabetes. Determination using a dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Pastor-Belda, M; Fernández-García, A J; Campillo, N; Pérez-Cárceles, M D; Motas, M; Hernández-Córdoba, M; Viñas, P

    2017-08-04

    Glyoxal (GO) and methylglyoxal (MGO) are α-oxoaldehydes that can be used as urinary diabetes markers. In this study, their levels were measured using a sample preparation procedure based on salting-out assisted liquid-liquid extraction (SALLE) and dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-mass spectrometry (GC-MS). The effect of the derivatization reaction with 2,3-diaminonaphthalene, the addition of acetonitrile and sodium chloride to urine, and the DLLME step using the acetonitrile extract as dispersant solvent and carbon tetrachloride as extractant solvent were carefully optimized. Quantification was performed by the internal standard method, using 5-bromo-2-chloroanisole. The intraday and interday precisions were lower than 6%. Limits of detection were 0.12 and 0.06ngmL -1 , and enrichment factors 140 and 130 for GO and MGO, respectively. The concentrations of these α-oxoaldehydes in urine were between 0.9 and 35.8ngg -1 levels (creatinine adjusted). A statistical comparison of the analyte contents of urine samples from non-diabetic and diabetic patients pointed to significant differences (P=0.046, 24 subjects investigated), particularly regarding MGO, which was higher in diabetic patients. The novelty of this study compared with previous procedures lies in the treatment of the urine sample by SALLE based on the addition of acetonitrile and sodium chloride to the urine. The DLLME procedure is performed with a sedimented drop of the extractant solvent, without a surfactant reagent, and using acetonitrile as dispersant solvent. Separation of the analytes was performed using GC-MS detection, being the analytes unequivocal identified. The proposed procedure is the first microextraction method applied to the analysis of urine samples from diabetic and non-diabetic patients that allows a clear differentiation between both groups using a simple analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Determination of Organophosphorus Pesticides in Soil by Dispersive Liquid–Liquid Microextraction and Gas Chromatography

    Science.gov (United States)

    Yang, Zhonghua; Liu, Yu; Liu, Donghui; Zhou, Zhiqiang

    2012-01-01

    In this article, a rapid and sensitive sample pretreatment technique for the determination of organophosphorus pesticides (OPPs) in soil samples is developed by using dispersive liquid–liquid microextraction (DLLME) combined with gas chromatography–flame photometric detection. Experimental conditions, including the kind of extraction and disperser solvent and their volumes, the extraction time, and the salt addition, are investigated, and the following experiment factors are used: 20 µL chlorobenzene as the extraction solvent; 1.0 mL acetonitrile as the disperser solvent; no addition of salt; and an extraction time of 1 min. Under the optimum conditions, the linearities for the three target OPPs (ethoprophos, chlorpyriphos, and profenofos) are obtained by five points in the concentration range of 2.5–1500 µg/kg, and three replicates are used for each point. Correlation coefficients vary from 0.9987 to 0.9997. The repeatability is tested by spiking soil samples at a concentration level of 5.0 µg/kg. The relative standard deviation (n = 3) varied between 2.0% and 6.6%. The limits of detection, based on a signal-to-noise ratio (S/N) of 3, range from 200 to 500 pg/g. This method is applied to the analysis of the spiked samples S1, S2, and S3, which are collected from the China Agriculture University's orchard, lawn, and garden, respectively. The recoveries for each target analyte are in the range between 87.9% and 108.0%, 87.4% and 108.0%, and 86.7% and 107.2%, respectively. PMID:22291051

  7. Comparison of micellar extraction combined with ionic liquid based vortex-assisted liquid-liquid microextraction and modified quick, easy, cheap, effective, rugged, and safe method for the determination of difenoconazole in cowpea.

    Science.gov (United States)

    Chen, Xiaochu; Bian, Yanli; Liu, Fengmao; Teng, Peipei; Sun, Pan

    2017-10-06

    Two simple sample pretreatment for the determination of difenoconazole in cowpea was developed including micellar extraction combined with ionic liquid based vortex-assisted liquid-liquid microextraction (ME-IL-VALLME) prior to high performance liquid chromatography (HPLC), and modified quick, easy, cheap, effective, rugged, and safe method (QuEChERS) coupled with HPLC-MS/MS. In ME-IL-VALLME method, the target analyte was extracted by surfactant Tween 20 micellar solution, then the supernatant was diluted with 3mL water to decrease the solubility of micellar solution. Subsequently, the vortex-assisted liquid-liquid microextraction (VALLME) procedure was performed in the diluted extraction solution by using the ionic liquid of 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF 6 ) as the extraction solvent and Tween 20 as an emulsifier to enhance the dispersion of the water-immiscible ionic liquid into the aqueous phase. Parameters that affect the extraction have been investigated in both methods Under the optimum conditions, the limits of quantitation were 0.10 and 0.05mgkg -1 , respectively. And good linearity was achieved with the correlation coefficient higher than 0.9941. The relative recoveries ranged from 78.6 to 94.8% and 92.0 to 118.0% with the relative standard deviations (RSD) of 7.9-9.6% and 1.2-3.2%, respectively. Both methods were quick, simple and inexpensive. However, the ME-IL-VALLME method provides higher enrichment factor compared with conventional QuEChERS method. The ME-IL-VALLME method has a strong potential for the determination of difenoconazole in complex vegetable matrices with HPLC. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Comparison of two novel in-syringe dispersive liquid-liquid microextraction techniques for the determination of iodide in water samples using spectrophotometry.

    Science.gov (United States)

    Kaykhaii, Massoud; Sargazi, Mona

    2014-01-01

    Two new, rapid methodologies have been developed and applied successfully for the determination of trace levels of iodide in real water samples. Both techniques are based on a combination of in-syringe dispersive liquid-liquid microextraction (IS-DLLME) and micro-volume UV-Vis spectrophotometry. In the first technique, iodide is oxidized with nitrous acid to the colorless anion of ICl2(-) at high concentration of hydrochloric acid. Rhodamine B is added and by means of one step IS-DLLME, the ion-pair formed was extracted into toluene and measured spectrophotometrically. Acetone is used as dispersive solvent. The second method is based on the IS-DLLME microextraction of iodide as iodide/1, 10-phenanthroline-iron((II)) chelate cation ion-pair (colored) into nitrobenzene. Methanol was selected as dispersive solvent. Optimal conditions for iodide extraction were determined for both approaches. Methods are compared in terms of analytical parameters such as precision, accuracy, speed and limit of detection. Both methods were successfully applied to determining iodide in tap and river water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Comparison of solidification of floating drop and homogenous liquid-liquid microextractions for the extraction of two plasticizers from the water kept in PET-bottles.

    Science.gov (United States)

    Yamini, Yadollah; Ghambarian, Mahnaz; Khalili-Zanjani, Mohammad Reza; Faraji, Mohammad; Shariati, Shahab

    2009-09-01

    Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid-liquid microextraction (HLLE) were compared for the extraction and preconcentration of di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1-undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME-GC-FID and HLLE-GC-FID, were ranged from 0.03 to 0.01 microg/L and 0.02 to 0.01 microg/L, respectively. HLLE provided higher preconcentration factors (472.5- and 551.2-fold) within the shorter extraction time as well as better RSDs (4.5-6.9%). While, in SFDME, high preconcentration factors in the range of 162-198 and good RSDs in the range of 5.2-9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.

  10. A dispersive liquid--liquid microextraction methodology for copper (II) in environmental samples prior to determination using microsample injection flame atomic absorption spectrometry.

    Science.gov (United States)

    Alothman, Zeid A; Habila, Mohamed; Yilmaz, Erkan; Soylak, Mustafa

    2013-01-01

    A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples.

  11. Simultaneous extraction and quantification of albendazole and triclabendazole using vortex-assisted hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography.

    Science.gov (United States)

    Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh

    2016-06-01

    A novel, simple, and rapid vortex-assisted hollow-fiber liquid-phase microextraction method was developed for the simultaneous extraction of albendazole and triclabendazole from various matrices before their determination by high-performance liquid chromatography with fluorescence detection. Several factors influencing the microextraction efficiency including sample pH, nature and volume of extraction solvent, ionic strength, vortex time, and sample volume were investigated and optimized. Under the optimal conditions, the limits of detection were 0.08 and 0.12 μg/L for albendazole and triclabendazole, respectively. The calibration curves were linear in the concentration ranges of 0.3-50.0 and 0.4-50.0 μg/L with the coefficients of determination of 0.9999 and 0.9995 for albendazole and triclabendazole, respectively. The interday and intraday relative standard deviations for albendazole and triclabendazole at three concentration levels (1.0, 10.0, and 30.0 μg/L) were in the range of 6.0-11.0 and 5.0-7.9%, respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, milk, honey, and urine samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Determination of some organophosphorus pesticides in water and watermelon samples by microextraction prior to high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Chun; Wu, Qiuhua; Wu, Chunxia; Wang, Zhi

    2011-11-01

    A novel method based on simultaneous liquid-liquid microextraction and carbon nanotube reinforced hollow fiber microporous membrane solid-liquid phase microextraction has been developed for the determination of six organophosphorus pesticides, i.e. isocarbophos, phosmet, parathion-methyl, triazophos, fonofos and phoxim, in water and watermelon samples prior to high-performance liquid chromatography (HPLC). Under the optimum conditions, the method shows a good linearity within a range of 1-200 ng/mL for water samples and 5-200 ng/g for watermelon samples, with the correlation coefficients (r) varying from 0.9990 to 0.9997 and 0.9986 to 0.9995, respectively. The limits of detection (LODs) were in the range between 0.1 and 0.3 ng/mL for water samples and between 1.0 and 1.5 ng/g for watermelon samples. The recoveries of the method at spiking levels of 5.0 and 50.0 ng/mL for water samples were between 85.4 and 100.8%, and at spiking levels of 5.0 and 50.0 ng/g for watermelon samples, they were between 82.6 and 92.4%, with the relative standard deviations (RSDs) varying from 4.5-6.9% and 5.2-7.4%, respectively. The results suggested that the developed method represents a simple, low-cost, high analytes preconcentration and excellent sample cleanup procedure for the determination of organophosphorus pesticides in water and watermelon samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Liquid-phase microextraction and fibre-optics-based cuvetteless CCD-array micro-spectrophotometry for trace analysis

    International Nuclear Information System (INIS)

    Sharma, Nisha; Pillai, Aradhana K.K.V.; Pathak, Neeraj; Jain, Archana; Verma, Krishna K.

    2009-01-01

    Liquid-phase microextraction (LPME) has been investigated for trace analysis in the present work in conjunction with fibre-optic-based micro-spectrophotometry which accommodates sample volume of 1 μL placed between the two ends of optical fibres. Methods have been evolved for the determination of (i) 1-100 μM and 0.5-20 μM of thiols by single drop microextraction (SDME) and LPME in 25 μL of the organic solvent, respectively, involving their reaction with the Ellman reagent and ion pair microextraction of thiolate ion formed; (ii) 70 μg to 7 mg L -1 of chlorine/chlorine dioxide by headspace in-drop reaction with alternative reagents, viz., mixed phenylhydrazine-4-sulphonic acid and N-(1-naphthyl)ethylenediamine dihydrochloride, o-dianisidine, o-tolidine, and N,N-diethyl-p-phenylenediamine; (iii) 0.2-4 mg L -1 of ammonia by reaction with 2,4-dinitro-1-fluorobenzene to give 2,4-dinitroaniline which was diazotized and coupled with 1-naphthylamine, the resulting dye was subjected to preconcentration by solid-phase extraction and LPME; and (iv) 25-750 μg L -1 of iodide/total iodine by oxidation of iodide by 2-iodosobenzoate, microextraction of iodine in organic solvent, and re-extraction into aqueous starch-iodide reagent drop held in the organic phase. LPME using 25-30 μL of organic solvent was found to produce more sensitive results than SDME. The cuvetteless spectrophotometry as used in combination with sample handling techniques produced limits of detection of analytes which were better than obtained by previously reported spectrophotometry.

  14. Elemental analysis by surface-enhanced Laser-Induced Breakdown Spectroscopy combined with liquid–liquid microextraction

    International Nuclear Information System (INIS)

    Aguirre, M.A.; Legnaioli, S.; Almodóvar, F.; Hidalgo, M.; Palleschi, V.; Canals, A.

    2013-01-01

    In this work, the possibility of using Laser-Induced Breakdown Spectrometry (LIBS) combined with liquid–liquid microextraction techniques is evaluated as a simple and fast method for trace elemental analysis. Two different strategies for LIBS analysis of manganese contained in microdroplets of extraction solvent (Triton X-114) are studied: (i) analysis by direct laser irradiation of microdroplets; and (ii) analysis by laser irradiation of microdroplets dried on metallic substrates (surface-enhanced LIBS — SENLIBS). Experiments were carried out using synthetic samples with different concentrations of manganese in a 10% w/w Triton X-114 matrix. The analysis by direct laser irradiation of microdroplets showed low precision, sensitivity and poor linearity across the concentration range evaluated (R 2 −1 of Mn. - Highlights: ► LIBS combined with microextraction procedures for trace analysis is proposed. ► The proposed combination depends on LIBS ability to analyze sample microvolumes. ► A surface-enhanced LIBS methodology for microdroplet analysis was evaluated. ► Results indicate this combination to be promising for trace analysis in liquids

  15. Simultaneous determination of organophosphorus pesticides and phthalates in baby food samples by ultrasound-vortex-assisted liquid-liquid microextraction and GC-IT/MS.

    Science.gov (United States)

    Notardonato, Ivan; Salimei, Elisabetta; Russo, Mario Vincenzo; Avino, Pasquale

    2018-05-01

    Baby foods are either a soft, liquid paste or an easily chewed food since babies lack developed muscles and teeth to chew effectively. Babies typically move to consuming baby food once nursing or formula is not sufficient for the child's appetite. Some commercial baby foods have been criticized for their contents. This article focuses on the simultaneous determination of organophosphorus pesticides and phthalates by means of a method based on ultrasound-vortex-assisted liquid-liquid microextraction coupled with gas chromatography-ion trap mass spectrometry (GC-IT/MS). The protocol developed allowed the determination of six phthalates [dimethyl phthalate, diethyl phthalate, dibutyl phthalate, isobutyl cyclohexyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate] and 19 organophosphorus pesticides. Freeze-dried product samples (0.1-0.2 g) were dissolved in 10 mL of warm distilled water along with 5 μL of an internal standard (anthracene at 10 mg mL -1 in acetone): the choice of extraction solvent was studied, with the most suitable being n-heptane, which is used for phthalate determination in similar matrices. The solution, held for 5 min in a vortex mixer and for 6 min in a 100-W ultrasonic bath to favor solvent dispersion and consequently analyte extraction, was centrifuged at 4000 rpm for 30 min. Then 1 μL was injected into the GC-IT/MS system (SE-54 capillary column; length 30 m, inner diameter 250 μm, film thickness 0.25 μm). All analytical parameters investigated are discussed in depth. The method was applied to real commercial freeze-dried samples: significant contaminant concentrations were not found. Graphical abstract Simultaneous and sensitive determination of organophosphorus pesticides and phthalates in baby foods by the ultrasound-vortex-assisted liquid-liquid microextraction ֪gas chromatography-ion trap mass spectrometry procedure. 1 methacrifos, 2 pirofos, 3 phorate, 4 seraphos, 5 diazinon, 6 etrimphos, 7 dichlofenthion, 8

  16. Ionic liquid-based microwave-assisted dispersive liquid–liquid microextraction and derivatization of sulfonamides in river water, honey, milk, and animal plasma

    International Nuclear Information System (INIS)

    Xu Xu; Su Rui; Zhao Xin; Liu Zhuang; Zhang Yupu; Li Dan; Li Xueyuan; Zhang Hanqi; Wang Ziming

    2011-01-01

    Graphical abstract: The extraction and derivatization efficiency of SAs is dependent on type and volume of extraction solvent, type and volume of disperser, microwave power and irradiation time, volume of derivatization reagent, pH of sample solution as well as ionic strength. Highlights: ► A new, rapid and sensitive method for determining sulfonamides (SAs) was proposed. ► Derivatization, extraction and preconcentration of SAs were performed in one step. ► IL-based MADLLME and derivatization were first applied for the determination of SAs. ► Trace SAs in river water, honey, milk, and pig plasma were determined. - Abstract: The ionic liquid-based microwave-assisted dispersive liquid–liquid microextraction (IL-based MADLLME) and derivatization was applied for the pretreatment of six sulfonamides (SAs) prior to the determination by high-performance liquid chromatography (HPLC). By adding methanol (disperser), fluorescamine solution (derivatization reagent) and ionic liquid (extraction solvent) into sample, extraction, derivatization, and preconcentration were continuously performed. Several experimental parameters, such as the type and volume of extraction solvent, the type and volume of disperser, amount of derivatization reagent, microwave power, microwave irradiation time, pH of sample solution, and ionic strength were investigated and optimized. When the microwave power was 240 W, the analytes could be derivatized and extracted simultaneously within 90 s. The proposed method was applied to the analysis of river water, honey, milk, and pig plasma samples, and the recoveries of analytes obtained were in the range of 95.0–110.8, 95.4–106.3, 95.0–108.3, and 95.7–107.7, respectively. The relative standard deviations varied between 1.5% and 7.3% (n = 5). The results showed that the proposed method was a rapid, convenient and feasible method for the determination of SAs in liquid samples.

  17. Assessment of strobilurin fungicides' content in soya-based drinks by liquid micro-extraction and liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Campillo, Natalia; Iniesta, María Jesús; Viñas, Pilar; Hernández-Córdoba, Manuel

    2015-01-01

    Seven strobilurin fungicides were pre-concentrated from soya-based drinks using dispersive liquid-liquid micro-extraction (DLLME) with a prior protein precipitation step in acid medium. The enriched phase was analysed by liquid chromatography (LC) with dual detection, using diode array detection (DAD) and electrospray-ion trap tandem mass spectrometry (ESI-IT-MS/MS). After selecting 1-undecanol and methanol as the extractant and disperser solvents, respectively, for DLLME, the Taguchi experimental method, an orthogonal array design, was applied to select the optimal solvent volumes and salt concentration in the aqueous phase. The matrix effect was evaluated and quantification was carried out using external aqueous calibration for DAD and matrix-matched calibration method for MS/MS. Detection limits in the 4-130 and 0.8-4.5 ng g(-1) ranges were obtained for DAD and MS/MS, respectively. The DLLME-LC-DAD-MS method was applied to the analysis of 10 different samples, none of which was found to contain residues of the studied fungicides.

  18. Preconcentration of valsartan by dispersive liquid-liquid microextraction based on solidification of floating organic drop and its determination in urine sample: Central composite design.

    Science.gov (United States)

    Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayesteh; Talebianpoor, Mohammad Sharif; Khodadoust, Saeid

    2016-05-01

    In this work, a fast, easy, and efficient dispersive liquid-liquid microextraction method based on solidification of floating organic drop followed by high-performance liquid chromatography with UV detection was developed for the separation/preconcentration and determination of the drug valsartan. Experimental design was applied for the optimization of the effective variables (such as volume of extracting and dispersing solvents, ionic strength, and pH) on the extraction efficiency of valsartan from urine samples. The optimized values were 250.0 μL ethanol, 65.0 μL 1-dodecanol, 4.0% w/v NaCl, pH 3.8, 1.0 min extraction time, and 4.0 min centrifugation at 4000 rpm min(-1) . The linear response (r(2) = 0.997) was obtained in the range of 0.013-10.0 μg mL(-1) with a limit of detection of 4.0 ng mL(-1) and relative standard deviations of less than 5.0 % (n = 6). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. An Ion-pair Dispersive Liquid-Liquid Microextraction for Simultaneous Determination of Synthetic Dyes in Ice Cream Samples by HPLC

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji

    2017-05-01

    Full Text Available An efficient, sensitive and fast method was developed based on an ultrasound-assisted extraction followed by an ion-pair dispersive liquid-liquid microextraction (USAE-IP-DLLME for the simultaneous determination of five commonly used synthetic sulfonate dyes (tartarazine, quinoline yellow, sunset yellow, azorubine, and brilliant blue in ice cream samples using high performance liquid chromatography. First, important parameters on USAE and samples clean-up were investigated and optimized. Then, some effective parameters on DLLME were studied and optimized. Under the optimum conditions, good linearity (0.5–1000 µg L-1, > r2=0.99 were obtained for the dyes. Limits of detection and limits of quantization were in the range of 0.01–0.05 µg L-1 and 0.03–0.15 µg L-1, respectively. The recoveries of the five synthetic colorants ranged from 90.3 to 109.7%. Intra (1.4–6.4% and inter-day precision (3.9–9.7% expressed as relative standard deviation (RSD at 10 and 100 µg L-1 levels less than 10% were also achieved. Finally, this method has been applied successfully in the determination of the colorants in the ice cream samples.

  20. Solid-phase extraction assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet to determine sildenafil and its analogues in dietary supplements.

    Science.gov (United States)

    Li, Jing; Roh, Si Hun; Shaodong, Jia; Hong, Ji Yeon; Lee, Dong-Kyu; Shin, Byong-Kyu; Park, Jeong Hill; Lee, Jeongmi; Kwon, Sung Won

    2017-08-01

    A novel analytical method for the simultaneous determination of the concentration of sildenafil and its five analogues in dietary supplements using solid-phase extraction assisted reversed-phase dispersive liquid-liquid microextraction based on solidification of floating organic droplet combined with ion-pairing liquid chromatography with an ultraviolet detector was developed. Parameters that affect extraction efficiency were systematically investigated, including the type of solid-phase extraction cartridge, pH of the extraction environment, and the type and volume of extraction and dispersive solvent. The method linearity was in the range of 5.0-100 ng/mL for sildenafil, homosildenafil, udenafil, benzylsildenafil, and thiosildenafil and 10-100 ng/mL for acetildenafil. The coefficients of determination were ≥0.996 for all regression curves. The sensitivity values expressed as limit of detection were between 2.5 and 7.5 ng/mL. Furthermore, intraday and interday precisions expressed as relative standard deviations were less than 5.7 and 9.9%, respectively. The proposed method was successfully applied to the analysis of sildenafil and its five analogues in complex dietary supplements. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Development of a novel 96-well format for liquid-liquid microextraction and its application in the HPLC analysis of biological samples.

    Science.gov (United States)

    Borijihan, Guirong; Li, Youxin; Gao, Jianguo; Bao, James J

    2014-05-01

    A novel 96-well liquid-liquid microextraction system combined with modern HPLC was developed and used for the simultaneous analysis of 96 biological samples. The system made use of hollow fibers, a 96-well plate, and a plastic base with a center hole and a side hole. One end of the hollow fiber was sealed, while the other end was attached to one of the holes positioned at the center for the plastic base. The needle was inserted into the liquid from inside or outside of the hollow fiber through the center or the side holes, respectively. The system was tested with plasma samples containing three compounds, acidic indomethacin, neutral dexamethasone, and basic propafenone. Some parameters, such as the kind and dimension of hollow fiber, pH and salt concentration of the donor phase, the selection of organic solvent for the acceptor phase, and the extraction time were investigated. Under the optimization conditions, the Log D and drug concentration of indomethacin, dexamethasone, and propafenone in plasma and urine samples were analyzed. Then, the methodology was validated. The results demonstrated that ng/mL levels could be exactly and rapidly analyzed by our system, which was equipped with an auto-injection sampler, making sample analysis more convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Dispersive liquid-liquid microextraction with solidification of floating organic droplets for simultaneous extraction of pesticides, pharmaceuticals and personal care products

    International Nuclear Information System (INIS)

    Marube, Liziane Cardoso; Caldas, Sergiane Souza; Soares, Karina Lotz; Primel, Ednei Gilberto

    2015-01-01

    Dispersive liquid-liquid microextraction based on solidification of floating organic droplets (DLLME-SFO) has been applied to the extraction of pharmaceutical and personal care products (PPCPs) and pesticides from water samples. The PPCPs included bisphenol A, sodium diclofenac, gemfibrozil, furosemide, glibenclamide, nifedipine, nimesulide, propylparaben and triclocarban. The pesticides included 2,4-D, atrazine, azoxystrobin, cyproconazole, clomazone, dichloran, difenoconazole, diuron, epoxiconazole, fenoxaprop-p-ethyl, fipronil, iprodione, irgarol, propanil, propiconazole, tebuconazole, and trifloxystrobin. The type and volume of extraction solvent, type and volume of disperser solvent, ionic strength and pH were optimized. All species were then quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). The limits of quantification (LOQs) ranged from 50 to 500 ng L −1 , and the linearity ranged from the LOQ of each compound up to 10,000 ng L −1 . Recoveries ranged from 63 to 120 %, with relative standard deviations lower than 14 %. It is making use of a low-toxicity and affordable extraction solvent (1-dodecanol) and was successfully applied to the analysis of surface water samples. (author)

  3. Simultaneous Pre-Concentration of Cadmium and Lead in Environmental Water Samples with Dispersive Liquid-Liquid Microextraction and Determination by Inductively Coupled Plasma-Atomic Emission Spectrometry

    Directory of Open Access Journals (Sweden)

    M. Salahinejad

    2013-06-01

    Full Text Available The dispersive liquid–liquid microextraction (DLLME method for determination of Pb+2 and Cd+2 ions in the environmental water samples was combined with inductively coupled plasma-atomic emission spectrometry (ICP-AES. Ammonium pyrrolidine dithiocarbamate (APDC, chloroform and ethanol were used as chelating agent, extraction solvent and disperser solvent, respectively. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters included extraction and disperser solvent type as well as their volume, extraction time, salt effect, pH, sample volume and amount of the chelating agent.   Under the optimum conditions, the enrichment factor of 75 and 105 for Cd+2 and Pb+2 ions respectively was obtained from only 5.00mL of water sample. The detection limit (S/N=3 was 12 and 0.8ngmL−1 for Pb and Cd respectively. The relative standard deviation (RSDs for five replicate measurements of 0.50 mgL−1 of lead and cadmium was 6.5 and 4.4 % respectively. Mineral, tap, river, sea, dam and spiked water samples were analyzed for Cd and Pb amount.

  4. A new combined method of stable isotope-labeling derivatization-ultrasound-assisted dispersive liquid-liquid microextraction for the determination of neurotransmitters in rat brain microdialysates by ultra high performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Zheng, Longfang; Zhao, Xian-En; Zhu, Shuyun; Tao, Yanduo; Ji, Wenhua; Geng, Yanling; Wang, Xiao; Chen, Guang; You, Jinmao

    2017-06-01

    In this work, for the first time, a new hyphenated technique of stable isotope-labeling derivatization-ultrasound-assisted dispersive liquid-liquid microextraction has been developed for the simultaneous determination of monoamine neurotransmitters (MANTs) and their biosynthesis precursors and metabolites. The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry detection using multiple-reaction monitoring mode. A pair of mass spectrometry sensitizing reagents, d 0 -10-methyl-acridone-2-sulfonyl chloride and d 3 -10-methyl-acridone-2-sulfonyl chloride, as stable isotope probes was utilized to facilely label neurotransmitters, respectively. The heavy labeled MANTs standards were prepared and used as internal standards for quantification to minimize the matrix effects in mass spectrometry analysis. Low toxic bromobenzene (extractant) and acetonitrile (dispersant) were utilized in microextraction procedure. Under the optimized conditions, good linearity was observed with the limits of detection (S/N>3) and limits of quantification (S/N>10) in the range of 0.002-0.010 and 0.015-0.040nmol/L, respectively. Meanwhile, it also brought acceptable precision (4.2-8.8%, peak area RSDs %) and accuracy (recovery, 96.9-104.1%) results. This method was successfully applied to the simultaneous determination of monoamine neurotransmitters and their biosynthesis precursors and metabolites in rat brain microdialysates of Parkinson's disease and normal rats. This provided a new method for the neurotransmitters related studies in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Application and optimization of microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for sensitive determination of polyamines in turkey breast meat samples.

    Science.gov (United States)

    Bashiry, Moein; Mohammadi, Abdorreza; Hosseini, Hedayat; Kamankesh, Marzieh; Aeenehvand, Saeed; Mohammadi, Zaniar

    2016-01-01

    A novel method based on microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by high-performance liquid chromatography (HPLC) was developed for the determination of three polyamines from turkey breast meat samples. Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the effective factors in DLLME process. The optimum microextraction efficiency was obtained under optimized conditions. The calibration graphs of the proposed method were linear in the range of 20-200 ng g(-1), with the coefficient determination (R(2)) higher than 0.9914. The relative standard deviations were 6.72-7.30% (n = 7). The limits of detection were in the range of 0.8-1.4 ng g(-1). The recoveries of these compounds in spiked turkey breast meat samples were from 95% to 105%. The increased sensitivity in using the MAE-DLLME-HPLC-UV has been demonstrated. Compared with previous methods, the proposed method is an accurate, rapid and reliable sample-pretreatment method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Simultaneous Determination of Food-Related Biogenic Amines and Precursor Amino Acids Using in Situ Derivatization Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction by Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry.

    Science.gov (United States)

    He, Yongrui; Zhao, Xian-En; Wang, Renjun; Wei, Na; Sun, Jing; Dang, Jun; Chen, Guang; Liu, Zhiqiang; Zhu, Shuyun; You, Jinmao

    2016-11-02

    A simple, rapid, sensitive, selective, and environmentally friendly method, based on in situ derivatization ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using multiple reaction monitoring (MRM) mode has been developed for the simultaneous determination of food-related biogenic amines and amino acids. A new mass-spectrometry-sensitive derivatization reagent 4'-carbonyl chloride rosamine (CCR) was designed, synthesized, and first reported. Parameters and conditions of in situ DUADLLME and UHPLC-MS/MS were optimized in detail. Under the optimized conditions, the in situ DUADLLME was completed speedily (within 1 min) with high derivatization efficiencies (≥98.5%). With the cleanup and concentration of microextraction step, good analytical performance was obtained for the analytes. The results showed that this method was accurate and practical for quantification of biogenic amines and amino acids in common food samples (red wine, beer, wine, cheese, sausage, and fish).

  7. Evaluation and application of microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of polar heterocyclic aromatic amines in hamburger patties.

    Science.gov (United States)

    Aeenehvand, Saeed; Toudehrousta, Zahra; Kamankesh, Marzieh; Mashayekh, Morteza; Tavakoli, Hamid Reza; Mohammadi, Abdorreza

    2016-01-01

    This study developed an analytical method based on microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of three polar heterocyclic aromatic amines from hamburger patties. Effective parameters controlling the performance of the microextraction process, such as the type and volume of extraction and disperser solvents, microwave time, nature of alkaline aqueous solution, pH and salt amount, were optimized. The calibration graphs were linear in the range of 1-200 ng g(-1), with a coefficient of determination (R(2)) better than 0.9993. The relative standard deviations (RSD) for seven analyses were between 3.2% and 6.5%. The recoveries of those compounds in hamburger patties were from 90% to 105%. Detection limits were between 0.06 and 0.21 ng g(-1). A comparison of the proposed method with the existing literature demonstrates that it is a simple, rapid, highly selective and sensitive, and it gives good enrichment factors and detection limits for determining HAAs in real hamburger patties samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Rapid and sensitive analysis of polychlorinated biphenyls and acrylamide in food samples using ionic liquid-based in situ dispersive liquid-liquid microextraction coupled to headspace gas chromatography.

    Science.gov (United States)

    Zhang, Cheng; Cagliero, Cecilia; Pierson, Stephen A; Anderson, Jared L

    2017-01-20

    A simple and rapid ionic liquid (IL)-based in situ dispersive liquid-liquid microextraction (DLLME) method was developed and coupled to headspace gas chromatography (HS-GC) employing electron capture (ECD) and mass spectrometry (MS) detection for the analysis of polychlorinated biphenyls (PCBs) and acrylamide at trace levels from milk and coffee samples. The chemical structures of the halide-based ILs were tailored by introducing various functional groups to the cations to evaluate the effect of different structural features on the extraction efficiency of the target analytes. Extraction parameters including the molar ratio of IL to metathesis reagent and IL mass were optimized. The effects of HS oven temperature and the HS sample vial volume on the analyte response were also evaluated. The optimized in situ DLLME method exhibited good analytical precision, good linearity, and provided detection limits down to the low ppt level for PCBs and the low ppb level for acrylamide in aqueous samples. The matrix-compatibility of the developed method was also established by quantifying acrylamide in brewed coffee samples. This method is much simpler and faster compared to previously reported GC-MS methods using solid-phase microextraction (SPME) for the extraction/preconcentration of PCBs and acrylamide from complex food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Alternative solvent-based methyl benzoate vortex-assisted dispersive liquid-liquid microextraction for the high-performance liquid chromatographic determination of benzimidazole fungicides in environmental water samples.

    Science.gov (United States)

    Santaladchaiyakit, Yanawath; Srijaranai, Supalax

    2014-11-01

    Vortex-assisted dispersive liquid-liquid microextraction using methyl benzoate as an alternative extraction solvent for extracting and preconcentrating three benzimidazole fungicides (i.e., carbendazim, thiabendazole, and fluberidazole) in environmental water samples before high-performance liquid chromatographic analysis has been developed. The selected microextraction conditions were 250 μL of methyl benzoate containing 300 μL of ethanol, 1.0% w/v sodium acetate, and vortex agitation speed of 2100 rpm for 30 s. Under optimum conditions, preconcentration factors were 14.5-39.0 for the target fungicides. Limits of detection were obtained in the range of 0.01-0.05 μg/L. The proposed method was then applied to surface water samples and the recovery evaluations at three spiked concentration levels of 5, 30, and 50 μg/L were obtained in the range of 77.4-110.9% with the relative standard deviation water samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Extraction and preconcentration of trace Al and Cr from vegetable samples by vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction prior to atomic absorption spectrometric determination.

    Science.gov (United States)

    Altunay, Nail; Yıldırım, Emre; Gürkan, Ramazan

    2018-04-15

    In the study, a simple, and efficient microextraction approach, which is termed as vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction (VA-IL-DLLME), was developed for flame atomic absorption spectrometric analysis of aluminum (Al) and chromium (Cr) in vegetables. The method is based on the formation of anionic chelate complexes of Al(III) and Cr(VI) with o-hydroxy azo dye, at pH 6.5, and then extraction of the hydrophobic ternary complexes formed in presence of cetyltrimethylammonium bromide (CTAB) into a 125 μL volume of 1-butyl-3-methylimidazolium bis(trifluorosulfonyl)imide [C 4 mim][Tf 2 N]) as extraction solvent. Under optimum conditions, the detection limits were 0.02 µg L -1 in linear working range of 0.07-100 µg L -1 for Al(III), and 0.05 µg L -1 in linear working range of 0.2-80 µg L -1 for Cr(VI). After the validation by analysis of a certified reference material (CRM), the method was successfully applied to the determination of Al and Cr in vegetables using standard addition method. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Optimisation of ultrasound-assisted reverse micelles dispersive liquid-liquid micro-extraction by Box-Behnken design for determination of acetoin in butter followed by high performance liquid chromatography.

    Science.gov (United States)

    Roosta, Mostafa; Ghaedi, Mehrorang; Daneshfar, Ali

    2014-10-15

    A novel approach, ultrasound-assisted reverse micelles dispersive liquid-liquid microextraction (USA-RM-DLLME) followed by high performance liquid chromatography (HPLC) was developed for selective determination of acetoin in butter. The melted butter sample was diluted and homogenised by n-hexane and Triton X-100, respectively. Subsequently, 400μL of distilled water was added and the microextraction was accelerated by 4min sonication. After 8.5min of centrifugation, sedimented phase (surfactant-rich phase) was withdrawn by microsyringe and injected into the HPLC system for analysis. The influence of effective variables was optimised using Box-Behnken design (BBD) combined with desirability function (DF). Under optimised experimental conditions, the calibration graph was linear over the range of 0.6-200mgL(-1). The detection limit of method was 0.2mgL(-1) and coefficient of determination was 0.9992. The relative standard deviations (RSDs) were less than 5% (n=5) while the recoveries were in the range of 93.9-107.8%. Copyright © 2014. Published by Elsevier Ltd.

  12. Combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry using microsample introduction for determination of lead in water samples.

    Science.gov (United States)

    Naseri, Mohammad Taghi; Hemmatkhah, Payam; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub

    2008-03-03

    The dispersive liquid-liquid microextraction (DLLME) was combined with the flame atomic absorption spectrometry (FAAS) for determination of lead in the water samples. Diethyldithiophosphoric acid (DDTP), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. A new FAAS sample introduction system was employed for the microvolume nebulization of the non-flammable chlorinated organic extracts. Injection of 20 microL volumes of the organic extract into an air-acetylene flame provided very sensitive spike-like and reproducible signals. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters include extraction and disperser solvent type as well as their volume, extraction time, salt effect, pH and amount of the chelating agent. Under the optimized conditions, the enrichment factor of 450 was obtained from a sample volume of 25.0 mL. The enhancement factor, calculated as the ratio of the slopes of the calibration graphs with and without preconcentration, which was about 1000. The calibration graph was linear in the range of 1-70 microgL(-1) with a detection limit of 0.5 microgL(-1). The relative standard deviation (R.S.D.) for seven replicate measurements of 5.0 and 50 microgL(-1) of lead were 3.8 and 2.0%, respectively. The relative recoveries of lead in tap, well, river and seawater samples at the spiking level of 20 microgL(-1) ranged from 93.8 to 106.2%. The characteristics of the proposed method were compared with those of the liquid-liquid extraction (LLE), cloud point extraction (CPE), on-line and off-line solid-phase extraction (SPE) as well as co-precipitation, based on bibliographic data. Operation simplicity, rapidity, low cost, high enrichment factor, good repeatability, and low consumption of the extraction solvent at a microliter level are the main advantages of the proposed method.

  13. Combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry using microsample introduction for determination of lead in water samples

    International Nuclear Information System (INIS)

    Naseri, Mohammad Taghi; Hemmatkhah, Payam; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub

    2008-01-01

    The dispersive liquid-liquid microextraction (DLLME) was combined with the flame atomic absorption spectrometry (FAAS) for determination of lead in the water samples. Diethyldithiophosphoric acid (DDTP), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. A new FAAS sample introduction system was employed for the microvolume nebulization of the non-flammable chlorinated organic extracts. Injection of 20 μL volumes of the organic extract into an air-acetylene flame provided very sensitive spike-like and reproducible signals. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters include extraction and disperser solvent type as well as their volume, extraction time, salt effect, pH and amount of the chelating agent. Under the optimized conditions, the enrichment factor of 450 was obtained from a sample volume of 25.0 mL. The enhancement factor, calculated as the ratio of the slopes of the calibration graphs with and without preconcentration, which was about 1000. The calibration graph was linear in the range of 1-70 μg L -1 with a detection limit of 0.5 μg L -1 . The relative standard deviation (R.S.D.) for seven replicate measurements of 5.0 and 50 μg L -1 of lead were 3.8 and 2.0%, respectively. The relative recoveries of lead in tap, well, river and seawater samples at the spiking level of 20 μg L -1 ranged from 93.8 to 106.2%. The characteristics of the proposed method were compared with those of the liquid-liquid extraction (LLE), cloud point extraction (CPE), on-line and off-line solid-phase extraction (SPE) as well as co-precipitation, based on bibliographic data. Operation simplicity, rapidity, low cost, high enrichment factor, good repeatability, and low consumption of the extraction solvent at a microliter level are the main advantages of the proposed method

  14. Solid-phase extraction in combination with dispersive liquid-liquid microextraction and ultra-high performance liquid chromatography-tandem mass spectrometry analysis: the ultra-trace determination of 10 antibiotics in water samples.

    Science.gov (United States)

    Liang, Ning; Huang, Peiting; Hou, Xiaohong; Li, Zhen; Tao, Lei; Zhao, Longshan

    2016-02-01

    A novel method, solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME), was developed for ultra-preconcentration of 10 antibiotics in different environmental water samples prior to ultra-high performance liquid chromatography-tandem mass spectrometry detection. The optimized results were obtained as follows: after being adjusted to pH 4.0, the water sample was firstly passed through PEP-2 column at 10 mL min(-1), and then methanol was used to elute the target analytes for the following steps. Dichloromethane was selected as extraction solvent, and methanol/acetonitrile (1:1, v/v) as dispersive solvent. Under optimal conditions, the calibration curves were linear in the range of 1-1000 ng mL(-1) (sulfamethoxazole, cefuroxime axetil), 5-1000 ng mL(-1) (tinidazole), 10-1000 ng mL(-1) (chloramphenicol), 2-1000 ng mL(-1) (levofloxacin oxytetracycline, doxycycline, tetracycline, and ciprofloxacin) and 1-400 ng mL(-1) (sulfadiazine) with a good precision. The LOD and LOQ of the method were at very low levels, below 1.67 and 5.57 ng mL(-1), respectively. The relative recoveries of the target analytes were in the range from 64.16% to 99.80% with relative standard deviations between 0.7 and 8.4%. The matrix effect of this method showed a great decrease compared with solid-phase extraction and a significant value of enrichment factor (EF) compared with dispersive liquid-liquid microextraction. The developed method was successfully applied to the extraction and analysis of antibiotics in different water samples with satisfactory results.

  15. Simultaneous determination of atorvastatin and valsartan in human plasma by solid-based disperser liquid-liquid microextraction followed by high-performance liquid chromatography-diode array detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Khorram, Parisa; Pazhohan, Azar

    2016-04-01

    A simple, sensitive, and efficient method has been developed for simultaneous estimation of valsartan and atorvastatin in human plasma by combination of solid-based dispersive liquid-liquid microextraction and high performance liquid chromatography-diode array detection. In the proposed method, 1,2-dibromoethane (extraction solvent) is added on a sugar cube (as a solid disperser) and it is introduced into plasma sample containing the analytes. After manual shaking and centrifugation, the resultant sedimented phase is subjected to back extraction into a small volume of sodium hydrogen carbonate solution using air-assisted liquid-liquid microextraction. Then the cloudy solution is centrifuged and the obtained aqueous phase is transferred into a microtube and analyzed by the separation system. Under the optimal conditions, extraction recoveries are obtained in the range of 81-90%. Calibration curves plotted in drug-free plasma sample are linear in the ranges of 5-5000μgL(-1) for valsartan and 10-5000μgL(-1) for atorvastatin with the coefficients of determination higher than 0.997. Limits of detection and quantification of the studied analytes in plasma sample are 0.30-2.6 and 1.0-8.2μgL(-1), respectively. Intra-day (n=6) and inter-days (n=4) precisions of the method are satisfactory with relative standard deviations less than 7.4% (at three levels of 10, 500, and 2000μgL(-1), each analyte). These data suggest that the method can be successfully applied to determine trace amounts of valsartan and atorvastatin in human plasma samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Zeng, Chujie; Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei

    2012-01-01

    Highlights: ► First reported enhancement effect of RTILs in HF-LPME for the speciation of chromium. ► The addition of RTILs led to 3.5 times improvement of the sensitivity of Cr(VI). ► The proposed method is a simplicity, sensitivity, low cost, green method. - Abstract: A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO 4 and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL −1 and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL −1 , n = 5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

  17. Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chujie, E-mail: cjzeng@126.com [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China); Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer First reported enhancement effect of RTILs in HF-LPME for the speciation of chromium. Black-Right-Pointing-Pointer The addition of RTILs led to 3.5 times improvement of the sensitivity of Cr(VI). Black-Right-Pointing-Pointer The proposed method is a simplicity, sensitivity, low cost, green method. - Abstract: A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO{sub 4} and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL{sup -1} and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL{sup -1}, n = 5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

  18. Simultaneous determination of furfural and its degradation products, furoic acid and maleic acid, in transformer oil by the reversed-phase vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Wang, Yifan; Li, Haiyan; Yang, Zhen; Zhang, Weijie; Hua, Jia

    2017-12-01

    To explore why the use of furfural as a transformer oil-paper insulation aging characteristic is problematic in real world application, we developed a method for the simultaneous determination of furfural, furoic acid, and maleic acid in transformer oil by reversed-phase vortex-assisted liquid-liquid microextraction combined with high-performance liquid chromatography. The conditions for the proposed method were optimized, and the obtained extract can be directly analyzed by high-performance liquid chromatography. The detection limits (signal-to-noise ratio = 3) of the method ranged from 1.0 to 4.6 μg/L, the enrichment factors for furfural, furoic acid, maleic acid, and fumaric acid were 4.6, 25.1, 15.6, and 17.5, respectively, and the recovery rates for three analytes (fumaric acid was undetected) range from 82.1 to 106.2%. The contents of furfural, furoic acid, and maleic acid resulted from accelerated aging of transformer insulation oil-paper were measured using the present method for the first time, and the aging samples were analyzed by liquid chromatography with mass spectrometry for the identification of furoic acid and maleic acid in the aging transformer oil samples. Using the optimal method, the target products of samples at different aging time were tracked and measured. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of the aqueous phase for preconcentration of heavy metals ions prior to determination by LC-UV.

    Science.gov (United States)

    Werner, Justyna

    2018-05-15

    Ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of the aqueous phase was used for preconcentration of Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ , Pb 2+ in natural water samples prior to liquid chromatography with UV detection. In the proposed method, the ammonium pyrrolidinedithiocarbamate was used as a complexing agent and the phosphonium ionic liquid trihexyl(tetradecyl)phosphonium bis[(2,4,4-trimethyl)pentyl]phosphinate (Cyphos IL 104) was used as an extractant. Ultrasound energy was used to disperse the extractant in the aqueous phase. After microextraction, the ionic liquid and aqueous phases were separated by centrifugation. Then the aqueous phase was frozen and the lighter than water ionic liquid phase containing metal ions complexes with pyrrolidinedithiocarbamate was separated and dissolved in a small volume of methanol prior to injection into the liquid chromatograph. Several parameters including the volume of extractant, the pH of the sample, the concentration of complexing agent, the time of ultrasound energy treatment, the time and speed of centrifugation and the effect of ionic strength were optimized. Under the optimized conditions (10 µL of Cyphos IL 104, pH = 5, 0.3% w/v ammonium pyrrolidinedithiocarbamate, 60 s of ultrasound use, 5 min/5000 rpm (2516×g) of centrifugation, 2.0 mg of NaCl), preconcentration factors were 211, 210, 209, 207 and 211 for Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ and Pb 2+ respectively. Linearity was observed in the ranges 0.2-75.0 µg L -1 for Pb 2+ , Cd 2+ , Co 2+ and 0.5-100.0 µg L -1 for Cu 2+ , Ni 2+ . The limits of detection were 0.03 µg L -1 for Ni 2+ , 0.03 µg L -1 for Co 2+ , 0.03 µg L -1 for Cd 2+ , 0.02 µg L -1 for Cu 2+ , 0.02 µg L -1 for Pb 2+ , respectively. The accuracy of this method was evaluated by preconcentration and determination of Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ , Pb 2+ in certified reference materials (TMRAIN-04 and NIST 1643e

  20. Development of a new extraction method based on counter current salting-out homogenous liquid-liquid extraction followed by dispersive liquid-liquid microextraction: Application for the extraction and preconcentration of widely used pesticides from fruit juices.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Feriduni, Behruz; Mogaddam, Mohammad Reza Afshar

    2016-01-01

    In this paper, a new extraction method based on counter current salting-out homogenous liquid-liquid extraction (CCSHLLE) followed by dispersive liquid-liquid microextraction (DLLME) has been developed for the extraction and preconcentration of widely used pesticides in fruit juice samples prior to their analysis by gas chromatography-flame ionization detection (GC-FID). In this method, initially, sodium chloride as a separation reagent is filled into a small column and a mixture of water (or fruit juice) and acetonitrile is passed through the column. By passing the mixture sodium chloride is dissolved and the fine droplets of acetonitrile are formed due to salting-out effect. The produced droplets go up through the remained mixture and collect as a separated layer. Then, the collected organic phase (acetonitrile) is removed with a syringe and mixed with 1,1,2,2-tetrachloroethane (extraction solvent at µL level). In the second step, for further enrichment of the analytes the above mixture is injected into 5 mL de-ionized water placed in a test tube with conical bottom in order to dissolve acetonitrile into water and to achieve a sedimented phase at µL-level volume containing the enriched analytes. Under the optimal extraction conditions (extraction solvent, 1.5 mL acetonitrile; pH, 7; flow rate, 0.5 mL min(-1); preconcentration solvent, 20 µL 1,1,2,2-tetrachloroethane; NaCl concentration; 5%, w/w; and centrifugation rate and time, 5000 rpm and 5 min, respectively), the extraction recoveries and enrichment factors ranged from 87% to 96% and 544 to 600, respectively. Repeatability of the proposed method, expressed as relative standard deviations, ranged from 2% to 6% for intra-day (n=6, C=250 or 500 µg L(-1)) and inter-days (n=4, C=250 or 500 µg L(-1)) precisions. Limits of detection are obtained between 2 and 12 µg L(-1). Finally, the proposed method is applied for the determination of the target pesticide residues in the juice samples. Copyright © 2015

  1. Method for the determination of carboxylic acids in industrial effluents using dispersive liquid-liquid microextraction with injection port derivatization gas chromatography-mass spectrometry.

    Science.gov (United States)

    Makoś, Patrycja; Fernandes, Andre; Boczkaj, Grzegorz

    2017-09-29

    The paper presents a new method for the determination of 15 carboxylic acids in samples of postoxidative effluents from the production of petroleum bitumens using ion-pair dispersive liquid-liquid microextraction and gas chromatography coupled to mass spectrometry with injection port derivatization. Several parameters related to the extraction and derivatization efficiency were optimized. Under optimized experimental conditions, the obtained limit of detection and quantification ranged from 0.0069 to 1.12μg/mL and 0.014 to 2.24μg/mL, respectively. The precision (RSD ranged 1.29-6.42%) and recovery (69.43-125.79%) were satisfactory. Nine carboxylic acids at concentrations ranging from 0.10μg/mL to 15.06μg/mL were determined in the raw wastewater and in samples of effluents treated by various oxidation methods. The studies revealed a substantial increase of concentration of benzoic acids, in samples of wastewater after treatment, which confirms the need of carboxylic acids monitoring during industrial effluent treatment processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Simple and fast method for iron determination in white and red wines using dispersive liquid-liquid microextraction and ultraviolet-visible spectrophotometry.

    Science.gov (United States)

    Maciel, Juliana V; Soares, Bruno M; Mandlate, Jaime S; Picoloto, Rochele S; Bizzi, Cezar A; Flores, Erico M M; Duarte, Fabio A

    2014-08-20

    This work reports the development of a method for Fe extraction in white and red wines using dispersive liquid-liquid microextraction (DLLME) and determination by ultraviolet-visible spectrophotometry. For optimization of the DLLME method, the following parameters were evaluated: type and volume of dispersive (1300 μL of acetonitrile) and extraction (80 μL of C(2)Cl(4)) solvents, pH (3.0), concentration of ammonium pyrrolidinedithiocarbamate (APDC, 500 μL of 1% m/v APDC solution), NaCl concentration (not added), and extraction time. The calibration curve was performed using the analyte addition method, and the limit of detection and relative standard deviation were 0.2 mg L(-1) and below 7%, respectively. The accuracy was evaluated by comparison of results obtained after Fe determination by graphite furnace atomic absorption spectrometry, with agreement ranging from 94 to 105%. The proposed method was applied for Fe determination in white and red wines with concentrations ranging from 1.3 to 4.7 mg L(-1).

  3. A Facile Vortex-Assisted Dispersive Liquid-Liquid Microextraction Method for the Determination of Uranyl Ion at Low Levels by Spectrophotometry.

    Science.gov (United States)

    Corazza, Marcela Zanetti; Pires, Igor Matheus Ruiz; Diniz, Kristiany Moreira; Segatelli, Mariana Gava; Tarley, César Ricardo Teixeira

    2015-08-01

    A facile and reliable UV-Vis spectrophotometric method associated with vortex-assisted dispersive liquid-liquid microextraction has been developed and applied to the determination of U(VI) at low levels in water samples. It was based on preconcentration of 24.0 mL sample at pH 8.0 in the presence of 7.4 µmol L(-1) 1-(2-pyridylazo)-2-naphthol, 1.0 mL of methanol as disperser solvent and 1.0 mL of chloroform as extraction solvent. A high preconcentration factor was achieved (396 times), thus providing a wide analytical curve from 6.9 up to 75.9 µg L(-1) (r=0.9982) and limits of detection and quantification of 0.40 and 1.30 µg L(-1), respectively. When necessary, EDTA or KCN can be used to remove interferences of foreign ions. The method was applied to the analysis of real water samples, such as tap, mineral and lake waters with good recovery values.

  4. Effervescence-assisted dispersive liquid-liquid microextraction using a solid effervescent agent as a novel dispersion technique for the analysis of fungicides in apple juice.

    Science.gov (United States)

    Jiang, Wenqing; Chen, Xiaochu; Liu, Fengmao; You, Xiangwei; Xue, Jiaying

    2014-11-01

    A novel effervescence-assisted dispersive liquid-liquid microextraction method has been developed for the determination of four fungicides in apple juice samples. In this method, a solid effervescent agent is added into samples to assist the dispersion of extraction solvent. The effervescent agent is environmentally friendly and only produces an increase in the ionic strength and a negligible variation in the pH value of the aqueous sample, which does not interfere with the extraction of the analytes. The parameters affecting the extraction efficiency were investigated including the composition of effervescent agent, effervescent agent amount, formulation of effervescent agent, adding mode of effervescent agent, type and volume of extraction solvent, and pH. Under optimized conditions, the method showed a good linearity within the range of 0.05-2 mg/L for pyrimethanil, fludioxonil, and cyprodinil, and 0.1-4 mg/L for kresoxim-methyl, with the correlation coefficients >0.998. The limits of detection for the method ranged between 0.005 and 0.01 mg/L. The recoveries of the target fungicides in apple juice samples were in the range of 72.4-110.8% with the relative standard deviations ranging from 1.2 to 6.8%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Determination of phthalic acid esters in Chinese white spirit using dispersive liquid-liquid microextraction coupled with sweeping β-cyclodextrin-modified micellar electrokinetic chromatography.

    Science.gov (United States)

    Sun, Jianzhi; He, Hui; Liu, Shuhui

    2014-07-01

    A simple method that consumes low organic solvent is proposed for the analysis of phthalic acid esters in Chinese white spirit using dispersive liquid-liquid microextraction coupled with sweeping-micellar electrokinetic chromatography. Tetrachloromethane and white-spirit-containing ethanol were used as the extraction and dispersing solvents, respectively. The electrophoresis separation buffer was composed of 5 mM β-cyclodextrin, 50 mM sodium dodecyl sulfate and 25 mM borate buffer (pH 9.2) with 9% acetonitrile, enabling the baseline resolution of the analytes within 13 min. Under the optimum conditions, satisfactory linearities (5-1000 ng/mL, r ≥ 0.9909), good reproducibility (RSD ≤ 6.7% for peak area, and RSD ≤ 2.8% for migration time), low detection limits (0.4-0.8 ng/mL) and acceptable recovery rates (89.6-105.7%) were obtained. The proposed method was successfully applied to 22 Chinese white spirits, and the content of dibutyl phthalate in 55% of the samples exceeded the Specific Migration Limit of 0.3 mg/kg established by the domestic and international regulations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Solid-phase extraction followed by dispersive liquid-liquid microextraction for the sensitive determination of ecstasy compounds and amphetamines in biological samples

    Directory of Open Access Journals (Sweden)

    H. A. Mashayekhi

    2014-09-01

    Full Text Available A novel approach for the determination of ecstasy and amphetamines (3,4-methylenedioxymethylamphetamine (MDMA, Ecstasy, 3,4-methylenedioxyamphetamine (MDA, 3,4-methylenedioxyethylamphetamine (MDEA and 3,4-methylenedioxypropylamphetamine (MDPA in biological samples is presented. The analytes were extracted from the matrix and transferred to a small volume of a high density, water insoluble solvent using solid-phase extraction (SPE followed by dispersive liquid-liquid microextraction (DLLME. This combination not only resulted in a high enrichment factor, but also it could be used in complex matrices (biological samples. Some important extraction parameters, such as sample solution flow rate, sample pH, type and volume of extraction and disperser solvents as well as the salt addition, were studied and optimized. Under the optimized conditions, the calibration graphs were linear in the range of 0.5-500 µg L-1 and 1.0-500 µg L-1 with detection limits in the range of 0.1-0.3 µg L-1 and 0.2-0.7 µg L-1 in urine and plasma samples, respectively. The results showed that SPE-DLLME is a suitable method for the determination of ecstasy components and amphetamines in biological and water samples. DOI: http://dx.doi.org/10.4314/bcse.v28i3.3

  7. Dispersive liquid-liquid microextraction coupled with digital image colorimetric analysis for detection of total iron in water and food samples.

    Science.gov (United States)

    Peng, Bo; Chen, Guorong; Li, Kai; Zhou, Min; Zhang, Ji; Zhao, Shengguo

    2017-09-01

    A simple and low cost assay for total iron in various samples based on dispersive liquid-liquid microextraction (DLLME) coupled with digital scanning image analysis was proposed. Orthogonal experiment design was utilized to optimize the amount of extraction solvent and disperser solvent, O-phenanthroline concentration and buffer pH. Under the optimum conditions, the calibration curve was linear over the range of 0.047-1.0μgmL -1 (R 2 >0.99) of iron. The limit of detection (LOD) for iron was 14.1μgL -1 and limit of quantification (LOQ) was 46.5μgL -1 . The relative standard deviations for seven replicate determinations of 0.5μgmL -1 of iron was 3.75%. The method was successfully applied for analysis of total iron in water and food samples without using any spectral instrument and it could have a potential industrial impact in developing fast and portable devices to analyze the iron content in water and certain foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Optimization of dispersive liquid-phase microextraction based on solidified floating organic drop combined with high-performance liquid chromatography for the analysis of glucocorticoid residues in food.

    Science.gov (United States)

    Huang, Yuan; Zheng, Zhiqun; Huang, Liying; Yao, Hong; Wu, Xiao Shan; Li, Shaoguang; Lin, Dandan

    2017-05-10

    A rapid, simple, cost-effective dispersive liquid-phase microextraction based on solidified floating organic drop (SFOD-LPME) was developed in this study. Along with high-performance liquid chromatography, we used the developed approach to determine and enrich trace amounts of four glucocorticoids, namely, prednisone, betamethasone, dexamethasone, and cortisone acetate, in animal-derived food. We also investigated and optimized several important parameters that influenced the extraction efficiency of SFOD-LPME. These parameters include the extractant species, volumes of extraction and dispersant solvents, sodium chloride addition, sample pH, extraction time and temperature, and stirring rate. Under optimum experimental conditions, the calibration graph exhibited linearity over the range of 1.2-200.0ng/ml for the four analytes, with a reasonable linearity(r 2 : 0.9990-0.9999). The enrichment factor was 142-276, and the detection limits was 0.39-0.46ng/ml (0.078-0.23μg/kg). This method was successfully applied to analyze actual food samples, and good spiked recoveries of over 81.5%-114.3% were obtained. Copyright © 2017. Published by Elsevier B.V.

  9. Simultaneous determination of three purines in Alysicarpus vaginalis (L.) DC. by hollow fiber-based liquid-phase microextraction combined with high-performance liquid chromatography.

    Science.gov (United States)

    Liu, Hongjiao; Lei, Ming; Liang, Xiao; Jiang, Zhen; Guo, Xingjie

    2014-02-01

    In this paper, a three-phase hollow fiber liquid-phase microextraction (HF-LPME) method combined with high-performance liquid chromatography (HPLC) was developed for the determination of hypoxanthine (HX), xanthine (Xan) and adenine (A) and then for the first time successfully applied to the analysis of HX, Xan and A in Alysicarpus vaginalis (L.) DC. medicinal materials. Different factors affecting the HF-LPME procedure were investigated and optimized. Under optimal extraction conditions (1-octanol as organic solvent, pH of the donor and acceptor phase 10.0 and 3.5, respectively, extraction time 40 min, stirring rate 800 rpm and salt addition 10%, w/v), HX, Xan and A could be determined within the test ranges with a good correlation coefficient (r(2) > 0.9992). The limit of detection for HX, Xan and A was 153, 173 and 97 ng/mL, respectively, and the intra- and inter-day relative standard deviations were no more than 9.8%. The content of HX, Xan and A in Alysicarpus vaginalis (L.) DC. medicinal materials was 120.40, 18.37 and 62.75 µg/g, respectively. This procedure afforded a convenient, sensitive, accurate and inexpensive method with a high extraction efficiency for determination of HX, Xan and A. Copyright © 2013 John Wiley & Sons, Ltd.

  10. Sensitive Detection of Organophosphorus Pesticides in Medicinal Plants Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with Sweeping Micellar Electrokinetic Chromatography.

    Science.gov (United States)

    Wei, Jin-Chao; Hu, Ji; Cao, Ji-Liang; Wan, Jian-Bo; He, Cheng-Wei; Hu, Yuan-Jia; Hu, Hao; Li, Peng

    2016-02-03

    A simple, rapid, and sensitive method using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) combined with sweeping micellar electrokinetic chromatography (sweeping-MEKC) has been developed for the determination of nine organophosphorus pesticides (chlorfenvinphos, parathion, quinalphos, fenitrothion, azinphos-ethyl, parathion-methyl, fensulfothion, methidathion, and paraoxon). The important parameters that affect the UA-DLLME and sweeping efficiency were investigated. Under the optimized conditions, the proposed method provided 779.0-6203.5-fold enrichment of the nine pesticides compared to the normal MEKC method. The limits of detection ranged from 0.002 to 0.008 mg kg(-1). The relative standard deviations of the peak area ranged from 1.2 to 6.5%, indicating the good repeatability of the method. Finally, the developed UA-DLLME-sweeping-MEKC method has been successfully applied to the analysis of the investigated pesticides in several medicinal plants, including Lycium chinense, Dioscorea opposite, Codonopsis pilosula, and Panax ginseng, indicating that this method is suitable for the determination of trace pesticide residues in real samples with complex matrices.

  11. Separation and determination of copper in bottled water samples by combination of dispersive liquid--liquid microextraction and microsample introduction flame atomic absorption spectrometry.

    Science.gov (United States)

    Citak, Demirhan; Tuzen, Mustafa

    2013-01-01

    A new and simple method for the determination of trace amounts of Cu(II) was developed by combination of dispersive liquid-liquid microextraction (DLLME) preconcentration and microsample introduction flame atomic absorption spectrometry. In this method, ethanol and chloroform were chosen as disperser and extraction solvents, respectively, and 1-nitroso-2-naphthol was used as the complexing agent. The factors affecting the extraction efficiency and determination of Cu(II), including extraction and disperser solvent nature and volume, concentration of the complexing agent, pH of the solution, extraction time, and matrix ions, were investigated. Under optimal conditions, the LOD for Cu(II) was 0.95 microg/L with a preconcentration factor of 70. The RSD was 1.9%. The accuracy of the developed DLLME method was verified by determination of Cu(II) in a certified reference material (NRCC-SLRS-4 river water). The relative error was -3.31%. The developed preconcentration procedure was successfully applied to the analysis of bottled drinking water samples.

  12. In-syringe magnetic-stirring-assisted liquid-liquid microextraction for the spectrophotometric determination of Cr(VI) in waters.

    Science.gov (United States)

    Henríquez, Camelia; Horstkotte, Burkhard; Solich, Petr; Cerdà, Víctor

    2013-08-01

    A fully automated method for the determination of chromate is described. It is based on the selective reaction of Cr(VI) with diphenylcarbazide in acidic media to form a colored complex of Cr(III) with the oxidation product diphenylcarbazone. The reaction was performed within the syringe of an automatic burette containing a magnetic stirrer for homogenization of the sample and the required reagents. In-syringe stirring was made possible using a specially designed driving device placed around the syringe barrel to achieve a rotating magnetic field in the syringe, forcing the stirrer to spin. In a second step, the reaction mixture in the syringe was neutralized to allow in-syringe magnetic-stirring-assisted dispersive liquid-liquid microextraction of the complex into 125 μL of n-hexanol. After phase separation by droplet flotation over 30 s, the organic phase was propelled into a coupled spectrophotometric detection cell. The entire multistep procedure including in-system standard preparation was done within 270 s. The method was used for the analysis of natural waters, achieving average analyte recovery of 103%, a limit of detection of 0.26 μg L(-1), and a repeatability of less than 4% relative standard deviation.

  13. A novel separation/preconcentration technique based on ultrasonic dispersion liquid-liquid microextraction for determination of trace cobalt by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Jingci Li

    2012-12-01

    Full Text Available An improved method for the determination of trace cobalt in water samples has been developed using ultrasonic dispersion liquid-liquid microextraction (US-DLLME prior to flame atomic absorption spectrometry (FAAS analysis. In this method, cobalt was extracted into the fine droplets of carbon tetrachloride after chelate formation with the water soluble ligand, ammonium pyrrolidine dithiocarbamate (APDC. The fine droplets of carbon tetrachloride were formed and dispersed in the aqueous sample with the help of ultrasonic waves which accelerated the formation of the fine cloudy solution without using disperser solvents. Under optimum conditions, the calibration curve was linear in the range of 2.5-500 μg L-1, with a detection limit of 0.8 μg L-1. The relative standard deviation (RSD for ten replicate measurements of 20 and 500 μg L-1 of cobalt were 3.3 and 2.2%. This proposed method was successfully applied to tap water, river water, and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments. Operation simplicity, low cost, high enrichment factor, and low consumption of the extraction solvent are the main advantages of the proposed method.DOI: http://dx.doi.org/10.4314/bcse.v26i1.2

  14. RAPID AND SENSITIVE DETERMINATION OF PALLADIUM USING HOMOGENEOUS LIQUID-LIQUID MICROEXTRACTION VIA FLOTATION ASSISTANCE FOLLOWED BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    Mohammad Rezaee

    2015-05-01

    Full Text Available A method for the determination of trace amounts of palladium was developed using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA followed by graphite furnace atomic absorption spectrometry (GFAAS. Ammonium pyrrolidine dithiocarbamate (APDC was used as a complexing agent. This was applied to determine palladium in three types of water samples. In this study, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added to the extraction cell which contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Parameters affecting extraction efficiency were investigated and optimized. Under the optimum conditions, the calibration graph was linear in the range of 1.0-200 µg L-1 with a limit of detection of 0.3 µg L-1. The performance of the method was evaluated for the extraction and determination of palladium in water samples and satisfactory results were obtained. In order to verify the accuracy of the approach, the standard addition method was applied for the determination of palladium in spiked synthetic samples and satisfactory results were obtained.

  15. Method for the simultaneous determination of monoaromatic and polycyclic aromatic hydrocarbons in industrial effluents using dispersive liquid-liquid microextraction with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Makoś, Patrycja; Fernandes, André; Boczkaj, Grzegorz

    2018-02-23

    We present a new method for simultaneous determination of 22 monoaromatic and polycyclic aromatic hydrocarbons in postoxidative effluents from the production of petroleum bitumen using dispersive liquid-liquid microextraction coupled to gas chromatography and mass spectrometry. The eight extraction parameters including the type and volume of extraction and disperser solvent, pH, salting out effect, extraction, and centrifugation time were optimized. The low detection limit ranging from 0.36 to 28 μg/L, limit of quantitation (1.1-84 μg/L), good reproducibility, and wide linear ranges, as well as the recoveries ranging from 71.74 to 114.67% revealed that the new method allows the determination of aromatic hydrocarbons at low concentration levels in industrial effluents having a very complex composition. The developed method was applied to the determination of content of mono- and polycyclic aromatic hydrocarbons in samples of raw postoxidative effluents in which 15 compounds were identified at concentrations ranging from 1.21 to 1017.0 μg/L as well as in effluents after chemical treatment. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Dispersive liquid-liquid microextraction for simultaneous determination of cadmium, cobalt, lead and nickel in water samples by inductively coupled plasma optical emission spectrometry

    International Nuclear Information System (INIS)

    Dos Santos Silva, E.; Correia, L.O.; Dos Santos, L.O.; Dos Santos Vieira, E.V.; Lemos, V.A.

    2012-01-01

    We report on a new method for the dispersive liquid-liquid microextraction of Cd(II), Co(II), Pb(II) and Ni (II) from water samples prior to their simultaneous determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on the injection of a ternary solvent system composed of appropriate quantities of extraction solvent (trichloroethylene), dispersive solvent (ethanol), and the chelating reagent 2-(2'-benzothiazolylazo)-p-cresol into the sample solution. The solution turns turbid immediately after injection, and the analytes are extracted into the droplets of the organic phase which was dried and dissolved in a mixture of Triton X-114, nitric acid, and ethanol. The metal ions in this mixture were quantified by ICP-OES. The detection limits under optimized conditions are 0.2, 0.3, 0.2 and 0.7 μg L -1 for Cd(II), Co(II), Pb(II) and Ni(II), respectively. The enrichment factors were also calculated for Cd (13), Co (11), Pb (11) and Ni (8). The procedure was applied to the determination of cadmium, cobalt, lead and nickel in certified reference material (waterway sediment) and water samples. (author)

  17. Development and Validation of a Sensitive Method for Trace Nickel Determination by Slotted Quartz Tube Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction.

    Science.gov (United States)

    Yolcu, Şükran Melda; Fırat, Merve; Chormey, Dotse Selali; Büyükpınar, Çağdaş; Turak, Fatma; Bakırdere, Sezgin

    2018-05-01

    In this study, dispersive liquid-liquid microextraction was systematically optimized for the preconcentration of nickel after forming a complex with diphenylcarbazone. The measurement output of the flame atomic absorption spectrometer was further enhanced by fitting a custom-cut slotted quartz tube to the flame burner head. The extraction method increased the amount of nickel reaching the flame and the slotted quartz tube increased the residence time of nickel atoms in the flame to record higher absorbance. Two methods combined to give about 90 fold enhancement in sensitivity over the conventional flame atomic absorption spectrometry. The optimized method was applicable over a wide linear concentration range, and it gave a detection limit of 2.1 µg L -1 . Low relative standard deviations at the lowest concentration in the linear calibration plot indicated high precision for both extraction process and instrumental measurements. A coal fly ash standard reference material (SRM 1633c) was used to determine the accuracy of the method, and experimented results were compatible with the certified value. Spiked recovery tests were also used to validate the applicability of the method.

  18. Determination of phthalate esters in distillates by ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction (USVADLLME) coupled with gas chromatography/mass spectrometry.

    Science.gov (United States)

    Montevecchi, Giuseppe; Masino, Francesca; Zanasi, Luca; Antonelli, Andrea

    2017-04-15

    A method for the extraction of phthalate esters (PAEs) by Ultrasound-Vortex-Assisted Dispersive Liquid-Liquid Micro-Extraction (USVADLLME) approach was optimised and applied for the first time to a historical series of brandies. These contaminants are widely spread in the environment as a consequence of about half century of use in different fields of applications. The concern about these substances and the recent legal restrictions of China in distillates import need a quick and sensitive method for their quantification. The proposed method, moreover, is environmentally oriented due to the disposal of micro-quantities of solvent required. In fact, sub-ppm-limits of detection were achieved with a solvent volume as low as 160μL. The analysed samples were within the legal limits, except for some very ancient brandies whose contamination was probably due to a PAEs concentration effect as a consequence of long ageing and for the use of plastic pipelines no more operative. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Magnetic silica nanomaterials for solid-phase extraction combined with dispersive liquid-liquid microextraction of ultra-trace quantities of plasticizers

    International Nuclear Information System (INIS)

    Yamini, Yadollah; Faraji, Mohammad; Adeli, Mahnaz

    2015-01-01

    We are presenting surface modified magnetic silica nanoparticles (m-Si-NPs) for use in solid-phase extraction combined with dispersive liquid-liquid microextraction (DLLME). The m-Si-NPs were surface-functionalized with octadecyl groups to give a material for the extraction of the plasticizers dibutyl phthalate, di(2-ethylhexyl) adipate and di(2-ethylhexyl) phthalate from water samples. The functionalized m-Si-NPs were characterized by scanning electron microscopy, FTIR spectroscopy, thermal gravimetric analysis, and vibrating sample magnetometry. The results showed that the m-Si-NPs were well functionalized with octadecyl groups. The effects of various experimental variables on the extraction efficiencies were investigated. The analytes were quantified by GC/FID. Under optimal conditions, the calibration plots are linear in the range from 0.01 to 100 μg∙L -1 , and very high enrichment factors (mean value ∼20,000) were obtained. As a result of the high enrichment factors, the detection limits are as low as 2–3 ng∙L -1 . The method was successfully employed to the extraction of the plasticizers from (spiked) water samples, and recoveries are in the order of 93.9 to 106.7 %. The method is low cost, fast, and very sensitive (author)

  20. Magnetic matrix solid phase dispersion assisted dispersive liquid liquid microextraction of ultra trace polychlorinated biphenyls in water prior to GC-ECD determination

    International Nuclear Information System (INIS)

    Diao, Chunpeng; Li, Cong; Yang, Xiao; Sun, Ailing; Liu, Renmin

    2016-01-01

    Magnetic matrix solid phase dispersion (MMSPD) assisted dispersive liquid liquid microextraction (DLLME) was applied to extract ultra traces of polychlorinated biphenyls (PCBs) from water samples prior to gas chromatography with electron capture detection. PCBs in water were adsorbed by micro particles of magnetic bamboo charcoal and then transferred into the elution solvent. PCBs in the elution solvent of the MMSPD were further concentrated into trace volume extraction solvent of the DLLME procedure. Under optimized conditions, good linearity in the range of 0.2–100 ng L"−"1 was obtained with regression coefficients (r) higher than 0.9987. Based on a signal-noise ratio of 3, the limits of detection (LODs) range from 0.05–0.1 ng L"−"1. These LODs are much lower than those of MMSPD or DLLME alone. Relative standard deviations are between 4.9–8.2 %. The method was successfully applied to the determination of PCBs in lake and river water. Relative recoveries were 85.5–117.4 % for the spiked environmental water samples. (author)

  1. Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

    2010-06-30

    A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Dispersive liquid-liquid microextraction followed by flow injection-inductively coupled plasma mass spectrometry (FI-ICPMS) determination of 14 lanthanides from ground water

    International Nuclear Information System (INIS)

    Chandrasekaran, K.; Karunasagar, D.; Arunachalam, J.

    2011-01-01

    The aim of the present work was to develop a dispersive liquid-liquid microextraction (DLLME) method for the sensitive determination of REEs at a few parts per billion in groundwater by flow injection-inductively coupled plasma mass spectrometry (FI-ICPMS). In the developed method, methanol (500 μl) and chloroform (200μl) were used as the disperser and extractant respectively. The REEs were complexed with 4-(2-pyridylazo resorcinol) (PAR) at a pH of 7. Acetate ion was added as an auxiliary ligand for neutralization of the charge on the lanthanide-PAR complex. The disperser (MeOH) - extraction solvent (CHCl 3 ) mixture was rapidly injected using a disposable syringe, thereby forming a cloudy solution. The lanthanide-PAR complex was extracted into the fine droplets of the chloroform dispersed in the aqueous phase. The solution was centrifuged and the aqueous layer at the top was discarded. The REEs were back extracted from the chloroform layer with nitric acid for determination by ICPMS. Important parameters for complex formation and extraction, such as volume of extraction/disperser solvent, extraction time, pH and concentration of the chelating agent and the auxiliary ligand are being optimized using ICP-MS. The optimization is being carried out at 5 μg L -1 concentration level of REE in the initial water sample. Preliminary studies have shown an extraction recovery of 80-85% for all the 14 lanthanide elements and these will be presented

  3. Simultaneous derivatisation and preconcentration of parabens in food and other matrices by isobutyl chloroformate and dispersive liquid-liquid microextraction followed by gas chromatographic analysis.

    Science.gov (United States)

    Jain, Rajeev; Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Ch, Ratnasekhar; Murthy, R C; Khan, Haider A

    2013-11-01

    A simple, rapid and economical method has been proposed for the quantitative determination of parabens (methyl, ethyl, propyl and butyl paraben) in different samples (food, cosmetics and water) based on isobutyl chloroformate (IBCF) derivatisation and preconcentration using dispersive liquid-liquid microextraction in single step. Under optimum conditions, solid samples were extracted with ethanol (disperser solvent) and 200 μL of this extract along with 50 μL of chloroform (extraction solvent) and 10 μL of IBCF was rapidly injected into 2 mL of ultra-pure water containing 150 μL of pyridine to induce formation of a cloudy state. After centrifugation, 1 μL of the sedimented phase was analysed using gas chromatograph-flame ionisation detector (GC-FID) and the peaks were confirmed using gas chromatograph-positive chemical ionisation-mass spectrometer (GC-PCI-MS). Method was found to be linear over the range of 0.1-10 μg mL(-1) with square of correlation coefficient (R(2)) in the range of 0.9913-0.9992. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029-0.102 μg mL(-1) and 0.095-0.336 μg mL(-1) with a signal to noise ratio of 3:1 and 10:1, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction

    Science.gov (United States)

    Martinis, Estefanía M.; Wuilloud, Rodolfo G.

    2016-10-01

    This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 μL and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL- 1. The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL- 1) and up to at least 120 ng mL- 1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL- 1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples.

  5. Centrifuge-less dispersive liquid-liquid microextraction base on the solidification of switchable solvent for rapid on-site extraction of four pyrethroid insecticides in water samples.

    Science.gov (United States)

    Hu, Lu; Wang, Huazi; Qian, Heng; Liu, Chaoran; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang; Xu, Donghui

    2016-11-11

    An on-site dispersive liquid liquid microextraction base on the solidification of switchable solvent has been developed as a simple, rapid and eco-friendly sample extraction method for the fast determination of pyrethroid insecticides in aqueous samples using high-performance liquid chromatography with ultraviolet detection. In this extraction method, medium-chain saturated fatty acids (n≥10), which can rapidly solidify at low temperatures (centrifugation. The microextraction process was performed in a 10mL syringe and the pretreatment process could thus be finished in 5min. No external energy resources were required in this method, which makes it a potential method for on-site extraction. The optimal experimental parameters were as follows: 350μL of decanoic acid (1mol/L) was used as the extraction solvent, 150μL of sulfuric acid (2mol/L) was used to decrease the pH of the samples, no salt was added, and the temperature of the samples was in the range of 20-40°C. Finally, the sample was cooled in an ice bath for three minutes. Under these optimal conditions, good responses for four pyrethroid insecticides were obtained in the concentration ranges of 1-500μg/L, with coefficients of determination greater than 0.9993. The recoveries of the four pyrethroid insecticides ranged from 84.7 to 95.3%, with relative standard deviations ranging from 1.6 to 4.6%. The limits of detection based on a signal-to-noise ratio of 3 were in the range of 0.24-0.68μg/L, and the enrichment factors were in the range of 121-136. The results demonstrate that this method was successfully applied to determine pyrethroid insecticides in real water samples. No centrifugation or any special apparatus are required, make this a promising method for rapid field-sampling procedures. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Hydrophilic interaction chromatography combined with dispersive liquid-liquid microextraction as a preconcentration tool for the simultaneous determination of the panel of underivatized neurotransmitters in human urine samples.

    Science.gov (United States)

    Konieczna, Lucyna; Roszkowska, Anna; Niedźwiecki, Maciej; Bączek, Tomasz

    2016-01-29

    A simple and sensitive method using dispersive liquid-liquid microextraction (DLLME) followed by liquid chromatography coupled to mass spectrometry (LC-MS) with a hydrophilic interaction chromatography (HILIC) column was developed for the simultaneous determination of 13 compounds of different polarities, comprising monoamine neurotransmitters (dopamine, norepinephrine, epinephrine and serotonin) along with their respective precursors and metabolites, in human urine samples. The microextraction procedure was based on the fast injection of a mixture of ethanol (disperser solvent) and dichloromethane (extraction solvent) into a human urine sample, forming a cloudy solution in the Eppendorf tube. After centrifugation, the sedimented phase was collected and subsequently analyzed by LC-HILIC-MS in about 12min without a derivatization step. The separation was performed on an XBridge Amide™ BEH column 3.0×100mm, 3.5mm and the mobile phase consisted of phase A: 10mM ammonium formate buffer in water pH 3.0 and phase B: 10 mM ammonium formate buffer in acetonitrile, under gradient program elution. Tyrosine, tryptophan, 5-hydroxytryptophan, dopamine, epinephrine, norepinephrine, serotonin, 3-methoxytyramine, 5-hydroxyindole-3-acetic acid, 3,4-dihydroxy-l-phenylalanine and norvaline (internal standard) were detected in the positive ionization mode. While vanillylmandelic acid, homovanillic acid, 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxybenzylamine (internal standard) were detected in the negative ionization mode. Parameters influencing DLLME and LC-HILIC-MS were investigated. Under the optimum conditions, the proposed method exhibited a low detection limit (5-10ngmL(-1)), and good linearity with R between 0.9991 and 0.9998. The recoveries in human urine samples were 99.0%±3.6%. for the 13 studied biogenic amines with intra- and inter-day RSDs of 0.24-9.55% and 0.31-10.0%, respectively. The developed DLLME-LC-MS method could be successfully applied for the

  7. Combination of electromembrane extraction and liquid-phase microextraction in a single step: Simultaneous group separation of acidic and basic drugs

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid

    2015-01-01

    at high concentration. This approach was further investigated from human plasma. Extraction recoveries were strongly dependent on dilution of plasma with buffer and on extraction time. Finally, this simultaneous EME/LPME approach was evaluated in combination with liquid chromatography (LC......Electromembrane extraction (EME) and liquid-phase microextraction (LPME) were combined in a single step for the first time to realize simultaneous and clear group separation of basic and acidic drugs. Using 2-nitrophenyl octyl ether as the supported liquid membrane (SLM) for EME and dihexyl ether...

  8. Determination of multi-class herbicides in soil by liquid-solid extraction coupled with headspace solid phase microextraction method

    Directory of Open Access Journals (Sweden)

    Đurović-Pejčev Rada

    2016-01-01

    Full Text Available A method is described for simultaneous determination of five herbicides (metribuzin, acetochlor, clomazone, oxyfluorfen and dimethenamid belonging to different pesticides groups in soil samples. Developed headspace solid phase microextraction method (HS-SPME in combination with liquid-solid sample preparation (LS was optimized and applied in the analysis of some agricultural samples. Optimization of microextraction conditions, such as temperature, extraction time and sodium chloride (NaCl content was perfor-med using 100 μm polydimethyl-siloxane (PDMS fiber. The extraction effi-ciencies of methanol, methanol:acetone=1:1 and methanol:acetone:hexane= =2:2:1 and the optimum number of extraction steps during the sample prepa-ration, were tested, as well. Gas chromatography-mass spectrometry (GC-MS was used for detection and quantification, obtaining relative standard deviation (RSD below 13%, and recovery values higher than 83% for multiple analyses of soil samples fortified at 30 μg kg-1 of each herbicide. Limits of detection (LOD were less than 1.2 μg kg-1 for all the studied herbicides. [Projekat Ministarstva nauke Republike Srbije, br. TR31043 i br. III43005

  9. A simple and sensitive vortex-assisted ionic liquid-dispersive microextraction and spectrophotometric determination of selenium in food samples.

    Science.gov (United States)

    Bağda, Esra; Tüzen, Mustafa

    2017-10-01

    In the present study, a novel and eco-friendly vortex-assisted ionic liquid-based microextraction method was developed for the determination of selenium in food. The microextraction method is based on the liberation of iodine in the presence of selenium; the liberated iodine reacts with I - to form I 3 - . Anionic I 3 - reacts with cationic crystal violet dye, and the product is extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate phase in the presence of Triton X-114. The proposed method is linear in the range of 2.0-70µgL -1 and has a detection limit of 9.8×10 -2 µgL -1 . Relative standard deviations were 3.67% and 2.89% for the five replicate measurements of 14 and 35µgL -1 Se(IV), respectively. The proposed method was successfully applied to different food samples (NIST SRM 2976 mussel tissue, pepper, ginger, wheat flour, red lentil, traditional soup, cornflour, cornstarch, and garlic) after microwave digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Carrier mediated hollow fiber liquid phase microextraction combined with HPLC-UV for preconcentration and determination of some tetracycline antibiotics.

    Science.gov (United States)

    Shariati, Shahab; Yamini, Yadollah; Esrafili, Ali

    2009-02-01

    In the present study, a simple and efficient preconcentration method was developed using carrier mediated three phase liquid phase microextraction prior to HPLC-UV for simultaneous extraction and determination of trace amounts of highly hydrophilic tetracycline antibiotics including tetracycline (TCN), oxytetracycline (OTCN) and doxycycline (DCN) in bovine milk, human plasma and water samples. For extraction, 11.0 mL of the aqueous sample containing TCNs and 0.05 M Na(2)HPO(4) (9.10.995). Finally, applicability of the proposed method was successfully confirmed by extraction and determination of the drugs in water and plasma samples as well as in bovine milk samples with low and high fat contents. Comparing to the traditional methods, the proposed method exhibits high sensitivity and high preconcentration factors as well as good precision. The extraction setup is simple and due to active transport of analytes, high cleanup effect and good selectivity are obtained in extraction process.

  11. A multiple hollow fibre liquid-phase microextraction method for the determination of halogenated solvent residues in olive oil.

    Science.gov (United States)

    Manso, J; García-Barrera, T; Gómez-Ariza, J L; González, A G

    2014-02-01

    The present paper describes a method based on the extraction of analytes by multiple hollow fibre liquid-phase microextraction and detection by ion-trap mass spectrometry and electron capture detectors after gas chromatographic separation. The limits of detection are in the range of 0.13-0.67 μg kg(-1), five orders of magnitude lower than those reached with the European Commission Official method of analysis, with three orders of magnitude of linear range (from the quantification limits to 400 μg kg(-1) for all the analytes) and recoveries in fortified olive oils in the range of 78-104 %. The main advantages of the analytical method are the absence of sample carryover (due to the disposable nature of the membranes), high enrichment factors in the range of 79-488, high throughput and low cost. The repeatability of the analytical method ranged from 8 to 15 % for all the analytes, showing a good performance.

  12. In-syringe-stirring: A novel approach for magnetic stirring-assisted dispersive liquid–liquid microextraction

    International Nuclear Information System (INIS)

    Horstkotte, Burkhard; Suárez, Ruth; Solich, Petr; Cerdà, Víctor

    2013-01-01

    Graphical abstract: -- Highlights: •We propose a new automatic magnetic stirring assisted dispersive liquid–liquid microextraction. •It allows the extraction of aluminum from seawater and freshwater samples within less than 4 min. •The method was applicable to the natural samples. -- Abstract: For the first time, the use of a magnetic stirrer within the syringe of an automated syringe pump and the resulting possible analytical applications are described. A simple instrumentation following roughly the one from sequential injection analyzer systems is used in combination with an adaptor, which is placed onto the barrel of a glass syringe. Swirling around the longitudinal axis of the syringe and holding two strong neodymium magnets, it causes a rotating magnetic field and serves as driver for a magnetic stirring bar placed inside of the syringe. In a first study it was shown that this approach leads to a sealed but also automatically adaptable reaction vessel, the syringe, in which rapid and homogeneous mixing of sample with the required reagents within short time can be carried out. In a second study in-a-syringe magnetic stirring-assisted dispersive liquid–liquid microextraction (MSA-DLLME) was demonstrated by the application of the analyzer system to fluorimetric determination of aluminum in seawater samples using lumogallion. A linear working range up to 1.1 μmol L −1 and a limit of detection of 6.1 nmol L −1 were found. An average recovery of 106.0% was achieved for coastal seawaters with a reproducibility of 4.4%. The procedure lasted 210 s including syringe cleaning and only 150 μL of hexanol and 4.1 mL of sample were required

  13. Hollow fiber-based liquid phase microextraction combined with high-performance liquid chromatography for extraction and determination of some antidepressant drugs in biological fluids.

    Science.gov (United States)

    Esrafili, Ali; Yamini, Yadollah; Shariati, Shahab

    2007-12-05

    The applicability of hollow fiber-based liquid phase microextraction (HF-LPME) was evaluated for the extraction and preconcentration of three antidepressant drugs (amitriptyline, imipramine and sertraline) prior to their determination by HPLC-UV. The target drugs were extracted from 11.0 mL of aqueous solution with pH 12.0 (source phase) into an organic extracting solvent (n-dodecane) impregnated in the pores of a hollow fiber and finally back extracted into 24 microL of aqueous solution located inside the lumen of the hollow fiber and adjusted to pH 2.1 using 0.1M of H3PO4 (receiving phase). The extraction was performed due to pH gradient between the inside and outside of the hollow fiber membrane. In order to obtain high extraction efficiency, the parameters affecting the HF-LPME including pH of the source and receiving phases, the type of organic phase, ionic strength and volume of the source phase, stirring rate and extraction time were studied and optimized. Under the optimized conditions, enrichment factors up to 300 were achieved and the relative standard deviation (R.S.D.%) of the method was in the range of 2-12%. The calibration curves were obtained in the range of 5-500 microg L(-1) with reasonable linearity (R2>0.998) and the limits of detection (LODs) ranged between 0.5 and 0.7 microg L(-1) (based on S/N=3). Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in urine, plasma and tap water samples. The results indicated that hollow fiber microextraction method has excellent clean-up and high-preconcentration factor and can be served as a simple and sensitive method for monitoring of antidepressant drugs in the biological samples.

  14. A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

    International Nuclear Information System (INIS)

    Pelit, Füsun Okçu; Pelit, Levent; Dizdaş, Tuğberk Nail; Aftafa, Can; Ertaş, Hasan; Yalçınkaya, E.E.; Türkmen, Hayati; Ertaş, F.N.

    2015-01-01

    Highlights: • A novel polythiophene – ionic liquid modified clay surface has been prepared. • Polymerization was performed electrochemically on a stainless steel wire. • This material was used as a SPME fiber in head space mode. • This new SPME fiber was applied for analysis of pesticides in juice samples. • Fiber adsorption properties were improved by modification of ionic liquids. - Abstract: This report comprises the novel usage of polythiophene – ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett–Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box–Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002–0.667 ng mL −1 . Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues

  15. A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pelit, Füsun Okçu, E-mail: fusun.okcu@ege.edu.tr; Pelit, Levent; Dizdaş, Tuğberk Nail; Aftafa, Can; Ertaş, Hasan; Yalçınkaya, E.E.; Türkmen, Hayati; Ertaş, F.N.

    2015-02-15

    Highlights: • A novel polythiophene – ionic liquid modified clay surface has been prepared. • Polymerization was performed electrochemically on a stainless steel wire. • This material was used as a SPME fiber in head space mode. • This new SPME fiber was applied for analysis of pesticides in juice samples. • Fiber adsorption properties were improved by modification of ionic liquids. - Abstract: This report comprises the novel usage of polythiophene – ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett–Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box–Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002–0.667 ng mL{sup −1}. Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues.

  16. Polymeric ionic liquid-based portable tip microextraction device for on-site sample preparation of water samples.

    Science.gov (United States)

    Chen, Lei; Pei, Junxian; Huang, Xiaojia; Lu, Min

    2018-06-05

    On-site sample preparation is highly desired because it avoids the transportation of large-volume samples and ensures the accuracy of the analytical results. In this work, a portable prototype of tip microextraction device (TMD) was designed and developed for on-site sample pretreatment. The assembly procedure of TMD is quite simple. Firstly, polymeric ionic liquid (PIL)-based adsorbent was in-situ prepared in a pipette tip. After that, the tip was connected with a syringe which was driven by a bidirectional motor. The flow rates in adsorption and desorption steps were controlled accurately by the motor. To evaluate the practicability of the developed device, the TMD was used to on-site sample preparation of waters and combined with high-performance liquid chromatography with diode array detection to measure trace estrogens in water samples. Under the most favorable conditions, the limits of detection (LODs, S/N = 3) for the target analytes were in the range of 4.9-22 ng/L, with good coefficients of determination. Confirmatory study well evidences that the extraction performance of TMD is comparable to that of the traditional laboratory solid-phase extraction process, but the proposed TMD is more simple and convenient. At the same time, the TMD avoids complicated sampling and transferring steps of large-volume water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Rapid determination of hydrophilic phenols in olive oil by vortex-assisted reversed-phase dispersive liquid-liquid microextraction and screen-printed carbon electrodes.

    Science.gov (United States)

    Fernández, Elena; Vidal, Lorena; Canals, Antonio

    2018-05-01

    A novel approach is presented to determine hydrophilic phenols in olive oil samples, employing vortex-assisted reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) for sample preparation and screen-printed carbon electrodes for voltammetric analysis. The oxidation of oleuropein, hydroxytyrosol, caffeic acid, ferulic acid and tyrosol was investigated, being caffeic acid and tyrosol selected for quantification. A matrix-matching calibration using sunflower oil as analyte-free sample diluted with hexane was employed to compensate matrix effects. Samples were analyzed under optimized RP-DLLME conditions, i.e., extractant phase, 1M HCl; extractant volume, 100µL; extraction time, 2min; centrifugation time, 10min; centrifugation speed, 4000rpm. The working range showed a good linearity between 0.075 and 2.5mgL -1 (r = 0.998, N = 7) for caffeic acid, and between 0.075 and 3mgL -1 (r = 0.999, N = 8) for tyrosol. The methodological limit of detection was empirically established at 0.022mgL -1 for both analytes, which is significantly lower than average contents found in olive oil samples. The repeatability was evaluated at two different spiking levels (i.e., 0.5mgL -1 and 2mgL -1 ) and coefficients of variation ranged from 8% to 11% (n = 5). The applicability of the proposed method was tested in olive oil samples of different quality (i.e., refined olive oil, virgin olive oil and extra virgin olive oil). Relative recoveries varied between 83% and 108% showing negligible matrix effects. Finally, fifteen samples were analyzed by the proposed method and a high correlation with the traditional Folin-Ciocalteu spectrophotometric method was obtained. Thereafter, the concentrations of the fifteen oil samples were employed as input variables in linear discriminant analysis in order to distinguish between olive oils of different quality. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Rapid determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction and ultraperformance convergence chromatography tandem mass spectrometry.

    Science.gov (United States)

    Deng, Huimin; Yang, Fei; Li, Zhonghao; Bian, Zhaoyang; Fan, Ziyan; Wang, Ying; Liu, Shanshan; Tang, Gangling

    2017-07-21

    Aromatic amines in mainstream cigarette smoke have long been monitored due to their carcinogenic toxicity. In this work, a reliable and rapid method was developed for the simultaneous determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction (DLLME) and ultraperformance convergence chromatography tandem mass spectrometry (UPC 2 -MS/MS). Briefly, the particulate phase of the cigarette smoke was captured by a Cambridge filter pad, and diluted hydrogen chloride aqueous solution is employed to extract the aromatic amines under mechanical shaking. After alkalization with sodium hydroxide solution, small amount of toluene was introduced to further extract and enrich aromatic amines by modified DLLME under vortexing. After centrifugation, toluene phase was purified by a universal QuEChERS cleanup kit and was finally analyzed by UPC 2 -MS/MS. Attributing to the superior performance of UPC 2 -MS/MS, this novel approach allowed the separation and determination of 9 aromatic amines within 5.0min with satisfactory resolution and sensitivity. The proposed method was finally validated using Kentucky reference cigarette 3R4F, and emission levels of targeted aromatic amines determined were comparable to previously reported methods At three different spiked levels, the recoveries of most analytes were ranged from 74.01% to 120.50% with relative standard deviation (RSD) less than 12%, except that the recovery of p-toluidine at low spiked level and 3-aminobiphenyl at medium spiked level was 62.77% and 69.37% respectively. Thus, this work provides a novel alternative method for the simultaneous analysis of 9 aromatic amines in mainstream cigarette smoke. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Determination of valproic acid in human plasma using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection

    Science.gov (United States)

    Fazeli-Bakhtiyari, Rana; Panahi-Azar, Vahid; Sorouraddin, Mohammad Hossein; Jouyban, Abolghasem

    2015-01-01

    Objective(s): Dispersive liquid-liquid microextraction coupled with gas chromatography (GC)-flame ionization detector was developed for the determination of valproic acid (VPA) in human plasma. Materials and Methods: Using a syringe, a mixture of suitable extraction solvent (40 µl chloroform) and disperser (1 ml acetone) was quickly added to 10 ml of diluted plasma sample containing VPA (pH, 1.0; concentration of NaCl, 4% (w/v)), resulting in a cloudy solution. After centrifugation (6000 rpm for 6 min), an aliquot (1 µl) of the sedimented organic phase was removed using a 1-µl GC microsyringe and injected into the GC system for analysis. One variable at a time optimization method was used to study various parameters affecting the extraction efficiency of target analyte. Then, the developed method was fully validated for its accuracy, precision, recovery, stability, and robustness. Results: Under the optimum extraction conditions, good linearity range was obtained for the calibration graph, with correlation coefficient higher than 0.998. Limit of detection and lower limit of quantitation were 3.2 and 6 μg/ml, respectively. The relative standard deviations of intra and inter-day analysis of examined compound were less than 11.5%. The relative recoveries were found in the range of 97 to 107.5%. Finally, the validated method was successfully applied to the analysis of VPA in patient sample. Conclusion: The presented method has acceptable levels of precision, accuracy and relative recovery and could be used for therapeutic drug monitoring of VPA in human plasma. PMID:26730332

  20. Application of derivative and derivative ratio spectrophotometry to simultaneous trace determination of rhodamine B and rhodamine 6G after dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Xiao, Ni; Deng, Jian; Huang, Kaihui; Ju, Saiqin; Hu, Canhui; Liang, Jun

    2014-07-15

    Two novel methods, first derivative spectrophotometric method ((1)D) and first derivative ratio spectrophotometric method ((1)DR), have been developed for the simultaneous trace determination of rhodamine B (RhB) and rhodamine 6G (Rh6G) in food samples after dispersive liquid-liquid microextraction (DLLME). The combination of derivative spectrophotometric techniques and DLLME procedure endows the presented methods with enhanced sensitivity and selectivity. Under optimum conditions, the linear calibration curves ranged from 5 to 450 ng mL(-1), with the correlation coefficients (r) of 0.9997 for RhB and 0.9977 for Rh6G by (1)D method, and 0.9987 for RhB and 0.9958 for Rh6G by (1)DR method, respectively. The calculated limits of detection (LODs) based on the variability of the blank solutions (S/N = 3 criterion) for 11 measurements were in the range of 0.48-1.93 ng mL(-1). The recoveries ranged from 88.1% to 111.6% (with RSD less than 4.4%) and 91.5-110.5% (with RSD less than 4.7%) for (1)D and (1)DR method, respectively. The influence of interfering substances such as foreign ions and food colorants which might be present in the food samples on the signals of RhB and Rh6G was examined. The developed methods have been successfully applied to the determination of RhB and Rh6G in black tea, red wine and chilli powder samples with the characteristics of simplicity, cost-effectiveness, environmental friendliness, and could be valuable for routine analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Sensitive and simple determination of zwitterionic morphine in human urine based on liquid-liquid micro-extraction coupled with surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Yu, Borong; Cao, Chentai; Li, Pan; Mao, Mei; Xie, Qiwen; Yang, Liangbao

    2018-08-15

    Morphine, a kind of illicit drugs, is also one of the main heroin metabolites. In consideration of a noninvasive way to monitor and identify drug abuse during forensic cases, the urine samples are usually detected. Here, colloidal gold nanorods (Au NRs) were introduced to act as active substrate, because of the strong optical extinction and spectral tunability of the longitudinal surface plasmon resonance (SPR). Thus, well surface-enhanced Raman spectra of morphine even at low concentrations could be obtained by portable Raman spectrometer. For the complex matrix environment of urine, liquid-liquid micro-extraction (LLME), a simple and inexpensive pretreatment, was employed to avoid the interferences. And then, the coupled surface-enhanced Raman spectroscopy (SERS) can give full play to the advantages of high sensitivity and unique spectroscopic fingerprint. According to the zwitterionic structure and physicochemical parameters of morphine molecules, the pH value of urine sample was adjusted to about 9 by buffer solution (KOH/NaB 4 O 7 ) and the mixture of chloroform and isopropyl alcohol (V/V=9:1) was chosen as extractant. Moreover, such pretreatment was proved to be appropriate for separation and concentration of morphine from urine. The developed LLME-SERS method could provide a detection limit less than 1 ppm in the human urine environment and the whole process of detection just needed take 5-6 min. What's more, the results of urine samples from heroin users exhibited application value of the proposed technique. The excellent performance makes it promising to become a rapid, reliable, and on-spot analyzer, especially for public safety and healthcare. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Study of the factors affecting the performance of microextraction by packed sorbent (MEPS) using liquid scintillation counter and liquid chromatography-tandem mass spectrometry

    International Nuclear Information System (INIS)

    Altun, Zeki; Abdel-Rehim, Mohamed

    2008-01-01

    Microextraction by packed sorbent (MEPS) is a new technique for sample preparation that can be connected on-line with LC or GC. In MEPS, approximately 1-2 mg of the solid packing material is inserted into a syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. The bed can be packed or coated to provide selective and suitable sampling conditions. The new method is very promising for extraction of drugs and metabolites from biological samples. In this paper, some factors affecting the performance of MEPS such as recovery, carry-over, leakage, washing volume and elution volume were studied using C18 and hydroxylated polystyrene-divinylbenzene copolymer (ENV+) as sorbents. Radioactively labelled bupivacaine in plasma samples was used as test analyte. For the extraction of this drug, using methanol/water 95:5 (v/v) (0.25% ammonium hydroxide) was used as elution solvent. The analyte response increased with increasing the elution volume and it was linear upp up to 100 μL utilizing liquid scintillation counter. Further, for concentrating the sample, we found that MEPS may be used such that the sample can be drawn through the needle, up and down, several times. The analyte leakage increases as the volume washing increases, though higher washing volumes may also result in cleaner extracts. To eliminate analyte carry-over, the sorbents were washed first with 3 x 250 μL elution solution and then with 3 x 250 μL washing solution. In addition, the reproducibility measurements show relatively good relative standard deviation (RSD) % values concerning analyte recovery and analyte leakage. The present study provides an understanding of basic aspects when optimizing methods for MEPS. In this study, MEPS was used off-line with liquid scintillation counter and on-line with LC-MS/MS

  3. Study of the factors affecting the performance of microextraction by packed sorbent (MEPS) using liquid scintillation counter and liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Altun, Zeki [Karlstad University, Faculty of Technology and Science, SE-651 88 Karlstad (Sweden); Abdel-Rehim, Mohamed [Karlstad University, Faculty of Technology and Science, SE-651 88 Karlstad (Sweden); Clinical Pharmacology and DMPK, AstraZeneca R and D Soedertaelje, SE-151 85 Soedertaelje (Sweden)], E-mail: Mohamed.Abdel-Rehim@Astrazeneca.com

    2008-12-23

    Microextraction by packed sorbent (MEPS) is a new technique for sample preparation that can be connected on-line with LC or GC. In MEPS, approximately 1-2 mg of the solid packing material is inserted into a syringe (100-250 {mu}L) as a plug. Sample preparation takes place on the packed bed. The bed can be packed or coated to provide selective and suitable sampling conditions. The new method is very promising for extraction of drugs and metabolites from biological samples. In this paper, some factors affecting the performance of MEPS such as recovery, carry-over, leakage, washing volume and elution volume were studied using C18 and hydroxylated polystyrene-divinylbenzene copolymer (ENV+) as sorbents. Radioactively labelled bupivacaine in plasma samples was used as test analyte. For the extraction of this drug, using methanol/water 95:5 (v/v) (0.25% ammonium hydroxide) was used as elution solvent. The analyte response increased with increasing the elution volume and it was linear upp up to 100 {mu}L utilizing liquid scintillation counter. Further, for concentrating the sample, we found that MEPS may be used such that the sample can be drawn through the needle, up and down, several times. The analyte leakage increases as the volume washing increases, though higher washing volumes may also result in cleaner extracts. To eliminate analyte carry-over, the sorbents were washed first with 3 x 250 {mu}L elution solution and then with 3 x 250 {mu}L washing solution. In addition, the reproducibility measurements show relatively good relative standard deviation (RSD) % values concerning analyte recovery and analyte leakage. The present study provides an understanding of basic aspects when optimizing methods for MEPS. In this study, MEPS was used off-line with liquid scintillation counter and on-line with LC-MS/MS.

  4. Ultra-trace determination of gold nanoparticles in environmental water by surfactant assisted dispersive liquid liquid microextraction coupled with electrothermal vaporization-inductively coupled plasma-mass spectrometry

    Science.gov (United States)

    Liu, Ying; He, Man; Chen, Beibei; Hu, Bin

    2016-08-01

    A new method by coupling surfactant assisted dispersive liquid liquid microextraction (SA-DLLME) with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the analysis of gold nanoparticles (AuNPs) in environmental water samples. Effective separation of AuNPs from ionic gold species was achieved by using sodium thiosulphate as a complexing agent. Various experimental parameters affecting SA-DLLME of AuNPs, such as the organic solvent, organic solvent volume, pH of the sample, the kind of surfactant, surfactant concentration, vortex time, speed of centrifugation, centrifugation time, and different coating as well as sizes of AuNPs were investigated carefully. Furthermore, the interference of coexisting ions, dissolved organic matter (DOM) and other metal nanoparticles (NPs) were studied. Under the optimal conditions, a detection limit of 2.2 ng L- 1 and an enrichment factor of 152-fold was achieved for AuNPs, and the original morphology of the AuNPs could be maintained during the extraction process. The developed method was successfully applied for the analysis of AuNPs in environmental water samples, including tap water, the East Lake water, and the Yangtze River water, with recoveries in the range of 89.6-102%. Compared with the established methods for metal NPs analysis, the proposed method has the merits of simple and fast operation, low detection limit, high selectivity, good tolerance to the sample matrix and no digestion or dilution required. It provides an efficient quantification methodology for monitoring AuNPs' pollution in the environmental water and evaluating its toxicity.

  5. Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Muniraj, Sarangapani; Yan, Cheing-Tong; Shih, Hou-Kung; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2012-11-19

    A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ng mL(-1)) based on SN(-1)=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Ultrasound assisted extraction combined with dispersive liquid-liquid microextraction (US-DLLME)-a fast new approach to measure phthalate metabolites in nails.

    Science.gov (United States)

    Alves, Andreia; Vanermen, Guido; Covaci, Adrian; Voorspoels, Stefan

    2016-09-01

    A new, fast, and environmentally friendly method based on ultrasound assisted extraction combined with dispersive liquid-liquid microextraction (US-DLLME) was developed and optimized for assessing the levels of seven phthalate metabolites (including the mono(ethyl hexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP), mono(2-ethyl-5-oxohexyl) phthalate (5-oxo-MEHP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), monoethyl phthalate (MEP), and mono-benzyl phthalate (MBzP)) in human nails by UPLC-MS/MS. The optimization of the US-DLLME method was performed using a Taguchi combinatorial design (L9 array). Several parameters such as extraction solvent, solvent volume, extraction time, acid, acid concentration, and vortex time were studied. The optimal extraction conditions achieved were 180 μL of trichloroethylene (extraction solvent), 2 mL trifluoroacetic acid in methanol (2 M), 2 h extraction and 3 min vortex time. The optimized method had a good precision (6-17 %). The accuracy ranged from 79 to 108 % and the limit of method quantification (LOQm) was below 14 ng/g for all compounds. The developed US-DLLME method was applied to determine the target metabolites in 10 Belgian individuals. Levels of the analytes measured in nails ranged between <12 and 7982 ng/g. The MEHP, MBP isomers, and MEP were the major metabolites and detected in every sample. Miniaturization (low volumes of organic solvents used), low costs, speed, and simplicity are the main advantages of this US-DLLME based method. Graphical Abstract Extraction and phase separation of the US-DLLME procedure.

  7. Dispersive liquid-liquid microextraction combined with gas chromatography-electron capture detection for the determination of polychlorinated biphenyls in soils

    International Nuclear Information System (INIS)

    Hu Jia; Fu Lingyan; Zhao Xinna; Liu Xiujuan; Wang Huili; Wang Xuedong; Dai Liyan

    2009-01-01

    In this article, dispersive liquid-liquid microextraction (DLLME) and gas chromatography-electron capture detection (GC-ECD) were presented for the extraction and determination of five polychlorinated biphenyls (PCBs) in soil samples. Acetone was used as extraction solvent for the extraction of PCBs from soil samples. In DLLME, the target analytes in the extraction solvent were rapidly transferred from the acetone extract to chlorobenzene when the extraction process began. The main advantages of this method are quick speed, high enrichment factor, high recovery and good repeatability. Under the optimum conditions, the method yields a linear calibration curve in the concentration range from 2 to 2000 μg kg -1 for PCB 52, and 0.4 to 400 μg kg -1 for other target analytes. Coefficients of correlation (r 2 ) ranged from 0.9993 to 0.9999. The repeatability was tested by spiking soil samples at a concentration level of 10 μg kg -1 for PCBs. The relative standard deviations (RSDs, n = 11) varied between 2.2% and 6.4%. The limits of detection (LODs), based on signal-to-noise (S/N) of 3, were between 0.20 and 0.50 μg kg -1 . The relative recoveries of the five PCBs from soil S1, S2 and S3 at spiking levels of 10, 20 and 50 μg kg -1 were in the range of 88.70-103.8%, 82.50-106.3% and 82.30-113.6%, respectively. Therefore, DLLME combined with GC-ECD can be successfully applied for the determination of trace PCB residues in real soil samples.

  8. Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods

    Science.gov (United States)

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-01

    In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (24) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL-1 with detection limit of 6.7 ng mL-1 (3δB/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n = 7, c = 50 ng mL-1). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination.

  9. Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods.

    Science.gov (United States)

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-25

    In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (2(4)) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL(-1) with detection limit of 6.7 ng mL(-1) (3δB/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n=7, c=50 ng mL(-1)). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination. Copyright © 2014. Published by Elsevier B.V.

  10. Novel proton-type ionic liquid doped polyaniline for the headspace solid-phase microextraction of amines

    International Nuclear Information System (INIS)

    Ai, Youhong; Zhao, Faqiong; Zeng, Baizhao

    2015-01-01

    Graphical abstract: The novel proton-type ionic liquid (1-sulfobutyl-3-methylimidazolium hydrosulfate) doped polyaniline coating showed granular porous nanostructure and it had high self-EF values and extraction efficiency for amines. - Highlights: • A proton-type ionic liquid-doped polyaniline was fabricated by electrodeposition. • It showed porous granular nanostructure and had large specific surface. • It had high extraction capacity to aromatic amines. • A reasonable self-enrichment factor of SPME fiber has been proposed. - Abstract: A novel proton-type ionic liquid doped polyaniline (HIL-doped PANI) coating was presented, which was prepared on a stainless steel wire by electrodeposition in an aqueous solution containing aniline and 1-sulfobutyl-3-methylimidazolium hydrosulfate. The HIL-doped PANI coating showed granular nanostructure and had large specific surface. When it was applied to the headspace solid-phase microextraction of several amines (i.e., aniline, N-methylaniline, 3-methylaniline, 2-chloroaniline and 3-chloroaniline), it showed high extraction efficiency. The enrichment factors were 191.8–343.9 for different amines, much higher than those of common PANI and commercial polydimethylsiloxane/divinylbenzene coatings. Coupled with gas chromatographic analysis, the linear ranges were 0.097–100 μg/L with correlation coefficients above 0.9942, and the detection limits were 0.012–0.048 μg/L (S/N = 3) for different amines. The relative standard deviations (RSD) were smaller than 8.1% for five successive measurements with single fiber and the fiber-to-fiber RSDs were 8.6–13.8% (n = 5) for these amines. The proposed method was successfully applied to the extraction and determination of amines in organic waste water samples, and the recoveries were 78.3–112.8% for different analytes

  11. Novel proton-type ionic liquid doped polyaniline for the headspace solid-phase microextraction of amines

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Youhong [Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules (Ministry of Education), College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Zhao, Faqiong [Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Zeng, Baizhao, E-mail: bzzeng@whu.edu.cn [Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2015-06-23

    Graphical abstract: The novel proton-type ionic liquid (1-sulfobutyl-3-methylimidazolium hydrosulfate) doped polyaniline coating showed granular porous nanostructure and it had high self-EF values and extraction efficiency for amines. - Highlights: • A proton-type ionic liquid-doped polyaniline was fabricated by electrodeposition. • It showed porous granular nanostructure and had large specific surface. • It had high extraction capacity to aromatic amines. • A reasonable self-enrichment factor of SPME fiber has been proposed. - Abstract: A novel proton-type ionic liquid doped polyaniline (HIL-doped PANI) coating was presented, which was prepared on a stainless steel wire by electrodeposition in an aqueous solution containing aniline and 1-sulfobutyl-3-methylimidazolium hydrosulfate. The HIL-doped PANI coating showed granular nanostructure and had large specific surface. When it was applied to the headspace solid-phase microextraction of several amines (i.e., aniline, N-methylaniline, 3-methylaniline, 2-chloroaniline and 3-chloroaniline), it showed high extraction efficiency. The enrichment factors were 191.8–343.9 for different amines, much higher than those of common PANI and commercial polydimethylsiloxane/divinylbenzene coatings. Coupled with gas chromatographic analysis, the linear ranges were 0.097–100 μg/L with correlation coefficients above 0.9942, and the detection limits were 0.012–0.048 μg/L (S/N = 3) for different amines. The relative standard deviations (RSD) were smaller than 8.1% for five successive measurements with single fiber and the fiber-to-fiber RSDs were 8.6–13.8% (n = 5) for these amines. The proposed method was successfully applied to the extraction and determination of amines in organic waste water samples, and the recoveries were 78.3–112.8% for different analytes.

  12. Hollow fibre-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of flavonoids in Echinophora platyloba DC. and Mentha piperita.

    Science.gov (United States)

    Hadjmohammadi, Mohammadreza; Karimiyan, Hanieh; Sharifi, Vahid

    2013-11-15

    A simple, inexpensive and efficient three phase hollow fibre liquid phase microextraction (HF-LPME) technique combined with HPLC was used for the simultaneous determination of flavonoids in Echinophora platyloba DC. and Mentha piperita. Different factors affecting the HF-LPME procedure were investigated and optimised. The optimised extraction conditions were as follows: 1-octanol as an organic solvent, pHdonor=2, pHacceptor=9.75, stirring rate of 1000rpm, extraction time of 80min, without addition of salt. Under these conditions, the enrichment factors ranged between 146 and 311. The values of intra and inter-day relative standard deviations (RSD) were in the range of 3.18-6.00% and 7.25-11.00%, respectively. The limits of detection (LODs) ranged between 0.5 and 7.0ngmL(-1). Among the investigated flavonoids quercetin was found in E. platyloba DC. and luteolin was found in M. piperita. Concentration of quercetin and luteolin was 0.015 and 0.025mgg(-1) respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Liquid–liquid microextraction in a multicommuted flow system for direct spectrophotometric determination of iodine value in biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Andréia C.; Rocha, Fábio R.P., E-mail: frprocha@cena.usp.br

    2014-06-01

    Highlights: • First flow-based procedure for iodine value determination in biodiesel. • Simple, fast and reliable procedure. • Detection without sample pretreatment or phase separation. • Liquid–liquid microextraction with low sample and reagent volumes. • Avoid toxic reagents and organic solvent used in the reference procedure. Abstract: A flow-based procedure was developed for the direct spectrophotometric determination of the iodine value (IV) in biodiesel. The procedure was based on the microextraction/reaction of unsaturated compounds with triiodide ions in an aqueous medium by inserting the reagent solution between the aliquots of biodiesel without any pretreatment. The interaction occurred through the biodiesel film formed on the inner walls of the hydrophobic tube used as the reactor and at the aqueous/biodiesel interfaces. The spectrophotometric detection was based on the discoloration of the I₃⁻ reagent in the aqueous phase by using a glass tube coupled to a fiber-optic spectrophotometer as the detection cell. Reference solutions were prepared by dilution of biodiesel samples with previously determined IV in hexane. The analytical response was linear for IV from 13 to 135 g I₂/100 g with a detection limit of 5 g I₂/100 g. A coefficient of variation of 1.7% (n = 10) and a sampling rate of 108 determinations per hour were achieved by consuming 224 μL of the sample and 200 μg of I₂ per determination. The slopes of analytical curves obtained with three different biodiesel samples were in agreement (variations in slopes lower than 3.1%), thus indicating an absence of any matrix effects. Results for biodiesel samples from different sources agreed with the volumetric official procedure at the 95% confidence level. The proposed procedure is therefore a simple, fast, and reliable alternative for estimating the iodine value of biodiesel.

  14. Liquid–liquid microextraction in a multicommuted flow system for direct spectrophotometric determination of iodine value in biodiesel

    International Nuclear Information System (INIS)

    Pereira, Andréia C.; Rocha, Fábio R.P.

    2014-01-01

    Highlights: • First flow-based procedure for iodine value determination in biodiesel. • Simple, fast and reliable procedure. • Detection without sample pretreatment or phase separation. • Liquid–liquid microextraction with low sample and reagent volumes. • Avoid toxic reagents and organic solvent used in the reference procedure. - Abstract: A flow-based procedure was developed for the direct spectrophotometric determination of the iodine value (IV) in biodiesel. The procedure was based on the microextraction/reaction of unsaturated compounds with triiodide ions in an aqueous medium by inserting the reagent solution between the aliquots of biodiesel without any pretreatment. The interaction occurred through the biodiesel film formed on the inner walls of the hydrophobic tube used as the reactor and at the aqueous/biodiesel interfaces. The spectrophotometric detection was based on the discoloration of the I 3 − reagent in the aqueous phase by using a glass tube coupled to a fiber-optic spectrophotometer as the detection cell. Reference solutions were prepared by dilution of biodiesel samples with previously determined IV in hexane. The analytical response was linear for IV from 13 to 135 g I 2 /100 g with a detection limit of 5 g I 2 /100 g. A coefficient of variation of 1.7% (n = 10) and a sampling rate of 108 determinations per hour were achieved by consuming 224 μL of the sample and 200 μg of I 2 per determination. The slopes of analytical curves obtained with three different biodiesel samples were in agreement (variations in slopes lower than 3.1%), thus indicating an absence of any matrix effects. Results for biodiesel samples from different sources agreed with the volumetric official procedure at the 95% confidence level. The proposed procedure is therefore a simple, fast, and reliable alternative for estimating the iodine value of biodiesel

  15. Determination of 2-Octanone in Biological Samples Using Liquid–Liquid Microextractions Followed by Gas Chromatography–Flame Ionization Detectio

    Directory of Open Access Journals (Sweden)

    Abolghasem Jouyban, Maryam Abbaspour, Mir Ali Farajzadeh, Maryam Khoubnasabjafari

    2017-06-01

    Full Text Available Background: Analysis of chemicals in biological fluids is required in many areas of medical sciences. Rapid, highly efficient, and reliable dispersive and air assisted liquid–liquid microextraction methods followed by gas chromatography-flame ionization detection were developed for the extraction, preconcentration, and determination of 2-octanone in human plasma and urine samples. Methods: Proteins of plasma samples are precipitated by adding methanol and urine sample is diluted with water prior to performing the microextraction procedure. Fine organic solvent droplets are formed by repeated suction and injection of the mixture of sample solution and extraction solvent into a test tube with a glass syringe. After extraction, phase separation is performed by centrifuging and the enriched analyte in the sedimented organic phase is determined by the separation system. The main factors influencing the extraction efficiency including extraction solvent type and volume, salt addition, pH, and extraction times are investigated. Results: Under the optimized conditions, the proposed method showed good precision (relative standard deviation less than 7%. Limit of detection and lower limit of quantification for 2-octanone were obtained in the range of 0.1–0.5 µg mL−1. The linear ranges were 0.5-500 and 0.5-200 µg mL−1 in plasma and urine, respectively (r2 ≥ 0.9995. Enrichment factors were in the range of 13-37. Good recoveries (55–86% were obtained for the spiked samples. Conclusion: Preconcentration methods coupled with GC analysis were developed and could be used to monitor 2-octanone in biological samples.

  16. Multi-residue method for determination of 58 pesticides, pharmaceuticals and personal care products in water using solvent demulsification dispersive liquid-liquid microextraction combined with liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Caldas, Sergiane Souza; Rombaldi, Caroline; Arias, Jean Lucas de Oliveira; Marube, Liziane Cardoso; Primel, Ednei Gilberto

    2016-01-01

    A rapid and efficient sample pretreatment using solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was studied for the extraction of 58 pharmaceuticals and personal care products (PPCPs) and pesticides from water samples. Type and volume of extraction and disperser solvents, pH, salt addition, amount of salt and type of demulsification solvent were evaluated. Limits of quantification (LOQ) in the range from 0.0125 to 1.25 µg L(-1) were reached, and linearity was in the range from the LOQ of each compound to 25 μg L(-1). Recoveries ranged from 60% to 120% for 84% of the compounds, with relative standard deviations lower than 29%. The proposed method demonstrated, for the first time, that sample preparation by SD-DLLME with determination by LC-MS/MS can be successfully used for the simultaneous extraction of 32 pesticides and 26 PPCPs from water samples. The entire procedure, including the extraction of 58 organic compounds from the aqueous sample solution and the breaking up of the emulsion after extraction with water, rather than with an organic solvent, was environmentally friendly. In addition, this technique was less expensive and faster than traditional techniques. Finally, the analytical method under study was successfully applied to the analysis of all 58 pesticides and PPCPs in surface water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Air-assisted liquid-liquid microextraction integrated with QuEChERS for determining endocrine-disrupting compounds in fish by high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Luo, Zhoufei; Lu, Jing; Li, Haipu; Tu, Yi; Wan, Yuehao; Yang, Zhaoguang

    2018-09-15

    A new, sensitive, and rapid method based on the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) approach and air-assisted liquid-liquid microextraction (AALLME) technology was developed for the determination of 20 endocrine-disrupting compounds (EDCs) in fish by high-performance liquid chromatography-tandem mass spectrometry. The method first integrates AALLME into QuEChERS to achieve clean-up and enrichment of the EDCs in one step. A self-made glass tube was enfolded with plasticine to withstand the high centrifugal force. The established method was developed by optimization of the parameters. High linearities (R 2  > 0.9924) and recoveries (78.2-118.6%) at three spiked levels (5, 10, and 20 ng g -1 ), and low relative standard deviation values (1.1-14.5%) and limits of detection (0.03-0.80 ng g -1 ) were obtained. The method comparison shows that the proposed method is superior as it involves less organic solvent usage, simple operation and high efficiency. This method was successfully applied to different fishes for analyzing EDCs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Dual ultrasonic-assisted dispersive liquid-liquid microextraction coupled with microwave-assisted derivatization for simultaneous determination of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol by ultra high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Zhao, Xian-En; Lv, Tao; Zhu, Shuyun; Qu, Fei; Chen, Guang; He, Yongrui; Wei, Na; Li, Guoliang; Xia, Lian; Sun, Zhiwei; Zhang, Shijuan; You, Jinmao; Liu, Shu; Liu, Zhiqiang; Sun, Jing; Liu, Shuying

    2016-03-11

    This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4'-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Trace determination of organophosphate esters in white wine, red wine, and beer samples using dispersive liquid-liquid microextraction combined with ultra-high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Pang, Long; Yang, Huiqiang; Yang, Peijie; Zhang, Hongzhong; Zhao, Jihong

    2017-08-15

    In this study, dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry was developed for the analysis of five representative organophosphate esters (OPEs) in wine samples. Under optimized conditions, the proposed method resulted in good linearity (R 2 >0.9933) over the range of 0.1-100μgL -1 , with limits of detection (LODs, S/N =3) and quantification (LOQs, S/N =10) in the ranges of 0.48-18.8ngL -1 and 1.58-62.5ngL -1 , respectively. Inter- and intra-assay precisions of RSD% ranged from 3.21% to 6.13% and from 1.69% to 7.63%, respectively. The spiked recoveries of target OPEs from white wine, red wine, and beer samples were in the ranges of 80-122%, 76-120%, and 76-110%, respectively, at two different concentration levels. The total concentrations of five OPEs found in white wine, red wine, and beer samples were in the ranges of 0.29-0.85μgL -1 , 1.00-3.05μgL -1 , and 0.86-1.47μgL -1 , respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  1. Liquid-liquid microextraction in a multicommuted flow system for direct spectrophotometric determination of iodine value in biodiesel.

    Science.gov (United States)

    Pereira, Andréia C; Rocha, Fábio R P

    2014-06-04

    A flow-based procedure was developed for the direct spectrophotometric determination of the iodine value (IV) in biodiesel. The procedure was based on the microextraction/reaction of unsaturated compounds with triiodide ions in an aqueous medium by inserting the reagent solution between the aliquots of biodiesel without any pretreatment. The interaction occurred through the biodiesel film formed on the inner walls of the hydrophobic tube used as the reactor and at the aqueous/biodiesel interfaces. The spectrophotometric detection was based on the discoloration of the I3(-) reagent in the aqueous phase by using a glass tube coupled to a fiber-optic spectrophotometer as the detection cell. Reference solutions were prepared by dilution of biodiesel samples with previously determined IV in hexane. The analytical response was linear for IV from 13 to 135 g I2/100 g with a detection limit of 5 g I2/100 g. A coefficient of variation of 1.7% (n=10) and a sampling rate of 108 determinations per hour were achieved by consuming 224 μL of the sample and 200 μg of I2 per determination. The slopes of analytical curves obtained with three different biodiesel samples were in agreement (variations in slopes lower than 3.1%), thus indicating an absence of any matrix effects. Results for biodiesel samples from different sources agreed with the volumetric official procedure at the 95% confidence level. The proposed procedure is therefore a simple, fast, and reliable alternative for estimating the iodine value of biodiesel. Copyright © 2014. Published by Elsevier B.V.

  2. Magnetic stirrer induced dispersive ionic-liquid microextraction for the determination of vanadium in water and food samples prior to graphite furnace atomic absorption spectrometry.

    Science.gov (United States)

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa

    2015-04-01

    A new dispersive liquid-liquid microextraction, magnetic stirrer induced dispersive ionic-liquid microextraction (MS-IL-DLLME) was developed to quantify the trace level of vanadium in real water and food samples by graphite furnace atomic absorption spectrometry (GFAAS). In this extraction method magnetic stirrer was applied to obtained a dispersive medium of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] in aqueous solution of (real water samples and digested food samples) to increase phase transfer ratio, which significantly enhance the recovery of vanadium - 4-(2-pyridylazo) resorcinol (PAR) chelate. Variables having vital role on desired microextraction methods were optimised to obtain the maximum recovery of study analyte. Under the optimised experimental variables, enhancement factor (EF) and limit of detection (LOD) were achieved to be 125 and 18 ng L(-1), respectively. Validity and accuracy of the desired method was checked by analysis of certified reference materials (SLRS-4 Riverine water and NIST SRM 1515 Apple leaves). The relative standard deviation (RSD) for 10 replicate determinations at 0.5 μg L(-1) of vanadium level was found to be <5.0%. This method was successfully applied to real water and acid digested food samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Ionic liquid-based single-drop microextraction followed by liquid chromatography-ultraviolet spectrophotometry detection to determine typical UV filters in surface water samples.

    Science.gov (United States)

    Vidal, Lorena; Chisvert, Alberto; Canals, Antonio; Salvador, Amparo

    2010-04-15

    A user-friendly and inexpensive ionic liquid-based single-drop microextraction (IL-SDME) procedure has been developed to preconcentrate trace amounts of six typical UV filters extensively used in cosmetic products (i.e., 2-hydroxy-4-methoxybenzophenone, isoamyl 4-methoxycinnamate, 3-(4'-methylbenzylidene)camphor, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, 2-ethylhexyl 4-dimethylaminobenzoate and 2-ethylhexyl 4-methoxycinnamate) from surface water samples prior to analysis by liquid chromatography-ultraviolet spectrophotometry detection (LC-UV). A two-stage multivariate optimization approach was developed by means of a Plackett-Burman design for screening and selecting the significant variables involved in the SDME procedure, which were later optimized by means of a circumscribed central composite design. The studied variables were drop volume, sample volume, agitation speed, ionic strength, extraction time and ethanol quantity. Owing to particularities, ionic liquid type and pH of the sample were optimized separately. Under optimized experimental conditions (i.e., 10 microL of 1-hexyl-3-methylimidazolium hexafluorophosphate, 20 mL of sample containing 1% (v/v) ethanol and NaCl free adjusted to pH 2, 37 min extraction time and 1300 rpm agitation speed) enrichment factors up to ca. 100-fold were obtained depending on the target analyte. The method gave good levels of repeatability with relative standard deviations varying between 2.8 and 8.8% (n=6). Limits of detection were found in the low microg L(-1) range, varying between 0.06 and 3.0 microg L(-1) depending on the target analyte. Recovery studies from different types of surface water samples collected during the winter period, which were analysed and confirmed free of all target analytes, ranged between 92 and 115%, showing that the matrix had a negligible effect upon extraction. Finally, the proposed method was applied to the analysis of different water samples (taken from two beaches, two swimming pools and a

  4. Development of a new microextraction method based on elevated temperature dispersive liquid-liquid microextraction for determination of triazole pesticides residues in honey by gas chromatography-nitrogen phosphorus detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Mogaddam, Mohammad Reza Afshar; Ghorbanpour, Houshang

    2014-06-20

    In the present study, a rapid, highly efficient, and reliable sample preparation method named "elevated temperature dispersive liquid-liquid microextraction" followed by gas chromatography-nitrogen-phosphorus detection was developed for the extraction, preconcentration, and determination of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and difenoconazole) in honey samples. In this method the temperature of high-volume aqueous phase was adjusted at an elevated temperature and then a disperser solvent containing an extraction solvent was rapidly injected into the aqueous phase. After cooling to room temperature, the phase separation was accelerated by centrifugation. Various parameters affecting the extraction efficiency such as type and volume of the extraction and disperser solvents, temperature, salt addition, and pH were evaluated. Under the optimum extraction conditions, the method resulted in low limits of detection and quantification within the range 0.05-0.21ngg(-1) in honey (15-70ngL(-1) in solution) and 0.15-1.1ngg(-1) in honey (45-210ngL(-1) in solution), respectively. Enrichment factors and extraction recoveries were in the ranges of 1943-1994 and 97-100%, respectively. The method precision was evaluated at 1.5ngg(-1) of each analyte, and the relative standard deviations were found to be less than 4% for intra-day (n=6) and less than 6% for inter-days. The method was successfully applied to the analysis of honey samples and difenoconazole was determined at ngg(-1) levels. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid-phase dispersion with vortex-assisted dispersive liquid-liquid microextraction and HPLC with diode array detection.

    Science.gov (United States)

    Wang, Xiaozhong; Li, Xuwen; Li, Lanjie; Li, Min; Liu, Ying; Wu, Qian; Li, Peng; Jin, Yongri

    2016-05-01

    A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid-phase dispersion combined with vortex-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid-phase dispersion and the eluate obtained was concentrated and further clarified by vortex-assisted dispersive liquid-liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6-2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Trace determination of five triazole fungicide residues in traditional Chinese medicine samples by dispersive solid-phase extraction combined with ultrasound-assisted dispersive liquid-liquid microextraction and UHPLC-MS/MS.

    Science.gov (United States)

    Ma, Shuping; Yuan, Xucan; Zhao, Pengfei; Sun, Hong; Ye, Xiu; Liang, Ning; Zhao, Longshan

    2017-08-01

    A novel and reliable method for determination of five triazole fungicide residues (triadimenol, tebuconazole, diniconazole, flutriafol, and hexaconazol) in traditional Chinese medicine samples was developed using dispersive solid-phase extraction combined with ultrasound-assisted dispersive liquid-liquid microextraction before ultra-high performance liquid chromatography with tandem mass spectrometry. The clean up of the extract was conducted using dispersive solid-phase extraction by directly adding sorbents into the extraction solution, followed by shaking and centrifugation. After that, a mixture of 400 μL trichloromethane (extraction solvent) and 0.5 mL of the above supernatant was injected rapidly into water for the dispersive liquid-liquid microextraction procedure. The factors affecting the extraction efficiency were optimized. Under the optimum conditions, the calibration curves showed good linearity in the range of 2.0-400 (tebuconazole, diniconazole, and hexaconazole) and 4.0-800 ng/g (triadimenol and flutriafol) with the regression coefficients higher than 0.9958. The limit of detection and limit of quantification for the present method were 0.5-1.1 and 1.8-4.0 ng/g, respectively. The recoveries of the target analytes ranged from 80.2 to 103.2%. The proposed method has been successfully applied to the analysis of five triazole fungicides in traditional Chinese medicine samples, and satisfactory results were obtained. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Dispersive solid-phase extraction followed by vortex-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet for the determination of benzoylurea insecticides in soil and sewage sludge.

    Science.gov (United States)

    Peng, Guilong; He, Qiang; Mmereki, Daniel; Lu, Ying; Zhong, Zhihui; Liu, Hanyang; Pan, Weiliang; Zhou, Guangming; Chen, Junhua

    2016-04-01

    A novel dispersive solid-phase extraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in soil and sewage sludge samples before high-performance liquid chromatography with ultraviolet detection. The analytes were first extracted from the soil and sludge samples into acetone under optimized pretreatment conditions. Clean-up of the extract was conducted by dispersive solid-phase extraction using activated carbon as the sorbent. The vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet procedure was performed by using 1-undecanol with lower density than water as the extraction solvent, and the acetone contained in the solution also acted as dispersive solvent. Under the optimum conditions, the linearity of the method was in the range 2-500 ng/g with correlation coefficients (r) of 0.9993-0.9999. The limits of detection were in the range of 0.08-0.56 ng/g. The relative standard deviations varied from 2.16 to 6.26% (n = 5). The enrichment factors ranged from 104 to 118. The extraction recoveries ranged from 81.05 to 97.82% for all of the analytes. The good performance has demonstrated that the proposed methodology has a strong potential for application in the multiresidue analysis of complex matrices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A green deep eutectic solvent dispersive liquid-liquid micro-extraction (DES-DLLME) for the UHPLC-PDA determination of oxyprenylated phenylpropanoids in olive, soy, peanuts, corn, and sunflower oil.

    Science.gov (United States)

    Ferrone, Vincenzo; Genovese, Salvatore; Carlucci, Maura; Tiecco, Matteo; Germani, Raimondo; Preziuso, Francesca; Epifano, Francesco; Carlucci, Giuseppe; Taddeo, Vito Alessandro

    2018-04-15

    A green dispersive liquid-liquid microextraction (DLLME) using deep eutectic solvent (DES) as the extracting solvent has been developed and applied for the simultaneous quantification of ferulic acid, umbelliferone, boropinic acid, 7-isopentenyloxycoumarin, 4'-geranyloxyferulic acid (GOFA), and auraptene in some vegetable oils using ultra high performance liquid chromatography (UHPLC) with photodiode array detection (PDA). All parameters in the extraction step, including selection and loading of both extracting and dispersing solvents, amount of both extractant and disperser solvent were investigated and optimized. PhAA/TMG DES achieved higher recovery and enrichment factor compared to other DESs. The validated method showed good linearity with correlation coefficients, r 2 >0.9990 for all the analytes. Furthermore, this is the first time that eco-friendly solvents are used for the extraction of oxyprenylated phenylpropanoids and the corresponding extract analyzed with ultra high performance liquid chromatography with photodiode array detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A novel task specific magnetic polymeric ionic liquid for selective preconcentration of potassium in oil samples using centrifuge-less dispersive liquid-liquid microextraction technique and its determination by flame atomic emission spectroscopy.

    Science.gov (United States)

    Beiraghi, Asadollah; Shokri, Masood

    2018-02-01

    In the present study a new centrifuge-less dispersive liquid-liquid microextraction technique based on application of a new task specific magnetic polymeric ionic liquid (TSMPIL) as a chelating and extraction solvent for selective preconcentration of trace amounts of potassium from oil samples is developed, for the first time. After extraction, the fine droplets of TSMPIL were transferred into an eppendorf tube and diluted to 500µL using distilled water. Then, the enriched analyte was determined by flame atomic emission spectroscopy (FAES). Several important factors affecting both the complexation and extraction efficiency including extraction time, rate of vortex agitator, amount of carbonyl iron powder, pH of sample solution, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) and quantification (LOQ) were 0.5 and 1.6µgL -1 respectively with the preconcentration factor of 128. The precision (RSD %) for seven replicate determinations at 10µgL -1 of potassium was better than 3.9%. The relative recoveries for the spiked samples were in the acceptable range of 95-104%. The results demonstrated that no remarkable interferences are created by other various ions in the determination of potassium, so that the tolerance limits (W Ion /W K ) of major cations and anions were in the range of 2500-10,000. The purposed method was successfully applied for the analysis of potassium in some oil samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Application of dispersive liquid-liquid microextraction and dispersive micro-solid-phase extraction for the determination of quinolones in swine muscle by high-performance liquid chromatography with diode-array detection

    International Nuclear Information System (INIS)

    Tsai, Wen-Hsien; Chuang, Hung-Yi; Chen, Ho-Hsien; Huang, Joh-Jong; Chen, Hwi-Chang; Cheng, Shou-Hsun; Huang, Tzou-Chi

    2009-01-01

    Dispersive liquid-liquid microextraction (DLLME) and dispersive micro-solid-phase extraction (DMSPE) are two simple and low-cost sample preparation methods for liquid samples. In this work, these two methods were applied to solid tissue sample for the determination of seven quinolones by high-performance liquid chromatography with diode-array detection (HPLC-DAD). After the homogenization of the swine muscle with acetonitrile and salt-promoted partitioning, small amounts of the extract were used for the DLLME and DMSPE methods. In the DLLME approach, the target analytes in the extraction solvent were rapidly extracted into a small volume of dichloromethane for drying and the residue was reconstituted for HPLC-DAD analysis. In the DMSPE approach, the target analytes in the extraction solvent were trapped by dispersive silica-based PSA (primary and secondary amine) sorbents and desorbed into a small amount of desorption solution for HPLC-DAD analysis. Under the optimal conditions, relative recoveries were determined for swine muscle spiked 50-200 μg kg -1 and quantification was achieved by matrix-matched calibration. The calibration curves of seven quinolones showed linearity with a correlation coefficient value above 0.998 for both approaches. Relative recoveries ranged from 93.0 to 104.7% and from 95.5 to 111.0% for DLLME and DMSPE, respectively. Limits of detection (LODs) ranged from 5.6 to 23.8 μg kg -1 and from 7.5 to 26.3 μg kg -1 for DLLME and DMSPE, respectively.

  11. Simple and Rapid Dual-Dispersive Liquid-Liquid Microextraction as an Innovative Extraction Method for Uranium in Real Water Samples Prior to the Determination of Uranium by a Spectrophotometric Technique.

    Science.gov (United States)

    Khan, Naeemullah; Tuzen, Mustafa; Kazi, Tasneem Gul

    2017-11-01

    An innovative, rapid, and simple dual-dispersive liquid-liquid microextraction (DDLL-ME) approach was used to extract uranium from real samples for the first time. The main objective of this study was to disperse extraction solvent by using an air-agitated syringe system to overcome matrix effects and avoid dispersion of hazardous dispersive organic solvents by using heat. The DDLL-ME method consisted of two dispersive liquid-liquid extraction steps with chloroform as the extracting solvent. Uranium formed complexes with 4-(2-thiazolylazo) resorcinol in the aqueous phase and was extracted in extracting solvent (chloroform) after the first dispersive liquid-liquid process. Uranium was then back-extracted in the acidic aqueous phase in a second dispersive liquid-liquid process. Finally, uranium was determined by a spectrophotometric detection technique. The variables that played a key role in the proposed method were studied and optimized. The LOD and sensitivity enhancement factor for uranium were found to be 0.60 µg/L and 45, respectively, under optimized conditions. Calibration graphs were found to be linear in the range of 5.0-600 µg/L. The RSD was 2.5%. Reliability of the proposed method was verified by analyzing certified reference material TM-28.3.

  12. Applications of Liquid-Phase Microextraction in the Sample Preparation of Environmental Solid Samples

    OpenAIRE

    Helena Prosen

    2014-01-01

    Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several...

  13. Ion-pair hollow-fiber liquid-phase microextraction of the quaternary ammonium surfactant dicocodimethylammonium chloride.

    Science.gov (United States)

    Hultgren, Sofie; Larsson, Niklas; Nilsson, Bo F; Jönsson, Jan Ake

    2009-02-01

    A two-phase hollow-fiber (HF) liquid-phase microextraction (LPME) method was developed for determination of a quaternary ammonium compound surfactant, dicocodimethylammonium chloride, in aqueous samples. The porous HF was fixed on a metal rod support and was impregnated with approximately 6.6 microL of organic extractant, which was immobilized in the HF pores. Surfactant extraction was facilitated by addition of carboxylic acid to the sample forming neutral ion pairs with the quaternary ammonium compound. After extraction, the analyte was transferred from the organic extractant in the fiber pores by dissolving the 1-octanol into 100 microL methanol. The methanol extract was analyzed by liquid chromatography-mass spectrometry. The method was optimized (with optimized parameters in brackets) with regard to type of organic extractant (1-octanol), fiber length (2 cm), choice and concentration of anionic carrier (600 microg L(-1) octanoate), procedure of transfer to methanol (15-min sonication), sample volume (250 mL), extraction time (17 h), pH (10), and ionic strength (50 mM carbonate). Aspects influencing repeatability in LPME of (quaternary ammonium) surfactants are discussed. The enrichment factor achieved in 250-mL carbonate buffer was around 400. Due to matrix effects, the enrichment factors achieved when industrial process water was analyzed were 120 or about 30% of that in carbonate buffer. Detection limits of 0.3 microg L(-1) in carbonate buffer and 0.9 microg L(-1) in industrial process water were obtained. If the studied compound is seen as a model substance representing quaternary dialkylated dimethylated ammonium surfactants in general, the developed method may be applied to other quaternary ammonium surfactants.

  14. Two-step microextraction combined with high performance liquid chromatographic analysis of pyrethroids in water and vegetable samples.

    Science.gov (United States)

    Mukdasai, Siriboon; Thomas, Chunpen; Srijaranai, Supalax

    2014-03-01

    Dispersive liquid microextraction (DLME) combined with dispersive µ-solid phase extraction (D-µ-SPE) has been developed as a new approach for the extraction of four pyrethroids (tetramethrin, fenpropathrin, deltamethrin and permethrin) prior to the analysis by high performance liquid chromatography (HPLC) with UV detection. 1-Octanol was used as the extraction solvent in DLME. Magnetic nanoparticles (Fe3O4) functionalized with 3-aminopropyl triethoxysilane (APTS) were used as the dispersive in DLME and as the adsorbent in D-µ-SPE. The extracted pyrethroids were separated within 30 min using isocratic elution with acetonitrile:water (72:28). The factors affecting the extraction efficiency were investigated. Under the optimum conditions, the enrichment factors were in the range of 51-108. Linearity was obtained in the range 0.5-400 ng mL(-1) (tetramethrin) and 5-400 ng mL(-1) (fenpropathrin, deltamethrin and permethrin) with the correlation coefficients (R(2)) greater than 0.995. Detection limits were 0.05-2 ng mL(-1) (water samples) and 0.02-2.0 ng g(-1) (vegetable samples). The relative standard deviations of peak area varied from 1.8 to 2.5% (n=10). The extraction recoveries of the four pyrethroids in field water and vegetable samples were 91.7-104.5%. The proposed method has high potential for use as a sensitive method for determination of pyrethroid residues in water and vegetable samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Organic solvent-free air-assisted liquid-liquid microextraction for optimized extraction of illegal azo-based dyes and their main metabolite from spices, cosmetics and human bio-fluid samples in one step.

    Science.gov (United States)

    Barfi, Behruz; Asghari, Alireza; Rajabi, Maryam; Sabzalian, Sedigheh

    2015-08-15

    Air-assisted liquid-liquid microextraction (AALLME) has unique capabilities to develop as an organic solvent-free and one-step microextraction method, applying ionic-liquids as extraction solvent and avoiding centrifugation step. Herein, a novel and simple eco-friendly method, termed one-step air-assisted liquid-liquid microextraction (OS-AALLME), was developed to extract some illegal azo-based dyes (including Sudan I to IV, and Orange G) from food and cosmetic products. A series of experiments were investigated to achieve the most favorable conditions (including extraction solvent: 77μL of 1-Hexyl-3-methylimidazolium hexafluorophosphate; sample pH 6.3, without salt addition; and extraction cycles: 25 during 100s of sonication) using a central composite design strategy. Under these conditions, limits of detection, linear dynamic ranges, enrichment factors and consumptive indices were in the range of 3.9-84.8ngmL(-1), 0.013-3.1μgmL(-1), 33-39, and 0.13-0.15, respectively. The results showed that -as well as its simplicity, fastness, and use of no hazardous disperser and extraction solvents- OS-AALLME is an enough sensitive and efficient method for the extraction of these dyes from complex matrices. After optimization and validation, OS-AALLME was applied to estimate the concentration of 1-amino-2-naphthol in human bio-fluids as a main reductive metabolite of selected dyes. Levels of 1-amino-2-naphthol in plasma and urinary excretion suggested that this compound may be used as a new potential biomarker of these dyes in human body. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Salicylic acid determination in estuarine and riverine waters using hollow fiber liquid-phase microextraction and capillary zone electrophoresis.

    Science.gov (United States)

    da Silva, Gilmar Silvério; Lima, Diana L D; Esteves, Valdemar Inocêncio

    2017-06-01

    A low-cost methodology using hollow fiber liquid-phase microextraction (HF-LPME) and capillary zone electrophoresis (CZE) with UV-Vis detector was developed to analyze the salicylic acid (SA) in estuarine and riverine waters. The technique is easy-to-use and rapid, and demands little volume of organic solvent. The extraction was carried out using a polypropylene membrane supporting into octan-1-ol. HF-LPME under optimized conditions (donor solution sample pH 2, acceptor solution pH 14, sample volume 25 mL, fiber length 10 cm, acceptor volume 25 μL, extraction time 3 h and stirring speed 350 rpm) presented high enrichment factor (407 times) and good recovery in real water samples (from 88 to 110%). A limit of detection of 2.6 μg L -1 was achieved using CZE with UV-Vis detector as quantification method. The method was applied to direct quantification of SA in environmental complex estuarine and riverine water matrices.

  17. A novel, donor-active solvent-assisted liquid-phase microextraction procedure for spectrometric determination of zinc

    Energy Technology Data Exchange (ETDEWEB)

    Kocurova, Livia; Fatlova, Martina; Bazel, Yaroslav; Serbin, Rastislav; Andruch, Vasil, E-mail: liviamonika.kocurova@gmail.com [Department of Analytical Chemistry, University of P. J. Safarik, Kosice (Slovakia); Balogh, Ioseph S. [Department of Chemistry, College of Nyiregyhaza (Hungary); Simon, Andras [Department of General and Analytical Chemistry, Budapest University of Technology and Economics, Budapest (Hungary); Badida, Miroslav; Rusnak, Radoslav [Department of Environmentalistics, Faculty of Mechanical Engineering, Technical University of Kosice (Slovakia)

    2014-02-15

    Based on the reaction of Zn(II), thiocyanate and 2-[2-(5-dimethylamino-thiophen-2-yl)-vinyl]- 1,3,3-trimethyl-3H-indolium bromide (DTVTI), a donor-active solvent-assisted liquid-phase microextraction procedure followed by spectrophotometric determination of zinc at 570 nm was developed. The optimum experimental conditions were investigated and found to be as follows: concentration of NH{sub 4}SCN 0.02 mol L{sup -1} concentration of DTVTI 4 x 10{sup -5} mol L{sup -1}. Various extraction solvents were studied alone as well as in mixtures with different improvers, and a mixture of toluene as the extraction solvent and tributylphosphate as the donor-active solvent in a 4:1 v/v ratio was selected. The calibration plot was linear up to 2.62 mg L{sup 1} of zinc with limit of detection 0.09 mg L{sup -1}. The developed procedure was applied for zinc determination in dietary supplements. (author)

  18. Determination of Ochratoxin A in Wheat and Maize by Solid Bar Microextraction with Liquid Chromatography and Fluorescence Detection

    Directory of Open Access Journals (Sweden)

    Nabil Al-Hadithi

    2015-08-01

    Full Text Available Solid bar microextraction (SBME, followed by liquid chromatography with fluorescence detection (HPLC-FLD, for the quantification of ochratoxin A in wheat and maize was developed. Ground wheat and maize grains were extracted with acetonitrile-water-acetic acid (79:20:1, v/v/v, followed by defatting with cyclohexane, and subjected to SBME-LC-FLD analysis. SBME devices were constructed by packing 2 mg sorbent (C18 into porous polypropylene micro-tubes (2.5 cm length, 600 μm i.d., and 0.2 μm pore size. SBME devices were conditioned with methanol and placed into 5 mL stirred sample solutions for 70 min. After extraction, OTA was desorbed into 200 μL of methanol for 15 min, the solution was removed in vacuum, the residue was dissolved in 50 μL of methanol-water (1:1, v/v and ochratoxin A content was determined by HPLC-FLD. Under optimized extraction conditions, the limit of detection of 0.9 μg·kg−1 and 2.5 μg·kg−1 and the precision of 3.4% and 5.0% over a concentration range of 1 to 100 μg·kg−1 in wheat and maize flour, respectively, were obtained.

  19. Headspace Hanging Drop Liquid Phase Microextraction and Gas Chromatography-Mass Spectrometry for the Analysis of Flavors from Clove Buds

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Mi Jin; Shin, Yeon Jae; Oh, Se Yeon; Kim, Nam Sun; Kim, Kun; Lee, Dong Sun [Seoul Women' s University, Seoul (Korea, Republic of)

    2006-02-15

    A novel sample pretreatment technique, headspace hanging drop liquid phase microextraction (HS-LPME) was studied and applied to the determination of flavors from solid clove buds by gas chromatography-mass spectrometry (GC-MS). Several parameters affecting on HS-LPME such as organic solvent drop volume, extraction time, extraction temperature and phase ratio were investigated. 1-Octanol was selected as the extracting solvent, drop size was fixed to 0.6 μL. 60 min extraction time at 25 .deg. C was chosen. HS-LPME has the good efficiency demonstrated by the higher partition equilibrium constant (K{sub lh}) values and concentration factor (CF) values. The limits of detection (LOD) were 1.5-3.2 ng. The amounts of eugenol, β-caryophyllene and eugenol acetate from the clove bud sample were 1.90 mg/g, 1.47 mg/g and 7.0 mg/g, respectively. This hanging drop based method is a simple, fast and easy sample enrichment technique using minimal solvent. HSLPME is an alternative sample preparation method for the analysis of volatile aroma compounds by GC-MS.

  20. A novel microextraction technique based on 1-hexylpyridinium hexafluorophosphate ionic liquid for the preconcentration of zinc in water and milk samples

    International Nuclear Information System (INIS)

    Abdolmohammad-Zadeh, H.; Sadeghi, G.H.

    2009-01-01

    A simple dispersive liquid-liquid microextraction methodology based on the application of 1-hexylpyridinium hexafluorophosphate [HPy][PF 6 ] ionic liquid (IL) as an extractant solvent was proposed for the preconcentration of trace levels of zinc as a prior step to determination by flame atomic absorption spectrometry (FAAS). Zinc was complexed with 8-hydroxyquinoline (oxine) and extracted into ionic liquid. Some effective factors that influence the microextraction efficiency such as pH, oxine concentration, amount of IL, ionic strength, temperature and centrifugation time were investigated and optimized. In the optimum experimental conditions, the limit of detection (3 s) and the enhancement factor were 0.22 μg L -1 and 71, respectively. The relative standard deviation (RSD) for six replicate determinations of 13 μg L -1 Zn was 1.92%. In order to validate the developed method, a certified reference material (NIST SRM 1549) was analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the trace determination of zinc in water and milk samples.

  1. Three-phase hollow-fiber liquid-phase microextraction combined with HPLC-UV for the determination of isothiazolinone biocides in adhesives used for food packaging materials.

    Science.gov (United States)

    Rosero-Moreano, Milton; Canellas, Elena; Nerín, Cristina

    2014-02-01

    The present study deals with the development of a liquid microextraction procedure for enhancing the sensitivity of the determination of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one in adhesives. The procedure involves a three-phase hollow-fiber liquid-phase microextraction using a semipermeable polypropylene membrane, which contained 1-octanol as the organic phase in the pores of the membrane. The donor and acceptor phases are aqueous acidic and alkaline media, respectively, and the final liquid phase (acceptor) is analyzed by HPLC coupled with diode array detection. The most appropriate conditions were extraction time 20 min, stirring speed 1400 rpm, extraction temperature 50°C. The quantification limits of the method were 0.123 and 0.490 μg/g for 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, respectively. Three different adhesive samples were successfully analyzed. The procedure was compared to direct analysis using ultra high pressure liquid chromatography coupled with TOF-MS, where the identification of the compounds and the quantification values were confirmed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.

    Science.gov (United States)

    Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

    2013-12-15

    A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Rapid and sensitive determination of phytosterols in functional foods and medicinal herbs by using UHPLC-MS/MS with microwave-assisted derivatization combined with dual ultrasound-assisted dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Sun, Jing; Zhao, Xian-En; Dang, Jun; Sun, Xiaoyan; Zheng, Longfang; You, Jinmao; Wang, Xiao

    2017-02-01

    In this work, a hyphenated technique of dual ultrasound-assisted dispersive liquid-liquid microextraction combined with microwave-assisted derivatization followed by ultra high performance liquid chromatography tandem mass spectrometry has been developed for the determination of phytosterols in functional foods and medicinal herbs. Multiple reaction monitoring mode was used for the tandem mass spectrometry detection. A mass spectrometry sensitive reagent, 4'-carboxy-substituted rosamine, has been used as the derivatization reagent for five phytosterols, and internal standard diosgenin was used for the first time. Parameters for the dual microextraction, microwave-assisted derivatization, and ultra high performance liquid chromatography tandem mass spectrometry were all optimized in detail. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect, extremely low limits of detection (0.005-0.015 ng/mL) and limits of quantification (0.030-0.10 ng/mL) were achieved. The proposed method was compared with previously reported methods. It showed better sensitivity, selectivity, and accuracy. The matrix effect was also significantly reduced. The proposed method was successfully applied to the determination of five phytosterols in vegetable oil (sunflower oil, olive oil, corn oil, peanut oil), milk and orange juice (soymilk, peanut milk, orange juice), and medicinal herbs (Ginseng, Ganoderma lucidum, Cordyceps, Polygonum multiflorum) for the quality control of functional foods and medicinal herbs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Deep eutectic solvent-based ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the determination of ultraviolet filters in water samples.

    Science.gov (United States)

    Wang, Huazi; Hu, Lu; Liu, Xinya; Yin, Shujun; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang

    2017-09-22

    In the present study, a simple and rapid sample preparation method designated ultrasound-assisted dispersive liquid-liquid microextraction based on a deep eutectic solvent (DES) followed by high-performance liquid chromatography with ultraviolet (UV) detection (HPLC-UVD) was developed for the extraction and determination of UV filters from water samples. The model analytes were 2,4-dihydroxybenzophenone (BP-1), benzophenone (BP) and 2-hydroxy-4-methoxybenzophenone (BP-3). The hydrophobic DES was prepared by mixing trioctylmethylammonium chloride (TAC) and decanoic acid (DecA). Various influencing factors (selection of the extractant, amount of DES, ultrasound duration, salt addition, sample volume, sample pH, centrifuge rate and duration) on UV filter recovery were systematically investigated. Under optimal conditions, the proposed method provided good recoveries in the range of 90.2-103.5% and relative standard deviations (inter-day and intra-day precision, n=5) below 5.9%. The enrichment factors for the analytes ranged from 67 to 76. The limits of detection varied from 0.15 to 0.30ngmL -1 , depending on the analytes. The linearities were between 0.5 and 500ngmL -1 for BP-1 and BP and between 1 and 500ngmL -1 for BP-3, with coefficients of determination greater than 0.99. Finally, the proposed method was applied to the determination of UV filters in swimming pool and river water samples, and acceptable relative recoveries ranging from 82.1 to 106.5% were obtained. Copyright © 2017. Published by Elsevier B.V.

  5. Dispersive liquid-liquid microextraction for the determination of vitamins D and K in foods by liquid chromatography with diode-array and atmospheric pressure chemical ionization-mass spectrometry detection.

    Science.gov (United States)

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

    2013-10-15

    A simple and rapid method was developed using reversed-phase liquid chromatography (LC) with both diode array (DAD) and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of the vitamins ergocalciferol (D2), cholecalciferol (D3), phylloquinone (K1), menaquinone-4 (K2) and a synthetic form of vitamin K, menadione (K3). The Taguchi experimental method, an orthogonal array design (OAD), was used to optimize an efficient and clean preconcentration step based on dispersive liquid-liquid microextraction (DLLME). A factorial design was applied with six factors and three levels for each factor, namely, carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The DLLME optimized procedure consisted of rapidly injecting 3 mL of acetonitrile (disperser solvent) containing 150 µL carbon tetrachloride (extraction solvent) into the aqueous sample, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was evaporated with nitrogen, reconstituted with 50 µL of acetonitrile, and injected. The LC analyses were carried out using a mobile phase composed of acetonitrile, 2-propanol and water, under gradient elution. Quantification was carried out by the standard additions method. The APCI-MS spectra, in combination with UV spectra, permitted the correct identification of compounds in the food samples. The method was validated according to international guidelines and using a certified reference material. The validated method was applied for the analysis of vitamins D and K in infant foods and several green vegetables. There was little variability in the forms of vitamin K present in vegetables, with the most abundant vitamer in all the samples being phylloquinone, while menadione could not be detected. Conversely, cholecalciferol, which is present in food of animal origin, was

  6. Rapid determination of triclosan in personal care products using new in-tube based ultrasound-assisted salt-induced liquid-liquid microextraction coupled with high performance liquid chromatography-ultraviolet detection.

    Science.gov (United States)

    Chen, Ming-Jen; Liu, Ya-Ting; Lin, Chiao-Wen; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2013-03-12

    This paper describes the development of a novel, simple and efficient in-tube based ultrasound-assisted salt-induced liquid-liquid microextraction (IT-USA-SI-LLME) technique for the rapid determination of triclosan (TCS) in personal care products by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. IT-USA-SI-LLME method is based on the rapid phase separation of water-miscible organic solvent from the aqueous phase in the presence of high concentration of salt (salting-out phenomena) under ultrasonication. In the present work, an indigenously fabricated home-made glass extraction device (8-mL glass tube inbuilt with a self-scaled capillary tip) was utilized as the phase separation device for USA-SI-LLME. After the extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus, the collection and measurement of the upper organic solvent layer was simple and convenient. The effects of various parameters on the extraction efficiency were thoroughly evaluated and optimized. Under optimal conditions, detection was linear in the concentration range of 0.4-100ngmL(-1) with correlation coefficient of 0.9968. The limit of detection was 0.09ngmL(-1) and the relative standard deviations ranged between 0.8 and 5.3% (n=5). The applicability of the developed method was demonstrated for the analysis of TCS in different commercial personal care products and the relative recoveries ranged from 90.4 to 98.5%. The present method was proven to be a simple, sensitive, less organic solvent consuming, inexpensive and rapid procedure for analysis of TCS in a variety of commercially available personal care products or cosmetic preparations. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Determination of trace bisphenol A in environmental water by high-performance liquid chromatography using magnetic reduced graphene oxide based solid-phase extraction coupled with dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Li, Danping; Ma, Xiaoguo; Wang, Rui; Yu, Yumian

    2017-02-01

    Bisphenol A (BPA), an endocrine-disrupting chemical, has received much attention from researchers and the general public. In this paper, a novel method of determining BPA at trace levels was developed, using magnetic reduced graphene oxide (rGO-Fe 3 O 4 )-based solid-phase extraction coupled with dispersive liquid-liquid microextraction (DLLME), followed by high-performance liquid chromatographic determination. The rGO-Fe 3 O 4 was prepared and then characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. The greatest saturation magnetization of rGO-Fe 3 O 4 was up to 43.8 emu g -1 , which allowed rapid isolation of the rGO-Fe 3 O 4 from solutions upon applying an appropriate magnetic field. The effects of solution pH, adsorbent amount, type and volume of eluent and extraction solvent, extraction time, and salt concentration on the extraction efficiency of BPA were examined and optimized. Under the optimum conditions, an enrichment factor of 5217 and an LOD of 0.01 μg L -1 for BPA were obtained. The reusability of rGO-Fe 3 O 4 for at least 12 repeated cycles without any significant decrease in the extraction recovery of BPA was demonstrated. The proposed method was applied to the determination of BPA in different real water samples, with relative recoveries of 84.8-104.9 % and RSDs of 0.8-8.3 % in the spiked concentration range 1-10 μg L -1 .

  8. A highly selective dispersive liquid-liquid microextraction approach based on the unique fluorous affinity for the extraction and detection of per- and polyfluoroalkyl substances coupled with high performance liquid chromatography tandem-mass spectrometry.

    Science.gov (United States)

    Wang, Juan; Shi, Yali; Cai, Yaqi

    2018-04-06

    In the present study, a highly selective fluorous affinity-based dispersive liquid-liquid microextraction (DLLME) technique was developed for the extraction and analysis of per- and polyfluoroalkyl substances (PFASs) followed by high performance liquid chromatography tandem-mass spectrometry. Perfluoro-tert-butanol with multiple C-F bonds was chosen as the extraction solvent, which was injected into the aqueous samples with a dispersive solvent (acetonitrile) in a 120:800 (μL, v/v) mixture for PFASs enrichment. The fluorous affinity-based extraction mechanism was confirmed by the significantly higher extraction recoveries for PFASs containing multiple fluorine atoms than those for compounds with fewer or no fluorine atoms. The extraction recoveries of medium and long-chain PFASs (CF 2  > 5) exceeded 70%, except perfluoroheptanoic acid, while those of short-chain PFASs were lower than 50%, implying that the proposed DLLME may not be suitable for their extraction due to weak fluorous affinity. This highly fluoroselective DLLME technique can greatly decrease the matrix effect that occurs in mass spectrometry detection when applied to the analysis of urine samples. Under the optimum conditions, the relative recoveries of PFASs with CF 2  > 5 ranged from 80.6-121.4% for tap water, river water and urine samples spiked with concentrations of 10, 50 and 100 ng/L. The method limits of quantification for PFASs in water and urine samples were in the range of 0.6-8.7 ng/L. Furthermore, comparable concentrations of PFASs were obtained via DLLME and solid-phase extraction, confirming that the developed DLLME technique is a promising method for the extraction of PFASs in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Trace analysis of three antihistamines in human urine by on-line single drop liquid-liquid-liquid microextraction coupled to sweeping micellar electrokinetic chromatography and its application to pharmacokinetic study.

    Science.gov (United States)

    Gao, Wenhua; Chen, Yunsheng; Chen, Gaopan; Xi, Jing; Chen, Yaowen; Yang, Jianying; Xu, Ning

    2012-09-01

    A rapid and efficient dual preconcentration method of on-line single drop liquid-liquid-liquid microextraction (SD-LLLME) coupled to sweeping micellar electrokinetic chromatography (MEKC) was developed for trace analysis of three antihistamines (mizolastine, chlorpheniramine and pheniramine) in human urine. Three analytes were firstly extracted from donor phase (4 mL urine sample) adjusted to alkaline condition (0.5 M NaOH). The unionized analytes were subsequently extracted into a drop of n-octanol layered over the urine sample, and then into a microdrop of acceptor phase (100 mM H(3)PO(4)) suspended from a capillary inlet. The enriched acceptor phase was on-line injected into capillary with a height difference and then analyzed directly by sweeping MEKC. Good linear relationships were obtained for all analytes in a range of 6.25 × 10(-6) to 2.5 × 10(-4)g/L with correlation coefficients (r) higher than 0.987. The proposed method achieved limits of detections (LOD) varied from 1.2 × 10(-7) to 9.5 × 10(-7)g/L based on a signal-to-noise of 3 (S/N=3) with 751- to 1372-fold increases in detection sensitivity for analytes, and it was successfully applied to the pharmacokinetic study of three antihistamines in human urine after an oral administration. The results demonstrated that this method was a promising combination for the rapid trace analysis of antihistamines in human urine with the advantages of operation simplicity, high enrichment factor and little solvent consumption. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Development of salt and pH-induced solidified floating organic droplets homogeneous liquid-liquid microextraction for extraction of ten pyrethroid insecticides in fresh fruits and fruit juices followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Torbati, Mohammadali; Farajzadeh, Mir Ali; Torbati, Mostafa; Nabil, Ali Akbar Alizadeh; Mohebbi, Ali; Afshar Mogaddam, Mohammad Reza

    2018-01-01

    A new microextraction method named salt and pH-induced homogeneous liquid-liquid microextraction has been developed in a home-made extraction device for the extraction and preconcentration of some pyrethroid insecticides from different fruit juice samples prior to gas chromatography-mass spectrometry. In the present work, an extraction device made from two parallel glass tubes with different lengths and diameters was used in the microextraction procedure. In this method, a homogeneous solution of a sample solution and an extraction solvent (pivalic acid) was broken by performing an acid-base reaction and the extraction solvent was produced in whole of the solution. The produced droplets of the extraction solvent went up through the solution and solidified using an ice-bath. They were collected without centrifugation step. Under the optimum conditions, limits of detection and quantification were obtained in the ranges of 0.006-0.038, and 0.023-0.134ngmL -1 , respectively. The enrichment factors and extraction recoveries of the selected analytes ranged from 365-460 to 73-92%, respectively. The relative standard deviations were lower than 9% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 1ngmL -1 of each analyte. Finally, some fruit juice samples were effectively analyzed by the proposed method. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Determination of bisphenol A in canned fatty foods by coacervative microextraction, liquid chromatography and fluorimetry.

    Science.gov (United States)

    Bendito, María Dolores Pérez; Bravo, Soledad Rubio; Reyes, María Loreto Lunar; Prieto, Amalia García

    2009-02-01

    Decanoic acid reverse micelle-based coacervates were used to provide simple, rapid and almost solventless extraction of bisphenol A (BPA) from canned fatty foods. The procedure involved the extraction of 200-400 mg of homogenised food sample with an aqueous solution containing 20% THF and 200 mg of decanoic acid, conditions under which the coacervate (around 550 microl) formed in situ and instantaneously. The overall sample treatment took about 30 min and several samples could be simultaneously treated using conventional laboratory equipment. No clean-up or solvent evaporation were required before determination of BPA by liquid chromatography and fluorescence detection. Recoveries in samples were between 90 and 99%, with relative standard deviations in the range 2-7%. The limit of quantification ranged 29-15 ng g(-1) for 200-400 mg of sample, being far below the current specific migration limit (SML) set by the European Commission (600 ng g(-1)). The method was successfully applied to the determination of BPA in the solid content of canned fish (from 20 to 129 ng g(-1)) and meat (from undetected to 37 ng g(-1)).

  12. Hollow-fiber liquid-phase microextraction of amphetamine-type stimulants in human hair samples.

    Science.gov (United States)

    do Nascimento Pantaleão, Lorena; Bismara Paranhos, Beatriz Aparecida Passos; Yonamine, Mauricio

    2012-09-07

    A fast method was optimized and validated in order to quantify amphetamine-type stimulants (amphetamine, AMP; methamphetamine, MAMP; fenproporex, FPX; 3,4-methylenedioxymethamphetamine, MDMA; and 3,4-methylenedioxyamphetamine, MDA) in human hair samples. The method was based in an initial procedure of decontamination of hair samples (50 mg) with dichloromethane, followed by alkaline hydrolysis and extraction of the amphetamines using hollow-fiber liquid-phase micro extraction (HF-LPME) in the three-phase mode. Gas chromatography-mass spectrometry (GC-MS) was used for identification and quantification of the analytes. The LoQs obtained for all amphetamines (around 0.05 ng/mg) were below the cut-off value (0.2 ng/mg) established by the Society of Hair Testing (SoHT). The method showed to be simple and precise. The intra-day and inter-day precisions were within 10.6% and 11.4%, respectively, with the use of only two deuterated internal standards (AMP-d5 and MDMA-d5). By using the weighted least squares linear regression (1/x²), the accuracy of the method was satisfied in the lower concentration levels (accuracy values better than 87%). Hair samples collected from six volunteers who reported regular use of amphetamines were submitted to the developed method. Drug detection was observed in all samples of the volunteers. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. On-line liquid phase micro-extraction based on drop-in-plug sequential injection lab-at-valve platform for metal determination

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, Constantina [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece); Anthemidis, Aristidis N., E-mail: anthemid@chem.auth.gr [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124 (Greece)

    2013-04-10

    Highlights: ► Drop-in-plug micro-extraction based on SI-LAV platform for metal preconcentration. ► Automatic liquid phase micro-extraction coupled with FAAS. ► Organic solvents with density higher than water are used. ► Lead determination in environmental water and urine samples. -- Abstract: A novel automatic on-line liquid phase micro-extraction method based on drop-in-plug sequential injection lab-at-valve (LAV) platform was proposed for metal preconcentration and determination. A flow-through micro-extraction chamber mounted at the selection valve was adopted without the need of sophisticated lab-on-valve components. Coupled to flame atomic absorption spectrometry (FAAS), the potential of this lab-at-valve scheme is demonstrated for trace lead determination in environmental and biological water samples. A hydrophobic complex of lead with ammonium pyrrolidine dithiocarbamate (APDC) was formed on-line and subsequently extracted into an 80 μL plug of chloroform. The extraction procedure was performed by forming micro-droplets of aqueous phase into the plug of the extractant. All critical parameters that affect the efficiency of the system were studied and optimized. The proposed method offered good performance characteristics and high preconcentration ratios. For 10 mL sample consumption an enhancement factor of 125 was obtained. The detection limit was 1.8 μg L{sup −1} and the precision expressed as relative standard deviation (RSD) at 50.0 μg L{sup −1} of lead was 2.9%. The proposed method was evaluated by analyzing certified reference materials and applied for lead determination in natural waters and urine samples.

  14. Analysis of Piroxicam in Pharmaceutical Formulation and Human Urine by Dispersive Liquid–Liquid Microextraction Combined with Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Nakisa Seyyedeh Tutunchi

    2013-02-01

    Full Text Available Purpose: Piroxicam, is non–steroidal anti–inflammatory and analgesic agent, which is widely used in the treatment of patients with rheumatologic disorders. A new analytical approach based on the dispersive liquid–liquid microextraction (DLLME has been developed for the extraction and determination of PX in pharmaceutical preparation and human urine. Methods: From the PX standard solution or solutions prepared from real samples, aliquot volumes were pipetted into centrifuge tubes and mixed with acetate buffer at pH 3.0 and NaCl solution. The contents were subjected to the DLLME, so 700 μL of methanol containing 70 μL of chloroform was injected rapidly into a sample solution. A cloudy solution was rapidly produced and the PX extracted into dispersed fine droplets. The mixture was centrifuged, thus these fine droplets of chloroform were settled. The supernatant aqueous phase was readily decanted, then the remained organic phase was diluted with ethanol and the absorbance measured at 355 ± 3 nm against a reagent blank. Results: The main factors affecting the extraction efficiency such as pH, extraction and disperser solvent types and etc. were studied and optimized systematically. Under optimized conditions, the calibration graphs were linear over the range of 0.2 to 4.8 μg/mL. The limit of detection and relative standard deviation were found to be 0.058 μg/mL and 2.83%, respectively. Relative recoveries in the spiked samples ranged from 97 to 110%. Conclusion: Using the developed method PX can be analyzed in pharmaceutical formulation and human urine sample in a simpler, cheaper and more rapid manner.

  15. Expanding the use of polymeric ionic liquids in headspace solid-phase microextraction: Determination of ultraviolet filters in water samples.

    Science.gov (United States)

    Trujillo-Rodríguez, María J; Nan, He; Anderson, Jared L

    2018-03-09

    Three crosslinked polymeric ionic liquid (PIL) sorbent coatings were used in headspace solid-phase microextraction for the determination of a group of ultraviolet filters. The developed crosslinked PIL-based materials include two polycations and a double confined PIL. The method, in combination with gas chromatography-mass spectrometry, is simple, solvent free, and does not require of any derivatization step. After proper optimization of the methodologies with each developed fiber, the analytical performance was compared with a commercial polyacrylate fiber. A study of the normalized calibration slopes, obtained by dividing the calibration slope of each analyte by the coating volume, revealed that the crosslinked fibers can be used as alternatives to commercial fibers for the determination of the selected group of compounds. In particular, the coating nature of the PIL containing the 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide IL as monomer and the 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide IL as crosslinker is the most suitable for the extraction of the selected compounds despite their coating volume, being 3.6 times lower than the commercial polyacrylate fiber. For this fiber, wide linear ranges, correlation coefficients higher than 0.990, limits of detection ranging from 2.8 ng L -1 to 26 ng L -1 and relative standard deviations ranging from 2.5 to 15% were achieved. Finally, all proposed PIL-based fibers were applied towards the analysis of tap water, pool water and lake water, with the majority of the ultraviolet filters being detected and quantified in the last two types of samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

    Science.gov (United States)

    Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

    2014-04-01

    The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Determination of partition coefficient and analysis of nitrophenols by three-phase liquid-phase microextraction coupled with capillary electrophoresis.

    Science.gov (United States)

    Sanagi, Mohd Marsin; Miskam, Mazidatulakmam; Wan Ibrahim, Wan Aini; Hermawan, Dadan; Aboul-Enein, Hassan Y

    2010-07-01

    A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.

  18. Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol–Gel Technique

    Science.gov (United States)

    Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

    2016-01-01

    A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography–flame ionization detector (GC–FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol–gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic–inorganic sol–gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol–gel active organic component for sol–gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001–0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3–10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%. PMID:26759488

  19. Determination of phenobarbital in hair matrix by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

    Science.gov (United States)

    Roveri, Flávia Lopes; Paranhos, Beatriz Aparecida Passos Bismara; Yonamine, Mauricio

    2016-08-01

    A method for identification and quantification of phenobarbital in hair samples by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS) has been presented. Drug-free hair specimens were collected and separated in 50mg aliquots. Each aliquot was washed with 2.0mL of dichloromethane for 15min at 37°C. Standards and deuterated internal standards for calibration and quality control samples were added to the washed hair aliquot and the sample was submitted to complete digestion with sodium hydroxide (NaOH) 1.0mol/L for 15min at 70°C. The dissolved sample was submitted to LPME. After extraction, the residue was derivatized with tetramethylammonium hydroxide (TMAH) and analyzed by GC-MS. The limit of detection (LOD) was 0.1ng/mg and the limit of quantification (LOQ) was 0.25ng/mg. The calibration curve was linear over a concentration range of 0.25ng/mg to 10ng/mg (r(2)>0.99). The intra- and inter-assay precisions, given by RSD, were less than 6% for phenobarbital. Fortified samples of secobarbital and pentobarbital were also submitted to the validated method. The method was successfully applied to hair samples collected from three volunteers who reported regular use of phenobarbital (clinical treatment). The concentrations found were 9.5, 15.1 and 16.3ng/mg of phenobarbital. To contemplate the concentrations found, dilution integrity tests were also validated. The LPME and GC-MS method showed to be suitable for the detection of phenobarbital in hair samples and can be promptly used for different purposes whenever required. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

    Science.gov (United States)

    Gao, Man; Qu, Jingang; Chen, Kai; Jin, Lide; Dahlgren, Randy Alan; Wang, Huili; Tan, Chengxia; Wang, Xuedong

    2017-11-01

    In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g., polarity or specific functional groups). Herein, we developed a salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan, and methyltriclosan, with log K ow ranging from -1.32 to 5.40 in complex milk and environmental water matrices. The disperser in the ionic-liquid-based dispersive liquid-liquid microextraction was converted to the extraction solvent in the subsequent salting-out-assisted microextraction procedures, and thus a single solvent performed a dual role as both extractant and disperser in the SILM-DS process. Acetonitrile was selected as the dual-role solvent because of its strong affinity for both ionic liquids and water, as well as the extractant in the salting-out step. Optimized experimental conditions were 115 μL [C 8 MIM][PF 6 ] as extractor, 1200 μL acetonitrile as dual-role solvent, pH 2.0, 5.0 min ultrasound extraction time, 3.0 g Na 2 SO 4 , and 3.0 min vortex extraction time. Under optimized conditions, the recoveries of the five pollutants ranged from 74.5 to 106.9%, and their LODs were 0.12-0.75 μg kg -1 in milk samples and 0.11-0.79 μg L -1 in environmental waters. Experimental precision based on relative standard deviation was 1.4-6.4% for intraday and 2.3-6.5% for interday analyses. Compared with previous methods, the prominent advantages of the newly developed method are simultaneous determination of pollutants with a wide range of polarities and a substantially reduced workload for ordinary environmental monitoring and food tests. Therefore, the new method has great application potential for simultaneous determination of trace pollutants with strongly contrasting polarities in several

  1. Determination of diphenylether herbicides in water samples by solid-phase microextraction coupled to liquid chromatography.

    Science.gov (United States)

    Sheu, Hong-Li; Sung, Yu-Hsiang; Melwanki, Mahaveer B; Huang, Shang-Da

    2006-11-01

    Solid-phase microextraction (SPME) coupled to LC for the analysis of five diphenylether herbicides (aclonifen, bifenox, fluoroglycofen-ethyl, oxyfluorfen, and lactofen) is described. Various parameters of extraction of analytes onto the fiber (such as type of fiber, extraction time and temperature, pH, impact of salt and organic solute) and desorption from the fiber in the desorption chamber prior to separation (such as type and composition of desorption solvent, desorption mode, soaking time, and flush-out time) were studied and optimized. Four commercially available SPME fibers were studied. PDMS/divinylbenzene (PDMS/DVB, 60 microm) and carbowax/ templated resin (CW/TPR, 50 microm) fibers were selected due to better extraction efficiencies. Repeatability (RSD, 0.994), and detection limit (0.33-1.74 and 0.22-1.94 ng/mL, respectively, for PDMS/DVB and CW/TPR) were investigated. Relative recovery (81-104% for PDMS/DVB and 83-100% for CW/TPR fiber) values have also been calculated. The developed method was successfully applied to the analysis of river water and water collected from a vegetable garden.

  2. Ultra-preconcentration and determination of selected pharmaceutical and personal care products in different water matrices by solid-phase extraction combined with dispersive liquid-liquid microextraction prior to ultra high pressure liquid chromatography tandem mass spectrometry analysis.

    Science.gov (United States)

    Celano, Rita; Piccinelli, Anna Lisa; Campone, Luca; Rastrelli, Luca

    2014-08-15

    Pharmaceutical and personal care products (PPCPs) are one of the most important classes of emerging contaminants. The potential of ecological and environmental impacts associated with PPCPs are of particular concern because they continually penetrate the aquatic environment. This work describes a novel ultra-preconcentration technique for the rapid and highly sensitive analysis of selected PPCPs in environmental water matrices at ppt levels. Selected PPCPs were rapidly extracted and concentrated from large volumes of aqueous solutions (500 and 250mL) by solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and then analyzed using UHPLC-MS/MS. Experimental parameters were carefully investigated and optimized to achieve the best SPE-DLLME efficiency and higher enrichment factors. The best results were obtained using the ternary mixture acetonitrile/methanol/dichloromethane 3:3:4, v/v/v, both as SPE eluent and DLLME extractant/dispersive mixture. DLLME aqueous solution (5% NaCl, 10mgL(-1) TBAB) was also modified to improve the extraction efficiency of more hydrophilic PPCPs. Under the optimal conditions, an exhaustive extraction for most of the investigated analytes (recoveries >70%), with a precision (RSD drinking, sea, river and wastewater). Method detection and quantification limits were at very low ppt levels and below 1 and 3ngL(-1), respectively, for 15 of selected PPCPs. The proposed analytical procedure offers numerous advantages such as the simplicity of operation, rapidity, a high enrichment factor and sensitivity. So it is suitable for monitoring and studies of occurrence of PPCPs in different environmental compartments. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Ionic liquid-based single-drop microextraction/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene and xylene isomers in waters.

    Science.gov (United States)

    Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

    2008-08-01

    The direct coupling between ionic liquid-based single-drop microextraction and gas chromatography/mass spectrometry is proposed for the rapid and simple determination of benzene, toluene, ethylbenzene and xylenes isomers (BTEX) in water samples. The extraction procedure exploits not only the high affinity of the selected ionic liquid (1-methyl-3-octyl-imidazolium hexaflourophosphate) to these aromatic compounds but also its special properties like viscosity, low vapour pressure and immiscibility with water. All the variables involved in the extraction process have been studied in depth. The developed method allows the determination of these single-ring compounds in water under the reference concentration level fixed by the international legislation. In this case, limits of detection were in the range 20 ng L(-1) (obtained for benzene) and 91 ng L(-1) (for o-xylene). The repeatability of the proposed method, expressed as RSD (n=5), varied between 3.0% (o-xylene) and 5.2% (toluene).

  4. Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry

    International Nuclear Information System (INIS)

    Ho, Tse-Tsung; Chen, Chung-Yu; Li Zuguang; Yang, Thomas Ching-Cherng; Lee, Maw-Rong

    2012-01-01

    Highlights: ► Ionic liquid (IL), ([C 4 MIM][PF 6 ]), was rapid synthesized by microwave radiation. ► Trace chlorophenols in landfill leachate were extract by SPME coated IL. ► The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive. - Abstract: A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 MIM][PF 6 ]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography–mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography–mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 °C for 4 min. Linearity was observed from 0.1 to 1000 μg L −1 with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 μg L −1 . The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 μg L −1 . The results demonstrate that the IL-SPME-GC/MS method is highly effective in analyzing trace chlorophenols in landfill leachate.

  5. Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Tse-Tsung; Chen, Chung-Yu [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); Li Zuguang [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, Zhejiang (China); Yang, Thomas Ching-Cherng [Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 82444, Taiwan (China); Lee, Maw-Rong, E-mail: mrlee@dragon.nchu.edu.tw [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Ionic liquid (IL), ([C{sub 4}MIM][PF{sub 6}]), was rapid synthesized by microwave radiation. Black-Right-Pointing-Pointer Trace chlorophenols in landfill leachate were extract by SPME coated IL. Black-Right-Pointing-Pointer The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive. - Abstract: A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}MIM][PF{sub 6}]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography-mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography-mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 Degree-Sign C for 4 min. Linearity was observed from 0.1 to 1000 {mu}g L{sup -1} with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 {mu}g L{sup -1}. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 {mu}g L{sup -1}. The results demonstrate that the IL-SPME-GC/MS method is highly effective in

  6. Solid-phase extraction combined with dispersive liquid-liquid microextraction and chiral liquid chromatography-tandem mass spectrometry for the simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

    Science.gov (United States)

    Zhao, Pengfei; Deng, Miaoduo; Huang, Peiting; Yu, Jia; Guo, Xingjie; Zhao, Longshan

    2016-09-01

    This report describes, for the first time, the simultaneous enantioselective determination of proton-pump inhibitors (PPIs-omeprazole, lansoprazole, pantoprazole, and rabeprazole) in environmental water matrices based on solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and chiral liquid chromatography-tandem mass spectrometry. The optimized results of SPE-DLLME were obtained with PEP-2 column using methanol-acetonitrile (1/1, v/v) as elution solvent, dichloroethane, and acetonitrile as extractant and disperser solvent, respectively. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralpak IC (250 mm × 4.6 mm, 5 μm) column, under isocratic conditions at 0.6 mL min(-1) flow rate. The analytes were detected in multiple reaction monitoring (MRM) mode by triple quadrupole mass spectrometry. Isotopically labeled internal standards were used to compensate matrix interferences. The method provided enrichment factors of around 500. Under optimal conditions, the mean recoveries for all eight enantiomers from the water samples were 89.3-107.3 % with 0.9-10.3 % intra-day RSD and 2.3-8.1 % inter-day RSD at 20 and 100 ng L(-1) levels. Correlation coefficients (r (2)) ≥ 0.999 were achieved for all enantiomers within the range of 2-500 μg L(-1). The method detection and quantification limits were at very low levels, within the range of 0.67-2.29 ng L(-1) and 2.54-8.68 ng L(-1), respectively. This method was successfully applied to the determination of the concentrations and enantiomeric fractions of the targeted analytes in wastewater and river water, making it applicable to the assessment of the enantiomeric fate of PPIs in the environment. Graphical Abstract Simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

  7. Simultaneous determination of 12 pharmaceuticals in water samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Guan, Jin; Zhang, Chi; Wang, Yang; Guo, Yiguang; Huang, Peiting; Zhao, Longshan

    2016-11-01

    A new analytical method was developed for simultaneous determination of 12 pharmaceuticals using ultrasound-assisted dispersive liquid-liquid microextraction (DLLME) followed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). Six nonsteroidal anti-inflammatory drugs (NSAIDs, ketoprofen, mefenamic acid, tolfenamic acid, naproxen, sulindac, and piroxicam) and six antibiotics (tinidazole, cefuroxime axetil, ciprofloxacin, sulfamethoxazole, sulfadiazine, and chloramphenicol) were extracted by ultrasound-assisted DLLME using dichloromethane (800 μL) and methanol/acetonitrile (1:1, v/v, 1200 μL) as the extraction and dispersive solvents, respectively. The factors affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, vortex and ultrasonic time, sample pH, and ionic strength, were optimized. The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution by using a small volume of dispersive solvent, which increased the extraction efficiency and reduced the equilibrium time. Under the optimal conditions, the calibration curves showed good linearity in the range of 0.04-20 ng mL -1 (ciprofloxacin and sulfadiazine), 0.2-100 ng mL -1 (ketoprofen, tinidazole, cefuroxime axetil, naproxen, sulfamethoxazole, and sulindac), and 1-200 ng mL -1 (mefenamic acid, tolfenamic acid, piroxicam, and chloramphenicol). The LODs and LOQs of the method were in the range of 0.006-0.091 and 0.018-0.281 ng mL -1 , respectively. The relative recoveries of the target analytes were in the range from 76.77 to 99.97 % with RSDs between 1.6 and 8.8 %. The developed method was successfully applied to the extraction and analysis of 12 pharmaceuticals in five kinds of water samples (drinking water, running water, river water, influent and effluent wastewater) with satisfactory results. Graphical Abstract Twelve pharmaceuticals in water samples analyted by UHPLC

  8. In situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction for the determination of neurotransmitters in Parkinson's rat brain microdialysates by ultra high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    He, Yongrui; Zhao, Xian-En; Zhu, Shuyun; Wei, Na; Sun, Jing; Zhou, Yubi; Liu, Shu; Liu, Zhiqiang; Chen, Guang; Suo, Yourui; You, Jinmao

    2016-08-05

    Simultaneous monitoring of several neurotransmitters (NTs) linked to Parkinson's disease (PD) has important scientific significance for PD related pathology, pharmacology and drug screening. A new simple, fast and sensitive analytical method, based on in situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) in a single step, has been proposed for the quantitative determination of catecholamines and their biosynthesis precursors and metabolites in rat brain microdialysates. The method involved the rapid injection of the mixture of low toxic bromobenzene (extractant) and acetonitrile (dispersant), which containing commercial Lissamine rhodamine B sulfonyl chloride (LRSC) as derivatization reagent, into the aqueous phase of sample and buffer, and the following in situ DUADLLME procedure. After centrifugation, 50μL of the sedimented phase (bromobenzene) was directly injected for ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection in multiple reaction monitoring (MRM) mode. This interesting combination brought the advantages of speediness, simpleness, low matrix effects and high sensitivity in an effective way. Parameters of in situ DUADLLME and UHPLC-MS/MS conditions were all optimized in detail. The optimum conditions of in situ DUADLLME were found to be 30μL of microdialysates, 150μL of acetonitrile containing LRSC, 50μL of bromobenzene and 800μL of NaHCO3-Na2CO3 buffer (pH 10.5) for 3.0min at 37°C. Under the optimized conditions, good linearity was observed with LODs (S/N>3) and LOQs (S/N>10) of LRSC derivatized-NTs in the range of 0.002-0.004 and 0.007-0.015 nmol/L, respectively. It also brought good precision (3.2-12.8%, peak area CVs%), accuracy (94.2-108.6%), recovery (94.5-105.5%) and stability (3.8-8.1%, peak area CVs%) results. Moreover, LRSC derivatization significantly improved chromatographic resolution and MS detection sensitivity of NTs when compared with the

  9. A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air-assisted liquid-liquid microextraction from human urine and plasma samples followed by gas chromatography-nitrogen phosphorous detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Alizadeh Nabil, Ali Akbar

    2015-12-01

    In present study, a simultaneous derivatization and air-assisted liquid-liquid microextraction method combined with gas chromatography-nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1-flouro-2,4-dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05-0.34 ng mL(-1) are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Dispersive liquid-liquid microextraction based on solidification of floating organic drop for simultaneous separation/preconcentration of nickel, cobalt and copper prior to determination by electrothermal atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mooud Amirkavei

    2013-01-01

    Full Text Available A dispersive liquid-liquid microextraction based on solidification of floating organic drop for simultaneous extraction of trace amounts of nickel, cobalt and copper followed by their determination with electrothermal atomic absorption spectrometry was developed. 300 µL of acetone and 1-undecanol was injected into an aqueous sample containing diethyldithiocarbamate complexes of metal ions. For a sample volume of 10 mL, enrichment factors of 277, 270 and 300 and detection limits of 1.2, 1.1 and 1 ng L-1 for nickel, cobalt and copper were obtained, respectively. The method was applied to the extraction and determination of these metals in different water samples.

  11. Hollow fiber based liquid-phase microextraction for the determination of mercury traces in water samples by electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Garcia, Ignacio; Rivas, Ricardo E. [Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence ' Campus Mare Nostrum' , University of Murcia, E-30071 Murcia (Spain); Hernandez-Cordoba, Manuel, E-mail: hcordoba@um.es [Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence ' Campus Mare Nostrum' , University of Murcia, E-30071 Murcia (Spain)

    2012-09-19

    Highlight: Black-Right-Pointing-Pointer Hg (II) traces are preconcentrated by means of a three-phase liquid microextraction system. Black-Right-Pointing-Pointer PAN and ammonium iodide are used in the donor and acceptor phase, respectively. Black-Right-Pointing-Pointer Hollow-fiber pores are continuously fed with toluene placed in the lumen. Black-Right-Pointing-Pointer Mercuric ions can be measured in waters below the {mu}g L{sup -1} level. - Abstract: A three-phase liquid microextraction procedure for the determination of mercury at low concentrations is discussed. To the aqueous sample placed at pH 7 by means of a phosphate buffer, 0.002% (m/v) 1-(2-pyridylazo)-2-naphthol (PAN) is incorporated, and the mixture submitted to microextraction with a hollow-fiber impregnated with toluene and whose lumen contains a 0.05 mol L{sup -1} ammonium iodide solution. The final measurement of the extract is carried out by electrothermal atomic absorption spectrometry (300 Degree-Sign C and 1100 Degree-Sign C for the calcination and atomization temperatures, respectively). The pyrolytic graphite atomizer is coated electrolytically with palladium. An enrichment factor of 270, which results in a 0.06 {mu}g L{sup -1} mercury for the detection limit is obtained. The relative standard deviation at the 1 {mu}g L{sup -1} mercury level is 3.2% (n = 5). The reliability of the procedure is verified by analyzing waters as well as six certified reference materials.

  12. Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography.

    Science.gov (United States)

    Tran, MinhPhuong; Turner, Erica B; Segro, Scott S; Fang, Li; Seyyal, Emre; Malik, Abdul

    2017-11-03

    A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0-pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Bio-dispersive liquid liquid microextraction based on nano rhaminolipid aggregates combined with magnetic solid phase extraction using Fe3O4@PPy magnetic nanoparticles for the determination of methamphetamine in human urine.

    Science.gov (United States)

    Haeri, Seyed Ammar; Abbasi, Shahryar; Sajjadifar, Sami

    2017-09-15

    In the present investigation, extraction and preconcentration of methamphetamine in human urine samples was carried out using a novel bio-dispersive liquid liquid microextraction (Bio-DLLME) technique coupled with magnetic solid phase extraction (MSPE). Bio-DLLME is a kind of microextraction technique based nano-materials which have potential capabilities in many application fields. Bio-DLLME is based on the use of a binary part system consisting of methanol and nano rhaminolipid biosurfactant. Use of this binary mixture is ecologically accepted due to their specificity, biocompatibility and biodegradable nature. The potential of nano rhaminolipid biosurfactant as a biological agent in the extraction of organic compounds has been investigated in recent years. They are able to partition at the oil/water interfaces and reduce the interfacial tension in order to increase solubility of hydrocarbons. The properties of the prepared Fe 3 O 4 @PPy magnetic nanoparticles were characterized using Fourier transform infrared spectroscopy and X-ray diffraction methods The influences of the experimental parameters on the quantitative recovery of analyte were investigated. Under optimized conditions, the enrichment factor was 310, the calibration graph was linear in the methamphetamine concentration range from 1 to 60μgL -1 , with a correlation coefficient of 0.9998. The relative standard deviations for six replicate measurements was 5.2%. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. An on-line push/pull perfusion-based hollow-fiber liquid-phase microextraction system for high-performance liquid chromatographic determination of alkylphenols in water samples.

    Science.gov (United States)

    Chao, Yu-Ying; Jian, Zhi-Xuan; Tu, Yi-Ming; Wang, Hsaio-Wen; Huang, Yeou-Lih

    2013-06-07

    In this study, we employed a novel on-line method, push/pull perfusion hollow-fiber liquid-phase microextraction (PPP-HF-LPME), to extract 4-tert-butylphenol, 2,4-di-tert-butylphenol, 4-n-nonylphenol, and 4-n-octylphenol from river and tap water samples; we then separated and quantified the extracted analytes through high-performance liquid chromatography (HPLC). Using this approach, we overcame the problem of fluid loss across the porous HF membrane to the donor phase, permitting on-line coupling of HF-LPME to HPLC. In our PPP-HF-LPME system, we used a push/pull syringe pump as the driving source to perfuse the acceptor phase, while employing a heating mantle and an ultrasonic probe to accelerate mass transfer. We optimized the experimental conditions such as the nature of the HF supported intermediary phase and the acceptor phase, the composition of the donor and acceptor phases, the sample temperature, and the sonication conditions. Our proposed method provided relative standard deviations of 3.1-6.2%, coefficients of determination (r(2)) of 0.9989-0.9998, and limits of detection of 0.03-0.2 ng mL(-1) for the analytes under the optimized conditions. When we applied this method to analyses of river and tap water samples, our results confirmed that this microextraction technique allows reliable monitoring of alkylphenols in water samples.

  15. Dispersive liquid-liquid microextraction and gas chromatography accurate mass spectrometry for extraction and non-targeted profiling of volatile and semi-volatile compounds in grape marc distillates.

    Science.gov (United States)

    Fontana, Ariel; Rodríguez, Isaac; Cela, Rafael

    2018-04-20

    The suitability of dispersive liquid-liquid microextraction (DLLME) and gas chromatography accurate mass spectrometry (GC-MS), based on a time-of-flight (TOF) MS analyzer and using electron ionization (EI), for the characterization of volatile and semi-volatile profiles of grape marc distillates (grappa) are evaluated. DLLME conditions are optimized with a selection of compounds, from different chemical families, present in the distillate spirit. Under final working conditions, 2.5 mL of sample and 0.5 mL of organic solvents are consumed in the sample preparation process. The absolute extraction efficiencies ranged from 30 to 100%, depending on the compound. For the same sample volume, DLLME provided higher responses than solid-phase microextraction (SPME) for most of the model compounds. The GC-EI-TOF-MS records of grappa samples were processed using a data mining non-targeted search algorithm. In this way, chromatographic peaks and accurate EI-MS spectra of sample components were linked. The identities of more than 140 of these components are proposed from comparison of their accurate spectra with those in a low resolution EI-MS database, accurate masses of most intense fragment ions of known structure, and available chromatographic retention index. The use of chromatographic and spectral data, associated to the set of components mined from different grappa samples, for multivariate analysis purposes is also illustrated in the study. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Simultaneous extraction and determination of albendazole and triclabendazole by a novel syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop combined with high performance liquid chromatography.

    Science.gov (United States)

    Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad

    2016-08-17

    A syringe to syringe dispersive liquid phase microextraction-solidified floating organic drop was introduced and used for the simultaneous extraction of trace amounts of albendazole and triclabendazole from different matrices. The extracted analytes were determined by high performance liquid chromatography along with fluorescence detection. The analytical parameters affecting the microextraction efficiency including the nature and volume of the extraction solvent, sample volume, sample pH, ionic strength and the cycles of extraction were optimized. The calibration curves were linear in the range of 0.1-30.0 μg L(-1) and 0.2-30.0 μg L(-1) with determination coefficients of 0.9999 and 0.9998 for albendazole and triclabendazole respectively. The detection limits defined as three folds of the signal to noise ratio were found to be 0.02 μg L(-1) for albendazole and 0.06 μg L(-1) for triclabendazole. The inter-day and intra-day precision (RSD%) for both analytes at three concentration levels (0.5, 2.0 and 10.0 μg L(-1)) were in the range of 6.3-10.1% and 5.0-7.5% respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, cow milk, honey, and urine samples. Copyright © 2016. Published by Elsevier B.V.

  17. Hollow fiber liquid phase microextraction combined with graphite furnace atomic absorption spectrometry for the determination of methylmercury in human hair and sludge samples

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Hongmei [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Hu Bin [Department of Chemistry, Wuhan University, Wuhan 430072 (China)], E-mail: binhu@whu.edu.cn; Chen Beibei; Zu Wanqing [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2008-07-15

    Two methods, based on hollow fiber liquid-liquid-liquid (three phase) microextraction (HF-LLLME) and hollow fiber liquid phase (two phase) microextraction (HF-LPME), have been developed and critically compared for the determination of methylmercury content in human hair and sludge by graphite furnace atomic absorption spectrometry (GFAAS). In HF-LPME, methylmercury was extracted into the organic phase (toluene) prior to its determination by GFAAS, while inorganic mercury remained as a free species in the sample solution. In HF-LLLME, methylmercury was first extracted into the organic phase (toluene) and then into the acceptor phase (4% thiourea in 1 mol L{sup -1} HCl) prior to its determination by GFAAS, while inorganic mercury remained in the sample solution. The total mercury was determined by inductively coupled plasma-mass spectrometry (ICP-MS), and the levels of inorganic mercury in both HF-LLLME and HF-LPME were obtained by subtracting methylmercury from total mercury. The factors affecting the microextraction of methylmercury, including organic solvent, extraction time, stirring rate and ionic strength, were investigated and the optimal extraction conditions were established for both HF-LLLPME and HF-LPME. With a consumption of 3.0 mL of the sample solution, the enrichment factors were 204 and 55 for HF-LLLPME and HF-LPME, respectively. The limits of detection (LODs) for methylmercury were 0.1 {mu}g L{sup -1} and 0.4 {mu}g L{sup -1} (as Hg) with precisions (RSDs (%), c = 5 {mu}g L{sup -1} (as Hg), n = 5) of 13% and 11% for HF-LLLPME-GFAAS and HF-LPME-GFAAS, respectively. For ICP-MS determination of total mercury, a limit of detection of 39 ng L{sup -} {sup 1} was obtained. Finally, HF-LLLME-GFAAS was applied to the determination of methylmercury content in human hair and sludge, and the recoveries for the spiked samples were in the range of 99-113%. In order to validate the method, HF-LLLME-GFAAS was also applied to the analysis of a certified reference

  18. In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Shokri, Masood; Beiraghi, Asadollah; Seidi, Shahram

    2015-01-01

    For the first time, a simple and efficient in situ emulsification microextraction method using a dicationic ionic liquid followed by magnetic assisted physisorption was presented to determine trace amounts of lead. In this method, 400 μL of 1.0 mol L −1 lithium bis (trifluoromethylsulfonyl) imide aqueous solution, Li[NTf 2 ], was added into the sample solution containing 100 μL of 1.0 mol L −1 1,3-(propyl-1,3-diyl) bis (3-methylimidazolium) chloride, [pbmim]Cl 2 , to form a water immiscible ionic liquid, [pbmim][NTf 2 ] 2 . This new in situ formed dicationic ionic liquid was applied as the acceptor phase to extract the lead-ammonium pyrrolidinedithiocarbamate (Pb-APDC) complexes from the sample solution. Subsequently, 30 mg of Fe 3 O 4 magnetic nanoparticles (MNPs) were added into the sample solution to collect the fine droplets of [pbmim][NTf 2 ] 2 , physisorptively. Finally, MNPs were eluted by acetonitrile, separated by an external magnetic field and the obtained eluent was subjected to micro-sampling flame atomic absorption spectrometry (FAAS) for further analysis. Comparing with other microextraction methods, no special devices and centrifugation step are required. Parameters influencing the extraction efficiency such as extraction time, pH, concentration of chelating agent, amount of MNPs and coexisting interferences were studied. Under the optimized conditions, this method showed high extraction recovery of 93% with low LOD of 0.7 μg L −1 . Good linearity was obtained in the range of 2.5–150 μg L −1 with determination coefficient (r 2 ) of 0.9921. Relative standard deviation (RSD%) for seven repeated measurements at the concentration of 10 μg L −1 was 4.1%. Finally, this method was successfully applied for determination of lead in some water and plant samples. - Highlights: • A dicationic ionic liquid was used as the extraction solvent, for the first time. • A simple and efficient in situ emulsification microextraction

  19. Combination of in situ metathesis reaction with a novel "magnetic effervescent tablet-assisted ionic liquid dispersive microextraction" for the determination of endogenous steroids in human fluids.

    Science.gov (United States)

    Wu, Jia; Xu, Zilin; Pan, Yixuan; Shi, Yi; Bao, Xiujie; Li, Jun; Tong, Yu; Tang, Han; Ma, Shuyan; Wang, Xuedong; Lyu, Jianxin

    2018-05-01

    Herein, a novel magnetic effervescence tablet-assisted microextraction coupled to in situ metathesis reaction of ionic liquid (IS-META-ILDM) is presented for the determination of four endogenous steroids in human urine, pregnant women's blood, and fetal umbilical cord blood. The magnetic effervescent tablets, which were composed of Fe 3 O 4 nanoparticles, sodium carbonate (alkaline source), and tartaric acid (acidic source), were used to disperse the extractant and for convenient magnetic separation. After the effervescent reaction, in situ reaction between NH 4 PF 6 and [C 6 MIM]BF 4 was adopted to change hydrophilic ionic liquid to hydrophobic liquid, which could be separated from the aqueous phase. The newly developed method has three obvious advantages: (1) combination of effervescent dispersion and magnetic nanoparticles' retrieval is cost-effective and the dispersion and collection of the extractant can be completed almost simultaneously; (2) as compared to temperature-controlled ionic liquid dispersive microextraction and cold-induced solidified microextraction, this method avoids a heating and cooling process which significantly reduces the extraction time and energy cost; and (3) the combination of adsorption by magnetic nanoparticles with extraction by in situ metathesis reaction easily produces high recoveries for target analytes. The optimized composition of effervescent tablet and experimental parameters are as follows: 0.64 g mixture of sodium carbonate and tartaric acid, 7 mg of Fe 3 O 4 (20 nm) as magnetic sorbents, 40 μL of [C 6 MIM]BF 4 as the extraction solvent, 0.15 g NH 4 PF 6 , and 300 μL of elution solvent. Under the optimized conditions, the newly developed method provided high extraction recoveries (90.0-118.5%) and low LODs (0.14-0.17 μg L -1 ) in urine and blood samples. In total, this IS-META-ILDM method provided high extraction efficiency, fast and convenient separation, and underutilization of any organic solvent, and thus

  20. Urea functionalized surface-bonded sol-gel coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

    Science.gov (United States)

    Jillani, Shehzada Muhammad Sajid; Alhooshani, Khalid

    2018-03-30

    Sol-gel urea functionalized-[bis(hydroxyethyl)amine] terminated polydimethylsiloxane coating was developed for capillary microextraction-high performance liquid chromatographic analysis from aqueous samples. A fused silica capillary is coated from the inside with surface bonded coating material and is created through in-situ sol-gel reaction. The urea-functionalized coating was immobilized to the inner surface of the capillary by the condensation reaction of silanol groups of capillary and sol-solution. The characterization of the coating material was successfully done by using X-ray photoelectron spectroscopy, thermogravimetric analysis, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. To make a setup of online capillary microextraction-high performance liquid chromatography, the urea functionalized capillary was installed in the HPLC manual injection port. The analytes of interest were pre-concentrated in the coated sampling loop, desorbed by the mobile phase, chromatographically separated on C-18 column, and analyzed by UV detector. Sol-gel coated capillaries were used for online extraction and high-performance liquid chromatographic analysis of phenols, ketones, aldehydes, and polyaromatic hydrocarbons. This newly developed coating showed excellent extraction for a variety of analytes ranging from highly polar to non-polar in nature. The analysis using sol-gel coating showed excellent overall sensitivity in terms of lower detection limits (S/N = 3) for the analytes (0.10 ng mL -1 -14.29 ng mL -1 ) with acceptable reproducibility that is less than 12.0%RSD (n = 3). Moreover, the capillary to capillary reproducibility of the analysis was also tested by changing the capillary of the same size. This provided excellent%RSD of less than 10.0% (n = 3). Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Analysis of amino acid and monoamine neurotransmitters and their metabolites in rat urine of Alzheimer's disease using in situ ultrasound-assisted derivatization dispersive liquid-liquid microextraction with UHPLC-MS/MS.

    Science.gov (United States)

    Zhao, Xian-En; He, Yongrui; Li, Meng; Chen, Guang; Wei, Na; Wang, Xiao; Sun, Jing; Zhu, Shuyun; You, Jinmao

    2017-02-20

    Neurotransmitters (NTs) may play an important role in neurodegenerative disorders such as Alzheimer's disease (AD). In order to investigate the potential links, a new simple, fast, accurate and sensitive analytical method, based on in situ ultrasound-assisted derivatization dispersive liquid-liquid microextraction (in situ UA-DDLLME) coupled with ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), has been developed and validated. The quantitation of amino acid neurotransmitters (AANTs) and monoamine neurotransmitters (MANTs) in urine of AD rats were performed in this work. The in situ UA-DDLLME procedure involved the rapid injection of the mixture of low toxic 4-bromoanisole (extractant) and acetonitrile (dispersant), which containing the new designed and synthesized 4'-carbonyl chloride rosamine (CCR) as derivatization reagent, into the aqueous phase of real sample and buffer. Under the selected conditions, the derivatization and microextraction of analytes were simultaneously completed within 1min. Good linearity for each analyte (R>0.992) was observed with low limit of detections (LODs, S/N>3). Moreover, the proposed method was compared with direct detection or other reported methods, and the results showed that low matrix effects and good recoveries results were obtained in this work. Taken together, in situ UA-DDLLME coupled with UHPLC-MS/MS analysis was demonstrated to be a good method for sensitive, accurate and simultaneous monitoring of AANTs and MANTs. This method would be expected to be highly useful in AD diseases' clinical diagnostics and may have potential value in monitoring the efficacy of treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. In-line carbon nanofiber reinforced hollow fiber-mediated liquid phase microextraction using a 3D printed extraction platform as a front end to liquid chromatography for automatic sample preparation and analysis: A proof of concept study.

    Science.gov (United States)

    Worawit, Chanatda; Cocovi-Solberg, David J; Varanusupakul, Pakorn; Miró, Manuel

    2018-08-01

    A novel concept for automation of nanostructured hollow-fiber supported microextraction, combining the principles of liquid-phase microextraction (LPME) and sorbent microextraction synergically, using mesofluidic platforms is proposed herein for the first time, and demonstrated with the determination of acidic drugs (namely, ketoprofen, ibuprofen, diclofenac and naproxen) in urine as a proof-of-concept applicability. Dispersed carbon nanofibers (CNF) are immobilized in the pores of a single-stranded polypropylene hollow fiber (CNF@HF) membrane, which is thereafter accommodated in a stereolithographic 3D-printed extraction chamber without glued components for ease of assembly. The analytical method involves continuous-flow extraction of the acidic drugs from a flowing stream donor (pH 1.7) into an alkaline stagnant acceptor (20 mmol L -1 NaOH) containing 10% MeOH (v/v) across a dihexyl ether impregnated CNF@HF membrane. The flow setup features entire automation of the microextraction process including regeneration of the organic film and on-line injection of the analyte-laden acceptor phase after downstream neutralization into a liquid chromatograph (LC) for reversed-phase core-shell column-based separation. Using a 12-cm long CNF@HF and a sample volume of 6.4 mL, linear dynamic ranges of ketoprofen, naproxen, diclofenac and ibuprofen, taken as models of non-steroidal anti-inflammatory drugs, spanned from ca. 5-15 µg L -1 to 500 µg L -1 with enhancement factors of 43-97 (against a direct injection of 10 µL standards into LC), and limits of detection from 1.6 to 4.3 µg L -1 . Relative recoveries in real urine samples ranged from 97% to 105%, thus demonstrating the reliability of the automatic CNF@HF-LPME method for in-line matrix clean-up and determination of drugs in urine at therapeutically relevant concentrations. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Parallel artificial liquid membrane extraction

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Rasmussen, Knut Einar; Parmer, Marthe Petrine

    2013-01-01

    This paper reports development of a new approach towards analytical liquid-liquid-liquid membrane extraction termed parallel artificial liquid membrane extraction. A donor plate and acceptor plate create a sandwich, in which each sample (human plasma) and acceptor solution is separated by an arti......This paper reports development of a new approach towards analytical liquid-liquid-liquid membrane extraction termed parallel artificial liquid membrane extraction. A donor plate and acceptor plate create a sandwich, in which each sample (human plasma) and acceptor solution is separated...... by an artificial liquid membrane. Parallel artificial liquid membrane extraction is a modification of hollow-fiber liquid-phase microextraction, where the hollow fibers are replaced by flat membranes in a 96-well plate format....

  4. Design and implementation of an automated liquid-phase microextraction-chip system coupled on-line with high performance liquid chromatography

    DEFF Research Database (Denmark)

    Li, Bin; Petersen, Nickolaj J.; Payán, María D Ramos

    2014-01-01

    . The composition of the supported liquid membrane (SLM) and carrier was optimized in order to achieve reasonable extraction performance of all the five alkaloids. With 1-octanol as SLM solvent and with 25mM sodium octanoate as anionic carrier, extraction recoveries for the different opium alkaloids ranged between...

  5. Poly(ionic liquids)-coated stainless-steel wires packed into a polyether ether ketone tube for in-tube solid-phase microextraction.

    Science.gov (United States)

    Feng, Juanjuan; Wang, Xiuqin; Tian, Yu; Luo, Chuannan; Sun, Min

    2017-12-01

    An in-tube solid-phase microextraction device was developed by packing poly(ionic liquids)-coated stainless-steel wires into a polyether ether ketone tube. An anion-exchange process was performed to enhance the extraction performance. Surface properties of poly(ionic liquids)-coated stainless-steel wires were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. The extraction device was connected to high-performance liquid chromatography equipment to build an online enrichment and analysis system. Ten polycyclic aromatic hydrocarbons were used as model analytes, and important conditions including extraction time and desorption time were optimized. The enrichment factors from 268 to 2497, linear range of 0.03-20 μg/L, detection limits of 0.010-0.020 μg/L, extraction and preparation repeatability with relative standard deviation less than 1.8 and 19%, respectively were given by the established online analysis method. It has been used to detect polycyclic aromatic hydrocarbons in environmental samples, with the relative recovery (5, 10 μg/L) in the range of 85.1-118.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Development of Hollow-Fiber Liquid-Phase Microextraction Method for Determination of Urinary -Muconic Acid as a Biomarker of Benzene Exposure

    Directory of Open Access Journals (Sweden)

    Farhad Ghamari

    2016-01-01

    Full Text Available For the first time, hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet was used to extract trans, trans -muconic acid, in urine samples of workers who had been exposed to benzene. The parameters affecting the metabolite extraction were optimized as follows: the volume of sample solution was 11 mL with pH 2, liquid membrane containing dihexyl ether as the supporter, 15% (w/v of trioctylphosphine oxide as the carrier, the time of extraction was 120 minutes, and stirring rate was 500 rpm. Organic phase impregnated in the pores of a hollow fiber was extracted into 24 μL solution of 0.05 mol L −1 Na 2 CO 3 located inside the lumen of the fiber. Under optimized conditions, a high enrichment factor of 153-182 folds, relative recovery of 83%-92%, and detection limit of 0.001 μg mL −1 were obtained. The method was successfully applied to the analysis of ttMA in real urine samples.

  7. Bis(trifluoromethylsulfonyl)imide-based frozen ionic liquid for the hollow-fiber solid-phase microextraction of dichlorodiphenyltrichloroethane and its main metabolites.

    Science.gov (United States)

    Pang, Long; Yang, Peijie; Pang, Rong; Li, Shunyi

    2017-08-01

    1-Hexadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide is a solid-phase ionic organic material under ambient temperature and is considered as a kind of "frozen" ionic liquid. Because of their solid-state and ultra-hydrophobicity, "frozen" ionic liquids are able to be confined in the pores of hollow fiber, based on which a simple method was developed for the hollow-fiber solid-phase microextraction of dichlorodiphenyltrichloroethane and its main metabolites. Under optimized conditions, the proposed method results in good linearity (R 2 > 0.9965) over the range of 0.5-50 μg/L, with low limits of detection and quantification in the range of 0.33-0.38 and 1.00-1.25 μg/L, respectively. Intra- and interday precisions evaluated by relative standard deviation were 3-6 and 1-6%, respectively. The spiked recoveries of dichlorodiphenyltrichloroethane and its main metabolites from real water samples were in the range of 64-113 and 79-112%, respectively, at two different concentration levels. The results suggest that "frozen" ionic liquids are promising for use as a class of novel sorbents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A new supramolecular based liquid solid microextraction method for preconcentration and determination of trace bismuth in human blood serum and hair samples by electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Kahe, Hadi; Chamsaz, Mahmoud

    2016-11-01

    A simple and reliable supramolecule-aggregated liquid solid microextraction method is described for preconcentration and determination of trace amounts of bismuth in water as well as human blood serum and hair samples. Catanionic microstructures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactants, dissolved in deionized water/propanol, are used as a green solvent to extract bismuth (III)-diethyldithiocarbamate complexes by dispersive microextraction methodology. The extracted solid phase is easily removed and dissolved in 50 μL propanol for subsequent measurement by electrothermal atomic absorption spectrometry (ET-AAS). The procedure benefits the merits of supramolecule aggregates' properties and dispersive microextraction technique using water as the main component of disperser solvent, leading to direct interaction with analyte. Phase separation behavior of extraction solvent and different parameters influencing the extraction efficiency of bismuth ion such as salt concentration, pH, centrifugation time, amount of chelating agent, SDS:CTAB mole ratio, and solvent amounts were thoroughly optimized. Under the optimal experimental conditions, the calibration curve was linear in the range of 0.3-6 μg L -1 Bi (III) with a limit of detection (LOD) of 0.16 μg L -1 (S/N = 3). The relative standard deviations (RSD) of determination were obtained to be 5.1 and 6.2 % for 1 and 3 μg L -1 of Bi (III), respectively. The developed method was successfully applied as a sensitive and accurate technique for determination of bismuth ion in human blood serum, hair samples, and a certified reference material.

  9. Novel amphiphilic polymeric ionic liquid-solid phase micro-extraction membrane for the preconcentration of aniline as degradation product of azo dye Orange G under sonication by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Cai, Mei-Qiang; Wei, Xiao-Qing; Du, Chun-Hui; Ma, Xu-Ming; Jin, Mi-Cong

    2014-07-04

    A novel amphiphilic polymeric ionic liquid membrane containing a hydrophilic bromide anion and a hydrophobic carbonyl group was synthesized in dimethylformamide (DMF) systems using the ionic liquid 1-butyl-3-vinylimidazolium bromide (BVImBr) and the methylmethacrylate (MMA) as monomers. The prepared amphiphilic ploy-methylmethacrylate-1-butyl-3-vinylimidazolium bromide (MMA-BVImBr) was characterized by a scanning electron microscope and an infrared spectrum instrument. The results of solid-phase micro-extraction membrane (SPMM) experiments showed that the adsorption capacity of membrane was about 0.76μgμg(-1) for aniline. Based on this, a sensitive method for the determination of trace aniline, as a degradation product of azo dye Orange G under sonication, was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The calibration curve showed a good linearity ranging from 0.5 to 10.0μgL(-1) with a correlation coefficient value of 0.9998. The limit of quantification was 0.5μgL(-1). The recoveries ranged from 90.6% to 96.1%. The intra- and inter-day relative standard deviations were less than 8.3% and 10.9%. The developed SPMM-LC-MS/MS method was used successfully for preconcentration of trace aniline produced during the sonication of Orange G solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Reversed-phase single drop microextraction followed by high-performance liquid chromatography with fluorescence detection for the quantification of synthetic phenolic antioxidants in edible oil samples.

    Science.gov (United States)

    Farajmand, Bahman; Esteki, Mahnaz; Koohpour, Elham; Salmani, Vahid

    2017-04-01

    The reversed-phase mode of single drop microextraction has been used as a preparation method for the extraction of some phenolic antioxidants from edible oil samples. Butylated hydroxyl anisole, tert-butylhydroquinone and butylated hydroxytoluene were employed as target compounds for this study. High-performance liquid chromatography followed by fluorescence detection was applied for final determination of target compounds. The most interesting feature of this study is the application of a disposable insulin syringe with some modification for microextraction procedure that efficiently improved the volume and stability of the solvent microdrop. Different parameters such as the type and volume of solvent, sample stirring rate, extraction temperature, and time were investigated and optimized. Analytical performances of the method were evaluated under optimized conditions. Under the optimal conditions, relative standard deviations were between 4.4 and 10.2%. Linear dynamic ranges were 20-10 000 to 2-1000 μg/g (depending on the analytes). Detection limits were 5-670 ng/g. Finally, the proposed method was successfully used for quantification of the antioxidants in some edible oil samples prepared from market. Relative recoveries were achieved from 88 to 111%. The proposed method had a simplicity of operation, low cost, and successful application for real samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Development of a Dispersive Liquid–Liquid Microextraction Technique for the Extraction and Spectrofluorimetric Determination of Fluoxetine in Pharmaceutical Formulations and Human Urine

    Directory of Open Access Journals (Sweden)

    Ahad Bavili Tabrizi

    2012-06-01

    Full Text Available Purpose: Fluoxetine is the most prescribed antidepressant drug worldwide. In this work, a new dispersive liquid–liquid microextraction (DLLME method combined with spectrofluorimetry has been developed for the extraction and determination of FLX in pharmaceutical formulations and human urine. Methods: For FLX determination, the pH of a 10 mL of sample solution containing FLX, was adjusted to 11.0. Then, 800 μL of ethanol containing 100 μL of chloroform was injected rapidly into the sample solution. A cloudy solution was formed and FLX extracted into the fine droplets of chloroform. After centrifugation, the extraction solvent was sedimented and supernatant aqueous phase was readily decanted. The remained organic phase was diluted with ethanol and its fluorescence was measured at 292±3 nm after excitation at 234±3 nm. Results: Some important parameters influencing microextraction efficiency were investigated. Under the optimum extraction conditions, a linear calibration curve in the range of 10 to 800 ng/mL with a correlation coefficient of r2 = 0.9993 was obtained. Limit of detection (LOD and limit of quantification (LOQ were found to be 2.78 and 9.28 ng/mL, respectively. The relative standard deviations (RSDs were less than 4%. Average recoveries for spiked samples were 93–104%. Conclusion: The proposed method gives a very rapid, simple, sensitive, wide dynamic range and low–cost procedure for the determination of FLX.

  12. Simultaneous extraction and quantification of lamotrigine, phenobarbital, and phenytoin in human plasma and urine samples using solidified floating organic drop microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Abbasi, Bijan

    2015-07-01

    A novel and simple method based on solidified floating organic drop microextraction followed by high-performance liquid chromatography with ultraviolet detection has been developed for simultaneous preconcentration and determination of phenobarbital, lamotrigine, and phenytoin in human plasma and urine samples. Factors affecting microextraction efficiency such as the type and volume of the extraction solvent, sample pH, extraction time, stirring rate, extraction temperature, ionic strength, and sample volume were optimized. Under the optimum conditions (i.e. extraction solvent, 1-undecanol (40 μL); sample pH, 8.0; temperature, 25°C; stirring rate, 500 rpm; sample volume, 7 mL; potassium chloride concentration, 5% and extraction time, 50 min), the limits of detection for phenobarbital, lamotrigine, and phenytoin were 1.0, 0.1, and 0.3 μg/L, respectively. Also, the calibration curves for phenobarbital, lamotrigine, and phenytoin were linear in the concentration range of 2.0-300.0, 0.3-200.0, and 1.0-200.0 μg/L, respectively. The relative standard deviations for six replicate extractions and determinations of phenobarbital, lamotrigine, and phenytoin at 50 μg/L level were less than 4.6%. The method was successfully applied to determine phenobarbital, lamotrigine, and phenytoin in plasma and urine samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Dispersive solid phase micro-extraction of mercury(II from environmental water and vegetable samples with ionic liquid modified graphene oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Nasrollahpour Atefeh

    2017-01-01

    Full Text Available A new dispersive solid phase micro-extraction (dispersive-SPME method for separation and preconcentration of mercury(II using ionic liquid modified magnetic reduced graphene oxide (IL-MrGO nanoparticles, prior to the measurement by cold vapour atomic absorption spectrometry (CV-AAS has been developed. The IL-MrGO composite was characterized by Brunauer– Emmett–Teller method (BET for adsorption-desorption measurement, thermogravimetric analysis (TGA, powder X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS. The method is based on the sorption of mercury( II on IL-MrGO nanoparticles due to electrostatic interaction and complex formation of ionic liquid part of IL-MrGO with mercury(II. The effect of experimental parameters for preconcentration of mercury(II, such as solution type, concentration and volume of the eluent, pH, time of the sorption and desorption, amount of the sorbent and coexisting ion concentration have been optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.08–10 ng mL-1 with a determination coefficient of 0.9995. The limit of detection (LOD of the method at a signal to noise ratio of 3 was 0.01 ng mL-1. Intra-day and inter-day precisions were obtained equal to 3.4 and 4.5 %, respectively. The dispersive solid phase micro-extraction of mercury(II on IL-MrGO nanoparticles coupled with cold vapour atomic absorption spectrometry was successfully used for extraction and determination of mercury(II in water and vegetable samples.

  14. Novel capsule phase microextraction in combination with liquid chromatography-tandem mass spectrometry for determining personal care products in environmental water.

    Science.gov (United States)

    Lakade, Sameer S; Borrull, Francesc; Furton, Kenneth G; Kabir, Abuzar; Marcé, Rosa Maria; Fontanals, Núria

    2018-05-01

    A novel sample preparation technique named capsule phase microextraction (CPME) is presented here. The technique utilizes a miniaturized microextraction capsule (MEC) as the extraction medium. The MEC consists of two conjoined porous tubular polypropylene membranes, one of which encapsulates the sorbent through sol-gel technology, while the other encapsulates a magnetic metal rod. As such, MEC integrates both the extraction and stirring mechanisms into a single device. The aim of this article is to demonstrate the application potential of CPME as sample preparation technique for the extraction of a group of personal care products (PCPs) from water matrices. Among the different sol-gel sorbent materials (UCON ® , poly(caprolactone-dimethylsiloxane-caprolactone) (PCAP-DMS-CAP) and Carbowax 20M (CW-20M)) evaluated, CW-20M MEC demonstrated the best extraction performance for the selected PCPs. The extraction conditions for sol-gel CW-20M MEC were optimized, including sample pH, stirring speed, addition of salt, extraction time, sample volume, liquid desorption solvent, and time. Under the optimal conditions, sol-gel CW-20M MEC provided recoveries, ranging between 47 and 90% for all analytes, except for ethylparaben, which showed a recovery of 26%. The method based on CPME with sol-gel CW-20M followed by liquid chromatography-tandem mass spectrometry was developed and validated for the extraction of PCPs from river water and effluent wastewater samples. When analyzing different environmental samples, some analytes such as 2,4-dihydroxybenzophenone, 2,2-dihydroxy-4-4 methoxybenzophenone and 3-benzophenone were found at low ng L -1 .

  15. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography–mass spectrometry

    International Nuclear Information System (INIS)

    Jiao, Jiao; Ma, Dan-Hui; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Fu, Yu-Jie; Ma, Wei

    2013-01-01

    Graphical abstract: -- Highlights: •A new ILAMD-HS-SDME method is developed for the microextraction of essential oil. •ILs used as destruction agent of plant cell walls and microwave absorption medium. •Parameters affecting the extraction efficiency are optimized by Box–Behnken design. •Procedure benefits: similar constituents, shorter duration and smaller sample amount. •ILAMD-HS-SDME followed by GC–MS is a promising technique in analytical fields. -- Abstract: A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography–mass spectrometry (GC–MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C 2 mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78 °C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences

  16. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography–mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Jiao [State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin 150040 (China); Ma, Dan-Hui [College of Life Sciences, Northeast Forestry University, Harbin 150040 (China); Gai, Qing-Yan; Wang, Wei; Luo, Meng [State Engineering Laboratory of Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040 (China); Fu, Yu-Jie, E-mail: yujie_fu2002@yahoo.com [State Engineering Laboratory of Bio-Resource Eco-Utilization, Northeast Forestry University, Harbin 150040 (China); Ma, Wei, E-mail: mawei@hljucm.net [State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin 150040 (China); School of Pharmaceutical, Heilongjiang University of Chinese Medicine, Harbin 150040 (China)

    2013-12-04

    Graphical abstract: -- Highlights: •A new ILAMD-HS-SDME method is developed for the microextraction of essential oil. •ILs used as destruction agent of plant cell walls and microwave absorption medium. •Parameters affecting the extraction efficiency are optimized by Box–Behnken design. •Procedure benefits: similar constituents, shorter duration and smaller sample amount. •ILAMD-HS-SDME followed by GC–MS is a promising technique in analytical fields. -- Abstract: A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography–mass spectrometry (GC–MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C{sub 2}mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78 °C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences.

  17. Air-assisted liquid–liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples

    Energy Technology Data Exchange (ETDEWEB)

    You, Xiangwei [Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101 (China); College of Science, China Agricultural University, Beijing 100193 (China); Xing, Zhuokan [College of Science, China Agricultural University, Beijing 100193 (China); Liu, Fengmao, E-mail: liufengmao@cau.edu.cn [College of Science, China Agricultural University, Beijing 100193 (China); Zhang, Xu [College of Science, China Agricultural University, Beijing 100193 (China)

    2015-05-22

    Highlights: • A novel AALLME-SFO method was firstly reported for pesticide residue analysis. • Solvent with low density and proper melting point was used as extraction solvent. • The formation of “cloudy solvent” with a syringe only. • The new method avoided the use of organic dispersive solvent. - Abstract: A novel air assisted liquid–liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μg L{sup −1}. The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3–13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly.

  18. Ionic liquid solvent bar micro-extraction of CdCln(n-2)- species for ultra-trace Cd determination in seawater.

    Science.gov (United States)

    Herce-Sesa, Belén; López-López, José A; Moreno, Carlos

    2018-02-01

    Water analysis of trace metals has been benefited by recent studies on sample preparation by liquid micro-extraction. However, there are still limitations for its application to seawater, such as the need of additives to preserve the sample or the availability of chemical extractants for the selective extraction from highly saline samples. In this work, a three phase solvent bar micro-extraction (3SBME) system containing the ionic liquid trioctylmethylammonium chloride (Aliquat ® 336) has been used for isolation and pre-concentration of Cd from seawater samples, due to its ability for ionic exchange of CdCl n (n-2)- . The system was optimized to work at the natural pH of seawater, and conditions for application to real samples were 0.18 M Aliquat ® 336 dissolved in kerosene with 0.25 M dodecan-1-ol as organic solution, 1.5 M HNO 3 as acceptor solution, 60 min extraction time, and 800 rpm stirring speed in the sample. Loss of organic solution into the sample during extraction was evaluated and revealed its dependence on stirring rate and extraction time. Under optimum conditions samples containing Cd 0.09-0.90 nM were pre-concentrated 65 times. GF-AAS was used for metal quantification with a limit of detection of 0.04 nM. Accuracy was successfully evaluated measuring Cd in a seawater certified reference material BCR-403. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. A fully automated effervescence assisted dispersive liquid–liquid microextraction based on a stepwise injection system. Determination of antipyrine in saliva samples

    International Nuclear Information System (INIS)

    Medinskaia, Kseniia; Vakh, Christina; Aseeva, Darina; Andruch, Vasil; Moskvin, Leonid; Bulatov, Andrey

    2016-01-01

    A first attempt to automate the effervescence assisted dispersive liquid–liquid microextraction (EA-DLLME) has been reported. The method is based on the aspiration of a sample and all required aqueous reagents into the stepwise injection analysis (SWIA) manifold, followed by simultaneous counterflow injection of the extraction solvent (dichloromethane), the mixture of the effervescence agent (0.5 mol L"−"1 Na_2CO_3) and the proton donor solution (1 mol L"−"1 CH_3COOH). Formation of carbon dioxide microbubbles generated in situ leads to the dispersion of the extraction solvent in the whole aqueous sample and extraction of the analyte into organic phase. Unlike the conventional DLLME, in the case of EA-DLLME, the addition of dispersive solvent, as well as, time consuming centrifugation step for disruption of the cloudy state is avoided. The phase separation was achieved by gentle bubbling of nitrogen stream (2 mL min"−"1 during 2 min). The performance of the suggested approach is demonstrated by determination of antipyrine in saliva samples. The procedure is based on the derivatization of antipyrine by nitrite-ion followed by EA-DLLME of 4-nitrosoantipyrine and subsequent UV–Vis detection using SWIA manifold. The absorbance of the yellow-colored extract at the wavelength of 345 nm obeys Beer's law in the range of 1.5–100 µmol L"−"1 of antipyrine in saliva. The LOD, calculated from a blank test based on 3σ, was 0.5 µmol L"−"1. - Highlights: • First attempt to automate the effervescence assisted dispersive liquid–liquid microextraction. • Automation based on Stepwise injection analysis manifold in flow batch system. • Counterflow injection of extraction solvent and the effervescence agent. • Phase separation performed by gentle bubbling of nitrogen. • Application for the determination of antipyrine in saliva samples.

  20. Air-assisted liquid–liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples

    International Nuclear Information System (INIS)

    You, Xiangwei; Xing, Zhuokan; Liu, Fengmao; Zhang, Xu

    2015-01-01

    Highlights: • A novel AALLME-SFO method was firstly reported for pesticide residue analysis. • Solvent with low density and proper melting point was used as extraction solvent. • The formation of “cloudy solvent” with a syringe only. • The new method avoided the use of organic dispersive solvent. - Abstract: A novel air assisted liquid–liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid–liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μg L −1 . The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3–13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly

  1. Ultrasonic-energy enhance the ionic liquid-based dual microextraction to preconcentrate the lead in ground and stored rain water samples as compared to conventional shaking method.

    Science.gov (United States)

    Nizamani, Sooraj; Kazi, Tasneem G; Afridi, Hassan I

    2018-01-01

    An efficient preconcentration technique based on ultrasonic-assisted ionic liquid-based dual microextraction (UA-ILDµE) method has been developed to preconcentrate the lead (Pb +2 ) in ground and stored rain water. In the current proposed method, Pb +2 was complexed with a chelating agent (dithizone), whereas an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was used for extraction purpose. The ultrasonic irradiation and electrical shaking system were applied to enhance the dispersion and extraction of Pb +2 complex in aqueous samples. For second phase, dual microextraction (DµE phase), the enriched Pb +2 complex in ionic liquid, extracted back into the acidic aqueous solution and finally determined by flame atomic absorption spectrometry. Some major analytical parameters that influenced the extraction efficiency of developed method, such as pH, concentration of ligand, volume of ionic liquid and samples, time of shaking in thermostatic electrical shaker and ultrasonic bath, effect of back extracting HNO 3 volume, matrix effect, centrifugation time and rate were optimized. At the sample volume of 25mL, the calculated preconcentration factor was 62.2. The limit of detection of proposed procedure for Pb +2 ions was found to be 0.54μgL -1 . The validation of developed method was performed by the analysis of certified sample of water SRM 1643e and standard addition method in a real water sample. The extraction recovery of Pb +2 was enhanced≥2% with shaking time of 80s in ultrasonic bath as compared to used thermostatic electrical shaker, where for optimum recovery up to 10min was required. The developed procedure was successfully used for the enrichment of Pb +2 in ground and stored rain water (surface water) samples of an endemic region of Pakistan. The resulted data indicated that the ground water samples were highly contaminated with Pb +2 , while some of the surface water samples were also have higher values of Pb +2 than permissible limit of

  2. A dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry for the determination of nine bisphenols in bottled carbonated beverages.

    Science.gov (United States)

    Mandrah, Kapil; Satyanarayana, G N V; Roy, Somendu Kumar

    2017-12-15

    In the present study, a method has been efficiently developed for the first time to determine nine bisphenol analogues [bisphenol A (BPA), bisphenol C (BPC), bisphenol AF (BPAF), bisphenol E (BPE), bisphenol F (BPF), bisphenol G (BPG), bisphenol M (BPM), bisphenol S (BPS), and bisphenol Z (BPZ)] together in bottled carbonated beverages (collected from the local market of Lucknow, India) using dispersive liquid-liquid microextraction process. This is based on solidification of floating organic droplet (DLLME-SFO) followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry. The process investigated parameters of DLLME-SFO (including the type of extraction and disperser solvents with their volumes, effect of pH, ionic strength, and the sample volume), factors influencing to injection port derivatization like, collision energy, injector port temperature, derivatizing reagent with sample injection volume, and type of organic solvent. BPA, BPF, BPZ, and BPS were detected in each sample; whereas, other bisphenols were also detected in some carbonated beverage samples. After optimizing the required conditions, good linearity of analytes was achieved in the range of 0.097-100ngmL -1 with coefficients of determination (R 2 )≥0.995. Intra-day and inter day precision of the method was good, with relative standard deviation (% RSD)≤10.95%. The limits of detection (LOD) and limits of quantification (LOQ) values of all bisphenols were ranged from 0.021 to 0.104ngmL -1 and 0.070 to 0.343ngmL -1 , respectively. The recovery of extraction was good (73.15-95.08%) in carbonated beverage samples and good enrichment factors (96.36-117.33) were found. Thus, the developed method of microextraction was highly precise, fast, and reproducible to determine the level of contaminants in bottled carbonated beverages. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Hollow fibre liquid phase micro-extraction by facilitated anionic exchange for the determination of flavonoids in faba beans (Vicia faba L.).

    Science.gov (United States)

    Chaieb, Nadia; López-Mesas, Montserrat; Luis González, Johannes; Mars, Messaoud; Valiente, Manuel

    2015-01-01

    Flavonoids are polyphenolic compounds found ubiquitously in foods of plant origin. They are commonly extracted from plant materials with ethanol, methanol, water, their combination or even with acidified extracting solutions. The disadvantages of these methods are the use of high quantity of organic solvent, the possible loss of analytes in the different steps and the laborious process of the techniques. In addition, the complexity of the phenolic mixtures present in plant materials requires a preliminary clean-up and fractionation of the crude extracts. To develop a hollow fibre liquid phase micro-extraction (HF-LPME) method for a one step clean-up and pre-concentration of flavonoids. Two flavonoids (catechin and rutin) has been extracted by HF-LPME and analysed by HPLC. The related driving force for the liquid membrane has been studied by means of facilitated and non-facilitated transport. Different ionic and non-ionic water insoluble compounds [trioctylamine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) and methyltrioctylammonium chloride (aliquat 336)] were used as carriers. The liquid membrane was constituted by a solution of n-decanol in the presence or absence of carriers. Maximum enrichment factors were obtained with n-decanol/aliquat 336 (20%) as organic liquid membrane, sodium hydroxide (NaOH) (0.1 M) as donor solution, sodium chloride (NaCl) (2 M) as acceptor solution and 3 h as extraction time. Under these conditions, good results for validation parameters were obtained [for linearity, limit of detection (LOD), limit of quantitation (LOQ) and repeatability]. The developed method is simple, effective and has been successfully applied to determine catechin and rutin in ethanolic extracts of faba beans. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Simultaneous determination of brazilin and protosappanin B in Caesalpinia sappan by ionic-liquid dispersive liquid-phase microextraction method combined with HPLC.

    Science.gov (United States)

    Xia, Zhaoyang; Li, Dongdong; Li, Qing; Zhang, Yan; Kang, Wenyi

    2017-11-13

    The conditions of heating, ionic liquid-based ultrasonic-assisted extraction combined with reverse-phase high performance liquid chromatography were optimized to simultaneously isolate and determinate brazilin and protosappanin B in Caesalpinia sappan. Ionic liquids, including [BMIM]Br, [BMIM]BF 4 , [BMIM]PF 6 and [HMIM]PF 6 , were selected as extraction solvents while methanol, acetone, acetonitrile, ethanol and water were selected as dispersants. The chromatographic column was Purospher star RP-C 18 (250 mm × 4.6 mm, 5 μm), a mixture of methanol and 0.2% phosphoric acid-water was used as mobile phase at a flow rate 0.65 mL/min. The result displayed that the extraction yields of brazilin and protosappanin B were highest when the concentration of [BMIM]Br methanol solution as extraction solvent was 0.5 mol/L and the solid-liquid ratio was 1:50 (g/mL). Under the optimal extraction conditions, the contents of brazilin showed a good linearity (r = 1.0000) within the range of 1.25-7.50 μg with the average recovery of 99.33%, the contents of protosappanin B also showed a good linearity (r = 0.9999) within the range of 0.50-3.00 μg with the average recovery of 98.31%. This experiment, which adopted environmentally friendly reagent as extraction solvent, not only improved the extraction efficiency, but also avoided the environmental pollution caused by organic solvent. Moreover, it was simple and reliable, and can be of important significance in the study of Traditional Chinese Medicine active ingredient extraction methods. The antibacterial activities of the ionic liquids and methanol extracts were determined using the paper disc diffusion method. The ionic liquid extract was found to possess antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus (MIC value of 37.5 mg crude drug/mL), β-Lactamase producing S. aureus (MIC values of 18.8 mg crude drug/mL), but not against E. coli, Extended spectrum β-Lactamases E. coli

  5. Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry.

    Science.gov (United States)

    Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

    2008-10-31

    A simple, rapid, solventless method for the determination of trihalomethanes (THMs) (chloroform, bromodichloromethane, dibromochloromethane and bromoform) in water samples is presented. The analytes are extracted from the headspace of the aqueous matrix into a 2 microL drop of the ionic liquid 1-octyl-3-methyl-imidazolium hexafluorophosphate working at 30 degrees C for 30 min. The separation and detection of the target compounds is accomplished by gas chromatography/mass spectrometry owing to the use of an interface that efficiently transfers the analytes extracted in the ionic liquid drop to the gas chromatograph while preventing the ionic liquid from entering the column. The detection limits obtained are below the values compelled by the legislation, ranging from 0.5 microg L(-1) for chloroform and bromodichloromethane to 0.9 microg L(-1) for dibromochloromethane. The use of ionic liquid in the extraction procedure avoids the use of organic solvents and leads to relative standard deviations that range from 3.1% to 4.8%.

  6. Comparison of two microextraction methods based on solidification of floating organic droplet for the determination of multiclass analytes in river water samples by liquid chromatography tandem mass spectrometry using Central Composite Design.

    Science.gov (United States)

    Asati, Ankita; Satyanarayana, G N V; Patel, Devendra K

    2017-09-01

    Two low density organic solvents based liquid-liquid microextraction methods, namely Vortex assisted liquid-liquid microextraction based on solidification of floating organic droplet (VALLME-SFO) and Dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO) have been compared for the determination of multiclass analytes (pesticides, plasticizers, pharmaceuticals and personal care products) in river water samples by using liquid chromatography tandem mass spectrometry (LC-MS/MS). The effect of various experimental parameters on the efficiency of the two methods and their optimum values were studied with the aid of Central Composite Design (CCD) and Response Surface Methodology(RSM). Under optimal conditions, VALLME-SFO was validated in terms of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery for which the respective values were (0.011-0.219ngmL -1 ), (0.035-0.723ngmL -1 ), (0.050-0.500ngmL -1 ), (R 2 =0.992-0.999), (40-56), (80-106%). However, when the DLLME-SFO method was validated under optimal conditions, the range of values of limit of detection, limit of quantification, dynamic linearity range, determination of coefficient, enrichment factor and extraction recovery were (0.025-0.377ngmL -1 ), (0.083-1.256ngmL -1 ), (0.100-1.000ngmL -1 ), (R 2 =0.990-0.999), (35-49), (69-98%) respectively. Interday and intraday precisions were calculated as percent relative standard deviation (%RSD) and the values were ≤15% for VALLME-SFO and DLLME-SFO methods. Both methods were successfully applied for determining multiclass analytes in river water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Determination of monoamine neurotransmitters in human urine by carrier-mediated liquid-phase microextraction based on solidification of stripping phase.

    Science.gov (United States)

    Jiang, Liwei; Chen, Yibang; Chen, Yejun; Ma, Ming; Tan, Yueming; Tang, Hao; Chen, Bo

    2015-11-01

    A novel method was developed for the analysis of monoamine neurotransmitters (MNTs) in human urine by carrier-mediated liquid-phase microextraction based on solidification of stripping phase method (CM-LPME-SSP) coupled with high performance liquid chromatography-electrochemical detector (HPLC-ECD). By adding an appropriate carrier in organic phase, simultaneous extraction of hydrophilic analytes, MNTs, with high enrichment factors (22.6-36.1 folds) and excellent sample cleanup was achieved. A new strategy, solidifying the aqueous stripping phase in the back-extraction process, was developed to facilitate the collection of the stripping phase as small as a few microliters. Combined with HPLC-ECD analysis, the linear ranges of the established method were 0.015-2.0 μg/mL for NE, E, DA, and 0.020-2.0 μg/mL for 5-HT. The limits of detection and quantification were in the range of 5.5-10.8 ng/mL and 15-20 ng/mL, respectively. The relative recoveries were in the range of 87-108%, with intraday and interday relative standard deviations lower than 13%. This method was successfully applied to analysis of MNTs in real urine. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Development of a polymeric ionic liquid coating for direct-immersion solid-phase microextraction using polyhedral oligomeric silsesquioxane as cross-linker.

    Science.gov (United States)

    Chen, Chunyan; Liang, Xiaotong; Wang, Jianping; Zou, Ying; Hu, Huiping; Cai, Qingyun; Yao, Shouzhuo

    2014-06-27

    A novel solid-phase microextraction (SPME) fiber was developed by chemical binding of a crosslinked polymeric ionic liquid (PIL) on the surface of an anodized Ti wire, and was applied in direct-immersion mode for the extraction of perfluorinated compounds (PFCs) from water samples coupled with high performance liquid chromatography-tandem mass spectrometry analysis. The PIL coatings were synthesized by using 1-vinyl-3-hexylimidazolium hexafluorophosphate as monomer and methylacryloyl-substituted polyhedral oligomeric silsesquioxane (POSS) as cross-linker via free radical reaction. The proposed fiber coating exhibited high mechanical stability due to the chemical bonding between the coating and the Ti wire surface. The integration of POSS reagent enhanced the organic solvent resistance of the coating. The parameters affecting the extraction performance of the fiber coating including extraction time, pH of solution, ionic strength and desorption conditions were optimized. The developed PIL-POSS fiber showed good linearity (R<0.998) between 0.1 and 50ngmL(-1) with method detection limits ranging from 0.005 to 0.08ngmL(-1) depending on the analyte, and with relative standard deviation for single-fiber repeatability and fiber-to-fiber reproducibility less than 8.6% and 9.5%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Combination of solid-phase extraction with dispersive liquid-liquid microextraction followed by GC-MS for determination of pesticide residues from water, milk, honey and fruit juice.

    Science.gov (United States)

    Shamsipur, Mojtaba; Yazdanfar, Najmeh; Ghambarian, Mahnaz

    2016-08-01

    In this work, an effective preconcentration method for the extraction and determination of traces of multi-residue pesticides was developed using solid-phase extraction (SPE) coupled with dispersive liquid-liquid microextraction and gas chromatography-mass spectrometry (GC-MS). Variables affecting the performance of both extraction steps such as type and volume of elution and extraction solvents, breakthrough volume, salt addition, extraction time were thoroughly investigated. The proposed method resulted in good linearities (R(2)>0.9915) over the ranges of 1-10,000ngkg(-1), limits of detection (LODs) in the range of 0.5-1.0ngkg(-1) at S/N=3, and precision of RSD% of ⩽11.8. Under optimal conditions, the preconcentration factors were obtained in the range of 2362-10,593 for 100mL sample solutions. Comparison of the proposed method with other ones demonstrated that SPE-DLLME method provides higher extraction efficiency and larger preconcentration factor for determination of pesticides residues. Further, it is simple, inexpensive, highly sensitive, and can be successfully applied to separation, preconcentration and determination of the pesticides (and other noxious materials) in different real food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Accurate determination of 3-alkyl-2-methoxypyrazines in wines by gas chromatography quadrupole time-of-flight tandem mass spectrometry following solid-phase extraction and dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Fontana, Ariel; Rodríguez, Isaac; Cela, Rafael

    2017-09-15

    A new reliable method for the determination 3-alkyl-2-methoxypyrazines (MPs) in wine samples based on the sequential combination of solid-phase extraction (SPE), dispersive liquid-liquid microextraction (DLLME) and gas chromatography (GC) quadrupole time-of-flight accurate tandem mass spectrometry (QTOF-MS/MS) is presented. Primary extraction of target analytes was carried out by using a reversed-phase Oasis HLB (200mg) SPE cartridge combined with acetonitrile as elution solvent. Afterwards, the SPE extract was submitted to DLLME concentration using 0.06mL carbon tetrachloride (CCl 4 ) as extractant. Under final working conditions, sample concentration factors above 379 times and limits of quantification (LOQs) between 0.3 and 2.1ngL -1 were achieved. Moreover, the overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 84 to 108% for samples spiked at concentrations from 5 to 25ngL -1 ) were obtained using matrix-matched standards, without using standard additions over every sample. Highly selective chromatographic records were achieved considering a mass window of 5mDa, centered in the quantification product ion corresponding to each compound. Twelve commercial wines, elaborated with grapes from different varieties and geographical origins, were processed with the optimized method. The 2-isobutyl-3-methoxypyrazine (IBMP) was determined at levels above the LOQs of the method in half of the samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Ultrasound-assisted leaching-dispersive solid-phase extraction followed by liquid-liquid microextraction for the determination of polybrominated diphenyl ethers in sediment samples by gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Fontana, Ariel R; Lana, Nerina B; Martinez, Luis D; Altamirano, Jorgelina C

    2010-06-30

    Ultrasound-assisted leaching-dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (USAL-DSPE-DLLME) technique has been developed as a new analytical approach for extracting, cleaning up and preconcentrating polybrominated diphenyl ethers (PBDEs) from sediment samples prior gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. In the first place, PBDEs were leached from sediment samples by using acetone. This extract was cleaned-up by DSPE using activated silica gel as sorbent material. After clean-up, PBDEs were preconcentrated by using DLLME technique. Thus, 1 mL acetone extract (disperser solvent) and 60 microL carbon tetrachloride (extraction solvent) were added to 5 mL ultrapure water and a DLLME technique was applied. Several variables that govern the proposed technique were studied and optimized. Under optimum conditions, the method detection limits (MDLs) of PBDEs calculated as three times the signal-to-noise ratio (S/N) were within the range 0.02-0.06 ng g(-1). The relative standard deviations (RSDs) for five replicates were or =0.9991. Validation of the methodology was carried out by standard addition method at two concentration levels (0.25 and 1 ng g(-1)) and by comparing with a reference Soxhlet technique. Recovery values were > or =80%, which showed a satisfactory robustness of the analytical methodology for determination of low PBDEs concentration in sediment samples. Copyright 2010 Elsevier B.V. All rights reserved.

  12. Ultra-fast liquid chromatography with tandem mass spectrometry determination of ochratoxin A in traditional Chinese medicines based on vortex-assisted solid-liquid microextraction and aptamer-affinity column clean-up.

    Science.gov (United States)

    Yang, Xihui; Hu, Yichen; Kong, Weijun; Chu, Xianfeng; Yang, Meihua; Zhao, Ming; Ouyang, Zhen

    2014-11-01

    A rapid, selective, and sensitive ultra-fast liquid chromatography with tandem mass spectrometry method was developed for the determination of ochratoxin A in traditional Chinese medicines based on vortex-assisted solid-liquid microextraction and aptamer-affinity column clean-up. Through optimizing the sample pretreatment procedures and chromatographic conditions, good linearity (r(2) ≥ 0.9993), low limit of detection (0.5-0.8 μg/kg), and satisfactory recovery (83.54-94.44%) expressed the good reliability and applicability of the established method in various traditional Chinese medicines. Moreover, the aptamer-affinity column, prepared in-house, showed an excellent feasibility owing to its specific identification of ochratoxin A in various kinds of selected traditional Chinese medicines. The maximum adsorption amount and applicability value were 188.96 ± 10.56 ng and 72.3%, respectively. The matrix effects were effectively eliminated, especially for m/z 404.2→358.0 of ochratoxin A. The application of the developed method for screening the natural contamination levels of ochratoxin A in 25 random traditional Chinese medicines on the market in China indicated that only eight samples were contaminated with low levels below the legal limit (5.0 μg/kg) set by the European Union. This study provided a preferred choice for the rapid and accurate monitoring of ochratoxin A in complex matrices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Polyol-enhanced dispersive liquid-liquid microextraction coupled with gas chromatography and nitrogen phosphorous detection for the determination of organophosphorus pesticides from aqueous samples, fruit juices, and vegetables.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Alizadeh Nabil, Ali Akbar

    2015-12-01

    Polyol-enhanced dispersive liquid-liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides from different samples. In the present study, a high volume of an aqueous phase containing a polyol (sorbitol) is prepared and then a disperser solvent along with an extraction solvent is rapidly injected into it. Sorbitol showed the best results and it was more effective on the extraction recoveries of the analytes than inorganic salts such as sodium chloride, potassium chloride, and sodium sulfate. Under the optimum extraction conditions, the method showed low limits of detection and quantification within the ranges of 12-56 and 44-162 pg/mL, respectively. Enrichment factors and extraction recoveries were in the ranges of 2799-3033 and 84-92%, respectively. The method precision was evaluated at a concentration of 10 ng/mL of each analyte, and relative standard deviations were found to be less than 5.9% for intraday (n = 6) and less than 7.8% for interday (n = 4). Finally, some aqueous samples were successfully analyzed using the proposed method and four analytes (diazinon, dimethoate, chlorpyrifos, and phosalone) were determined, some of them at ng/mL level. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Determination of lead at trace levels in mussel and sea water samples using vortex assisted dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry.

    Science.gov (United States)

    Erarpat, Sezin; Özzeybek, Gözde; Chormey, Dotse Selali; Bakırdere, Sezgin

    2017-12-01

    In this study, dispersive liquid-liquid microextraction (DLLME) and slotted quartz tube (SQT) were coupled to flame atomic absorption spectrometry (FAAS) to increase the sensitivity of lead. Conditions such as the formation of the lead-dithizone complex, efficiency of the DLLME method and the output of the SQT were systematically optimized to improve the detection limit for the analyte. The conventional FAAS system was improved upon by about 3.0 times with SQT-FAAS, 32 times with DLLME-FAAS and 142 times with DLLME-SQT-FAAS. The method was applicable over a wide linear range (10-500 μg L -1 ). The limit of detection (LOD) determined by DLLME-SQT-FAAS for seawater and mussel were 2.7 μg L -1 and 270 μg kg -1 , respectively. The percent recoveries obtained for mussel and seawater samples (spiked at 20 and 50 μg L -1 ) were 95-96% and 98-110%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Development of Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop for the Sensitive Determination of Trace Copper in Water and Beverage Samples by Flame Atomic Absorption Spectrometry

    International Nuclear Information System (INIS)

    Wu, Chunxia; Zhao, Bin; Li, Yingli; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2011-01-01

    A dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) has been developed as a new approach for the extraction of trace copper in water and beverage samples followed by the determination with flame atomic absorption spectrometry. In the DLLME-SFO, 8-hydroxy quinoline, 1-dodecanol, and methanol were used as chelating agent, extraction solvent and dispersive solvent, respectively. The experimental parameters related to the DLLME-SFO such as the type and volume of the extraction and dispersive solvent, extraction time, sample volume, the concentration of chelating agent and salt addition were investigated and optimized. Under the optimum conditions, the enrichment factor for copper was 122. The method was linear in the range from 0.5 to 300 ng mL -1 of copper in the samples with a correlation coefficient (r) of 0.9996 and a limit of detection of 0.1 ng mL -1 . The method was applied to the determination of copper in water and beverage samples. The recoveries for the spiked water and beverage samples at the copper concentration levels of 5.0 and 10.0 ng mL -1 were in the range between 92.0% and 108.0%. The relative standard deviations (RSD) varied from 3.0% to 5.6%

  16. Determination of twelve herbicides in tobacco by a combination of solid–liquid–solid dispersive extraction using multi-walled carbon nanotubes, dispersive liquid-liquid micro-extraction, and detection by GC with triple quadrupole mass spectrometry

    International Nuclear Information System (INIS)

    Liao, Qie Gen; Zhou, Yao Min; Luo, Lin Guang; Wang, Li Bing; Feng, Xiao Hu

    2014-01-01

    We report on a method for the determination of twelve herbicides using solid–liquid–solid dispersive extraction (SLSDE), followed by dispersive liquid-liquid micro-extraction (DLLME) and quantitation by gas chromatography with triple quadrupole mass spectrometric detection. SLSDE was applied to the extraction of herbicides from tobacco samples using multi-walled carbon nanotubes (MWCNTs) as clean-up adsorbents. The effect of the quantity of MWCNTs on SLSDE, and of type and volume of extraction and disperser solvents and of salt effect on DLLME were optimized. Good linearity is obtained in the 5.0 - 500 μg kg −1 concentration range, with regression coefficients of >0.99. Intra-day and inter-day repeatability, expressed as relative standard deviations, are between 3 and 9 %. The recoveries in case of herbicide-spiked tobacco at concentration levels of 20.0, 50.0 and 100.0 g kg −1 ranged from 79 to 105 %, and LODs are between 1.5 and 6.1 μg kg −1 . All the tobacco samples were found to contain butralin and pendimethalin at levels ranging from 15.8 to 500.0 μg kg −1 . (author)

  17. Application of dispersive Liquid-Liquid microextraction based on solidification of floating organic droplet multi-residue method for the simultaneous determination of polychlorinated biphenyls, organochlorine, and pyrethroid pesticides in aqueous sample

    International Nuclear Information System (INIS)

    Zuo, Mei; Li, Man-Liang; Cheng, Jing; Matsadiq, Guzalnur; Liu, Lu; Zhang, Miao

    2012-01-01

    Dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique was successfully applied for simultaneous assay of eight polychlorinated biphenyls, two organochlorine, and four pyrethroid pesticides multi-residue in aqueous samples by using GC-electron capture detection. The effects of various parameters such as kind of extractant and dispersant and volume of them, extraction time, effect of salt addition, and pH were optimized. As a result, 5.0 μL 1-dodecanol was chosen as extraction solvent, 600 μL methanol were used as dispersive solvent without salt addition, pH was adjusted to 7. Under the optimized conditions, the limits of detection (LOD) were ranged from 1.4 to 8.3 ng L -1 . Satisfactory linear range was observed from 5.0 to 2000 ng L -1 with correlation coefficient better than 0.9909. Good precisions were also acquired with RSD better than 13.6% for all target analytes. The enrichment factors of the method were ranged from 786 to 1427. The method can be successfully applied to simultaneous separation and determination of three class residues in real water samples and good recoveries were obtained ranging from 76 to 130, 73 to 129, and 78 to 130% for tap water, lake water, and industrial waste water, respectively. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Development of dispersive liquid-liquid microextraction technique using ternary solvents mixture followed by heating for the rapid and sensitive analysis of phthalate esters and di(2-ethylhexyl) adipate.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Khoshmaram, Leila

    2015-01-30

    In this study, for the first time, a dispersive liquid-liquid microextraction technique using a ternary solvent mixture is reported. In order to extract five phthalate esters and di(2-ethylhexyl) adipate with different polarities from aqueous samples, a simplex centroid experimental design method was used to select an optimal mixture of ternary solvents prior to gas chromatographyflame ionization detection. In this work, dimethyl formamide as a disperser solvent containing dichloromethane, chloroform, and carbon tetrachloride as a ternary extraction solvent mixture is injected into sample solution and a cloudy solution is formed. After centrifuging, 250μL of the obtained sedimented phase was transferred into another tube and 5μL DMF was added to it. Then, the tube was heated in a water bath at 75°C for 5min in order to evaporate the main portion of the extraction solvents. Finally, 2μL of the remained phase is injected into the separation system. Under the optimum extraction conditions, the method shows wide linear ranges and low limits of detection and quantification between 0.03-0.15 and 0.09-0.55μgL(-1), respectively. Enrichment factors and extraction recoveries are in the ranges of 980-4500 and 20-90%, respectively. The method is successfully applied in the determination of the target analytes in mineral water, soda, lemon juice, vinegar, dough, and yogurt packed in plastic packages. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Air-assisted Liquid Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry for Preconcentration and Determination of Trace Amount of Co(II and Ni(II Ions in Water Samples

    Directory of Open Access Journals (Sweden)

    Saeed Mohammad Sorouraddin

    2017-12-01

    Full Text Available A simple, rapid and efficient method has been developed for the extraction, preconcentration and determination of cobalt (II and nickel (II ions in water samples by air-assisted liquid-liquid microextraction (AALLME coupled with graphite furnace atomic absorption spectrometry (GFAAS. In the proposed method, much less volume of an organic solvent was used as the extraction solvent in the absence of disperser solvent. Fine organic droplets were formed by sucking and injecting of the mixture of aqueous sample solution and extraction solvent with a syringe for several times in a conical test tube. After extraction, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by GFAAS. Several variables that could affect the extraction efficiency were investigated and optimized. Calibration graphs were linear in the range of 6.5-100 ng L-1. Detection limits for Co and Ni were 2.3 ng L-1 and 3 ng L-1, respectively. The accuracy of the developed procedure was checked by analyzing NRCC-SLRS4 Riverine water as a certified reference material. Finally, the proposed method has been successfully applied for the determination of cobalt (II and nickel (II ions in tap, surface and river water samples.

  20. Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid-Liquid Microextraction Coupled with UV-Vis Spectrophotometry.

    Science.gov (United States)

    Nejad, Mina Ghasemi; Faraji, Hakim; Moghimi, Ali

    2017-04-01

    In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86 μL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100 µg mL -1 . LOD and LOQ were 3.4 and 11.6 ng mL -1 , respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

  1. Sensitive trace enrichment of environmental andiandrogen vinclozolin from natural waters and sediment samples using hollow-fiber liquid-phase microextraction.

    Science.gov (United States)

    Lambropoulou, Dimitra A; Albanis, Triantafyllos A

    2004-12-17

    The presence of vinclozolin in the environment as far as the endocrine disruption effects in biota are concerned has raised interest in the environmental fate of this compound. In this respect, the present study attempts to investigate the feasibility of applying a novel quantitative method, liquid-phase microextraction (LPME), so as to determine this environmental andiandrogen in environmental samples such as water and sediment samples. The technique involved the use of a small amount (3 microL) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The extracted samples were analyzed by gas chromatography coupled with electron-capture detection. Experimental LPME conditions such as extraction solvent, stirring rate, content of NaCl and pH were tested. Once LPME was optimized, the performance of the proposed technique was evaluated for the determination of vinclozolin in different types of natural water samples. The recovery of spiked water samples was from 80 to 99%. The procedure was adequate for quantification of vinclozolin in waters at levels of 0.010 to 50 microg/L (r> 0.994) with a detection limit of 0.001 microg/L (S/N= 3). Natural sediment samples from the Aliakmonas River area (Macedonia, Greece) spiked with the target andiandrogen compound were liquid-liquid extracted and analyzed by the methodology developed in this work. No significant interferences from the samples matrix were noticed, indicating that the reported methodology is an innovative tactic for sample preparation in sediment analysis, with a considerable improvement in the achieved detection limits. The results demonstrated that apart from analyte enrichment, the proposed LPME procedure also serves as clean-up method and could be successfully performed to determine trace amounts of vinclozolin in water and sediment samples.

  2. Development of an in situ solvent formation microextraction and preconcentration method based on ionic liquids for the determination of trace cobalt (II in water samples by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Jamali

    2017-02-01

    Full Text Available A simple in situ solvent formation microextraction (ISFME methodology based on the application of ionic liquid (IL as an extractant solvent and sodium hexafluorophosphate (NaPF6 as an ion-pairing agent was proposed for the preconcentration of the trace levels of cobalt ions. In this method cobalt was complexed with 2-(5-bromo-2-pyridylazo-5-diethylaminophenol (5-Br-PADAP and extracted into an ionic liquid phase. After phase separation, the enriched analyte in the final solution is determined by flame atomic absorption spectrometry (FAAS. Some effective factors that influence the microextraction efficiency were investigated and optimized. Under the optimum experimental conditions, the limit of detection and the enrichment factor were 0.97 μg L−1 and 50, respectively. The relative standard deviation (R.S.D. was obtained as 2.4%. The proposed method was assessed through the analysis of certified reference water and recovery experiments.

  3. Air assisted dispersive liquid-liquid microextraction with solidification of the floating organic droplets (AA-DLLME-SFO) and UHPLC-PDA method: Application to antibiotics analysis in human plasma of hospital acquired pneumonia patients.

    Science.gov (United States)

    Ferrone, Vincenzo; Cotellese, Roberto; Carlucci, Maura; Di Marco, Lorenzo; Carlucci, Giuseppe

    2018-03-20

    An ultra high-performance liquid chromatographic (UHPLC) method with PDA detection was developed and validated for the simultaneous quantification of metronidazole, meropenem, ciprofloxacin, linezolid and piperacillin in human plasma and applied to patients suffering from hospital acquired pneumonia (HAP). The method uses an air assisted dispersive liquid-liquid microextraction for sample preparation. All parameters in the extraction step, including selection of extractant, amount of extractant, ionic strength, pH, and extraction cycles, were investigated and optimized. Chromatography was carried out using a Poroshell 120 SB C 18 (50 × 2.1 mm I.D. 2.6 μm particle size) column and a gradient mobile phase consisting of ammonium acetate buffer (10 mM, pH 4.0) (eluent A); and a mixture of acetonitrile-methanol in a ratio (80/20)(eluent B). Ulifloxacin was used as internal standard. The method demonstrated good linearity with correlation coefficients, r 2  > 0.9995 for the drugs, as well as high precision (RSD% ≤ 9.87%), accuracy ranged from -8.14% to +8.98. The enrichment factor (EF) obtained ranged within 87 and 121. During the validation, the concentrations of the analytes were found to be stable after 3 freeze-thaw cycles and for at least 24 h after extraction. Subsequently, this method was used to quantify the drugs in patients with HAP in order to establish if the dosage regimen given was sufficient to eradicate the infection at the target site. Copyright © 2017. Published by Elsevier B.V.

  4. Molecularly imprinted sol-gel nanofibers based solid phase microextraction coupled on-line with high performance liquid chromatography for selective determination of acesulfame.

    Science.gov (United States)

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz

    2015-03-01

    Sol-gel based molecularly imprinted polymer (MIP) nanofiber was successfully fabricated by electrospinning technique on the surface of a stainless steel bar. The manufactured tool was applied for on-line selective solid phase microextraction (SPME) and determination of acesulfame (ACF) as an artificial sweetener with high performance liquid chromatography (HPLC). The selective ability of method for the extraction of ACF was investigated in the presence of some selected sweeteners such as saccharine (SCH), aspartame (ASP) and caffeine (CAF). Electrospinning of MIP sol-gel solution on the stainless steel bar provided an unbreakable sorbent with high thermal, mechanical, and chemical stability. Moreover, application of the MIP-SPME tool revealed a unique approach for the selective microextraction of the analyte in beverage samples. In this work, 3-(triethoxysilyl)-propylamine (TMSPA) was chosen as a precursor due to its ability to imprint the analyte by hydrogen bonding, Van der Walls, and dipole-dipole interactions. Nylon 6 was also added as a backbone and support for the precursor in which sol could greatly growth during the sol-gel process and makes the solution electrospinable. Various effective parameters in the extraction efficiency of the MIP-SPME tool such as loading time, flow rate, desorption time, selectivity, and the sample volume were evaluated. The linearity for the ACF in beverage sample was in the range of 0.78-100.5 ng mL(-1). Limit of detection (LOD) and quantification (LOQ) were 0.23 and 0.78 ng mL(-1) respectively. The RSD values (n=5) were all below 3.5%at the 20 ng mL(-1) level. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Solid-state chemiluminescence assay for ultrasensitive detection of antimony using on-vial immobilization of CdSe quantum dots combined with liquid–liquid–liquid microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Costas-Mora, Isabel; Romero, Vanesa; Lavilla, Isela; Bendicho, Carlos, E-mail: bendicho@uvigo.es

    2013-07-25

    Graphical abstract: -- Highlights: •Solid-state chemiluminescence based on CdSe QDs was developed. •QDs immobilization in a vial was achieved in a simple and fast way. •Antimony detection was achieved by inhibition of the CdSe QDs/H{sub 2}O{sub 2} CL reaction. •LLLME allowed improving the selectivity and sensitivity of the CL assay. •The capping ligand played a critical role in the selectivity of the CL system. -- Abstract: On-vial immobilized CdSe quantum dots (QDs) are applied for the first time as chemiluminescent probes for the detection of trace metal ions. Among 17 metal ions tested, inhibition of the chemiluminescence when CdSe QDs are oxidized by H{sub 2}O{sub 2} was observed for Sb, Se and Cu. Liquid–liquid–liquid microextraction was implemented in order to improve the selectivity and sensitivity of the chemiluminescent assay. Factors influencing both the CdSe QDs/H{sub 2}O{sub 2} chemiluminescent system and microextraction process were optimized for ultrasensitive detection of Sb(III) and total Sb. In order to investigate the mechanism by which Sb ions inhibit the chemiluminescence of the CdSe QDs/H{sub 2}O{sub 2} system, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), UV–vis absorption and fluorescence measurements were performed. The selection of the appropriate CdSe QDs capping ligand was found to be a critical issue. Immobilization of QDs caused the chemiluminescence signal to be enhanced by a factor of 100 as compared to experiments carried out with QDs dispersed in the bulk aqueous phase. Under optimized conditions, the detection limit was 6 ng L{sup −1} Sb and the repeatability expressed as relative standard deviation (N = 7) was about 1.3%. An enrichment factor of 95 was achieved within only 3 min of microextraction. Several water samples including drinking, spring, and river waters were analyzed. The proposed method was validated against CRM NWTM-27.2 fortified lake water, and a recovery study was

  6. A fully automated effervescence assisted dispersive liquid–liquid microextraction based on a stepwise injection system. Determination of antipyrine in saliva samples

    Energy Technology Data Exchange (ETDEWEB)

    Medinskaia, Kseniia; Vakh, Christina; Aseeva, Darina [Department of Analytical Chemistry, Institute of Chemistry, Saint Petersburg State University, RU-198504 Saint Petersburg (Russian Federation); Andruch, Vasil, E-mail: vasil.andruch@upjs.sk [Department of Analytical Chemistry, University of P.J. Šafárik, SK-04154 Košice (Slovakia); Moskvin, Leonid [Department of Analytical Chemistry, Institute of Chemistry, Saint Petersburg State University, RU-198504 Saint Petersburg (Russian Federation); Bulatov, Andrey, E-mail: bulatov_andrey@mail.ru [Department of Analytical Chemistry, Institute of Chemistry, Saint Petersburg State University, RU-198504 Saint Petersburg (Russian Federation)

    2016-01-01

    A first attempt to automate the effervescence assisted dispersive liquid–liquid microextraction (EA-DLLME) has been reported. The method is based on the aspiration of a sample and all required aqueous reagents into the stepwise injection analysis (SWIA) manifold, followed by simultaneous counterflow injection of the extraction solvent (dichloromethane), the mixture of the effervescence agent (0.5 mol L{sup −1} Na{sub 2}CO{sub 3}) and the proton donor solution (1 mol L{sup −1} CH{sub 3}COOH). Formation of carbon dioxide microbubbles generated in situ leads to the dispersion of the extraction solvent in the whole aqueous sample and extraction of the analyte into organic phase. Unlike the conventional DLLME, in the case of EA-DLLME, the addition of dispersive solvent, as well as, time consuming centrifugation step for disruption of the cloudy state is avoided. The phase separation was achieved by gentle bubbling of nitrogen stream (2 mL min{sup −1} during 2 min). The performance of the suggested approach is demonstrated by determination of antipyrine in saliva samples. The procedure is based on the derivatization of antipyrine by nitrite-ion followed by EA-DLLME of 4-nitrosoantipyrine and subsequent UV–Vis detection using SWIA manifold. The absorbance of the yellow-colored extract at the wavelength of 345 nm obeys Beer's law in the range of 1.5–100 µmol L{sup −1} of antipyrine in saliva. The LOD, calculated from a blank test based on 3σ, was 0.5 µmol L{sup −1}. - Highlights: • First attempt to automate the effervescence assisted dispersive liquid–liquid microextraction. • Automation based on Stepwise injection analysis manifold in flow batch system. • Counterflow injection of extraction solvent and the effervescence agent. • Phase separation performed by gentle bubbling of nitrogen. • Application for the determination of antipyrine in saliva samples.

  7. Comparison between dispersive solid-phase and dispersive liquid-liquid microextraction combined with spectrophotometric determination of malachite green in water samples based on ultrasound-assisted and preconcentration under multi-variable experimental design optimization.

    Science.gov (United States)

    Alipanahpour Dil, Ebrahim; Ghaedi, Mehrorang; Asfaram, Arash; Zare, Fahimeh; Mehrabi, Fatemeh; Sadeghfar, Fardin

    2017-11-01

    The ultrasound-assisted dispersive solid-phase microextraction (USA-DSPME) and the ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) developed for as an ultra preconcentration and/or technique for the determination of malachite green (MG) in water samples. Central composite design based on analysis of variance and desirability function guide finding best operational conditions and represent dependency of response to variables viz. volume of extraction, eluent and disperser solvent, pH, adsorbent mass and ultrasonication time has significant influence on methods efficiency. Optimum conditions was set for USA-DSPME as: 1mg CNTs/Zn:ZnO@Ni 2 P-NCs; 4min sonication time and 130μL eluent at pH 6.0. Meanwhile optimum point for USA-DLLME conditions were fixed at pH 6.0; 4min sonication time and 130, 650μL and 10mL of extraction solvent (CHCl 3 ), disperser solvent (ethanol) and sample volume, respectively. Under the above specified best operational conditions, the enrichment factors for the USA-DSPME and USA-DLLME were 88.89 and 147.30, respectively. The methods has linear response in the range of 20.0 to 4000.0ngmL -1 with the correlation coefficients (r) between 0.9980 to 0.9995, while its reasonable detection limits viz. 1.386 to 2.348ngmL -1 and good relative standard deviations varied from 1.1% to 2.8% (n=10) candidate this method for successful monitoring of analyte from various media. The relative recoveries of the MG dye from water samples at spiking level of 500ngmL -1 were in the range between 94.50% and 98.86%. The proposed methods has been successfully applied to the analysis of the MG dye in water samples, and a satisfactory result was obtained. Copyright © 2017. Published by Elsevier B.V.

  8. Evaluation of Carbon Nanotubes Functionalized Polydimethylsiloxane Based Coatings for In-Tube Solid Phase Microextraction Coupled to Capillary Liquid Chromatography

    OpenAIRE

    Neus Jornet-Martínez; Pascual Serra-Mora; Yolanda Moliner-Martínez; Rosa Herráez-Hernández; Pilar Campíns-Falcó

    2015-01-01

    In the present work, the performance of carbon nanotubes (c-CNTs) functionalized polydimethylsiloxane (PDMS) based coatings as extractive phases for in-tube solid phase microextraction (IT-SPME) coupled to Capillary LC (CapLC) has been evaluated. Carboxylic-single walled carbon nanotubes (c-SWNTs) and carboxylic-multi walled carbon nanotubes (c-MWNTs) have been immobilized on the activated surface of PDMS capillary columns. The effect of different percentages of diphenyl groups in the PDMS ex...

  9. Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Erkan, E-mail: kimyager_erkan@hotmail.com; Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr

    2015-07-30

    A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2} (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L{sup −1} (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. - Highlights: • Switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2}. • The switchable polarity solvent has been used for the microextraction of cadmium(II). • The important factors were optimized. • The method was applied to determination of cadmium in real samples.

  10. Determination of volatile polycyclic aromatic hydrocarbons in waters using headspace solid-phase microextraction with a benzyl-functionalized crosslinked polymeric ionic liquid coating.

    Science.gov (United States)

    Merdivan, Melek; Pino, Verónica; Anderson, Jared L

    2017-08-01

    A benzyl-functionalized crosslinked polymeric ionic liquid (PIL), produced through the co-polymerization of the 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide (VBHDIM-NTf 2 ) ionic liquid (IL) monomer and 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide ((DVBIM) 2 C 12- 2NTf 2 ) IL crosslinker, was successfully used as a sorbent coating in headspace solid-phase microextraction (SPME) coupled to gas chromatography (GC) with flame-ionization detection (FID) to determine seven volatile polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Optimum extraction conditions for the PAHs when using the novel sorbent include an extraction temperature of 50°C, an ionic strength content adjusted with 30% (w/v) NaCl in the aqueous sample, and an extraction time of 60 min. The extraction performance of the crosslinked PIL fiber was compared to the SPME commercial coating polydimethylsiloxane fiber. The calibration ranges of the studied PAHs were linear in the range of 0.02-20 µg L -1 for the crosslinked PIL fiber. The accuracy of the proposed method was demonstrated by examining the spiked recoveries of seven PAHs which produced values ranging from 67.2% to 130% (for river- and seawater samples), and precision values lower than 9.4% for a spiked level of 1 µg L -1 , and detection limits between 0.01 and 0.04 µg L -1 , which supports the sensitivity of the method using GC-FID.

  11. Microfunnel-supported liquid-phase microextraction: application to extraction and determination of Irgarol 1051 and diuron in the Persian Gulf seawater samples.

    Science.gov (United States)

    Saleh, Abolfazl; Sheijooni Fumani, Neda; Molaei, Saeideh

    2014-08-22

    In the present work, microfunnel-supported liquid-phase microextraction method (MF-LPME) based on applying low density organic solvent was developed for the determination of antifoulings (Irgarol 1051, diuron and 3,4-dichloroaniline) from seawater samples. In this method, home-designed MF device was used for facile loading and retrieving of organic solvent during the extraction procedure. The extraction was carried out with introduction of 400 μL of toluene via syringe into the MF device placed on the surface of sample solution (300 mL) containing analytes. After the extraction, extractant layer was narrowed into the capillary part of MF by pushing the device inside the sample and withdrawn by using a syringe to evaporate by nitrogen purging. The residual redissolved into 50 μL methanol, diluted to 100 μL with deionized water and injected into the high performance liquid chromatography with UV detection (HPLC-UV). Several factors influencing the extraction such as the type and volume of extraction solvent, sample pH, extraction time and ionic strength were investigated and optimized. Under the optimized conditions, the limits of detection in seawater were 1.4, 4.8 and 1.0 ng L(-1) for 3,4-dichloroaniline (DCA), diuron and Irgarol 1051, respectively. Enrichment factors were obtained 333, 150 and 373 for DCA, diuron and Irgarol 1051, respectively. The precision of the technique was evaluated in terms of repeatability which was less than 12.0% (n=5). The applicability of the proposed method was evaluated by the extraction and determination of antifoulings from seawater samples collected from harbors of Bushehr located in northern Persian Gulf coast. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Automation of static and dynamic non-dispersive liquid phase microextraction. Part 2: Approaches based on impregnated membranes and porous supports.

    Science.gov (United States)

    Alexovič, Michal; Horstkotte, Burkhard; Solich, Petr; Sabo, Ján

    2016-02-11

    A critical overview on automation of modern liquid phase microextraction (LPME) approaches based on the liquid impregnation of porous sorbents and membranes is presented. It is the continuation of part 1, in which non-dispersive LPME techniques based on the use of the extraction phase (EP) in the form of drop, plug, film, or microflow have been surveyed. Compared to the approaches described in part 1, porous materials provide an improved support for the EP. Simultaneously they allow to enlarge its contact surface and to reduce the risk of loss by incident flow or by components of surrounding matrix. Solvent-impregnated membranes or hollow fibres are further ideally suited for analyte extraction with simultaneous or subsequent back-extraction. Their use can therefore improve the procedure robustness and reproducibility as well as it "opens the door" to the new operation modes and fields of application. However, additional work and time are required for membrane replacement and renewed impregnation. Automation of porous support-based and membrane-based approaches plays an important role in the achievement of better reliability, rapidness, and reproducibility compared to manual assays. Automated renewal of the extraction solvent and coupling of sample pretreatment with the detection instrumentation can be named as examples. The different LPME methodologies using impregnated membranes and porous supports for the extraction phase and the different strategies of their automation, and their analytical applications are comprehensively described and discussed in this part. Finally, an outlook on future demands and perspectives of LPME techniques from both parts as a promising area in the field of sample pretreatment is given. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. A novel ionic liquid-modified organic-polymer monolith as the sorbent for in-tube solid-phase microextraction of acidic food additives.

    Science.gov (United States)

    Wang, Ting-Ting; Chen, Yi-Hui; Ma, Jun-Feng; Hu, Min-Jie; Li, Ying; Fang, Jiang-Hua; Gao, Hao-Qi

    2014-08-01

    A novel ionic liquid-modified organic-polymer monolithic capillary column was prepared and used for in-tube solid-phase microextraction (SPME) of acidic food additives. The primary amino group of 1-aminopropyl-3-methylimidazolium chloride was reacted with the epoxide group of glycidyl methacrylate. The as-prepared new monomer was then copolymerized in situ with acrylamide and N,N'-methylenebisacrylamide in the presence of polyethylene glycol (PEG)-8000 and PEG-10,000 as porogens. The extraction performance of the developed monolithic sorbent was evaluated for benzoic acid, 3-hydroxybenzoic acid, cinnamic acid, 2,4-dichlorophenoxyacetic acid, and 3-(trifluoromethyl)-cinnamic acid. Such a sorbent, bearing hydrophobic and anion-exchange groups, had high extraction efficiency towards the test compounds. The adsorption capacities for the analytes dissolved in water ranged from 0.18 to 1.74 μg cm(-1). Good linear calibration curves (R(2) > 0.99) were obtained, and the limits of detection (S/N = 3) for the analytes were found to be in the range 1.2-13.5 ng mL(-1). The recoveries of five acidic food additives spiked in Coca-Cola beverage samples ranged from 85.4 % to 98.3 %, with RSD less than 6.9 %. The excellent applicability of the ionic liquid (IL)-modified monolithic column was further tested by the determination of benzoic acid content in Sprite samples, further illustrating its good potential for analyzing food additives in complex samples.

  14. Determination of melamine in soil samples using surfactant-enhanced hollow fiber liquid phase microextraction followed by HPLC–UV using experimental design

    Directory of Open Access Journals (Sweden)

    Ali Sarafraz Yazdi

    2015-11-01

    Full Text Available Surfactant-enhanced hollow fiber liquid phase (SE-HF-LPME microextraction was applied for the extraction of melamine in conjunction with high performance liquid chromatography with UV detection (HPLC–UV. Sodium dodecyl sulfate (SDS was added firstly to the sample solution at pH 1.9 to form hydrophobic ion-pair with protonated melamine. Then the protonated melamine–dodecyl sulfate ion-pair (Mel–DS was extracted from aqueous phase into organic phase immobilized in the pores and lumen of the hollow fiber. After extraction, the analyte-enriched 1-octanol was withdrawn into the syringe and injected into the HPLC. Preliminary, one variable at a time method was applied to select the type of extraction solvent. Then, in screening step, the other variables that may affect the extraction efficiency of the analyte were studied using a fractional factorial design. In the next step, a central composite design was applied for optimization of the significant factors having positive effects on extraction efficiency. The optimum operational conditions included: sample volume, 5 mL; surfactant concentration, 1.5 mM; pH 1.9; stirring rate, 1500 rpm and extraction time, 60 min. Using the optimum conditions, the method was analytically evaluated. The detection limit, relative standard deviation and linear range were 0.005 μg mL−1, 4.0% (3 μg mL−1, n = 5 and 0.01–8 μg mL−1, respectively. The performance of the procedure in extraction of melamine from the soil samples was good according to its relative recoveries in different spiking levels (95–109%.

  15. Analysis of new psychoactive substances in oral fluids by means of microextraction by packed sorbent followed by ultra-high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Rocchi, Rachele; Simeoni, Maria Chiara; Montesano, Camilla; Vannutelli, Gabriele; Curini, Roberta; Sergi, Manuel; Compagnone, Dario

    2017-10-27

    In recent years, new drugs, commonly known as new psychoactive substances (NPS), appeared on the market, which include, among others, synthetic cannabinoids, cathinones, and tryptamine analogs of psilocin. The aim of this work was to develop and validate a new method for simultaneous screening and quantification of 31 NPS in oral fluid by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The chosen target analytes represented different chemical and toxicological NPS classes, such as synthetic cathinones, piperazines, phenethylamines, synthetic cannabinoids, and their metabolites. The procedure involved a rapid sample preparation based on protein precipitation followed by clean-up utilizing microextraction by packed sorbent (MEPS); the quantitative analysis was performed by UHPLC-MS/MS. The MEPS clean-up, regardless of non-quantitative recoveries for some analytes, provided an effective removal of interfering compounds, as demonstrated by reduced matrix effects found at different concentrations for all the analytes. The validation protocol, based on SWGTOX guidelines, demonstrated the suitability of the proposed method for quantitative analysis: linearity range ranged over 3 or 4 orders of magnitude; precision and accuracy tests gave RSD% values below 25%, and accuracy ranged from 85.9% to 107%, accomplishing SWGTOX requirements. Limits of detection (LODs) ranged between 0.005 ng/mL and 0.850 ng/mL and limits of quantification (LOQs) from 0.015 to 2.600 ng/mL. Copyright © 2017 John Wiley & Sons, Ltd.

  16. Application of ultrasound-assisted emulsification microextraction for simultaneous determination of aminophenol isomers in human urine, hair dye, and water samples using high-performance liquid chromatography.

    Science.gov (United States)

    Asghari, Alireza; Fazl-Karimi, Hamidreza; Barfi, Behruz; Rajabi, Maryam; Daneshfar, Ali

    2014-08-01

    Aminophenol isomers (2-, 3-, and 4-aminophenols) are typically classified as industrial pollutants with genotoxic and mutagenic effects due to their easy penetration through the skin and membranes of human, animals, and plants. In the present study, a simple and efficient ultrasound-assisted emulsification microextraction procedure coupled with high-performance liquid chromatography with ultraviolet detector was developed for preconcentration and determination of these compounds in human fluid and environmental water samples. Effective parameters (such as type and volume of extraction solvent, pH and ionic strength of sample, and ultrasonication and centrifuging time) were investigated and optimized. Under optimum conditions (including sample volume: 5 mL; extraction solvent: chloroform, 80 µL; pH: 6.5; without salt addition; ultrasonication: 3.5 min; and centrifuging time: 3 min, 5000 rpm min(-1)), the enrichment factors and limits of detection were ranged from 42 to 51 and 0.028 to 0.112 µg mL(-1), respectively. Once optimized, analytical performance of the method was studied in terms of linearity (0.085-157 µg mL(-1), r (2) > 0.998), accuracy (recovery = 88.6- 101.7%), and precision (repeatability: intraday precision water samples. © The Author(s) 2014.

  17. Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples

    Directory of Open Access Journals (Sweden)

    Zarrin Es’haghi

    2014-11-01

    Full Text Available A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol–gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV using a hanging mercury drop electrode (HMDE was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H-one and 2-{[2-(2-Hydroxy-ethylamino-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05–500 ng mL−1 for Cd (II and Pb (II. The limits of detection for lead and cadmium were 0.015 ng mL−1 and 0.012 ng mL−1, respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II and Pb (II in 5 mL of water sample, respectively.

  18. Simultaneous extraction and determination of trace amounts of diclofenac from whole blood using supported liquid membrane microextraction and fast Fourier transform voltammetry.

    Science.gov (United States)

    Mofidi, Zahra; Norouzi, Parviz; Sajadian, Masumeh; Ganjali, Mohammad Reza

    2018-04-01

    A novel, simple, and inexpensive analytical technique based on flat sheet supported liquid membrane microextraction coupled with fast Fourier transform stripping cyclic voltammetry on a reduced graphene oxide carbon paste electrode was used for the extraction and online determination of diclofenac in whole blood. First, diclofenac was extracted from blood samples using a polytetrafluoroethylene membrane impregnated with 1-octanol and then into an acceptor solution, subsequently it was oxidized on a carbon paste electrode modified with reduced graphene oxide nanosheets. The optimal values of the key parameters influencing the method were as follows: scan rate, 6 V/s; stripping potential, 200 mV; stripping time, 5 s; pH of the sample solution, 5; pH of the acceptor solution,7; and extraction time, 240 min. The calibration curves were plotted for the whole blood samples and the method was found to have a good linearity within the range of 1-25 μg/mL with a determination coefficient of 0.99. The limits of detection and quantification were 0.1 and 1.0 μg/mL, respectively. Using this coupled method, the extraction and determination were merged into one step. Accordingly, the speed of detection for sensitive determination of diclofenac in complex samples, such as blood, increased considerably. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Liquid-phase microextraction with solidification of the organic floating drop for the preconcentration and determination of mercury traces by electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Garcia, I.; Rivas, R.E.; Hernandez-Cordoba, M. [Faculty of Chemistry, University of Murcia, Department of Analytical Chemistry, Murcia (Spain)

    2010-04-15

    A procedure for the determination of traces of mercury by liquid-phase microextraction based on solidification of a floating organic droplet for separation and electrothermal atomic absorption spectrometry for final measurement has been developed. For this purpose, 50 {mu}L of pre-heated (50 C) undecanoic acid (UA), are added to 25 mL of aqueous sample solution at pH 5. The mixture, maintained at 50 C, is stirred for 10 min using a high stirring rate in order to fragment the UA drop into droplets, thus favoring the extraction process. Next, the vial is immersed in an ice bath, which results in the solidification of the UA drop that is easily separated. Injection into the atomizer is carried out after gentle heating. The pyrolytic atomizers are coated with electrolytically reduced palladium that acts as an effective chemical modifier for more than 500 firings. Under the optimized conditions, the detection limit was 70 ng L{sup -1} mercury with an enrichment factor of 430. The relative standard deviation of the measurements was in the 2.1-3.5% range. Recovery studies applied to the determination of mercuric ions in bottled and tap water samples were in the 92-104% range. (orig.)

  20. In-coupled syringe assisted octanol-water partition microextraction coupled with high-performance liquid chromatography for simultaneous determination of neonicotinoid insecticide residues in honey.

    Science.gov (United States)

    Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax

    2015-07-01

    A simple and fast method namely in-coupled syringe assisted octanol-water partition microextraction combined with high performance liquid chromatography (HPLC) has been developed for the extraction, preconcentration and determination of neonicotinoid insecticide residues (e.g. imidacloprid, acetamiprid, clothianidin, thiacloprid, thiamethoxam, dinotefuran, and nitenpyram) in honey. The experimental parameters affected the extraction efficiency, including kind and concentration of salt, kind of disperser solvent and its volume, kind of extraction solvent and its volume, shooting times and extraction time were investigated. The extraction process was carried out by rapid shooting of two syringes. Therefore, rapid dispersion and mass transfer processes was created between phases, and thus affects the extraction efficiency of the proposed method. The optimum extraction conditions were 10.00 mL of aqueous sample, 10% (w/v) Na2SO4, 1-octanol (100µL) as an extraction solvent, shooting 4 times and extraction time 2min. No disperser solvent and centrifugation step was necessary. Linearity was obtained within the range of 0.1-3000 ngmL(-1), with the correlation coefficients greater than 0.99. The high enrichment factor of the target analytes was 100 fold and low limit of detection (0.25-0.50 ngmL(-1)) could be obtained. This proposed method has been successfully applied in the analysis of neonicotinoid residues in honey, and good recoveries in the range of 96.93-107.70% were obtained. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Hollow-fiber-supported liquid phase microextraction with in situ derivatization and gas chromatography-mass spectrometry for determination of chlorophenols in human urine samples.

    Science.gov (United States)

    Ito, Rie; Kawaguchi, Migaku; Honda, Hidehiro; Koganei, Youji; Okanouchi, Noriya; Sakui, Norihiro; Saito, Koichi; Nakazawa, Hiroyuki

    2008-09-01

    A simple and highly sensitive method that involves hollow-fiber-supported liquid phase microextraction (HF-LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) was developed for the determination of chlorophenols (CPs) such as 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TrCP), 2,3,4,6-tetrachlorophenol (TeCP) and pentachlorophenol (PCP) in human urine samples. Human urine samples were enzymatically de-conjugated with beta-glucuronidase and sulfatase. After de-conjugation, HF-LPME with in situ derivatization was performed. After extraction, 2 microl of extract was carefully withdrawn into a syringe and injected into the GC-MS system. The limits of detection (S/N=3) and quantification (S/N>10) of CPs in the human urine samples are 0.1-0.2 ng ml(-1) and 0.5-1 ng ml(-1), respectively. The calibration curve for CPs is linear with a correlation coefficient of >0.99 in the range of 0.5-500 ng ml(-1) for DCP and TrCP, and of 1-500 ng ml(-1) for TeCP and PCP, respectively. The average recoveries of CPs (n=6) in human urine samples are 81.0-104.0% (R.S.D.: 1.9-6.6%) with correction using added surrogate standards. When the proposed method was applied to human urine samples, CPs were detected at sub-ng ml(-1) level.

  2. Biocompatible in-tube solid phase microextraction coupled with liquid chromatography-fluorescence detection for determination of interferon α in plasma samples.

    Science.gov (United States)

    Chaves, Andréa R; Silva, Bruno J G; Lanças, Fernando M; Queiroz, Maria Eugênia C

    2011-05-27

    The present work demonstrates the successful application of automated biocompatible in-tube solid-phase microextraction coupled with liquid chromatography (in-tube SPME/LC) for determination of interferon alpha(2a) (IFN α(2a)) in plasma samples for therapeutic drug monitoring. A restricted access material (RAM, protein-coated silica) was employed for preparation of a lab-made biocompatible in-tube SPME capillary that enables the direct injection of biological fluids as well as the simultaneous exclusion of macromolecules by chemical diffusion barrier and drug pre-concentration. The in-tube SPME variables, such as sample volume, draw/eject volume, number of draw-eject cycles, and desorption mode were optimized, to improve the sensitivity of the proposed method. The IFN α(2a) analyses in plasma sample were carried out within 25min (sample preparation and LC analyses). The response of the proposed method was linear over a dynamic range, from 0.06 to 3.0MIUmL(-1), with correlation coefficient equal to 0.998. The interday precision of the method presented coefficient of variation lower than 8%. The proposed automated method has adequate analytical sensitivity and selectivity for determination of IFN α(2a) in plasma samples for therapeutic drug monitoring. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Application of solid phase microextraction followed by liquid chromatography-mass spectrometry in the determination of antibiotic drugs and their metabolites in human whole blood and tissue samples.

    Science.gov (United States)

    Szultka-Mlynska, Malgorzata; Pomastowski, Pawel; Buszewski, Boguslaw

    2018-06-01

    A sensitive, rapid and specific analytical method using high performance liquid chromatography coupled with mass spectrometry (HPLC-QqQ-MS) was developed to determine selected antibiotic drugs and their metabolites (amoxicillin, cefotaxime, ciprofloxacin, clindamycin and metronidazole; amoxycilloic acid, 4-hydroxyphenyl glycyl amoxicillin, desacetyl cefotaxime, 3-desacetyl cefotaxime lactone, ciprofloxacin N-oxide, N-demethylclindamycin, clindamycin sulfoxide, and hydroxy metronidazole) in human whole blood and vascularized tissue after single oral administration. The samples were prepared by solid phase microextraction with C18 fibers (SPME C18 ) and determined on a GRACE analytical C18 column, Vision HT (50 × 2 mm, 1.5 μm) at the flow rate of 0.4 mL min -1 using water and acetonitrile (containing 0.1% formic acid) as the mobile phase. The proposed method was successfully applied in a pharmacokinetic study of the selected antibiotic drugs and their metabolites in real human samples. Additionally, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS) was used for identification and qualification analysis of the target compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Dispersive liquid-phase microextraction with solidification of floating organic droplet coupled with high-performance liquid chromatography for the determination of Sudan dyes in foodstuffs and water samples.

    Science.gov (United States)

    Chen, Bo; Huang, Yuming

    2014-06-25

    Dispersive liquid-phase microextraction with solidification of floating organic drop (SFO-DLPME) is one of the most interesting sample preparation techniques developed in recent years. In this paper, a new, rapid, and efficient SFO-DLPME coupled with high-performance liquid chromatography (HPLC) was established for the extraction and sensitive detection of banned Sudan dyes, namely, Sudan I, Sudan II, Sudan III, and Sudan IV, in foodstuff and water samples. Various factors, such as the type and volume of extractants and dispersants, pH and volume of sample solution, extraction time and temperature, ion strength, and humic acid concentration, were investigated and optimized to achieve optimal extraction of Sudan dyes in one single step. After optimization of extraction conditions using 1-dodecanol as an extractant and ethanol as a dispersant, the developed procedure was applied for extraction of the target Sudan dyes from 2 g of food samples and 10 mL of the spiked water samples. Under the optimized conditions, all Sudan dyes could be easily extracted by the proposed SFO-DLPME method. Limits of detection of the four Sudan dyes obtained were 0.10-0.20 ng g(-1) and 0.03 μg L(-1) when 2 g of foodstuff samples and 10 mL of water samples were adopted, respectively. The inter- and intraday reproducibilities were below 4.8% for analysis of Sudan dyes in foodstuffs. The method was satisfactorily used for the detection of Sudan dyes, and the recoveries of the target for the spiked foodstuff and water samples ranged from 92.6 to 106.6% and from 91.1 to 108.6%, respectively. These results indicated that the proposed method is simple, rapid, sensitive, and suitable for the pre-concentration and detection of the target dyes in foodstuff samples.

  5. Speciation of As(III) and As(V) in water samples by graphite furnace atomic absorption spectrometry after solid phase extraction combined with dispersive liquid-liquid microextraction based on the solidification of floating organic drop.

    Science.gov (United States)

    Shamsipur, Mojtaba; Fattahi, Nazir; Assadi, Yaghoub; Sadeghi, Marzieh; Sharafi, Kiomars

    2014-12-01

    A solid phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) method, using diethyldithiphosphate (DDTP) as a proper chelating agent, has been developed as an ultra preconcentration technique for the determination of inorganic arsenic in water samples prior to graphite furnace atomic absorption spectrometry (GFAAS). Variables affecting the performance of both steps were thoroughly investigated. Under optimized conditions, 100mL of As(ΙΙΙ) solution was first concentrated using a solid phase sorbent. The extract was collected in 2.0 mL of acetone and 60.0 µL of 1-undecanol was added into the collecting solvent. The mixture was then injected rapidly into 5.0 mL of pure water for further DLLME-SFO. Total inorganic As(III, V) was extracted similarly after reduction of As(V) to As(III) with potassium iodide and sodium thiosulfate and As(V) concentration was calculated by difference. A mixture of Pd(NO3)2 and Mg(NO3)2 was used as a chemical modifier in GFAAS. The analytical characteristics of the method were determined. The calibration graph was linear in the rage of 10-100 ng L(-1) with detection limit of 2.5 ng L(-1). Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 80 ng L(-1) of As(ΙΙΙ) were 6.8% and 7.5%, respectively. The method was successfully applied to speciation of As(III), As(V) and determination of the total amount of As in water samples and in a certified reference material (NIST RSM 1643e). Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Simultaneous derivatization and lighter-than-water air-assisted liquid-liquid microextraction using a homemade device for the extraction and preconcentration of some parabens in different samples.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Aghdam, Mehri Bakhshizadeh; Mogaddam, Mohammad Reza Afshar; Nabil, Ali Akbar Alizadeh

    2018-06-06

    Simultaneous derivatization and air-assisted liquid-liquid microextraction using an organic solvent lighter than water has been developed for the extraction of some parabens in different samples with the aid of a newly designed device for collecting the extractant. For this purpose, the sample solution is transferred into a glass test tube and a few microliters of acetic anhydride (as a derivatization agent) and p-xylene (as an extraction solvent) are added to the solution. After performing the procedure, the homemade device consists of an inverse funnel with a capillary tube placed into the tube. In this step, the collected extraction solvent and a part of the aqueous solution are transferred into the device and the organic phase indwells in the capillary tube of the device. Under the optimal conditions, limits of detection and quantification for the analytes were obtained in the ranges of 0.90-2.7 and 3.0-6.1 ng mL -1 , respectively. The enrichment and enhancement factors were in the ranges of 370-430 and 489-660, respectively. The method precision, expressed as the relative standard deviation, was within the ranges of 4-6% (n = 6) and 4-9% (n = 4) for intra- and inter-day precisions, respectively. The proposed method was successfully used for the determination of methyl-, ethyl-, and propyl parabens in cosmetic, hygiene, and food samples, and personal care products. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  7. Quantification of free and total bisphenol A and bisphenol B in human urine by dispersive liquid-liquid microextraction (DLLME) and heart-cutting multidimensional gas chromatography-mass spectrometry (MD-GC/MS).

    Science.gov (United States)

    Cunha, S C; Fernandes, J O

    2010-11-15

    A novel method combining dispersive liquid-liquid microextraction (DLLME) and heart-cutting multidimensional gas chromatography coupled to mass spectrometry was developed for the determination of free and total bisphenol A (BPA) and bisphenol B (BPB) in human urine samples. The DLLME procedure combines extraction, derivatization and concentration of the analytes into one step. Several important variables influencing the extraction efficiency and selectivity such as nature and volume of extractive and dispersive solvents as well as the amount of acetylating reagent were investigated. The temperature and time to hydrolyze BPA and BPB conjugates with a β-glucuronidase and sulfatase enzyme preparation were also studied. Under the optimized conditions good efficiency extraction (71-93%) and acceptable total DLLME yields (56-77%) were obtained for both analytes. Matrix-matched calibration curves were linear with correlation coefficients higher than 0.996 in the range level 0.1-5 μg/l, and the relative standard deviations (%RSD) were lower than 20% (n=6). The limits of detection were 0.03 and 0.05 μg/l for BPA and BPB, respectively. The applicability of the proposed method for determining urinary free and total BPA and BPB was assessed by analyzing the human urine of a group of 20 volunteers. Free BPA was detected in 45% of the sample whereas total BPA was detected in 85% of the samples at concentrations ranging between 0.39 and 4.99 μg/l. BPB was detected in conjugated form in two samples. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. LIQUID-LIQUID EXTRACTION COLUMNS

    Science.gov (United States)

    Thornton, J.D.

    1957-12-31

    This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.

  9. Dried blood spots and parallel artificial liquid membrane extraction-A simple combination of microsampling and microextraction.

    Science.gov (United States)

    Ask, Kristine Skoglund; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid

    2018-06-07

    In this paper, parallel artificial liquid membrane extraction (PALME) was used for the first time to clean-up dried blood spots (DBS) prior to ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Fundamental studies exploring amongst others desorption from the DBS in alkaline or acidic aqueous conditions, total extraction time and absolute recoveries were executed. Desorption and PALME were performed using a set of two 96-well plates, one of them housing the sample and the other comprising the supported liquid membrane (SLM) and the acceptor solution. In one procedure, amitriptyline and quetiapine (basic model analytes) were desorbed from the DBS using 250 μL of 10 mM sodium hydroxide solution (aqueous), and subsequently extracted through the SLM consisting of 4 μL of 1% trioctylamine in dodecyl acetate, and further into an acceptor solution consisting of 50 μL of 20 mM formic acid. In a second procedure, ketoprofen, fenoprofen, flurbiprofen, and ibuprofen (acidic model analytes) were desorbed from the DBS into 20 mM formic acid, extracted through an SLM with dihexyl ether, and further into an acceptor solution of 25 mM ammonia. Within 60 min of PALME, both basic and acidic model analytes were effectively desorbed from the DBS and extracted into the acceptor solution, which was injected directly into the analytical instrument. Recoveries between 63 and 85% for the six model analytes were obtained. PALME provided excellent clean-up from the DBS samples, and acceptor solutions were free from phospholipids. Linearity was obtained with r 2  > 0.99 for five of the six analytes. Accuracy, precision and UHPLC-MS/MS matrix effects were in accordance with the European Medicines Agency (EMA) guideline. Based on these experiments, PALME shows great potential for future processing of DBS in a short and simple way, and with the presented setup, up to 96 DBS can be processed within a total extraction time of 60

  10. Microextração em fase líquida (LPME: fundamentos da técnica e aplicações na análise de fármacos em fluidos biológicos Liquid-phase microextraction (LPME: fundamentals and applications to the analysis of drugs in biological samples

    Directory of Open Access Journals (Sweden)

    Anderson Rodrigo Moraes de Oliveira

    2008-01-01

    Full Text Available The analysis of drugs and metabolites in biological fluids usually requires extraction procedures to achieve sample clean-up and analyte preconcentration. Commonly, extraction procedures are performed using liquid-liquid extraction or solid-phase extraction. Nevertheless, these extraction techniques are considered to be time-consuming and require a large amount of organic solvents. On this basis, microextraction techniques have been developed. Among them, liquid-phase microextraction has been standing out. This review describes the liquid-phase microextraction technique based on hollow fibers as a novel and promising alternative in sample preparation prior to chromatographic or electrophoretic analysis. The basic concepts related to this technique and its applicability in extraction of drugs are discussed.

  11. Liquid Ventilation

    Directory of Open Access Journals (Sweden)

    Qutaiba A. Tawfic

    2011-01-01

    Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.

  12. Subsidizing Liquidity

    DEFF Research Database (Denmark)

    Malinova, Katya; Park, Andreas

    2015-01-01

    the breakdown of trading fees between liquidity demanders and suppliers matters. Posted quotes adjust after the change in fee composition, but the transaction costs for liquidity demanders remain unaffected once fees are taken into account. However, as posted bid-ask spreads decline, traders (particularly......Facing increased competition over the last decade, many stock exchanges changed their trading fees to maker-taker pricing, an incentive scheme that rewards liquidity suppliers and charges liquidity demanders. Using a change in trading fees on the Toronto Stock Exchange, we study whether and why...... retail) use aggressive orders more frequently, and adverse selection costs decrease....

  13. Simultaneous determination of bisphenol A and bisphenol B in beverages and powdered infant formula by dispersive liquid-liquid micro-extraction and heart-cutting multidimensional gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cunha, S C; Almeida, C; Mendes, E; Fernandes, J O

    2011-04-01

    The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was canned beverages were 5.0 and 2.0 ng l(-1) for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0 ng l(-1), respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0 ng l-1 for BPA and BPB, respectively, whereas LOQ in powdered infant formula were

  14. Analysis of heterocyclic amines in hair by on-line in-tube solid-phase microextraction coupled with liquid chromatography−tandem mass spectrometry

    International Nuclear Information System (INIS)

    Kataoka, Hiroyuki; Inoue, Tsutomu; Saito, Keita; Kato, Hisato; Masuda, Kazufumi

    2013-01-01

    Graphical abstract: Mutagenic and carcinogenic heterocyclic amines are accumulated in the hair of smoker. -- Highlights: •On-line in-tube solid-phase microextraction of heterocyclic amines was optimized. •Fourteen heterocyclic amines were simultaneously determined by LC–MS/MS. •Pico gram levels of heterocyclic amines could be easily analyzed within 15 min. •Heterocyclic amines could be quantitatively analyzed from several milligrams of hair. •The method is useful for the assessment of long-term exposure to heterocyclic amines. -- Abstract: Mutagenic and carcinogenic heterocyclic amines (HCAs) are formed during heating of various proteinaceous foods, but human exposure to HCAs has not yet been elucidated in detail. To assess long-term exposure to HCAs, we developed a simple and sensitive method for measuring HCAs in hair by automated on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS). Using a Zorbax Eclipse XDB-C8 column, 16 HCAs were analyzed within 15 min. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 μL sample at a flow rate of 200 μL min −1 using a Supel-Q PLOT capillary column as an extraction device. The extracted HCAs were easily desorbed from the column by passage of the mobile phase, with no carryover observed. This in-tube SPME LC–MS/MS method showed good linearity for HCAs in the range of 10–2000 pg mL −1 , with correlation coefficients above 0.9989 (n = 18), using stable isotope-labeled HCA internal standards. The detection limits (S/N = 3) of 14 HCAs except for MeAαC and Glu-P-1 were 0.10–0.79 pg mL −1 . This method was successfully utilized to analyze 14 HCAs in hair samples without any interference peaks, with quantitative limits (S/N = 10) of about 0.17–1.32 pg mg −1 hair. Using this method, we evaluated the exposure to HCAs in cigarette smoke and the suitability of using hair HCAs as exposure biomarkers

  15. Liquidity Runs

    NARCIS (Netherlands)

    Matta, R.; Perotti, E.

    2016-01-01

    Can the risk of losses upon premature liquidation produce bank runs? We show how a unique run equilibrium driven by asset liquidity risk arises even under minimal fundamental risk. To study the role of illiquidity we introduce realistic norms on bank default, such that mandatory stay is triggered

  16. Managing liquidity

    DEFF Research Database (Denmark)

    Pokutta, Sebastian; Schmaltz, Christian

    2011-01-01

    Large banking groups face the question of how to optimally allocate and generate liquidity: in a central liquidity hub or in many decentralized branches. We translate this question into a facility location problem under uncertainty. We show that volatility is the key driver behind (de......-)centralization. We provide an analytical solution for the 2-branch model and show that a liquidity center can be interpreted as an option on immediate liquidity. Therefore, its value can be interpreted as the price of information, i.e., the price of knowing the exact demand. Furthermore, we derive the threshold...... above which it is advantageous to open a liquidity center and show that it is a function of the volatility and the characteristic of the bank network. Finally, we discuss the n-branch model for real-world banking groups (10-60 branches) and show that it can be solved with high granularity (100 scenarios...

  17. Hydride generation coupled to microfunnel-assisted headspace liquid-phase microextraction for the determination of arsenic with UV-Vis spectrophotometry.

    Science.gov (United States)

    Hashemniaye-Torshizi, Reihaneh; Ashraf, Narges; Arbab-Zavar, Mohammad Hossein

    2014-12-01

    In this research, a microfunnel-assisted headspace liquid-phase microextraction technique has been used in combination with hydride generation to determine arsenic (As) by UV-Vis spectrophotometry. The method is based on the reduction of As to arsine (AsH3) in acidic media by sodium tetrahydroborate (NaBH4) followed by its subsequent reaction with silver diethyldithiocarbamate (AgDDC) to give an absorbing complex at 510 nm. The complexing reagent (AgDDC) has been dissolved in a 1:1 (by the volume ratio) mixture of chloroform/chlorobenzene microdroplet and exposed to the generated gaseous arsine via a reversed microfunnel in the headspace of the sample solution. Several operating parameters affecting the performance of the method have been examined and optimized. Acetonitrile solvent has been added to the working samples as a sensitivity enhancement agent. Under the optimized operating conditions, the detection limit has been measured to be 0.2 ng mL(-1) (based on 3sb/m criterion, n b = 8), and the calibration curve was linear in the range of 0.5-12 ng mL(-1). The relative standard deviation for eight replicate measurements was 1.9 %. Also, the effects of several potential interferences have been studied. The accuracy of the method was validated through the analysis of JR-1 geological standard reference material. The method has been successfully applied for the determination of arsenic in raw and spiked soft drink and water samples with the recoveries that ranged from 91 to 106 %.

  18. Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples

    International Nuclear Information System (INIS)

    Farahani, Hadi; Yamini, Yadollah; Shariati, Shahab; Khalili-Zanjani, Mohammad Reza; Mansour-Baghahi, Saeed

    2008-01-01

    A simple and efficient liquid-phase microextraction (LPME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of 11 organochlorine pesticides (OCPs) from water samples. In this technique a microdrop of 1-dodecanol containing pentachloronitrobenzene (internal standard) is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Following completion of extraction, the sample vial was cooled by putting it into an ice bath for 5 min. Finally 2 μL of the drop was injected into the GC for analysis. Factors relevant to the extraction efficiency were studied and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 65 deg. C; sodium chloride concentration: 0.25 M; microdrop and sample volumes: 8 μL and 20 mL respectively; the stirring rate: 750 rpm and the extraction time: 30 min), figures of merit of the proposed method were evaluated. The detection limits of the method were in the range of 7-19 ng L -1 and the RSD% for analysis of 2 μg L -1 of OCPs was below 7.2% (n = 5). A good linearity (r 2 ≥ 0.993) and a relatively broad dynamic linear range (25-2000 ng L -1 ) were obtained. After 30 min of extraction, preconcentration factors were in the range of 708-1337 for different organochlorine pesticides and the relative errors ranged from -10.1 to 10.9%. Finally the proposed method was successfully utilized for preconcentration and determination of OCPs in different real samples

  19. Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples

    Energy Technology Data Exchange (ETDEWEB)

    Farahani, Hadi [Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Yamini, Yadollah [Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of)], E-mail: yyamini@modares.ac.ir; Shariati, Shahab [Department of Chemistry, Faculty of Sciences, Islamic Azad University, Rasht Branch, Rasht (Iran, Islamic Republic of); Khalili-Zanjani, Mohammad Reza [Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Mansour-Baghahi, Saeed [Department of Water Quality Control and Laboratories, Tehran Water and Sewerage Company, Tehran (Iran, Islamic Republic of)

    2008-09-26

    A simple and efficient liquid-phase microextraction (LPME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of 11 organochlorine pesticides (OCPs) from water samples. In this technique a microdrop of 1-dodecanol containing pentachloronitrobenzene (internal standard) is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Following completion of extraction, the sample vial was cooled by putting it into an ice bath for 5 min. Finally 2 {mu}L of the drop was injected into the GC for analysis. Factors relevant to the extraction efficiency were studied and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 65 deg. C; sodium chloride concentration: 0.25 M; microdrop and sample volumes: 8 {mu}L and 20 mL respectively; the stirring rate: 750 rpm and the extraction time: 30 min), figures of merit of the proposed method were evaluated. The detection limits of the method were in the range of 7-19 ng L{sup -1} and the RSD% for analysis of 2 {mu}g L{sup -1} of OCPs was below 7.2% (n = 5). A good linearity (r{sup 2} {>=} 0.993) and a relatively broad dynamic linear range (25-2000 ng L{sup -1}) were obtained. After 30 min of extraction, preconcentration factors were in the range of 708-1337 for different organochlorine pesticides and the relative errors ranged from -10.1 to 10.9%. Finally the proposed method was successfully utilized for preconcentration and determination of OCPs in different real samples.

  20. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

    Science.gov (United States)

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2016-08-26

    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Doping of three-dimensional porous carbon nanotube-graphene-ionic liquid composite into polyaniline for the headspace solid-phase microextraction and gas chromatography determination of alcohols

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lulu; Wu, Mian; Feng, Yingying; Zhao, Faqiong; Zeng, Baizhao, E-mail: bzzeng@whu.edu.cn

    2016-12-15

    In this work, ionic liquid (IL, i.e. 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate), carboxyl multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) were used to prepare three-dimensional porous material (MWCNTs-rGO-IL) by one-step self-assembly, then it was co-electrodeposited with polyaniline (PANI) on stainless steel wires by cyclic voltammetry. The resulting coating (PANI-MWCNTs-rGO-IL) was characterized by using FT-IR and scanning electron microscopy etc, and it showed porous structure and had high thermal stability. Furthermore, it was found to be very suitable for the headspace solid-phase microextraction of alcohols (i.e. octanol, nonanol, geraniol, decanol, undecanol and dodecanol). By coupling with gas chromatography, wide linear ranges and low limits of detection (i.e. 2.2–28.3 ng L{sup −1}) were obtained for the alcohols. The coating also presented good repeatability and reproducibility; the relative standard deviations for intra-fiber and fiber-to-fiber were less than 5.6% (n = 5) and 7.0% (n = 5) respectively. In addition, the proposed method was successfully applied to the determination of alcohols in tea drinks, and the recoveries for standards added were 85.6–114%. - Highlights: • A three-dimensional porous material (MWCNTs-rGO-IL) was synthesized by self-assembly. • A new PANI-MWCNTs-rGO-IL composite coating was prepared by electrochemical method. • It presented high thermal stability and extraction selectivity for alcohols.

  2. Determination of organophosphorus flame retardants in fish by pressurized liquid extraction using aqueous solutions and solid-phase microextraction coupled with gas chromatography-flame photometric detector.

    Science.gov (United States)

    Gao, Zhanqi; Deng, Yuehua; Yuan, Wenting; He, Huan; Yang, Shaogui; Sun, Cheng

    2014-10-31

    A novel method was developed for the determination of organophosphorus flame retardants (PFRs) in fish. The method consists of a combination of pressurized liquid extraction (PLE) using aqueous solutions and solid-phase microextraction (SPME), followed by gas chromatography-flame photometric detector (GC-FPD). The experimental parameters that influenced extraction efficiency were systematically evaluated. The optimal responses were observed by extracting 1g of fish meat with the solution of water:acetonitrile (90:10, v/v) at 150°C for 5min and acid-washed silica gel used as lipid sorbent. The obtained extract was then analyzed by SPME coupled with GC-FPD without any additional clean-up steps. Under the optimal conditions, the proposed procedure showed a wide linear range (0.90-5000ngg(-1)) obtained by analyzing the spiked fish samples with increasing concentrations of PFRs and correlation coefficient (R) ranged from 0.9900 to 0.9992. The detection limits (S/N=3) were in the range of 0.010-0.208ngg(-1) with standard deviations (RSDs) ranging from 2.0% to 9.0%. The intra-day and inter-day variations were less than 9.0% and 7.8%, respectively. The proposed method was successfully applied to the determination of PFRs in real fish samples with recoveries varying from 79.8% to 107.3%. The results demonstrate that the proposed method is highly effective for analyzing PFRs in fish samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Simultaneous determination of 41 multiclass organic pollutants in environmental waters by means of polyethersulfone microextraction followed by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Mijangos, Leire; Ziarrusta, Haizea; Olivares, Maitane; Zuloaga, Olatz; Möder, Monika; Etxebarria, Nestor; Prieto, Ailette

    2018-01-01

    A new procedure using polyethersulfone (PES) microextraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was developed in this work for the simultaneous determination of 41 multiclass priority and emerging organic pollutants including herbicides, hormones, personal care products, and pharmaceuticals, among others, in seawater, wastewater treatment plant (WWTP) effluents, and estuary samples. The optimization of the analysis included two different chromatographic columns and different variables (polarity, fragmentor voltage, collision energy, and collision cell accelerator) of the mass spectrometer. In the case of PES extraction, ion strength of the water, pH, addition of EDTA, and the amount of the polymeric material were thoroughly investigated. The developed procedure was compared with a previously validated one based on a standard solid-phase extraction (SPE). In contrast to the SPE protocol, the PES method allowed a cost-efficient extraction of complex aqueous samples with lower matrix effect from 120 mL of water sample. Satisfactory and comparable apparent recovery values (80-119 and 70-131%) and method quantification limits (MQLs, 0.4-26 and 0.2-23 ng/L) were obtained for PES and SPE procedures, respectively, regardless of the matrix. Repeatability values lower than 27% were obtained. Finally, the developed methods were applied to the analysis of real samples from the Basque Country and irbesartan, valsartan, acesulfame, and sucralose were the analytes most often detected at the highest concentrations (51-1096 ng/L). Graphical abstract Forty-one multiclass pollutant determination in environmental waters by means of PES/SPE-LC-MS/MS.

  4. Spectrophotometric determination of iron species using a combination of artificial neural networks and dispersive liquid–liquid microextraction based on solidification of floating organic drop

    International Nuclear Information System (INIS)

    Moghadam, Masoud Rohani; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh

    2011-01-01

    Highlights: ► Combination of DLLME-SFO/fiber optic-linear array detection/chemometric methods. ► Simultaneous determination of complexes with overlapping spectra. ► A novel DLLME-SFO method is proposed for extraction of iron species. ► The extracted iron species are simultaneous determined using PC-ANNs. ► The enhancement factor of 162 and 125 are achieved for Fe 3+ and Fe 2+ , respectively. - Abstract: A dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and artificial neural networks method was developed for the simultaneous separation/preconcentration and speciation of iron in water samples. In this method, an appropriate mixture of ethanol (as the disperser solvent) and 1-undecanol (as the extracting solvent) containing appropriate amount of 2-thenoyltrifluoroacetone (TTA) (as the complexing agent) was injected rapidly into the water sample containing iron (II) and iron (III) species. At this step, the iron species interacted with the TTA and extracted into the 1-undecanol. After the phase separation, the absorbance of the extracted irons was measured in the wavelength region of 450–600 nm. The artificial neural networks were then applied for simultaneous determination of individual iron species. Under optimum conditions, the calibration graphs were linear in the range of 95–1070 μg L −1 and 31–350 μg L −1 with detection limits of 25 and 8 μg L −1 for iron (II) and iron (III), respectively. The relative standard deviations (R.S.D., n = 6) were lower than 4.2%. The enhancement factor of 162 and 125 were obtained for Fe 3+ and Fe 2+ ions, respectively. The procedure was applied to power plant drum water and several potable water samples; and accuracy was assessed through the recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

  5. Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M.M.; Duarte, Fabio A.

    2015-01-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L −1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L −1 and from 1.38 to 3.74 mg L −1 , respectively. - Highlights: • Determination of Cu and Fe in wine using DLLME and F AAS • High preconcentration factors and low LODs were achieved. • Alternative method for the determination of Cu and Fe in wine for routine analysis

  6. Selective dispersive liquid–liquid microextraction and preconcentration of Ni(II) into a micro droplet followed by ETAAS determination using a yellow Schiff's base bisazanyl derivative

    International Nuclear Information System (INIS)

    Alizadeh, Kamal; Nemati, Hadi; Zohrevand, Somaieh; Hashemi, Payman; Kakanejadifard, Ali; Shamsipur, Mojtaba; Ganjali, Mohammad Reza; Faridbod, Farnoush

    2013-01-01

    A simple, rapid and sensitive method was developed for the selective separation and preconcentration of Ni(II) using dispersive liquid–liquid microextraction, by a yellow Schiff's base bisazanyl derivative, as a selective complexing agent. In this method, a mixture of 45 μL chloroform (extraction solvent) and 450 μL tetrahydrofuran (dispersive solvent) is rapidly injected by syringe into a 5 mL aqueous sample containing 3% (w/v) sodium chloride and an appropriate amount of the Schiff's base. As a result, a cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase. After centrifuging for 5 min at 5000 rpm, the sedimented phase is directly injected into the electrothermal atomic absorption spectrometry for Ni(II) determination. Some important parameters, such as kind and volume of extraction and dispersive solvents, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor for the presented method is 138. The calibration curve was linear over a nickel concentration range of 10–50 ng mL −1 . The detection limit and relative standard deviation were 0.04 ng mL −1 and 2.1%, respectively. The method was successfully applied to the extraction and determination of Ni(II) in different water samples. - Highlights: ► A new synthesized schiff's base was used for selective separation of Ni(II) ions. ► The method based on DLLME was successfully applied to the determination of Ni(II). ► A cloudy solution is formed by entire dispersion of the extraction solvent into the aqueous phase. ► In this work, the response surface analysis was used for the optimization purpose. ► The curvature of response surface reflects the interactive effect of the variables.

  7. Doping of three-dimensional porous carbon nanotube-graphene-ionic liquid composite into polyaniline for the headspace solid-phase microextraction and gas chromatography determination of alcohols

    International Nuclear Information System (INIS)

    Li, Lulu; Wu, Mian; Feng, Yingying; Zhao, Faqiong; Zeng, Baizhao

    2016-01-01

    In this work, ionic liquid (IL, i.e. 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate), carboxyl multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) were used to prepare three-dimensional porous material (MWCNTs-rGO-IL) by one-step self-assembly, then it was co-electrodeposited with polyaniline (PANI) on stainless steel wires by cyclic voltammetry. The resulting coating (PANI-MWCNTs-rGO-IL) was characterized by using FT-IR and scanning electron microscopy etc, and it showed porous structure and had high thermal stability. Furthermore, it was found to be very suitable for the headspace solid-phase microextraction of alcohols (i.e. octanol, nonanol, geraniol, decanol, undecanol and dodecanol). By coupling with gas chromatography, wide linear ranges and low limits of detection (i.e. 2.2–28.3 ng L"−"1) were obtained for the alcohols. The coating also presented good repeatability and reproducibility; the relative standard deviations for intra-fiber and fiber-to-fiber were less than 5.6% (n = 5) and 7.0% (n = 5) respectively. In addition, the proposed method was successfully applied to the determination of alcohols in tea drinks, and the recoveries for standards added were 85.6–114%. - Highlights: • A three-dimensional porous material (MWCNTs-rGO-IL) was synthesized by self-assembly. • A new PANI-MWCNTs-rGO-IL composite coating was prepared by electrochemical method. • It presented high thermal stability and extraction selectivity for alcohols.

  8. Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M.M.; Duarte, Fabio A., E-mail: fabioand@gmail.com

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L{sup −1} for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L{sup −1} and from 1.38 to 3.74 mg L{sup −1}, respectively. - Highlights: • Determination of Cu and Fe in wine using DLLME and F AAS • High preconcentration factors and low LODs were achieved. • Alternative method for the determination of Cu and Fe in wine for routine analysis.

  9. Determination of anabolic steroids in human urine by automated in-tube solid-phase microextraction coupled with liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Saito, Keita; Yagi, Katsuharu; Ishizaki, Atsushi; Kataoka, Hiroyuki

    2010-09-05

    A simple, rapid and sensitive method was developed for determining the presence of seven anabolic steroids (boldenone, nandrolone, testosterone, methyltestosterone, epiandrosterone, androsterone, and atnozolol) in human urine. Glucuronide-conjugates of these compounds were hydrolyzed with beta-glucuronidase. The anabolic steroids were analyzed by on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-mass spectrometry (LC-MS). The steroids were separated within 14 min by high performance liquid chromatography using a Chromolith RP-18e column and 5 mM ammonium formate/methanol (35/65, v/v) as a mobile phase at a flow rate of 1.0 mL/min. Electrospray ionization conditions in the positive ion mode were optimized for the MS detection of these compounds. The optimum in-tube SPME conditions were 20 draw/eject cycles with a sample size of 40 microL using a Supel-Q PLOT capillary column for the extraction. The extracted compounds could be desorbed readily from the capillary column by flow of the mobile phase, and no carryover was observed. Using the in-tube SPME LC-MS with SIM mode detection, good linearity of the calibration curve (r>0.995) was obtained in the concentration range of 0.5-20 ng/mL, except for stanozolol. The detection limits (S/N=3) of anabolic steroids were in the range 9-182 pg/mL and the proposed method showed 20-33-fold higher sensitivity than the direct injection method. The within-day and between-day precisions were below 4.0% and 7.3% (n=5), respectively. This method was applied successfully to the analysis of urine samples without the interference peaks. The recovery rates of anabolic steroids spiked into urine samples were above 85%. This method is useful to analyze the urinary levels of these compounds in anti-doping tests. 2010 Elsevier B.V. All rights reserved.

  10. Evaluation of Carbon Nanotubes Functionalized Polydimethylsiloxane Based Coatings for In-Tube Solid Phase Microextraction Coupled to Capillary Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Neus Jornet-Martínez

    2015-08-01

    Full Text Available In the present work, the performance of carbon nanotubes (c-CNTs functionalized polydimethylsiloxane (PDMS based coatings as extractive phases for in-tube solid phase microextraction (IT-SPME coupled to Capillary LC (CapLC has been evaluated. Carboxylic-single walled carbon nanotubes (c-SWNTs and carboxylic-multi walled carbon nanotubes (c-MWNTs have been immobilized on the activated surface of PDMS capillary columns. The effect of different percentages of diphenyl groups in the PDMS extractive phase has also been evaluated. The extraction capability of the capillary columns has been tested for different organic pollutants, nitrogen heterocyclic compounds and polycyclic aromatic compounds (PAHs. The results indicated that the use of the c-CNTs-PDMS capillary columns improve pyriproxyfen and mainly PAH extraction. Triazines were better extracted by unmodified TRB-35 and modified c-CNTs-PDMSTRB-5. The results showed that the extraction capability of the c-CNT capillary columns depends not only on the polarity of the analytes (as it occurs with PDMS columns but also on the interactions that the analytes can establish with the immobilized c-CNTs on the PDMS columns. The extraction efficiency has been evaluated on the basis of the preconcentration rate that can be achieved, and, in this sense, the best c-CNTs-PDMS capillary column for each group of compounds can be proposed.

  11. Three-phase molecularly imprinted sol-gel based hollow fiber liquid-phase microextraction combined with liquid chromatography-tandem mass spectrometry for enrichment and selective determination of a tentative lung cancer biomarker.

    Science.gov (United States)

    Moein, Mohammad Mahdi; Javanbakht, Mehran; Karimi, Mohammad; Akbari-Adergani, Behrouz; Abdel-Rehim, Mohamed

    2015-07-15

    In the present study, the modification of a polysulfone hollow fiber membrane with in situ molecularly imprinted sol-gel process (as a novel and one-step method) was prepared and investigated. 3-(propylmethacrylate)trimethoxysilane (3PMTMOS) as an inorganic precursor was used for preparation of molecularly imprinted sol-gel. The modified molecularly imprinted sol-gel hollow fiber membrane (MSHM) was used for the liquid-phase microextraction (LPME) of hippuric acid (HA) in human plasma and urine samples. MSHM as a selective, robust, and durable tool was used for at least 50 extractions without significant decrease in the extraction efficiency. The non-molecularly imprinted sol-gel hollow fiber membrane (NSHM) as blank hollow fiber membrane was prepared by the same process, only without HA. To achieve the best condition, influential parameters on the extraction efficiency were thoroughly investigated. The capability of this robust, green, and simple method for extraction of HA was successfully accomplished with LC/MS/MS. The limits of detection (LOD) and quantification (LOQ) in human plasma and urine samples were 0.3 and 1.0nmolL(-1), respectively. The standard calibration curves were obtained within the concentration range 1-2000nmolL(-1) for HA in human plasma and urine. The coefficients of determination (r(2)) were ≥0.998. The obtained data exhibited recoveries were higher than 89% for the extraction of HA in human plasma and urine samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Utilization of highly robust and selective crosslinked polymeric ionic liquid-based sorbent coatings in direct-immersion solid-phase microextraction and high-performance liquid chromatography for determining polar organic pollutants in waters.

    Science.gov (United States)

    Pacheco-Fernández, Idaira; Najafi, Ali; Pino, Verónica; Anderson, Jared L; Ayala, Juan H; Afonso, Ana M

    2016-09-01

    Several crosslinked polymeric ionic liquid (PIL)-based sorbent coatings of different nature were prepared by UV polymerization onto nitinol wires. They were evaluated in a direct-immersion solid-phase microextraction (DI-SPME) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The studied PIL coatings contained either vinyl alkyl or vinylbenzyl imidazolium-based (ViCnIm- or ViBCnIm-) IL monomers with different anions, as well as different dicationic IL crosslinkers. The analytical performance of these PIL-based SPME coatings was firstly evaluated for the extraction of a group of 10 different model analytes, including hydrocarbons and phenols, while exhaustively comparing the performance with commercial SPME fibers such as polydimethylsyloxane (PDMS), polyacrylate (PA) and polydimethylsiloxane/divinylbenzene (PDMS/DVB), and using all fibers under optimized conditions. Those fibers exhibiting a high selectivity for polar compounds were selected to carry out an analytical method for a group of 5 alkylphenols, including bisphenol-A (BPA) and nonylphenol (n-NP). Under optimum conditions, average relative recoveries of 108% and inter-day precision values (3 non-consecutive days) lower than 19% were obtained for a spiked level of 10µgL(-1). Correlations coefficients for the overall method ranged between 0.990 and 0.999, and limits of detection were down to 1µgL(-1). Tap water, river water, and bottled water were analyzed to evaluate matrix effects. Comparison with the PA fiber was also performed in terms of analytical performance. Partition coefficients (logKfs) of the alkylphenols to the SPME coating varied from 1.69 to 2.45 for the most efficient PIL-based fiber, and from 1.58 to 2.30 for the PA fiber. These results agree with those obtained by the normalized calibration slopes, pointing out the affinity of these PILs-based coatings. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. A new high-speed hollow fiber based liquid phase microextraction method using volatile organic solvent for determination of aromatic amines in environmental water samples prior to high-performance liquid chromatography.

    Science.gov (United States)

    Sarafraz-Yazdi, A; Mofazzeli, F; Es'haghi, Z

    2009-07-15

    A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6 mL basic aqueous sample solution (donor phase, NaOH 1 mol L(-1)) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20 microL), then back-extracted into the 6 mL acidified aqueous solution (acceptor phase, HCl 0.5 mol L(-1)) in the lumen of the two-end sealed hollow fiber. After the extraction, 5 microL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6 mL of 1 mol L(-1) NaOH with 10% NaCl; organic phase: 20 microL of toluene; acceptor phase: 6 microL of 0.5 mol L(-1) HCl and 600 mmol L(-1) 18-crown-6 ether; pre-extraction and back-extraction times: 75 s and 10 min, respectively; stirring rate: 800 rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1-1000 microg L(-1) (R>0.9991), and also the limits of detection were in the range of 0.01-0.1 micro gL(-1). The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91-102%) were obtained for the spiked sample solutions.

  14. Determination of blood concentrations of main active compounds in Zi-Cao-Cheng-Qi decoction and their total plasma protein binding rates based on hollow fiber liquid phase microextraction coupled with high performance liquid chromatography.

    Science.gov (United States)

    Li, Miaomiao; Chen, Xuan; Hu, Shuang; Wang, Runqin; Peng, Xiaoli; Bai, Xiaohong

    2018-01-01

    Oil-in-salt hollow fiber liquid phase microextraction coupled with high performance liquid chromatography ultraviolet detection (HPLC-UV) was developed for determination of the blood concentrations of the main active compounds, hesperidin, honokiol, shikonin, magnolol, emodin and β,β'-dimethylacrylshikonin, after oral administration of Zi-Cao-Cheng-Qi decoction (ZCCQD) and their total plasma protein binding rates. In the procedure, a hollow fiber segment was immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent. Various factors affecting the procedure, such as extraction solvent, sample phase pH, stirring rate, extraction time, NaCl concentration and fiber immersion time in the NaCl solution, were optimized. Under the optimum conditions, good linearities (r 2 ≥0.9905), low limits of detection (0.7-2.5ng/mL) or quantitation (1.2-12ng/mL), satisfactory precision (2.6%-12.8%) and accuracy (81.0%-114.2%) of this method, were observed. The results showed that, after oral administration of a 25g/kg dose, (1) the blood concentrations (at 0.5h) of hesperidin, honokiol, shikonin, magnolol, emodin and β,β'-dimethylacrylshikonin were 0.45, 0.40, 0.48, 0.74, 0.11 and 1.11μg/mL, respectively; (2) the total plasma protein binding rates of the six active compounds were 42.0% (hesperidin), 71.8% (honokiol), 64.6% (shikonin), 77.7% (magnolol), 75.3% (emodin) and 75.7% (β,β'-dimethylacrylshikonin), respectively. The proposed procedure coupled with HPLC shows obvious advantages, such as low solvent consumption, simple operation, high sensitivity and strong purifying and can be used for the determination of both the blood concentrations and total plasma protein binding rates of active compounds in traditional Chinese medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Adsorptive behavior and solid-phase microextraction of bare stainless steel sample loop in high performance liquid chromatography.

    Science.gov (United States)

    Zhang, Wenpeng; Zhang, Zixin; Meng, Jiawei; Zhou, Wei; Chen, Zilin

    2014-10-24

    In this work, we interestingly happened to observe the adsorption of stainless steel sample loop of HPLC. The adsorptive behaviors of the stainless steel loop toward different kinds of compounds were studied, including polycyclic aromatic hydrocarbons (PAHs), halogeno benzenes, aniline derivatives, benzoic acid derivatives, phenols, benzoic acid ethyl ester, benzaldehyde, 1-phenyl-ethanone and phenethyl alcohol. The adsorptive mechanism was probably related to hydrophobic interaction, electron-rich element-metal interaction and hydrogen bond. Universal adsorption of stainless steels was also testified. Inspired by its strong adsorptive capability, bare stainless steel loop was developed as a modification-free in-tube device for solid-phase microextraction (SPME), which served as both the substrate and sorbent and possessed ultra-high strength and stability. Great extraction efficiency toward PAHs was obtained by stainless steel loop without any modification, with enrichment factors of 651-834. By connecting the stainless steel loop onto a six-port valve, an online SPME-HPLC system was set up and an SPME-HPLC method has been validated for determination of PAHs. The method has exceptionally low limits of detection of 0.2-2pg/mL, which is significantly lower than that of reported methods with different kinds of sorbents. Wide linear range (0.5-500 and 2-1000pg/mL), good linearity (R(2)≥0.9987) and good reproducibility (RSD≤2.9%) were also obtained. The proposed method has been applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 88.5% to 93.8%. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Liquid explosives

    CERN Document Server

    Liu, Jiping

    2015-01-01

    The book drawing on the author's nearly half a century of energetic materials research experience intends to systematically review the global researches on liquid explosives. The book focuses on the study of the conception, explosion mechanism, properties and preparation of liquid explosives. It provides a combination of theoretical knowledge and practical examples in a reader-friendly style. The book is likely to be interest of university researchers and graduate students in the fields of energetic materials, blasting engineering and mining.

  17. PREFACE: Functionalized Liquid Liquid Interfaces

    Science.gov (United States)

    Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael

    2007-09-01

    Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to

  18. Optimal Liquidation under Stochastic Liquidity

    OpenAIRE

    Becherer, Dirk; Bilarev, Todor; Frentrup, Peter

    2016-01-01

    We solve explicitly a two-dimensional singular control problem of finite fuel type for infinite time horizon. The problem stems from the optimal liquidation of an asset position in a financial market with multiplicative and transient price impact. Liquidity is stochastic in that the volume effect process, which determines the inter-temporal resilience of the market in spirit of Predoiu, Shaikhet and Shreve (2011), is taken to be stochastic, being driven by own random noise. The optimal contro...

  19. Effects of push/pull perfusion and ultrasonication on the extraction efficiencies of phthalate esters in sports drink samples using on-line hollow-fiber liquid-phase microextraction.

    Science.gov (United States)

    Chao, Yu-Ying; Lee, Chien-Hung; Chien, Tzu-Yang; Shih, Yu-Hsuan; Lu, Yin-An; Kuo, Ting-Hsuan; Huang, Yeou-Lih

    2013-08-28

    In previous studies, we developed a process, on-line ultrasound-assisted push/pull perfusion hollow-fiber liquid-phase microextraction (UA-PPP-HF-LPME), combining the techniques of push/pull perfusion (PPP) and ultrasonication with hollow-fiber liquid-phase microextraction (HF-LPME), to achieve rapid extraction of acidic phenols from water samples. In this present study, we further evaluated three more-advanced and novel effects of PPP and ultrasonication on the extraction efficiencies of neutral high-molecular-weight phthalate esters (HPAEs) in sports drinks. First, we found that inner-fiber fluid leakage occurs only in push-only perfusion-based and pull-only perfusion-based HF-LPME, but not in the PPP mode. Second, we identified a significant negative interaction between ultrasonication and temperature. Third, we found that the extraction time of the newly proposed system could be shortened by more than 93%. From an investigation of the factors affecting UA-PPP-HF-LPME, we established optimal extraction conditions and achieved acceptable on-line enrichment factors of 92-146 for HPAEs with a sampling time of just 2 min.

  20. Automated direct-immersion solid-phase microextraction using crosslinked polymeric ionic liquid sorbent coatings for the determination of water pollutants by gas chromatography.

    Science.gov (United States)

    Cordero-Vaca, María; Trujillo-Rodríguez, María J; Zhang, Cheng; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

    2015-06-01

    Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.

  1. In tube-solid phase microextraction-nano liquid chromatography: Application to the determination of intact and degraded polar triazines in waters and recovered struvite.

    Science.gov (United States)

    Serra-Mora, P; Jornet-Martinez, N; Moliner-Martinez, Y; Campíns-Falcó, P

    2017-09-01

    In-tube solid-phase microextraction (IT-SPME) coupled to miniaturized liquid chromatography (LC) techniques are attractive mainly due to the column efficiency improvement, sensitivity enhancement and reduction of solvent consumption. In addition, the nanomaterials based sorbents can play a key role in the improvement of the extraction efficiency taking into account their interesting physical and chemical properties. Thus, in this work the performance of IT-SPME coupled to nano LC (NanoLC) has been compared with the performance of IT-SPME coupled to capillary LC (CapLC) with similar configurations for the determination of polar triazines including their degradation products. In both cases, a DAD detector was used. Different extractive phases such as TRB-5, TRB-5/c-SWNTs, TRB-5/c-MWNTs capillary columns have been tested. The dimensions of the capillary columns were 0.32mm id×40cm length and 0.1 or 0.075mm i.d.×15cm length for the couplings with CapLC and NanoLC, respectively. The processed volume was 4mL for CapLC and 0.5mL for NanoLC. The elution was carried out with ACN:H 2 O (30:70, v/v). IT-SPME-NanoLC has shown a higher performance than IT-SPME-CapLC for the target analytes demonstrating the enhancement of the extraction efficiency with the former configuration. A new phase TEOS-MTEOS-SiO 2 NPs has been also proposed for IT-SPME-NanoLC, which improves the retention of polar compounds. Compared with previously published works, improved LODs were achieved (0.025-0.5μgL -1 ). The practical application of the proposed procedure has been demonstrated for the analysis of water samples and recovered struvite samples from wastewater treatment plants. Therefore, the proposed procedure can be an alternative method for regulatory purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Liquidity risk and contagion for liquid funds

    OpenAIRE

    Darolles , Serge; Dudek , Jeremy; Le Fol , Gaëlle

    2014-01-01

    Fund managers face liquidity problems but they have to distinguish the market liquidity risk implied by their assets and the funding liquidity risk. This latter is due to both the liquidity mismatch between assets and liabilities and the redemption risk due to the possible outflows from clients. The main contribution of this paper is the analysis of contagion looking at common market liquidity problems to detect funding liquidity problems. Using the CDS Bond Spread basis as a liquidity indica...

  3. Hidden Liquidity

    OpenAIRE

    Cebiroglu, Gökhan; Horst, Ulrich

    2012-01-01

    We cross-sectionally analyze the presence of aggregated hidden depth and trade volume in the S&P 500 and identify its key determinants. We find that the spread is the main predictor for a stock’s hidden dimension, both in terms of traded and posted liquidity. Our findings moreover suggest that large hidden orders are associated with larger transaction costs, higher price impact and increased volatility. In particular, as large hidden orders fail to attract (latent) liquidity to the market, hi...

  4. Liquid ventilation.

    Science.gov (United States)

    Sarkar, Suman; Paswan, Anil; Prakas, S

    2014-01-01

    Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

  5. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    International Nuclear Information System (INIS)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2009-01-01

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included

  6. Liquid Marbles

    KAUST Repository

    Khalil, Kareem

    2012-12-01

    Granulation, the process of formation of granules from a combination of base powders and binder liquids, has been a subject of research for almost 50 years, studied extensively for its vast applications, primarily to the pharmaceutical industry sector. The principal aim of granulation is to form granules comprised of the active pharmaceutical ingredients (API’s), which have more desirable handling and flowability properties than raw powders. It is also essential to ensure an even distribution of active ingredients within a tablet with the goal of achieving time‐controlled release of drugs. Due to the product‐specific nature of the industry, however, data is largely empirical [1]. For example, the raw powders used can vary in size by two orders of magnitude with narrow or broad size distributions. The physical properties of the binder liquids can also vary significantly depending on the powder properties and required granule size. Some significant progress has been made to better our understanding of the overall granulation process [1] and it is widely accepted that the initial nucleation / wetting stage, when the binder liquid first wets the powders, is key to the whole process. As such, many experimental studies have been conducted in attempt to elucidate the physics of this first stage [1], with two main mechanisms being observed – classified by Ivenson [1] as the “Traditional description” and the “Modern Approach”. See Figure 1 for a graphical definition of these two mechanisms. Recent studies have focused on the latter approach [1] and a new, exciting development in this field is the Liquid Marble. This interesting formation occurs when a liquid droplet interacts with a hydrophobic (or superhydrophobic) powder. The droplet can become encased in the powder, which essentially provides a protective “shell” or “jacket” for the liquid inside [2]. The liquid inside is then isolated from contact with other solids or liquids and has some

  7. Development of a new green non-dispersive ionic liquid microextraction method in a narrow glass column for determination of cadmium prior to couple with graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Naeemullah, E-mail: naeemullah433@yahoo.com [Gaziosmanpaşa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Kazi, Tasneem Gul [National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Tuzen, Mustafa [Gaziosmanpaşa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Shah, Faheem; Afridi, Hassan Imran [National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Citak, Demirhan [Gaziosmanpaşa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey)

    2014-02-17

    Graphical abstract: -- Highlights: •A novel and rapid non-dispersive ionic liquid based microextractions. •We used a long narrow glass column to provide more contact area between two media (aqueous and extractive). •APDC using as complexing agent and analyzed by GFAAS. •Introduced a novel approach that reduced solvent consumption, effort, time. •It was applied for determination of understudy analytes in real water sample. -- Abstract: Easy and innovative non-dispersive ionic liquid based microextraction (NDILME) has been developed for preconcentration of trace level of cadmium (Cd) in aqueous real surface water samples prior to couple with graphite furnace atomic absorption spectrometry (GFAAS). A 200 cm long narrow glass column containing aqueous solution of standard/sample was used to increase phase transfer ratio by providing more contact area between two medium (aqueous and extractive), which drastically improve the recoveries of labile hydrophobic chelate of Cd ammonium pyrrolidinedithiocarbamate (APDC), into ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [C{sub 4}mim][PF{sub 6}]. Different aspect of the desire method have been investigated and optimized. Under the optimized key experimental variables, limit of detection (LOD) and enhancement factor (EF) were achieved to be 0.5 ng L{sup −1} and 150, respectively. Reliability of the model method was checked by relative standard deviation (%RSD), which was found to be < 5%. Validity and accuracy of the developed method was checked by analysis of certified reference water samples (SLRS-4 Riverine water) using standard addition method. Application of the model method was productively performed by analysis of Cd in real surface water samples (tap and sea)

  8. Liquid helium

    CERN Document Server

    Atkins, K R

    1959-01-01

    Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

  9. The determination of V and Mo by dispersive liquid–liquid microextraction (DLLME) combined with laser-induced breakdown spectroscopy (LIBS)

    OpenAIRE

    Jesus, Amanda M. D. de; Aguirre Pastor, Miguel Ángel; Hidalgo Núñez, Montserrat; Canals Hernández, Antonio; Pereira-Filho, Edenir R.

    2014-01-01

    Laser-induced breakdown spectroscopy (LIBS) is a promising analytical technique with well-known advantages and limitations. However, despite its growing popularity, this technique has been applied mainly to solid samples and there have been a smaller number of studies devoted to liquid samples. This lack of studies is mainly due to experimental difficulties in the analysis of liquid matrices. Sensitivity can be improved and matrix effects minimized in the LIBS analysis of aqueous samples by u...

  10. A novel poly(3,4-ethylenedioxythiophene)-ionic liquid composite coating for the headspace solid-phase microextraction and gas chromatography determination of several alcohols in soft drinks.

    Science.gov (United States)

    Wu, Mian; Zhang, Haibo; Zhao, Faqiong; Zeng, Baizhao

    2014-11-19

    A novel poly(3,4-ethylenedioxythiophene)-ionic liquid (i.e., 1-hydroxyethyl-3-methyl imidazolium-bis[(trifluoromethyl)sulfonyl]imide) composite film was electrodeposited on a Pt wire for headspace solid-phase microextraction. The film showed nodular structure and had large specific surface. In addition, it displayed high thermal stability (up to 300°C) and durable property (could be used for more than 200 times). Coupled with gas chromatography-flame ionization detection, the resulting fiber was applied to the headspace solid-phase microextraction and determination of several alcohols (i.e., linalool, nonanol, terpineol, geraniol, decanol and dodecanol). It presented higher extraction capability in comparison with the poly(3,4-ethylenedioxythiophene) and commercial polydimethylsiloxane/divinylbenzene fiber. Under the optimized conditions, the linear ranges exceeded three magnitudes with correlation coefficients above 0.9952 and the low limits of detection were 34.2-81.3ng L(-1). For different alcohols the repeatabilities (defined as RSD) were alcohols in real samples with acceptable recoveries from 81.1% to 106.6%. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Furanic compounds and furfural in different coffee products by headspace liquid-phase micro-extraction followed by gas chromatography-mass spectrometry: survey and effect of brewing procedures.

    Science.gov (United States)

    Chaichi, Maryam; Ghasemzadeh-Mohammadi, Vahid; Hashemi, Maryam; Mohammadi, Abdorreza

    2015-01-01

    In this study, the levels of furan, 2-methylfuran, 2,5-dimethylfuran, vinyl furan, 2-methoxymethyl-furan and furfural in different coffee products were evaluated. Simultaneous determination of these six furanic compounds was performed by a head space liquid-phase micro-extraction (HS-LPME) method. A total of 67 coffee powder samples were analysed. The effects of boiling and espresso-making procedures on the levels of furanic compounds were investigated. The results showed that different types of coffee samples contained different concentrations of furanic compounds, due to the various processing conditions such as temperature, degree of roasting and fineness of grind. Among the different coffee samples, the highest level of furan (6320 µg kg⁻¹) was detected in ground coffee, while coffee-mix samples showed the lowest furan concentration (10 µg kg⁻¹). Levels in brewed coffees indicated that, except for furfural, brewing by an espresso machine caused significant loss of furanic compounds.

  12. Liquid electrode

    Science.gov (United States)

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  13. Liquid diode

    International Nuclear Information System (INIS)

    1976-01-01

    The liquid diode is designed for a flowmeter chamber which has an inlet and an outlet duct, and a flow chamber with a cross-section which is greater than inlet. In the space between the inlet and outlet are two screens with a number of spheres, which may be of different sizes and weights. The screen on the inlet side is smaller than that at the outlet, so that the spheres are able to block the inlet under reverse flow conditions, but do not block the outlet. The system functions as a non-return valve. (G.C.)

  14. From Funding Liquidity to Market Liquidity

    DEFF Research Database (Denmark)

    Dick-Nielsen, Jens; Lund, Jesper; Gyntelberg, Jacob

    This paper shows empirically that funding liquidity drives market liquidity. As it becomes harder to secure term funding in the money markets, liquidity deteriorates in the Danish bond market. We show that the first principal component of bond market liquidity is driven by the market makers...... for other European government bonds using MTS data. The findings suggest that regulatory bond based liquidity buffers for banks will have limited effectiveness....

  15. The Liquid State

    Indian Academy of Sciences (India)

    like iron, aluminium, lead, zinc, etc .. Metals are cast ... dropping molten liquid of the alloys on a rapidly spinning copper wheel. ... Ed. Computer simulation studies in ... liquids, modelling ofliquids and study of the dynamic behaviour of liquids ...

  16. Remotely controllable liquid marbles

    KAUST Repository

    Zhang, Lianbin; Cha, Dong Kyu; Wang, Peng

    2012-01-01

    Liquid droplets encapsulated by self-organized hydrophobic particles at the liquid/air interface - liquid marbles - are prepared by encapsulating water droplets with novel core/shell-structured responsive magnetic particles, consisting of a

  17. Bis(trifluoromethanesulfonyl)imide-based ionic liquids grafted on graphene oxide-coated solid-phase microextraction fiber for extraction and enrichment of polycyclic aromatic hydrocarbons in potatoes and phthalate esters in food-wrap.

    Science.gov (United States)

    Hou, Xiudan; Guo, Yong; Liang, Xiaojing; Wang, Xusheng; Wang, Lei; Wang, Licheng; Liu, Xia

    2016-06-01

    A class of novel, environmental friendly ionic liquids (ILs) were synthesized by on-fiber preparation strategy and modified on graphene oxide (GO)-coated stainless steel wire, which was used as a solid-phase microextraction (SPME) fiber for efficient enrichment of polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs). Surface characteristic of the ILs and polymeric-ILs (PILs) fibers with the wave-structure were inspected by scanning electron microscope. The successfully synthesis of bis(trifluoromethanesulfonyl)imide (NTf2(-))-based ILs were also characterized by energy dispersive spectrometer analysis. Through the chromatograms of the proposed two ILs (1-aminoethyl-3-methylimidazolium bromide (C2NH2MIm(+)Br(-)), C2NH2MIm(+)NTf2(-)) and two PILs (polymeric 1-vinyl-3-hexylimidazolium bromide (poly(VHIm(+)Br(-))), poly(VHIm(+)NTf2(-)))-GO-coated fibers for the extraction of analytes, NTf2(-)-based PIL demonstrated higher extraction capacity for hydrophobic compounds than other as-prepared ILs. Analytical performances of the proposed fibers were investigated under the optimized extraction and desorption conditions coupled with gas chromatography (GC). Compared with the poly(VHIm(+)Br(-))-GO fiber, the poly(VHIm(+)NTf2(-))-GO SPME fiber brought wider linear ranges for analytes with correlation coefficient in the range of 0.9852-0.9989 and lower limits of detection ranging from 0.015-0.025μgL(-1). The obtained results indicated that the newly prepared PILs-GO coating was a feasible, selective and green microextraction medium, which could be suitable for extraction and determination of PAHs and PAEs in potatoes and food-wrap sample, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. (Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids

    International Nuclear Information System (INIS)

    Martinho, S.; Araújo, J.M.M.; Rebelo, L.P.N.; Pereiro, A.B.; Marrucho, I.M.

    2013-01-01

    Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data

  19. CASH AND LIQUIDITY/LIQUIDITY AND LIQUIDITY RATIO

    Directory of Open Access Journals (Sweden)

    BEATRIX LIGHEZAN BREUER

    2012-12-01

    Full Text Available The present paper aims to present the correlation as well as the differences between liquidity/cash and liquidity ratio in terms of economic entities. Researches on this topic are based on the opinions of some specialists in accounting and in the economic-financial analysis, as well as on the national legal stipulations and the ones set out in the International Accounting Standards, the Financial report, respectively. The object of this paper is represented by the correlation between liquidity/cash and liquidity ratios representing the liquidity as current assets, assets implied in the determination of liquidity ratios. The end of the paper consists of the conclusions drawn from the issues presented in the paper but also our views on this research topic.

  20. Combination of solid phase extraction and dispersive liquid–liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination

    International Nuclear Information System (INIS)

    Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

    2013-01-01

    Graphical abstract: Pass the sample through the basic alumina column ⇒ elute retained uranium along with the cations ⇒ convert the uranium to its anionic benzoate complex ⇒ extract its ion pair with malachite green into small volume of chloroform by DLLME ⇒ measure its absorption at 621 nm using fiber optic-linear array detection spectrophotometry. -- Highlights: • By combination of SPE and DDLME a high preconcentration factor of 2500 was obtained. • Development of SPE-DDLME-Spectrophotometric method for det. of trace amounts of uranium. • Ultra trace amount of uranium in water samples was det. by the proposed method. • The detection limit of the proposed method is comparable to the most sensitive method. • The proposed method is a free interference spectrophotometric method for uranium det. -- Abstract: A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid–liquid microextraction. Thus, by passing the sam