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Sample records for arsenazo previous liquid-liquid

  1. Spectrophotometric determination of uranium with arsenazo previous liquid-liquid extraction and colour development in organic medium; Determinacion espectrofotometrica de uranio con arsenazo, previa extraccion y desarrollo del color en medio organico

    Energy Technology Data Exchange (ETDEWEB)

    Palomares Delgado, F.; Vera Palomino, J.; Petrement Eguiluz, J. C.

    1964-07-01

    The determination of uranium with arsenazo is hindered by a great number of cation which form stable complexes with the reactive and may given rise to serious interferences. By studying the optimum conditions of uranium the extraction be means of tributylphosphate solutions dissolved in methylisobuthylketone, under conditions for previous masking of the interfering cations, an organic extract was obtained containing all the uranium together with small amounts of iron. The possible interference derived from the latter element is avoided by reduction with hydroxylammoniumchlorid followed by complex formation of the Fe(II)-ortophenantroline compound in alcoholic medium. (Author) 17 refs.

  2. Method for determining microamounts of uranium in solutions from copper ores, by liquid-liquid extraction and spectrophotometry with arsenazo III

    International Nuclear Information System (INIS)

    A spectrophotometric method is described for determining small amounts of uranium in aqueous solutions from copper ores. Uranium is quantitatively separated in a single extraction by a solution of tri-n-octylphosphine oxide in benzene, using ethylendiaminetetracetic acid and sodium fluoride as complexing agents, for improving the selectivity of the procedure. An aliquot of the extract is diluted with a hydrocolloidal solution of arsenazo III. Optical density is measured at 650 nm. (Author) 3 refs

  3. Method for determining microamounts of uranium in solutions from copper ores, by liquid-liquid extraction and spectrophotometry with arsenazo III.; Metodo para determinar microcantidades de uranio en disoluciones de minerales de cobre, por extraccion liquido-liquido y espectrofotometria con arsenazo III

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, B.

    1972-07-01

    A spectrophotometric method is described for determining small amounts of uranium in aqueous solutions from copper ores. Uranium is quantitatively separated in a single extraction by a solution of tri-n-octylphosphine oxide in benzene, using ethylendiaminetetracetic acid and sodium fluoride as complexing agents, for improving the selectivity of the procedure. An aliquot of the extract is diluted with a hydrocolloidal solution of arsenazo III. Optical density is measured at 650 nm. (Author) 3 refs.

  4. Fluid Mechanics of Liquid-Liquid Systems.

    Science.gov (United States)

    Richards, John Reed

    The detailed hydrodynamics of selected liquid -liquid flow systems are investigated to provide a firm foundation for the rational design of separation processes. The implementation of this objective centers on the development of a robust code to simulate liquid-liquid flows. We have applied this code to the realistic simulation of aspects of the complex fluid mechanical behavior, and developed quantitative insight into the underlying processes involved. The Volume of Fluid (VOF) method is combined with the Continuous Surface Force (CSF) algorithm to provide a numerically stable code capable of solving high Reynolds numbers free surface flows. One of the developments during the testing was an efficient method for solving the Young-Laplace equation describing the shape of the meniscus in a vertical cylinder for a constrained liquid volume. The steady-state region near the nozzle for the laminar flow of a Newtonian liquid jet injected vertically into another immiscible Newtonian liquid is investigated for various Reynolds numbers by solving the axisymmetric transient equations of motion and continuity. The analysis takes into account pressure, viscous, inertial, gravitational, and surface tension forces, and comparison with previous experimental measurements shows good agreement. Comparisons of the present numerical method with the numerical results of previous boundary-layer methods help establish their range of validity. A new approximate equation for the shape of the interface of the steady jet, based on an overall momentum balance, is also developed. The full transient from liquid-liquid jet startup to breakup into drops is also simulated numerically. In comparison with experiment, the results of the present numerical method show a greater sensitivity of the jet length to the Reynolds number than the best predictions of previous linear stability analyses. The formation of drops is investigated at low to high Reynolds numbers before and after jet formation. The

  5. Neptunium Binding Kinetics with Arsenazo(III)

    Energy Technology Data Exchange (ETDEWEB)

    Leigh R. Martin; Aaron T. Johnson; Stephen P. Mezyk

    2014-08-01

    This document has been prepared to meet FCR&D level 2 milestone M2FT-14IN0304021, “Report on the results of actinide binding kinetics with aqueous phase complexants” This work was carried out under the auspices of the Thermodynamics and Kinetics of Advanced Separations Systems FCR&D work package. The report details kinetics experiments that were performed to measure rates of aqueous phase complexation for pentavalent neptunium with the chromotropic dye Arsenazo III (AAIII). The studies performed were designed to determine how pH, ionic strength and AAIII concentration may affect the rate of the reaction. A brief comparison with hexavalent neptunium is also made. It was identified that as pH was increased the rate of reaction also increased, however increasing the ionic strength and concentration of AAIII had the opposite effect. Interestingly, the rate of reaction of Np(VI) with AAIII was found to be slower than that of the Np(V) reaction.

  6. Spectrophotometric determination of thorium using arsenazo III in water

    International Nuclear Information System (INIS)

    A spectrophotometric determination of thorium with arsenazo III (1,8 dihidroxynaphtaline - 3,6 sulfanic acid - 2,7 bis (azo-2) - phenil argonic acid) was carried out aiming to analyse this element in water. In order to eliminate possible interferences, a coprecipitation with lantanium fluoride was used followed by an extration with 0,2 M TTA (tenoil-trifluor - aceton) / Benzen. The results showed a good agreement with the ones obtained by alfa-spectrometry. (Author)

  7. Treatment of Arsenazo III contaminated heavy water stored at Darlington

    International Nuclear Information System (INIS)

    Darlington Nuclear Generating Station (DNGS) has accumulated over 48 drums of chemistry laboratory waste arising from analysis of heavy water (D2O). Several organic, including Arsenazo III, and inorganic contaminants present in these drums results in high total organic carbon (TOC) and conductivity. These drums have not been processed due to uncertainties related to clean-up of Arsenazo III contaminated heavy water. This paper provides details of chemical characterization as well as bench scale studies performed to demonstrate the feasibility of treating the downgraded D2O to the stringent target specifications of <1 ppm TOC and <0.1mS/m conductivity, required for feed to the Station Upgrading Plant (SUP). Both ionic organic species such as glycolate, acetate and formate as well as neutral organics such as acetone, methanol and ethylene glycol were detected in all the samples. Morpholine and propylene glycol were detected in one sample. Arsenazo III was determined to be not a major contaminant (maximum 8.4 ppm) in these waste drums, compared to the other organic contaminants present. Various unit processes such as pH adjustment, granular activated carbon (GAC), ion exchange resin (IX), UV-peroxide oxidation (UV-H2O2) treatments, nanofiltration (NF) as well as reverse osmosis (RO) were tested on a bench scale both singly as well as in various combinations to evaluate their ability to achieve the stringent target conductivity and TOC specifications. Among the various bench scale tests evaluated, the successive processing train used at DNGS and consisting of GAC+IX+UV/H2O2+IX (polishing) unit operations was found to meet target specifications for both conductivity and TOC. Unit processes comprising (GAC+IX) and (RO-double pass + GAC+IX) met conductivity targets but failed to meet TOC specifications. The results of GAC+IX tests clearly emphasize the importance of using low flow rates for successful reduction in both conductivity as well as TOC. Detailed assessment of

  8. Treatment of Arsenazo III contaminated heavy water stored at Darlington

    Energy Technology Data Exchange (ETDEWEB)

    Suryanarayan, S.; Husain, A., E-mail: sriram.s@kinectrics.com [Kinectrics Inc., Toronto, Ontario (Canada); Williams, D., E-mail: denny.williams@opg.com [Ontario Power Generation, Darlington Nuclear Generating Station, Bowmanville, Ontario (Canada)

    2010-07-01

    Darlington Nuclear Generating Station (DNGS) has accumulated over 48 drums of chemistry laboratory waste arising from analysis of heavy water (D{sub 2}O). Several organic, including Arsenazo III, and inorganic contaminants present in these drums results in high total organic carbon (TOC) and conductivity. These drums have not been processed due to uncertainties related to clean-up of Arsenazo III contaminated heavy water. This paper provides details of chemical characterization as well as bench scale studies performed to demonstrate the feasibility of treating the downgraded D{sub 2}O to the stringent target specifications of <1 ppm TOC and <0.1mS/m conductivity, required for feed to the Station Upgrading Plant (SUP). Both ionic organic species such as glycolate, acetate and formate as well as neutral organics such as acetone, methanol and ethylene glycol were detected in all the samples. Morpholine and propylene glycol were detected in one sample. Arsenazo III was determined to be not a major contaminant (maximum 8.4 ppm) in these waste drums, compared to the other organic contaminants present. Various unit processes such as pH adjustment, granular activated carbon (GAC), ion exchange resin (IX), UV-peroxide oxidation (UV-H{sub 2}O{sub 2}) treatments, nanofiltration (NF) as well as reverse osmosis (RO) were tested on a bench scale both singly as well as in various combinations to evaluate their ability to achieve the stringent target conductivity and TOC specifications. Among the various bench scale tests evaluated, the successive processing train used at DNGS and consisting of GAC+IX+UV/H{sub 2}O{sub 2}+IX (polishing) unit operations was found to meet target specifications for both conductivity and TOC. Unit processes comprising (GAC+IX) and (RO-double pass + GAC+IX) met conductivity targets but failed to meet TOC specifications. The results of GAC+IX tests clearly emphasize the importance of using low flow rates for successful reduction in both conductivity as

  9. In vitro photoacoustic sensing of calcium dynamics with arsenazo III

    Science.gov (United States)

    Dana, N.; Fowler, R. A.; Allen, A.; Zoldan, J.; Suggs, L.; Emelianov, S.

    2016-07-01

    Imaging of cellular electric potential via calcium-ion sensitive contrast agents is a useful tool, but current techniques lack sufficient depth penetration. We explore contrast-enhanced photoacoustic (PA) imaging, using Arsenazo III dye, to visualize cardiac myocyte depolarization in vitro. Phantom results show strong linearity of PA signal with dye concentration (R 2  >  0.95), and agree spectrally with extinction measurements with varying calcium concentration. Cell studies indicate a significant (>100-fold) increase in PA signal for dye-treated cells, as well as a 10-fold increase in peak-to-peak variation during a 30 s window. This suggests contrast-enhanced PA imaging may have sufficient sensitivity and specificity for depth-resolved visualization of tissue depolarization in real-time.

  10. A novel aeration-assisted homogenous liquid-liquid microextration for determination of thorium and uranium in water and hair samples by inductively coupled plasma-mass spectroscopy.

    Science.gov (United States)

    Veyseh, Somayeh; Niazi, Ali

    2016-01-15

    A novel method based on aeration-assisted homogeneous liquid-liquid microextraction using high density solvent is presented, which is combined with inductively coupled plasma-mass spectroscopy in which simultaneous preconcentration and determination of thorium and uranium with arsenazo III as the chelating reagent is carried out. To achieve optimum conditions, several parameters such as pH, concentration of arsenazo III, extraction and homogenous solvent types and their volumes, salt concentration and extraction time were investigated. Under which, the calibration graphs were linear in the range of 0.5-600.0ng L(-1) for thorium and 0.3-550.0ng L(-1) for uranium. Good linearities were obtained for both analytes with R(2) values larger than 0.9990. The limits of detection (LOD, 3Sb/m, n=5) of this method were 0.12 and 0.09ng L(-1), and the enrichment factors were estimated to be 370 and 410 for thorium and uranium, respectively. The proposed method was applied to determine the thorium and uranium in human hair and different environmental water samples. Acceptable recoveries ranged from 99.4% to 100.7% with standard deviation of 0.05 to 0.17.

  11. A novel aeration-assisted homogenous liquid-liquid microextration for determination of thorium and uranium in water and hair samples by inductively coupled plasma-mass spectroscopy.

    Science.gov (United States)

    Veyseh, Somayeh; Niazi, Ali

    2016-01-15

    A novel method based on aeration-assisted homogeneous liquid-liquid microextraction using high density solvent is presented, which is combined with inductively coupled plasma-mass spectroscopy in which simultaneous preconcentration and determination of thorium and uranium with arsenazo III as the chelating reagent is carried out. To achieve optimum conditions, several parameters such as pH, concentration of arsenazo III, extraction and homogenous solvent types and their volumes, salt concentration and extraction time were investigated. Under which, the calibration graphs were linear in the range of 0.5-600.0ng L(-1) for thorium and 0.3-550.0ng L(-1) for uranium. Good linearities were obtained for both analytes with R(2) values larger than 0.9990. The limits of detection (LOD, 3Sb/m, n=5) of this method were 0.12 and 0.09ng L(-1), and the enrichment factors were estimated to be 370 and 410 for thorium and uranium, respectively. The proposed method was applied to determine the thorium and uranium in human hair and different environmental water samples. Acceptable recoveries ranged from 99.4% to 100.7% with standard deviation of 0.05 to 0.17. PMID:26592585

  12. Critical Phenomena in Liquid-Liquid Mixtures

    Science.gov (United States)

    Jacobs, D. T.

    2000-04-01

    Critical phenomena provide intriguing and essential insight into many issues in condensed matter physics because of the many length scales involved. Large density or concentration fluctuations near a system's critical point effectively mask the identity of the system and produce universal phenomena that have been well studied in simple liquid-vapor and liquid-liquid systems. Such systems have provided useful model systems to test theoretical predictions which can then be extended to more complicated systems. Along various thermodynamic paths, several quantities exhibit a simple power-law dependence close to the critical point. The critical exponents describing these relationships are universal and should depend only on a universality class determined by the order-parameter and spatial dimensionality of the system. Liquid gas, binary fluid mixtures, uniaxial ferromagnetism, polymer-solvent, and protein solutions all belong to the same (Ising model) universality class. The diversity of critical systems that can be described by universal relations indicates that experimental measurements on one system should yield the same information as on another. Our experimental investigations have tested existing theory and also extended universal behavior into new areas. By measuring the coexistence curve, heat capacity, thermal expansion and static light scattering (turbidity) in various liquid-liquid and polymer-solvent systems, we have determined critical exponents and amplitudes that have sometimes confirmed and other times challenged current theory. Recent experiments investigating the heat capacity and light scattering in a liquid-liquid mixture very close to the critical point will be discussed. This research is currently supported by The Petroleum Research Fund and by NASA grant NAG8-1433 with some student support from NSF-DMR 9619406.

  13. Spectrophotometric determination of zirconium in nickel-base alloys with Arsenazo III after separation by froth flotation

    International Nuclear Information System (INIS)

    0.02-0.1% of zirconium can be determined in nickel alloys by spectrophotometry with Arsenazo III after its separation from the sample solution by means of froth flotation using Arsenazo III and Zephiramine. Nickel, chromium and iron do not interfere. Analysis of standard alloys yielded a standard deviation of 2.2%. (orig.)

  14. Electron transfer kinetics at polarized nanoscopic liquid/liquid interfaces.

    Science.gov (United States)

    Cai, Chenxin; Mirkin, Michael V

    2006-01-11

    Rapid kinetics of electron transfer (ET) reactions across the interface between water and 1,2-dichloroethane were measured by steady-state voltammetry at nanopipet electrodes (50- to 400-nm orifice radius). The origins of previously reported imperfect voltammetric responses of ET reactions at micropipets were investigated. Several new experimental systems were explored, and two of them yielded high-quality voltammograms suitable for kinetic experiments. The determined standard rate constants were compared to those measured previously at polarized and nonpolarized liquid/liquid interfaces. The effect of the interfacial dimensions on the magnitude of the apparent ET rate constant is discussed. A new approach to ET kinetic measurements based on the use of the scanning electrochemical microscope with a nanopipet tip and a metallic substrate has been developed and employed to check the validity of determined kinetic parameters. PMID:16390144

  15. Chiral separation by enantioselective liquid-liquid extraction.

    Science.gov (United States)

    Schuur, Boelo; Verkuijl, Bastiaan J V; Minnaard, Adriaan J; de Vries, Johannes G; Heeres, Hero J; Feringa, Ben L

    2011-01-01

    The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants. PMID:21107491

  16. Liquid--liquid contact in vapor explosion

    International Nuclear Information System (INIS)

    The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This well-known phenomenon is called a ''vapor explosion.'' One method of producing intimate, liquid--liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. In this experiment cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials (mineral oil, silicone oil, water, mercury, molten Wood's metal or molten salt mixture). The main conclusion from the experimental study is that hydrodynamic effects may be very significant in any shock tube analyses, especially when multiple interactions are observed. A theoretical study was performed to check the possibility of vapor film squeezing (between a drop in film boiling and a surface) as a controlling mechanism for making liquid--liquid contact. Using experimental data, the film thickness was calculated and it was found to be too thick for any conceivable film rupture mechanism. It was suggested that the coalescence is a two-stage process, in which the controlling stage depends mainly on temperature and surface properties and can be described as the ability of cold liquid to spread on a hot surface

  17. Chiral separation by enantioselective liquid-liquid extraction

    NARCIS (Netherlands)

    Schuur, B.; Verkuijl, B. J. V.; Minnaard, A. J.; De Vries, J. G.; Heeres, H. J.; Feringa, B. L.

    2011-01-01

    The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and ch

  18. 13 CFR 307.20 - Partial liquidation; liquidation upon termination.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Partial liquidation; liquidation upon termination. 307.20 Section 307.20 Business Credit and Assistance ECONOMIC DEVELOPMENT... Revolving Loan Funds and Use of Grant Funds § 307.20 Partial liquidation; liquidation upon termination....

  19. Macromolecular sensing at the liquid-liquid interface

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, Gregoire; Flynn, Shane [Tyndall National Institute, Lee Maltings, University College, Cork (Ireland); Arrigan, Damien W M, E-mail: gregoire.herzog@tyndall.ie [Nanochemistry Research Institute, Department of Chemistry, Curtin University, Perth (Australia)

    2011-08-17

    We report here the electrochemical sensing of macromolecules, such as polyLysine dendrimers, at the polarised liquid | liquid interface. Electrochemistry at the liquid | liquid interface is a powerful analytical technique which allows the detection of non-redox active molecules via ion transfer reactions at a polarised water - oil interface. We demonstrate here that different parameters of the polyLysine dendrimers (charge number, molecular weight) have a strong influence on the sensitivity and limit of detection of these macromolecules. This work will help to the development of sensors based on charge transfer at the liquid | liquid interface.

  20. Beyond dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Leong, Mei-I; Fuh, Ming-Ren; Huang, Shang-Da

    2014-03-28

    Dispersive liquid-liquid microextraction (DLLME) and other dispersion liquid-phase microextraction (LPME) methods have been developed since the first DLLME method was reported in 2006. DLLME is simple, rapid, and affords high enrichment factor, this is due to the large contact surface area of the extraction solvent. DLLME is a method suitable for the extraction in many different water samples, but it requires using chlorinated solvents. In recent years, interest in DLLME or dispersion LPME has been focused on the use of low-toxicity solvents and more conveniently practical procedures. This review examines some of the most interesting developments in the past few years. In the first section, DLLME methods are separated in two categories: DLLME with low-density extraction solvent and DLLME with high-density extraction solvent. Besides these methods, many novel special devices for collecting low-density extraction solvent are also mentioned. In addition, various dispersion techniques with LPME, including manual shaking, air-assisted LPME (aspirating and injecting the extraction mixture by syringe), ultrasound-assisted emulsification, vortex-assisted emulsification, surfactant-assisted emulsification, and microwave-assisted emulsification are described. Besides the above methods, combinations of DLLME with other extraction techniques (solid-phase extraction, stir bar sorptive extraction, molecularly imprinted matrix solid-phase dispersion and supercritical fluid extraction) are introduced. The combination of nanotechnique with DLLME is also introduced. Furthermore, this review illustrates the application of DLLME or dispersion LPME methods to separate and preconcentrate various organic analytes, inorganic analytes, and samples. PMID:24582396

  1. Liquid-Liquid-Liquid Three Phase Extraction Apparatus: Operation Strategy and Influences on Mass Transfer Efficiency

    Institute of Scientific and Technical Information of China (English)

    何秀琼; 黄昆; 于品华; 张超; 谢铿; 李鹏飞; 王娟; 安震涛; 刘会洲

    2012-01-01

    Abstract A new mixer-settler-mixer three chamber integrated extractor is proposed in this work for liquid-liquid- liquid three phase countercurrent and continuous extraction. Experiments revealed the influences of the structural design of the three-liquid-phase extractor and some key operational parameters on three-phase partition of two phenolic isomers, p-nitrophenol (p-NP) and o-nitrophenol (o-NP). The model three-liquid-phase extraction system used here is nonane (organic top-plaase)-polyethylene glycol (PEG 20UU) (polymer mlddle-phase)-(NH4)2SO4 aqueous solution (aqueous bottom-phase). It is indicated that agitating speed and retention time in three-phase mixer are key parameters to extraction fraction of nitrophenol. Dispersion band behavior is related to agitating intensity, and its occurrence does not affect the extraction fraction of target compounds. The present work highlights the possibility of a feasible approach of scaling up of the proposed three-phase extraction apparatus for future in- dustrial-aimed applications.

  2. Spectrophotometric determination of uranium and thorium with arsenazo III in the flow injection system

    International Nuclear Information System (INIS)

    A simple system for flow injection analysis (FIA) with double confluence was built using a filter photocolorimeter, an analogic potentiometer, 'plexiglass' flow cuvettes, polyethylene colls and tubes, 'plexiglass' commuter and peristaltic pump to introduce solutions and gravity as flow source. The system was dimensioned and studied using only Arsenazo III solutions. Spectrophotometric methods for uranium and thorium using Arsenazo III were studied using a scanning spectrophotometer and after chosing adequate red filter, adapted to photocolorimetry using flow cuvettes and FIA. Synthetic samples, phosphate rock, and process samples from uranium recovery of dolomites were analysed. Rocks of Morro do Ferro (MG, Brazil), Caldasite (Baddeleyte + Zirconite), Zirconite, Monazite from a program for certification and certified rocks (Dunite DC-1, CANMET) were analysed without chemical separation of Th (IV) and with ion exchange separation in semi-micro columns of cation exchange resin (Dowex 50). (Author)

  3. Thermodynamics of liquid-liquid crossover transition in liquid Si15Te85 eutectic alloy

    Directory of Open Access Journals (Sweden)

    Tsuchiya Y.

    2011-05-01

    Full Text Available Specific heat of liquid Si15Te85 was measured using both the adiabatic scanning calorimetry and modulation calorimetry. The specific heat has a very broad peak around 660°C of which the peak value is 46 J/mol.K. The results are totally different from the previous results that the specific heat is as large as 140 J/mol.K at the liquidus temperature and decreases rapidly with raising temperature. Combining the molar volume and sound velocity as a function of temperature, the thermodynamic susceptibilities, i.e. constant pressure specific heat, isothermal compressibility and thermal expansion coefficient, have been evaluated. Their temperature dependences and magnitudes are in good accordance with the predictions for a crossover transition in a liquid. Comparison is made to a liquid-liquid crossover transition in Ge15Te85 which is sharpest among crossover liquid-liquid transitions of this kind so far found.

  4. Gas absorption in an agitated gas-liquid-liquid system

    NARCIS (Netherlands)

    Cents, A.H.G.; Brilman, D.W.F.; Versteeg, G.F.

    2001-01-01

    Gas-liquid-liquid systems have gained interest in the past decade and are encountered in several important industrial applications. In these systems an immiscible liquid phase may affect the gas absorption rate significantly. This phenomenon, however, is not completely understood and underlying mech

  5. Liquid-Liquid Hydrocyclone Adopted in Jilin Oil Fields

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ As a new invention with high technique, liquid-liquid hydrocyclone (LLH) was developed in the world in the 1980s. It is designed to separate mutually insoluble liquid mixtures by its geometry and structure which cause an eddy motion in the internal of the liquid. It is characterized by the absence of moving parts in itself.

  6. Redox-active Crosslinkable Poly(ionic liquid)s

    NARCIS (Netherlands)

    Sui, Xiaofeng; Hempenius, Mark A.; Vancso, G. Julius

    2012-01-01

    The synthesis of a new class of cross-linkable redox-responsive poly(ferrocenylsilane)-based poly(ionic liquid)s (PFS-PILs) is reported. PFS-PILs self-cross-link at low concentrations into nanogels or form macroscopic hydrogel networks at higher concentrations. PFS-PILs proved to be efficient disper

  7. Polymer Crystallization at Curved Liquid/Liquid Interface

    Science.gov (United States)

    Wang, Wenda

    Liquid/liquid interface, either flat or curved, is a unique template for studying self-assembly of a variety of nanomaterials such as nanoparticles and nanorods. The resultant monolayer films can be ordered or disordered depending on the regularity of the nanomaterials. Integration of nanoparticles into two-dimensional structure leads to intriguing collective properties of the nanoparticles. Crystallization can also be guided by liquid/liquid interface. Due to the particular shape of the interface, crystallization can happen in a different manner comparing to the normal solution crystallization. In this dissertation, liquid/liquid interface is employed to guide the crystallization of polymers, mainly focusing on using curved liquid/liquid interface. Due to the unique shape of the interface and feasibility to control the curvature, polymer crystallization can take place in different manner and lead to the formation of curved or vesicular crystals. Curved liquid/liquid interface is typically created through o/w emulsions. With the presence of surfactant, the emulsions are controlled to be stable at least for the polymer crystallization periods. The difference to normal solution crystallization is: the nuclei will diffuse to the curved interface due to the Pickering effect and guide the crystallization along the curved liquid/liquid interface. If the supercooling can be controlled to be very small, crystal growth in the bulk droplets can be avoided. The advantages of this strategy are: 1) the formation process of vesicular type crystals can be monitored by controlling the polymer supply; 2) curved crystals, bowl-like structures and enclosed capsules can be easily obtained comparing to the self-assembly method for vesicle formation; 3) the obtained vesicles will be made of polymer crystals, which will possess the extraordinary mechanical properties. Based on the nucleation type, this dissertation is divided into two parts. The first part is focused on the self

  8. High-yield resin fractionation using a liquid/liquid centrifuge

    Science.gov (United States)

    Wanat, Stan F.; Rahman, M. D.; Narasimhan, Balaji; McKenzie, Douglas S.; Cook, Michelle M.

    2000-06-01

    Resins used in photoresist manufacturing are often relatively expensive once processing steps (fractionation e.g.) and yield losses are factored into the net cost. We have previously reported on the merits of using an economically more attractive fractionation process using a liquid/liquid centrifuge. Further refinements of this method indicate that waste streams could be reduced by recycling the extractant phase and that lower molecular weight fractions removed from the starting resin might be used in making other resist ingredients [speed enhancers, photoactive compound (PAC) backbones e.g.]. Both of these improvements would reduce the overall manufacturing costs of making resist raw materials and the final products made with them.

  9. Polymer single crystal membrane from liquid/liquid interface

    Science.gov (United States)

    Wang, Wenda; Li, Christopher; Soft Matter Research Group-Drexel University Team

    2013-03-01

    Vesicles, mimicking the structure of cell membrane at the molecular scale, are small membrane-enclosed sacks that can store or transport substances. The weak mechanical properties and the nature of environment-sensitivity of the current available vesicles: liposomes, polymersomes, colloidsomes limit their applications as an excellent candidate for targeting delivery of drugs/genes in biomedical engineering and treatment. Recently, we developed an emulsion-based method to grow curved polymer single crystals. Varying the polymer concentration and/or the emulsification conditions (such as surfactant concentration, water-oil volume ratio), curved crystals with different sizes and different openness could be obtained. This growing process was attributed to polymer crystal growth along the liquid/liquid interface. In addition, the liquid/liquid interfacial crystal growth is promising for synthesis of enclosed hollow sphere.

  10. Liquid-liquid extraction by reversed micelles in biotechnological processes

    Directory of Open Access Journals (Sweden)

    Kilikian B. V.

    2000-01-01

    Full Text Available In biotechnology there is a need for new purification and concentration processes for biologically active compounds such as proteins, enzymes, nucleic acids, or cells that combine a high selectivity and biocompatibility with an easy scale-up. A liquid-liquid extraction with a reversed micellar phase might serve these purposes owing to its capacity to solubilize specific biomolecules from dilute aqueous solutions such as fermentation and cell culture media. Reversed micelles are aggregates of surfactant molecules containing an inner core of water molecules, dispersed in a continuous organic solvent medium. These reversed micelles are capable of selectively solubilizing polar compounds in an apolar solvent. This review gives an overview of liquid-liquid extraction by reversed micelles for a better understanding of this process.

  11. Separation of Asphaltenes by Polarity using Liquid-Liquid Extraction

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar

    1997-01-01

    phase. The asphaltenes were analysed using FTir, Elemental analysis, and HPLC-SEC with a diode array detector. With increasing content of toluene in the methanol the molecular weight distribution of the asphaltenes significantly move to higher molecular weights. The content of nitrogen and sulfur......In order to investigate the nature of petroleum asphaltenes in terms of polarity a process was developed using initial liquid-liquid extraction of the oil phase followed by precipitation of the asphaltenes using n-heptane. The liquid-liquid extraction was performed using toluene-methanol mixtures...... with increasing content of toluene. Although large fractions of the crude oil (Alaska ´93) was extracted in the higher polarity solvents (high concentration of methanol), the asphaltene content of the dissolved material was low. As the toluene content increased more asphaltenes were transferred to the solvent...

  12. Optimized Liquid-Liquid Extractive Rerefining of Spent Lubricants

    OpenAIRE

    2014-01-01

    Central composite design methodology has been employed to model the sludge yield data obtained during liquid-liquid extractive rerefining of spent lubricants using an alcohol (1-butanol) and a ketone (methyl ethyl ketone) as prospective solvents. The study has resulted in two reasonably accurate multivariate process models that relate the sludge yield (R 2 = 0.9065 and 0.9072 for alcohol and ketone, resp.) to process variables (settling time t, operating temperature T, and oil to solvent rati...

  13. Fine Drop Recovery in Batch Gas-Agitated Liquid-Liquid Dispersions

    Science.gov (United States)

    Shahrokhi, H.; Shaw, J. M.

    1996-11-01

    The hydrodynamics of batch gas-agitated liquid-liquid dispersions has received comparatively little attention in the open literature1-5. Such systems arise in diverse contexts but operate on the same basic principle. Two immiscible liquids form stratified layers initially and return to this stratified state at the end of a batch. Liquid from the lower liquid phase is entrained and then dispersed by gas bubbles passing from the lower to the upper liquid phase. At the end of a batch, the liquids separate under the influence of gravity. Fine drops separate slowly. For industrial processes such as nickel conversion, long settling periods reduce equipment productivity. Metal drops entrained in the lower density slag phase also pose leaching problems in slag heaps. We assessed fine drop production in such batch systems previously5. In this work, we address fine drop recovery. The net rate of fine drop recovery can be up to five times greater than Standard Settling experiments if low speed recirculation loops are imposed within the upper liquid phase that are perpendicular to the liquid-liquid interface. The principal mechanism for enhanced fine drop recovery, in this case, arises from improving drop liquid-liquid interface coalescence. 1. Hatzikiriakos et al., A.I.Ch.E. J., 36, 677-684 (1990). 2. Hatzikiriakos et al., Chem. Eng. Sci., 45, 2349-2356 (1990). 3. Konduru & Shaw, Proc. Int. Symp. Materials Handling in Pyromet., Hamilton, Cda, 14-24 (1991). 4. ibid, Can. J. Chem. Eng., 70, 381-384 (1992). 5. Shahrokhi & Shaw, Chem. Eng. Sci., 49, 5203-5213 (1994).

  14. Color-Fading Spectrophotometric Determination of Cerium with DBC-Arsenazo

    Institute of Scientific and Technical Information of China (English)

    翟庆洲; 张晓霞

    2004-01-01

    In the medium of 0.18~1.08 mol·L-1 sulfuric acid, cerium(Ⅳ) has the color-fading effect on DBC-arsenazo. The apparent molar absorptivity of the color-fading reaction is ε530 nm=1.03×104 L·mol-1·cm-1. Beer′s law is obeyed over the range of 1.20~12.0 μg·ml-1 of Ce (Ⅳ) which shows a linear relationship with the decrease in the absorbance of the colored solution. The effect of thirty-six coexisting ions was studied. The method was applied to the determination of the trace amount of cerium in water samples and has the advantage of high accuracy and good selectivity.

  15. Spectroscopic Detection of Chiral Aggregation at Liquid-Liquid Interfaces

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Two new spectroscopic methods to detect the optical activity of liquid-liquid interfaces have been developed. The first one is the centrifugal liquid membrane (CLM) method combined with a conventional circular dichroism (CD) spectropolarimetry and the second one is a more interfacial specific second harmonic generation CD (SHG-CD) spectrometry. In the CLM-CD method, a cylindrical glass cell containing small amounts of organic and aqueous phases was rotated at about 7000 r/min in a sample chamber of a CD spectropolarimeter to generate an interface with a high specific interfacial area between the two-phase liquid membranes. The CD spectra of the J-aggregate of protonated 5,10,15, 20-tetraphenylporphyrin formed at the toluene-sulfuric acid interface have been measured. As for the SHG-CD, a circularly polarized wavelength-variable fs-laser system was constructed to measure the interfacial SHG spectra of a flat liquid-liquid interface. The ion-associated aggregation of a water-soluble anionic porphyrin promoted with a cationic amphiphile at the heptane-water interface was observed by this technique and the observed SHG-CD spectra proved the generation of a characteristic optical activity accompanied by the formation of the interfacial aggregate of inherently achiral porphyrin molecules. These methods will pioneer a new field of interfacial chiral chemistry in the studies of solvent extraction mechanisms.

  16. Performance Characterization of a Microchannel Liquid/Liquid Heat Exchanger Throughout an Extended Duration Life Test

    Science.gov (United States)

    Sheth, Rubik B.; Stephan, Ryan A.; Hawkins-Reynolds Ebony

    2011-01-01

    Liquid/Liquid Heat Exchangers (L/L HX) are an integral portion of any spacecraft active thermal control system. For this study the X-38 L/L HX was used as a baseline. As detailed in a previous ICES manuscript, NASA paired with Pacific Northwest National Laboratory to develop a Microchannel L/L HX (MHX). This microchannel HX was designed to meet the same performance characteristics as the aforementioned X-38 HX. The as designed Microchannel HX has a 26% and 60% reduction in mass and volume, respectively. Due to the inherently smaller flow passages the design team was concerned about fouling affecting performance during extended missions. To address this concern, NASA has developed a test stand and is currently performing an 18 month life test on the MHX. This report will detail the up-to-date performance of the MHX during life testing.

  17. Extraction/spectrophotometric determination of trace amounts of zirconium in niobium bearing steels using Arsenazo III

    International Nuclear Information System (INIS)

    A spectrophotometric method with Arsenazo III combined the extraction of Zr by thenoyltrifluoroacetone (TTA)-xylene was studied for the determination of trace amounts of Zr in Nb-containing steels and Ni-base alloys. Sample (0.5 g or 0.1 g) was dissolved in 10 ml of aqua regia, 2 ml of hydrofluoric acid and 15 ml of perchloric acid by heating, and the solution was evaporated until all perchloric acid fumes were expelled. After cooling, the salts were dissolved by adding 1 ml of hydrochloric acid and 2.0 ml sufuric acid (9 M) and by heating. The solution was evaporated until fumes of perchloric acid were visible. After cooling, the salts were dissolved by adding 20 ml of hydrochloric acid (4 M) and by heating. L-Ascoribic acid (0.5 g per 0.1 g of sample) was added for reduction of ferric ion and the solution was adjusted to 50 ml with hydrochloric acid (4 M). Zirconium was extracted into 10 ml of TTA (0.5 M)-xylene solution and then back-extracted into 10 ml of hydrofluoric acid (0.4 M)-nitric acid (0.4 M) mixture. The organic phase was washed with 5 ml of the acids mixture. The sample and washing solutions with 1 ml of nitric acid and 15 ml of perchloric acid were evaporated below 1 ml by heating. After cooling, 30 ml of nitric acid was added and the sample solution was heated just before boiling and cooled. After the sample solution was adjusted to 40 ml with water, 2.5 ml of urea solution (10 g/l) and 5.0 ml of Arsenazo III solution (1.5 x 10-3 M) were added and the solution was adjusted to 50.0 ml with water. Absorbance of the solution was measured at 670 nm with 10mm quartz cell against reagent blank. Niobium up to 3 mg did not interfere; at 4 mg Nb caused slightly negative error. The relative standard deviations were 3 % and 0.8 % for 0.004 % and 0.02 % of Zr content respectively. The limit of determination minimum by this method was 0.0004 %. (author)

  18. Liquid-liquid contact in vapor explosion. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Segev, A.

    1978-08-01

    The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This phenomenon is called a vapor explosion. One method of producing intimate, liquid-liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. The report describes experiments in which cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials (mineral oil, silicone oil, water, mercury, molten Wood's metal or molten salt mixture).

  19. Thermal energy storage with liquid-liquid systems

    Energy Technology Data Exchange (ETDEWEB)

    Santana, E.A.; Stiel, L.I. [Polytechnic Univ., Brooklyn, NY (United States)

    1989-03-01

    The use of liquid-liquid mixtures for heat and cool storage applications has been investigated. Suitable mixtures exhibit large changes in the heat of mixing above and below the critical solution temperature of the system. Analytical procedures have been utilized to determine potential energy storage capabilities of systems with upper or lower critical solution temperatures. It has been found that aqueous systems with lower critical solution temperatures in a suitable range can result in large increases in the effective heat capacity in the critical region. For cool storage with a system of this type, the cooling process results in a transformation from two liquid phases to a single phase. Heats of mixing have been measured with a flow calorimeter system for a number of potential mixtures, and the results are summarized.

  20. Liquid-Liquid Phase Transition in Nanoconfined Silicon Carbide.

    Science.gov (United States)

    Wu, Weikang; Zhang, Leining; Liu, Sida; Ren, Hongru; Zhou, Xuyan; Li, Hui

    2016-03-01

    We report theoretical evidence of a liquid-liquid phase transition (LLPT) in liquid silicon carbide under nanoslit confinement. The LLPT is characterized by layering transitions induced by confinement and pressure, accompanying the rapid change in density. During the layering transition, the proportional distribution of tetracoordinated and pentacoordinated structures exhibits remarkable change. The tricoordinated structures lead to the microphase separation between silicon (with the dominant tricoordinated, tetracoordinated, and pentacoordinated structures) and carbon (with the dominant tricoordinated structures) in the layer close to the walls. A strong layer separation between silicon atoms and carbon atoms is induced by strong wall-liquid forces. Importantly, the pressure confinement phase diagram with negative slopes for LLPT lines indicates that, under high pressure, the LLPT is mainly confinement-induced, but under low pressure, it becomes dominantly pressure-induced.

  1. Study on liquid-liquid bimetal composite casting hammers

    Institute of Scientific and Technical Information of China (English)

    Rong Shoufan; Zhou Haitao; ZhuYongchang; Wang Junfa; Yao Jia; Li Chunhong

    2014-01-01

    Crusher hammers for the mineral processing industry must meet the demands of both high wear resistance at the hammer head and high impact toughness at the hammer handle. The crusher hammers made of Hadfield steel have typical y low service life of less than 40 hours. To solve the problem, a kind of bimetal crusher hammers made of high chromium cast iron (HCCI) and low al oy steel (LAS) has been successful y developed by using liquid-liquid composite casting. The microstructure and composite interface bonding was analyzed using optical microscope, SEM, EDX and XRD. Micrographs indicate that the composite interface is metal urgical y bonded with a zigzag shape across the boundary and without unbound region or void. After heat treatment, the composite hammers have shown excellent properties. The hardness of HCCI is at least 63 HRC and its αk is greater than 3.5 J•cm-2; the hardness of LAS is greater than 35 HRC and its αk is no less than 80 J•cm-2. Diffusion of elements takes place at the interface and forms a transition region. The micro hardness increases from LAS to the interface and then to HCCI. Wear comparison was made separately between the bimetal composite hammer and a Hadfield steel hammer in two quarries of Jilin province and Liaoning province. The results showed that the liquid-liquid bimetal composite hammers did not have the fal ing off of hammer head or impact fracture phenomenon, and their service life was 3.75 times as long as that of the Hadfield steel hammers.

  2. Microrheology and Particle Dynamics at Liquid-Liquid Interfaces

    Science.gov (United States)

    Song, Yanmei

    The rheological properties at liquid-liquid interfaces are important in many industrial processes such as manufacturing foods, pharmaceuticals, cosmetics, and petroleum products. This dissertation focuses on the study of linear viscoelastic properties at liquid-liquid interfaces by tracking the thermal motion of particles confined at the interfaces. The technique of interfacial microrheology is first developed using one- and two-particle tracking, respectively. In one-particle interfacial microrheology, the rheological response at the interface is measured from the motion of individual particles. One-particle interfacial microrheology at polydimethylsiloxane (PDMS) oil-water interfaces depends strongly on the surface chemistry of different tracer particles. In contrast, by tracking the correlated motion of particle pairs, two-particle interfacial microrheology significantly minimizes the effects from tracer particle surface chemistry and particle size. Two-particle interfacial microrheology is further applied to study the linear viscoelastic properties of immiscible polymer-polymer interfaces. The interfacial loss and storage moduli at PDMS-polyethylene glycol (PEG) interfaces are measured over a wide frequency range. The zero-shear interfacial viscosity, estimated from the Cross model, falls between the bulk viscosities of two individual polymers. Surprisingly, the interfacial relaxation time is observed to be an order of magnitude larger than that of the PDMS bulk polymers. To explore the fundamental basis of interfacial nanorheology, molecular dynamics (MD) simulations are employed to investigate the nanoparticle dynamics. The diffusion of single nanoparticles in pure water and low-viscosity PDMS oils is reasonably consistent with the prediction by the Stokes-Einstein equation. To demonstrate the potential of nanorheology based on the motion of nanoparticles, the shear moduli and viscosities of the bulk phases and interfaces are calculated from single

  3. Behavior of Liquid-Liquid Dispersions in a Stirred Vessel——Part 1:Uniformity Property

    Institute of Scientific and Technical Information of China (English)

    LIU Jinchen; CHEN Jian; KAWASAKI Junjiro

    2001-01-01

    The conductivity of liquid-liquid dispersions in a stirred vessel was measured at different sampling positions inside the vessel.The results showed that both O/W dispersions and W/O dispersions are not spatially uniform inside the vessel,especially the W/O dispersions.The results provide further understanding of the properties of the liquid-liquid dispersions.

  4. Catalytic Spectrophotometry for Vanadium Determination Based on Oxidation of Arsenazo Ⅲ by Bichromate

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A catalytic spectrophotometry for the determination of trace amount of vanadium was developed based on its catalytic effect on the oxidation of arsenazo Ⅲ by potassium bichromate in weak acidic medium. The optimized conditions for determinations are: cK2Cr2O7=3.0×10-5 mol·L-1, carsenazo Ⅲ=3.0×10-5 mol·L-1, pH=4.0, t=90℃. The calibration graph is linear for 0.02~0.2 μg·ml-1, and the detection limit is 0.02 μg·ml-1 V. The apparent active energy of this catalytic reaction is 21.72 kJ·mol-1. Most foreign ions do not interfere with the determination of vadadium, except for Fe(Ⅱ) and Co(Ⅱ), and their interferences could be eliminated by ion exchange. The present method has been used to make the determination of vanadium in human hair, tea, potato and wastewater, and the results were satisfactory.

  5. Liquid-liquid extraction for surfactant-contaminant separation and surfactant reuse

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, M.A. [Surbec Environmental, Norman, OK (United States); Sabatini, D.A.; Harwell, J.H. [Univ. of Oklahoma, Norman, OK (United States)

    1997-07-01

    Liquid-liquid extraction was investigated for use with surfactant enhanced subsurface remediation. A surfactant liquid-liquid extraction model (SLLEM) was developed for batch equilibrium conditions based on contaminant partitioning between micellar, water, and solvent phases. The accuracy of this fundamental model was corroborated with experimental results (using naphthalene and phenanthrene as contaminants and squalane as the extracting solvent). The SLLEM model was then expanded to nonequilibrium conditions. The effectiveness of this nonequilibrium model was corroborated with experimental results from continuous flow hollow fiber membrane systems. The validated models were used to conduct a sensitivity analysis evaluating the effects of surfactants on the removal of the contaminants in liquid-liquid extraction systems. In addition, liquid-liquid extraction is compared to air stripping for surfactant-contaminant separation. Finally, conclusions are drawn as to the impact of surfactants on liquid-liquid extraction processes, and the significance of these impacts on the optimization of surfactant-enhanced subsurface remediation.

  6. Properties of the metallochromic dyes Arsenazo III, Antipyrylazo III and Azo1 in frog skeletal muscle fibres at rest.

    Science.gov (United States)

    Baylor, S M; Hollingworth, S; Hui, C S; Quinta-Ferreira, M E

    1986-08-01

    Intact single twitch fibres from frog muscle were isolated and mounted in a normal Ringer solution (16 degrees C) on an optical bench apparatus for measuring fibre absorbance as a function of the wave-length and polarization of the incident light. Fibre absorbance was measured in resting fibres both in the absence and in the presence of one of three metallochromic dyes: Arsenazo III, Antipyrylazo III and Azo1. In the absence of dye, the fibre intrinsic absorbance, Ai(lambda), measured as a function of wave-length, lambda, was well described by the equation: Ai(lambda) = Ai(lambda long) (lambda long/lambda)X, where lambda long is a reference wave-length selected to lie beyond the absorbance band of the dyes and X is the exponential index. For wave-lengths between 480 and 810 nm, the average value of X was 1.1 for 0 deg polarized light (electric vector parallel to the fibre axis) and 1.3 for 90 deg polarized light (electric vector perpendicular to the fibre axis). The intrinsic absorbance at 0 deg, Ai,0(lambda), was somewhat larger than the intrinsic absorbance at 90 deg, Ai,90(lambda); for example, on average (n = 6), Ai,0 (810 nm) was 0.22, whereas Ai,90 (810 nm) was 0.016. Following dye injection, dye-related absorbance was estimated from the measured total fibre absorbance by subtracting the component attributable to the intrinsic absorbance; additionally, for comparison with in vitro calibrations as a function of wave-length, myoplasmic dye absorbance was corrected for the steady change in dye-concentration with time that was attributable to dye diffusion. In fibres injected with either Arsenazo III or Antipyrylazo III, the dye-related absorbance measured with 0 deg light, A0(lambda), was found to be significantly greater than that measured with 90 deg light, A90(lambda), indicating the presence of a resting 'dichroic' signal, A0(lambda)-A90(lambda), attributable to bound and oriented dye molecules. On average, the lower limit estimated for the percentage of

  7. Treatment of biomass gasification wastewaters using liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Bell, N.E.

    1981-09-01

    Pacific Northwest Laboratory (PNL) investigated liquid-liquid extraction as a treatment method for biomass gasification wastewaters (BGW). Distribution coefficients for chemical oxygen demand (COD) removal were determined for the following solvents: methylisobutyl ketone (MIBK), n-butyl acetate, n-butanol, MIBK/n-butyl acetate (50:50 vol), MIBK/n-butanol (50:50 vol), tri-butyl phosphate, tri-n-octyl phosphine oxide (TOPO)/MIBK (10:90 wt), TOPO/kerosene (10:90 wt), kerosene, and toluene. The best distribution coefficient of 1.3 was given by n-butanol. Chemical analysis of the wastewater by gas chromatography (GC) showed acetic acid and propionic acid concentrations of about 4000 mg/1. Methanol, ethanol, and acetone were identified in trace amounts. These five compounds accounted for 45% of the measured COD of 29,000 mg/1. Because of the presence of carboxylic acids, pH was expected to affect extraction of the wastewater. At low pH the acids should be in the acidic form, which increased extraction by MIBK. Extraction by n-butanol was increased at high pH, where the acids should be in the ionic form.

  8. Compartmentalized Droplets for Continuous Flow Liquid-Liquid Interface Catalysis.

    Science.gov (United States)

    Zhang, Ming; Wei, Lijuan; Chen, Huan; Du, Zhiping; Binks, Bernard P; Yang, Hengquan

    2016-08-17

    To address the limitations of batch organic-aqueous biphasic catalysis, we develop a conceptually novel method termed Flow Pickering Emulsion, or FPE, to process biphasic reactions in a continuous flow fashion. This method involves the compartmentalization of bulk water into micron-sized droplets based on a water-in-oil Pickering emulsion, which are packed into a column reactor. The compartmentalized water droplets can confine water-soluble catalysts, thus "immobilizing" the catalyst in the column reactor, while the interstices between the droplets allow the organic (oil) phase to flow. Key fundamental principles underpinning this method such as the oil phase flow behavior, the stability of compartmentalized droplets and the confinement capability of these droplets toward water-soluble catalysts are experimentally and theoretically investigated. As a proof of this concept, case studies including a sulfuric acid-catalyzed addition reaction, a heteropolyacid-catalyzed ring opening reaction and an enzyme-catalyzed chiral reaction demonstrate the generality and versatility of the FPE method. Impressively, in addition to the excellent durability, the developed FPE reactions exhibit up to 10-fold reaction efficiency enhancement in comparison to the existing batch reactions, indicating a unique flow interface catalysis effect. This study opens up a new avenue to allow conventional biphasic catalysis reactions to access more sustainable and efficient flow chemistry using an innovative liquid-liquid interface protocol. PMID:27429173

  9. Theoretical considerations of laser induced liquid-liquid interface deformation

    CERN Document Server

    Aanensen, Nina Sasaki; Brevik, Iver

    2013-01-01

    In the increasingly active field of optofluidics, a series of experiments involving near-critical two-fluid interfaces have shown a number of interesting non-linear effects. We here offer, for the first time to our knowledge, an explanation for one such feature, observed in experiments by Casner and Delville [Phys. Rev. Lett. {\\bf 90}, 144503 (2003)], namely the sudden formation of "shoulder"-like shapes in a laser-induced deformation of the liquid-liquid interface at high laser power. Two candidate explanations are the following: firstly, that the shape can be explained by balancing forces of buoyancy, laser pull and surface tension only, and that the observed change of deformation shape is the sudden jump from one solution of the strongly nonlinear governing differential equation to another. Secondly, it might be that the nontrivial shape observed could be the result of temperature gradients due to local absorptive heating of the liquid. We report that a systematic search for solutions of the governing equa...

  10. Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

    Directory of Open Access Journals (Sweden)

    Jessica R. Breen

    2011-08-01

    Full Text Available 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials.

  11. Detection of food additives by voltammetry at the liquid-liquid interface.

    Science.gov (United States)

    Herzog, Grégoire; Kam, Victor; Berduque, Alfonso; Arrigan, Damien W M

    2008-06-25

    Electrochemistry at the liquid-liquid interface enables the detection of nonredoxactive species with electroanalytical techniques. In this work, the electrochemical behavior of two food additives, aspartame and acesulfame K, was investigated. Both ions were found to undergo ion-transfer voltammetry at the liquid-liquid interface. Differential pulse voltammetry was used for the preparation of calibration curves over the concentration range of 30-350 microM with a detection limit of 30 microM. The standard addition method was applied to the determination of their concentrations in food and beverage samples such as sweeteners and sugar-free beverages. Selective electrochemically modulated liquid-liquid extraction of these species in both laboratory solutions and in beverage samples was also demonstrated. These results indicate the suitability of liquid-liquid electrochemistry as an analytical approach in food analysis. PMID:18512937

  12. Simultaneous determination of uranium and plutonium at trace levels in process streams using Arsenazo III by derivative spectrophotometry

    International Nuclear Information System (INIS)

    A derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at trace levels in various process streams in 3M HNO3 medium using Arsenazo III. The method was developed with the objective of measuring both uranium and plutonium in the same aliquot in fairly high burn-up fuels. The first derivative absorbances of the uranium and plutonium Arsenazo III complexes at 632 nm and 606.5 nm, respectively, were used for their quantification. Mixed aliquots of uranium (20-28 μg/ml) and plutonium (0.5-1.5 μg/ml) with U/Pu ratio varying from 25 to 40 were analysed using this technique. A relative error of about 5% was obtained for uranium and plutonium. The method is simple, fast and does not require separation of uranium and plutonium. The effect of presence of many fission products, corrosion products and complexing anions on determination of uranium and plutonium was also studied. (author)

  13. Behavior of Supercooled Aqueous Solutions Stemming from Hidden Liquid-Liquid Transition in Water

    OpenAIRE

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-01-01

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two...

  14. Membrane assisted liquid-liquid extraction of cerium

    International Nuclear Information System (INIS)

    Membrane assisted liquid-liquid extraction of cerium was investigated, with emphasis placed on the study of the reaction chemistry and the kinetics of non-dispersive solvent extraction and stripping with microporous membranes. A bulk liquid membrane process was developed for the purification of cerium(IV) from sulfate solutions containing other rare earth elements. The cerium process was studied in both a flat sheet contained liquid membrane configuration and with hollow fibre contactors. Di-2-ethylhexyl phosphoric acid (DEHPA) was identified as a suitable extractant for cerium(IV) from sulfuric acid solution, with due consideration of factors such as extraction ability, resistance to degradation, solvent selectivity and potential for sulfate transfer into a strip solution. A detailed study of the extraction of cerium(IV) with DEHPA defined the extraction reaction chemistry. The Ce/DEHPA/sulfate system was also investigated with a flat sheet bulk liquid membrane configuration, using both sulfuric and hydrochloric acid as receiver solutions. These tests identified that hydrophobic membranes provide better mass transfer for extraction and hydrophilic membranes are better for stripping. The presence of an impurity, mono 2-ethylhexyl phosphoric acid (MEHPA), was found to have a dramatic accelerating effect on the rate of the chemical extraction reaction. This was attributed to its higher interfacial activity and population compared to DEHPA, and the fact that MEHPA was also found to be an active carrier for cerium(IV). The mass transfer rate of membrane assisted extraction and stripping of cerium, using hydrophobic and hydrophilic microporous membranes, respectively, was investigated using a modified Lewis-type cell. It was quantitatively demonstrated that the extraction process was mainly controlled by membrane diffusion and the stripping process was controlled by the chemical reaction rate, with membrane diffusion becoming important at low distribution coefficients

  15. Liquid-Liquid Phase Separation in Supersaturated Lysozyme Solutions and Associated Precipitate Formation/Crystallization

    Science.gov (United States)

    Muschol, Martin; Rosenberger, Franz

    1997-01-01

    Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (wlv) NaCl at pH= 4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

  16. Determination of Rare Earth Elements in Hypersaline Solutions Using Low-Volume, Liquid-Liquid Extraction.

    Science.gov (United States)

    Noack, Clinton W; Dzombak, David A; Karamalidis, Athanasios K

    2015-08-18

    Complex, hypersaline brines-including those coproduced with oil and gas, rejected from desalination technologies, or used as working fluids for geothermal electricity generation-could contain critical materials such as the rare earth elements (REE) in valuable concentrations. Accurate quantitation of these analytes in complex, aqueous matrices is necessary for evaluation and implementation of systems aimed at recovering those critical materials. However, most analytical methods for measuring trace metals have not been validated for highly saline and/or chemically complex brines. Here we modified and optimized previously published liquid-liquid extraction (LLE) techniques using bis(2-ethylhexyl) phosphate as the extractant in a heptane diluent, and studied its efficacy for REE recovery as a function of three primary variables: background salinity (as NaCl), concentration of a competing species (here Fe), and concentration of dissolved organic carbon (DOC). Results showed that the modified LLE was robust to a range of salinity, Fe, and DOC concentrations studied as well as constant, elevated Ba concentrations. With proper characterization of the natural samples of interest, this method could be deployed for accurate analysis of REE in small volumes of hyper-saline and chemically complex brines. PMID:25920439

  17. Direct Spectrophotometric Determination of the Total Amount of Light Rare Earths with Arsenazo-DBS as a Chelator

    Institute of Scientific and Technical Information of China (English)

    Yuan Fuzhen

    1999-01-01

      A direct spectrophotometric method for the determination of the total light rare earths has been developed. In this method, arsenazo-DBS is used as a chelating agent with light rare earth elements in strong acidic medium (0.04-0.48 mol l-1 of acidity). The concentrations of total rare earths in 0-15 μg /(25 ml) range can be determined accurately by this method. An absorption maximum was observed at 630 nm at which a molar absorptivity of 1.14x105 l mol-1 cm-1 was determined. The method offers high selectivity and good sensitivity towards light rare earths and features simplicity and rapidity in operation. It has been applied to the determination of light rare earths in cast iron and Ni-Fe alloys.

  18. Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

    International Nuclear Information System (INIS)

    Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor are reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup

  19. Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

    Energy Technology Data Exchange (ETDEWEB)

    Wardle, K.E. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-07-01

    Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor are reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup.

  20. Studies on the liquid-liquid interfacial mass transfer process using holographic interferometry

    Institute of Scientific and Technical Information of China (English)

    Chaofan ZHAO; Youguang MA; Chunying ZHU

    2008-01-01

    This paper aims at the interracial phenomena of liquid-liquid mass transfer and its characteristic. By using the real-time holographic technique, the concen-tration distributions on the aqueous side were obtained according to holographic diagrams of mass transfer of ethanol through the interface of oil and water at different initial concentrations. Furthermore, the concentrations near the interface and the mass transfer coefficients were attained. A correlation of concentration near the interface to the concentration of the solute in the oil side was proposed. An approach of interfacial energy with solute concentration was established, and the calculated results are at good agreement with the experimental data. It is indicated that the liquid-liquid mass transfer process is approximately in accordance with two-film theory, the interfacial performance may be changed by the addition of the solute, and the interface of liquid-liquid is non-equilibrium thermodynamically during the mass transfer process.

  1. (Liquid + liquid), (solid + liquid), and (solid + liquid + liquid) equilibria of systems containing cyclic ether (tetrahydrofuran or 1,3-dioxolane), water, and a biological buffer MOPS

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • MOPS buffer induced liquid phase splitting for mixtures of water with THF or 1,3-dioxolane. • Phase boundaries of LLE, SLE, and SLLE were determined experimentally. • Tie-lines at LLE and at SLLE were also measured. • Phase diagrams of MOPS + water + THF or 1,3-dioxolane are prepared. • LLE tie-line data are correlated satisfactorily with the NRTL model. - Abstract: Two liquid phases were formed as the addition of a certain amount of biological buffer 3-(N-morpholino)propane sulfonic acid (MOPS) in the aqueous solutions of tetrahydrofuran (THF) or 1,3-dioxolane. To evaluate the feasibility of recovering the cyclic ethers from their aqueous solutions with the aid of MOPS, we determined experimentally the phase diagrams of the ternary systems of {cyclic ether (THF or 1,3-dioxolane) + water + MOPS} at T = 298.15 K under atmospheric pressure. In this study, the solubility data of MOPS in water and in the mixed solvents of water/cyclic ethers were obtained from the results of a series of density measurements, while the (liquid + liquid) and the (solid + liquid + liquid) phase boundaries were determined by visually inspection. Additionally, the tie-line results for (liquid + liquid) equilibrium (LLE) and for (solid + liquid + liquid) equilibrium (SLLE) were measured using an analytical method. The reliability of the experimental LLE tie-line results data was validated by using the Othmer–Tobias correlation. These LLE tie-line values were correlated well with the NRTL model. The phase diagrams obtained from this study reveal that MOPS is a feasible green auxiliary agent to recover the cyclic ethers from their aqueous solutions, especially for 1,3-dioxolane

  2. Effect of Brownian Coagulation on the Liquid-liquid Decomposition in Gas-atomized Alloy Drops

    Institute of Scientific and Technical Information of China (English)

    Jiuzhou ZHAO; Lingling GAO; Jie HE; L.Ratke

    2006-01-01

    Modeling and simulation have been carried out for Al-Pb alloys to investigate the Brownian coagulation effect on the microstructure development in a gas-atomized drop during the liquid-liquid decomposition.The results indicate that Brownian coagulation has a weak effect on the nucleation and a relatively strong effect on coarsening the minority phase droplets. The influence of Brownian coagulation on the liquid-liquid decomposition decreases with the increase in the diameter (or the decrease in the cooling rate) of the atomized drop.

  3. An inkjet-printed microfluidic device for liquid-liquid extraction.

    Science.gov (United States)

    Watanabe, Masashi

    2011-04-01

    A microfluidic device for liquid-liquid extraction was quickly produced using an office inkjet printer. An advantage of this method is that normal end users, who are not familiar with microfabrication, can produce their original microfluidic devices by themselves. In this method, the printer draws a line on a hydrophobic and oil repellent surface using hydrophilic ink. This line directs a fluid, such as water or xylene, to form a microchannel along the printed line. Using such channels, liquid-liquid extraction was successfully performed under concurrent and countercurrent flow conditions.

  4. Experimental and calculated liquid-liquid interfacial tension in demixing metal alloys

    Institute of Scientific and Technical Information of China (English)

    Walter Hoyer; Ivan Kaban

    2006-01-01

    Liquid-liquid interfacial tension in binary and ternary Al-based monotectic systems has been determined experimentally with a tensiometric method in a wide temperature interval. The temperature dependence of the interfacial tension is well described by a power law function of the type σαβ~ (1 - T/Tc)δ with the critical exponent δ = 1.3 and a critical tem perature TC. Theoretical models describing the liquid-liquid interface in monotectic alloys and their applicability for calculation of the interfacial tension and its temperature dependence in binary systems are considered.

  5. Prediction of liquid-liquid equilibria for polyethylene glycol based aqueous two-phase system by ASOG and UNIFAC method

    Directory of Open Access Journals (Sweden)

    M. Perumalsamy

    2009-03-01

    Full Text Available Liquid-Liquid equilibrium data were obtained for the polyethylene glycol2000(PEG2000-sodium citrate-water system at 298.15, 308.15 and 318.15 K. The effect of temperature on binodal and tie line data was studied and published in a previous article (Murugesan and Perumalsamy, 2005. The interaction parameters of ASOG and UNIFAC models were estimated using the LLE data of PEG2000-sodium citrate-water system and are used to predict the LLE data for PEG6000-sodium citrate-water system at 298.15, 308.15 and 318.15 K (literature data. The predicted LLE data by both ASOG and UNIFAC models showed good agreement with the experimental and literature data.

  6. Apparent First-Order Liquid-Liquid Transition with Pre-transition Density Anomaly, in Water-Rich Ideal Solutions.

    Science.gov (United States)

    Zhao, Zuofeng; Angell, C Austen

    2016-02-12

    The striking increases in response functions observed during supercooling of pure water have been the source of much interest and controversy. Imminent divergences of compressibility etc. unfortunately cannot be confirmed due to pre-emption by ice crystallization. Crystallization can be repressed by addition of second components, but these usually destroy the anomalies of interest. Here we study systems in which protic ionic liquid second components dissolve ideally in water, and ice formation is avoided without destroying the anomalies. We observe a major heat capacity spike during cooling, which is reversed during heating, and is apparently of first order. It occurs just before the glassy state is reached and is preceded by water-like density anomalies. We propose that it is the much-discussed liquid-liquid transition previously hidden by crystallization. Fast cooling should allow the important fluctuations/structures to be preserved in the glassy state for leisurely investigation. PMID:26756943

  7. (Liquid + liquid) equilibrium data for the system (propylene glycol + water + tetraoctyl ammonium 2-methyl-1-naphthoate)

    International Nuclear Information System (INIS)

    Highlights: ► Recovery of PG from water using a task specific ionic liquid [TOA MNaph]. ► LLE data was correlated using the NRTL and UNIQUAC at three different temperatures. ► Both models describe the system adequately RSMD: 1.51% NRTL and 1.20% UNIQUAC. - Abstract: Propylene glycol (PG) is an important low toxic glycol, widely used in the food, cosmetics, pharmaceutical and the chemical industries. The recovery of PG from aqueous streams using conventional unit operations such as evaporation is highly energy demanding because of the large amounts of water that need to be evaporated. An alternative, more energy efficient technology could be liquid–liquid extraction. The use of tetraoctyl ammonium 2-methyl-1-naphtoate [TOA MNaph], a previously reported tailor made ionic liquid, (L.Y. Garcia-Chavez, B. Schuur, A.B. de Haan, J. Chem. Thermodyn. (2012). Doi: 10.1016/j.jct.2012.03.009) , for the extraction of mono ethylene glycol, was experimentally investigated for the liquid–liquid extraction of PG from aqueous streams by measuring the (liquid + liquid) equilibrium data for the system PG + water + [TOA MNaph] at three different temperatures. The data were correlated with both the NRTL and UNIQUAC models. Both thermodynamic models were able to correlate the experimental data well, with root square mean deviations (RMSD) of 1.51% and 1.20% for NRTL and UNIQUAC, respectively. From the high distribution of PG compared to traditional solvents, it could be concluded that [TOA MNaph] is a promising solvent for PG recovery from aqueous broths.

  8. Determination of Niacinamide in Lotions and Creams Using Liquid-Liquid Extraction and High-Performance Liquid Chromatography

    Science.gov (United States)

    Usher, Karyn M.; Simmons, Carolyn R.; Keating, Daniel W.; Rossi, Henry F., III

    2015-01-01

    Chemical separations are an important part of an undergraduate chemistry curriculum. Sophomore students often get experience with liquid-liquid extraction in organic chemistry classes, but liquid-liquid extraction is not as often introduced as a quantitative sample preparation method in honors general chemistry or quantitative analysis classes.…

  9. Liquid-liquid equilibria for glycols plus hydrocarbons: Data and correlation

    DEFF Research Database (Denmark)

    Derawi, Samer; Kontogeorgis, Georgios; Stenby, Erling Halfdan;

    2002-01-01

    Liquid-liquid equilibrium data for seven binary glycol-hydrocarbon systems have been measured in the temperature range 32 degreesC to 80 degreesC and at the pressure 1 bar. The measured systems are monoethylene glycol (MEG) + heptane, methyleyclohexane (MCH) + hexane, propylene glycol (PG) + hept...

  10. Solid-Liquid and Liquid-Liquid Mixing Laboratory for Chemical Engineering Undergraduates

    Science.gov (United States)

    Pour, Sanaz Barar; Norca, Gregory Benoit; Fradette, Louis; Legros, Robert; Tanguy, Philippe A.

    2007-01-01

    Solid-liquid and liquid-liquid mixing experiments have been developed to provide students with a practical experience on suspension and emulsification processes. The laboratory focuses on the characterization of the process efficiency, specifically the influence of the main operating parameters and the effect of the impeller type. (Contains 2…

  11. Hybrid Multiphase CFD Solver for Coupled Dispersed/Segregated Flows in Liquid-Liquid Extraction

    Directory of Open Access Journals (Sweden)

    Kent E. Wardle

    2013-01-01

    Full Text Available The flows in stage-wise liquid-liquid extraction devices include both phase segregated and dispersed flow regimes. As a additional layer of complexity, for extraction equipment such as the annular centrifugal contactor, free-surface flows also play a critical role in both the mixing and separation regions of the device and cannot be neglected. Traditionally, computional fluid dynamics (CFD of multiphase systems is regime dependent—different methods are used for segregated and dispersed flows. A hybrid multiphase method based on the combination of an Eulerian multifluid solution framework (per-phase momentum equations and sharp interface capturing using Volume of Fluid (VOF on selected phase pairs has been developed using the open-source CFD toolkit OpenFOAM. Demonstration of the solver capability is presented through various examples relevant to liquid-liquid extraction device flows including three-phase, liquid-liquid-air simulations in which a sharp interface is maintained between each liquid and air, but dispersed phase modeling is used for the liquid-liquid interactions.

  12. Liquid-liquid equilibria for binary and ternary polymer solutions with PC-SAFT

    DEFF Research Database (Denmark)

    Lindvig, Thomas; Michelsen, Michael Locht; Kontogeorgis, Georgios

    2004-01-01

    Two algorithms for evaluating liquid-liquid equilibria (LLE) for binary and ternary polymer solutions are presented. The binary algorithm provides the temperature versus concentration cloud-point curve at fixed pressure, whereas the ternary algorithm provides component 1 versus component 2...... accuracy, even by using interaction parameters obtained from binary vapor-liquid equlibrium data....

  13. Ultrastable Liquid-Liquid Interface as Viable Route for Controlled Deposition of Biodegradable Polymer Nanocapsules.

    Science.gov (United States)

    Vecchione, Raffaele; Iaccarino, Giulia; Bianchini, Paolo; Marotta, Roberto; D'autilia, Francesca; Quagliariello, Vincenzo; Diaspro, Alberto; Netti, Paolo A

    2016-06-01

    Liquid-liquid interfaces are highly dynamic and characterized by an elevated interfacial tension as compared to solid-liquid interfaces. Therefore, they are gaining an increasing interest as viable templates for ordered assembly of molecules and nanoparticles. However, liquid-liquid interfaces are more difficult to handle compared to solid-liquid interfaces; their intrinsic instability may affect the assembly process, especially in the case of multiple deposition. Indeed, some attempts have been made in the deposition of polymer multilayers at liquid-liquid interfaces, but with limited control over size and stability. This study reports on the preparation of an ultrastable liquid-liquid interface based on an O/W secondary miniemulsion and its possible use as a template for the self-assembly of polymeric multilayer nanocapsules. Such polymer nanocapsules are made of entirely biodegradable materials, with highly controlled size-well under 200 nm-and multi-compartment and multifunctional features enriching their field of application in drug delivery, as well as in other bionanotechnology fields. PMID:27060934

  14. Aromatic nitrations by mixed acid. Fast liquid-liquid reaction regime

    NARCIS (Netherlands)

    Zaldivar, J.M.; Molga, E.J.; Alos, M.A.; Hernandez, H.; Westerterp, K.R.

    1996-01-01

    Aromatic nitration by mixed acid was selected as a specific case of heterogeneous liquid-liquid reaction. An extensive experimental programme was followed using adiabatic and heat flow calorimetry and pilot reactor experiments, supported by chemical analysis. A series of nitration experiments was ca

  15. Liquid-Liquid Extraction of Insecticides from Juice: An Analytical Chemistry Laboratory Experiment

    Science.gov (United States)

    Radford, Samantha A.; Hunter, Ronald E., Jr.; Barr, Dana Boyd; Ryan, P. Barry

    2013-01-01

    A laboratory experiment was developed to target analytical chemistry students and to teach them about insecticides in food, sample extraction, and cleanup. Micro concentrations (sub-microgram/mL levels) of 12 insecticides spiked into apple juice samples are extracted using liquid-liquid extraction and cleaned up using either a primary-secondary…

  16. Elastic properties of surfactant monolayers at liquid-liquid interfaces: A molecular dynamics study

    DEFF Research Database (Denmark)

    Laradji, Mohamed; Mouritsen, Ole G.

    2000-01-01

    Using a simple molecular model based on the Lennard-Jones potential, we systematically study the elastic properties of liquid-liquid interfaces containing surfactant molecules by means of extensive and large-scale molecular dynamics simulations. The main elastic constants of the interface...

  17. 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...

  18. Numerical simulation of Marangoni effects of single drops induced by interphase mass transfer in liquid-liquid extraction systems by the level set method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mathematical model of mass transfer-induced Marangoni effect is formulated. The drop surface evolution is captured by the level set method, in which the interface is represented by the embedded set of zero level of a scalar distance function defined in the whole computational domain. Numerical simulation of the Marangoni effect induced by interphase mass transfer to/from deformable single drops in unsteady motion in liquid-liquid extraction systems is performed in a Eulerian axisymmetric reference frame. The occurrence and development of the Marangoni effect are simulated, and the re- sults are in good agreement with the classical theoretical analysis and previous simulation.

  19. Numerical simulation of Marangoni effects of single drops induced by interphase mass transfer in liquid-liquid extraction systems by the level set method

    Institute of Scientific and Technical Information of China (English)

    WANG JianFeng; YANG Chao; MAO ZaiSha

    2008-01-01

    The mathematical model of mass transfer-induced Marangoni effect is formulated. The drop surface evolution is captured by the level set method, in which the interface is represented by the embedded set of zero level of a scalar distance function defined in the whole computational domain. Numerical simulation of the Marangoni effect induced by interphase mass transfer to/from deformable single drops in unsteady motion in liquid-liquid extraction systems is performed in a Eulerian axisymmetric reference frame. The occurrence and development of the Marangoni effect are simulated, and the re-sults are in good agreement with the classical theoretical analysis and previous simulation.

  20. Analysis of amantadine in biological fluids using hollow fiber-based liquid-liquid-liquid microextraction followed by corona discharge ion mobility spectrometry.

    Science.gov (United States)

    Saraji, Mohammad; Khayamian, Taghi; Mirmahdieh, Shiva; Bidgoli, Ali Akbar Hajialiakbari

    2011-10-15

    A method based on liquid-liquid-liquid microextraction combined with corona discharge ion mobility spectrometry was developed for the analysis of amantadine in human urine and plasma samples. Amantadine was extracted from alkaline aqueous sample as donor phase through a thin phase of organic solvent (n-dodecane) filling the pores of the hollow fiber wall and then back extracted into the organic acceptor phase (methanol) located in the lumen of the hollow fiber. All variables affecting the extraction of analyte including acceptor organic solvent type, concentration of NaOH in donor phase, ionic strength of the sample and extraction time were studied. The linear range was 20-1000 and 5-250 ng/mL for plasma and urine, respectively (r(2)≥0.990). The limits of detection were calculated to be 7.2 and 1.6 ng/mL for plasma and urine, respectively. The relative standard deviation was lower than 8.2% for both urine and plasma samples. The enrichment factors were between 45 and 54. The method was successfully applied for the analysis of amantadine in urine and plasma samples. PMID:21956021

  1. Automated dynamic hollow fiber liquid-liquid-liquid microextraction combined with capillary electrophoresis for speciation of mercury in biological and environmental samples.

    Science.gov (United States)

    Li, Pingjing; He, Man; Chen, Beibei; Hu, Bin

    2015-10-01

    A simple home-made automatic dynamic hollow fiber based liquid-liquid-liquid microextraction (AD-HF-LLLME) device was designed and constructed for the simultaneous extraction of organomercury and inorganic mercury species with the assistant of a programmable flow injection analyzer. With 18-crown-6 as the complexing reagent, mercury species including methyl-, ethyl-, phenyl- and inorganic mercury were extracted into the organic phase (chlorobenzene), and then back-extracted into the acceptor phase of 0.1% (m/v) 3-mercapto-1-propanesulfonic acid (MPS) aqueous solution. Compared with automatic static (AS)-HF-LLLME system, the extraction equilibrium of target mercury species was obtained in shorter time with higher extraction efficiency in AD-HF-LLLME system. Based on it, a new method of AD-HF-LLLME coupled with large volume sample stacking (LVSS)-capillary electrophoresis (CE)/UV detection was developed for the simultaneous analysis of methyl-, phenyl- and inorganic mercury species in biological samples and environmental water. Under the optimized conditions, AD-HF-LLLME provided high enrichment factors (EFs) of 149-253-fold within relatively short extraction equilibrium time (25min) and good precision with RSD between 3.8 and 8.1%. By combining AD-HF-LLLME with LVSS-CE/UV, EFs were magnified up to 2195-fold and the limits of detection (at S/N=3) for target mercury species were improved to be sub ppb level.

  2. Hollow fiber-based liquid-liquid-liquid microextraction followed by flow injection analysis using column-less HPLC for the determination of phenazopyridine in plasma and urine.

    Science.gov (United States)

    Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari; Farajmand, Bahman

    2011-07-01

    Hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) followed by flow injection analysis and diode array detection (FIA-DAD) was applied as a simple and sensitive quantitative method for the determination of phenazopyridine in urine and plasma samples. Flow injection system included a conventional HPLC system (without a chromatographic column) and a diode array detector. The extraction of phenazopyridine was carried out using diphenyl ether as the organic phase for filling the pores of the hollow fiber wall, and 0.1 M H(2)SO(4) solution as acceptor phase in the lumen of the fiber. The factors affecting the HF-LLLME and flow injection analysis including type of organic solvent, pH of donor phase, extraction temperature, extraction time, stirring rate, and pH of mobile phase were investigated and the optimal extraction conditions were established. With the consumption of 5 mL of sample solution, the enrichment factor was about 230. The limit of detection was 0.5 μg/L with inter- and intra-day precision being (RSD%) 6.9 and 4.9, respectively. Excellent linearity was found between 5 and 200 μg/L. PMID:21681956

  3. Study on the Holdup and Mass Transfer Performances for Gas-Liquid-Liquid System in a Screen Plate Column

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gas and dispersed phase holdups and mass transfer coefficients of liquid-iquid were determined for gas-liquid-liquid three phase system in a screen plate column. The flow pattern of gas-liquid-liquid three phase system was studied under different gas velocities. The shape factors showed the geometric properties of screen plates and the corrected drop characteristic velocities were introduced. The phase holdup in two phases was correlated. The research results indicated that mass transfer coefficient for liquid-liquid system in a column with screen plates and gas agitation was found to increase apparently.

  4. SIMULTANEOUS REACTION AND LIQUID-LIQUID EXTRACTION IN THE HYDROGEN PEROXIDE PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    Shuxiang L(u); Li Wang; Zhentao Mi; Yaquan Wang

    2004-01-01

    The gas-liquid-liquid reactive extraction system for preparing hydrogen peroxide via anthraquinone was investigated. The oxidation reaction of hydrogenated working solution was combined with the extraction of hydrogen peroxide from working solution in a sieve plate column. The reaction of 2-ethylanthrahydroquionone with oxygen and the liquid-liquid extraction of hydrogen peroxide take place simultaneously. The oxygen was introduced with hydrogenated working solution through a nozzle in the bottom of the column, which worked as agitated air as well as oxidation reagent. The results showed the oxidation and extraction do not hamper each other, on the contrary, the presence of oxidation gas in the column can promote the transfer of hydrogen peroxide from organic phase to aqueous phase, thus the reaction efficiency and extraction efficiency increased with increasing gas superficial velocity. Furthermore, the oxidation efficiency is almost 100% and the extraction efficiency is higher than 90% in this process.

  5. Liquid-Liquid equilibria of the water-acetic acid-butyl acetate system

    Directory of Open Access Journals (Sweden)

    E. Ince

    2002-04-01

    Full Text Available Experimental liquid-liquid equilibria of the water-acetic acid-butyl acetate system were studied at temperatures of 298.15± 0.20, 303.15± 0.20 and 308.15± 0.20 K. Complete phase diagrams were obtained by determining solubility and tie-line data. The reliability of the experimental tie-line data was ascertained by using the Othmer and Tobias correlation. The UNIFAC group contribution method was used to predict the observed ternary liquid-liquid equilibrium (LLE data. It was found that UNIFAC group interaction parameters used for LLE did not provide a good prediction. Distribution coefficients and separation factors were evaluated for the immiscibility region.

  6. Theoretical background and the flow fields in downhole liquid-liquid hydrocyclone (LLHC

    Directory of Open Access Journals (Sweden)

    Osei Harrison

    2014-07-01

    Full Text Available Hydrocyclone system for downhole oil-water separation provides an effective technique of enhancing the economic viability of higher water-cut wells while at the same time reducing the risk of environmental pollution. This paper describes the hydrodynamics of the liquid-liquid hydrocyclones and the flow fields within it are paramount for achieving successful separation process. Some of the important hydrodynamic flow phenomenon within the liquid-liquid hydrocyclone and how they influence the separation efficiency of water/oil was analyzed through analytical solution. The properties of the liquids were based on Bayan offshore field measured properties. The results indicated that there are two swirling zones separated by stagnant flow field. The inner is the light liquid zone, while the outer is the heavy liquid zone.

  7. Measuring the optical chirality of molecular aggregates at liquid-liquid interfaces.

    Science.gov (United States)

    Watarai, Hitoshi; Adachi, Kenta

    2009-10-01

    Some new experimental methods for measuring the optical chirality of molecular aggregates formed at liquid-liquid interfaces have been reviewed. Chirality measurements of interfacial aggregates are highly important not only in analytical spectroscopy but also in biochemistry and surface nanochemistry. Among these methods, a centrifugal liquid membrane method was shown to be a highly versatile method for measuring the optical chirality of the liquid-liquid interface when used in combination with a commercially available circular dichroism (CD) spectropolarimeter, provided that the interfacial aggregate exhibited a large molar absorptivity. Therefore, porphyrin and phthalocyanine were used as chromophoric probes of the chirality of itself or guest molecules at the interface. A microscopic CD method was also demonstrated for the measurement of a small region of a film or a sheet sample. In addition, second-harmonic generation and Raman scattering methods were reviewed as promising methods for detecting interfacial optical molecules and measuring bond distortions of chiral molecules, respectively.

  8. LIQUID-LIQUID PHASE EQUILIBRIUM OF POLYMER SOLUTIONS AND POLYMER BLENDS UNDER POSITIVE AND NEGATIVE PRESSURE

    Institute of Scientific and Technical Information of China (English)

    Attila R.Imre

    2003-01-01

    In this paper we would like to give a brief review about the extensibility of the liquid-liquid locus into the negative pressure region. Negative pressure states are hardly explored; most researchers believe that the pressure scale ends at p = 0.We would like to show that this is not true, thep = 0 point is not a special point for liquids, it can be "easily" crossed. We are going to give a few example, where the extension of liquid-liquid locus for polymer blends and solutions below p = 0 gives us some interesting results, like the merging of UCST and LCST branches in weakly interacting polymer solutions or the reason why most UCST blends exhibit pressure induced immiscibility. Also, we will see what happens with the immiscibility island of aqueous polymer solutions when - reaching the critical molar mass - it "disappears".

  9. Liquid-Liquid Phase Transition and Glass Transition in a Monoatomic Model System

    Directory of Open Access Journals (Sweden)

    Nicolas Giovambattista

    2010-12-01

    Full Text Available We review our recent study on the polyamorphism of the liquid and glass states in a monatomic system, a two-scale spherical-symmetric Jagla model with both attractive and repulsive interactions. This potential with a parametrization for which crystallization can be avoided and both the glass transition and the liquid-liquid phase transition are clearly separated, displays water-like anomalies as well as polyamorphism in both liquid and glassy states, providing a unique opportunity to study the interplay between the liquid-liquid phase transition and the glass transition. Our study on a simple model may be useful in understanding recent studies of polyamorphism in metallic glasses.

  10. Development, Fabrication, and Testing of a Liquid/Liquid Microchannel Heat Exchanger for Constellation Spacecrafts

    Science.gov (United States)

    Hawkins-Reynolds, Ebony; Le, Hung; Stephan, Ryan

    2010-01-01

    Microchannel technology can be incorporated into heat exchanger designs to decrease the mass and volume of space hardware. The National Aeronautics and Space Administration at the Johnson Space Center (NASA JSC) partnered with Pacific Northwest National Laboratories (PNNL) to develop a liquid/liquid microchannel heat exchanger that has significant mass and volume savings without sacrificing thermal and pressure drop performance. PNNL designed the microchannel heat exchanger to the same performance design requirements of a conventional plate and fin liquid/liquid heat exchanger; 3 kW duty with inlet temperatures of 26 C and 4 C. Both heat exchangers were tested using the same test parameters on a test apparatus and performance data compared.

  11. SIMULTANEOUS REACTION AND LIQUID-LIQUID EXTRACTION IN THE HYDROGEN PEROXIDE PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    ShuxiangLǖ; LiWang; ZhentaoMi; YaquanWang

    2004-01-01

    The gas-liquid-liquid reactive extraction system for preparing hydrogen peroxide via anthraquinone was investigated. The oxidation reaction of hydrogenated working solution was combined with the extraction of hydrogen peroxide from working solution in a sieve plate column. The reaction of 2-ethylanthrahydroquionone with oxygen and the liquid-liquid extraction of hydrogen peroxide take place simultaneously. The oxygen was introduced with hydrogenated working solution through a nozzle in the bottom of the column, which worked as agitated air as well as oxidation reagent. The results showed the oxidation and extraction do not hamper each other, on the contrary, the presence of oxidation gas in the column can promote the transfer of hydrogen peroxide fi'om organic phase to aqueous phase, thus the reaction efficiency and extraction efficiency increased with increasing gas superficial velocity. Furthermore, the oxidation efficiency is almost 100% and the extraction efficiency is higher than 90% in this process.

  12. Computational Fluid Dynamics Aided Design of Stirred Liquid-Liquid Extraction Columns

    OpenAIRE

    Hlawitschka, Mark

    2013-01-01

    Aim of this work was the extension and development of a coupled Computational Fluid Dynamics (CFD) and population balance model (PBM) solver to enable a simulation aided design of stirred liquid-liquid extraction columns. The principle idea is to develop a new design methodology based on a CFD-PBM approach and verify it with existing data and correlations. On this basis, the separation performance in any apparatus geometry should be possible to predict without any experimental input. Reliable...

  13. Liquid-Liquid Structure Transition in Metallic Melts: Experimental Evidence by Viscosity Measurement

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-Qing; WU Yu-Qin; BIAN Xiu-Fang

    2007-01-01

    Temperature dependence of viscosity for more than ten kinds of metallic melts is analysed based on viscosity measurements. An obvious turning point is observed on the Arrhenius curves. Since viscosity is one of the physical properties sensitive to structure, its discontinuous change with temperature reveals the possible liquidliquid structure transition in the metallic melts. Furthermore, an integrated liquid structure transition diagram of the Sn-Bi system is presented. The universality of liquid-liquid structure transition is also discussed simply.

  14. Experimental Study on Liquid-Liquid Equilibria of Alcohol-Ester-Water-CaCl2 System

    Institute of Scientific and Technical Information of China (English)

    Fu Jiquan; Fu Die

    2014-01-01

    The binary liquid-liquid equilibrium (LLE) data for salt-containing systems of 1-butanol+water+CaCl2, n-butyl acetate+water+CaCl2 and ethyl acetate+acetic acid+water+CaCl2 were determined and the salt effect was analyzed. The results showed that an obvious salt effect could be identified for the systems of 1-butanol+water+CaCl2 and ethyl acetate+acetic acid+water.

  15. Melittin Adsorption and Lipid Monolayer Disruption at Liquid-Liquid Interfaces

    OpenAIRE

    Mendez, Manuel A.; Nazemi, Zahra; Uyanik, Ibrahim; Lu, Yu; Girault, Hubert H.

    2011-01-01

    Melittin, a membrane-active peptide with antimicrobial activity, was investigated at the interface formed between two immiscible electrolyte solutions (ITIES) supported on a metallic electrode. Ion-transfer voltammetry showed well-defined semi-reversible transfer peaks along with adsorptive peaks. The reversible adsorption of melittin at the liquid-liquid interface is qualitatively discussed from voltammetric data and experimentally confirmed by real-time image analysis of video snapshots. It...

  16. Spectrophotometric determination of iron species using ionic liquid ultrasound assisted dispersive liquid--liquid microextraction

    OpenAIRE

    BAZMANDEGAN, ALIREZA; SHABANI, Ali Mohammad HAJI; DADFARNIA, SAYESSTEH; SAEIDI, MAHBOUBEH; MOGHADAM, MASOUD ROHANI

    2015-01-01

    A simple and efficient method for speciation and determination of iron in different water samples was developed. The method is based on ionic liquid ultrasound assisted dispersive liquid--liquid microextraction (IL-USA-DLLME) followed by spectrophotometric determination. Fe(II) is complexed with 2,4,6-tri(2'-pyridyl)-l,3,5-triazine (TPTZ{)}, neutralized through ion pair formation with sodium dodecyl sulfate (SDS) and extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate [C$_{6}$...

  17. Experimental and modelling studies on liquid-liquid slug flow capillary microreactors

    OpenAIRE

    Kashid, Madhvanand N.

    2008-01-01

    Microreactor technology, an important method of process intensification, offers potential benefits to the chemical process industries due to the well-defined high specific interfacial area available for heat and mass transfer, which increases transfer rates, and enhances safety resulting from low hold-ups. The liquid-liquid slug flow capillary microreactor intensifies the mass transfer in biphasic systems through internal circulation caused by the shear between continuous phase/wall surface a...

  18. Structure and Depletion at Fluoro- and Hydro-carbon/Water Liquid/Liquid Interfaces

    OpenAIRE

    Kashimoto, Kaoru; Yoon, Jaesung; Hou, Binyang; Chen, Chiu-hao; Lin, Binhua; Aratono, Makoto; Takiue, Takanori; Schlossman, Mark L.

    2008-01-01

    The results of x-ray reflectivity studies of two oil/water (liquid/liquid) interfaces are inconsistent with recent predictions of the presence of a vapor-like depletion region at hydrophobic/aqueous interfaces. One of the oils, perfluorohexane, is a fluorocarbon whose super-hydrophobic interface with water provides a stringent test for the presence of a depletion layer. The other oil, heptane, is a hydrocarbon and, therefore, is more relevant to the study of biomolecular hydrophobicity. These...

  19. Redox-active cross-linkable poly(ionic liquid)s.

    Science.gov (United States)

    Sui, Xiaofeng; Hempenius, Mark A; Vancso, G Julius

    2012-03-01

    The synthesis of a new class of cross-linkable redox-responsive poly(ferrocenylsilane)-based poly(ionic liquid)s (PFS-PILs) is reported. PFS-PILs self-cross-link at low concentrations into nanogels or form macroscopic hydrogel networks at higher concentrations. PFS-PILs proved to be efficient dispersants in the microemulsion polymerization of methyl methacrylate, producing stable PFS-poly(methyl methacrylate) latex suspensions. PMID:22353019

  20. Equation of State for Supercooled Water Near the Liquid-Liquid Critical Point

    OpenAIRE

    Anisimov, M. A.; Fuentevilla, D. A.

    2006-01-01

    We have developed a scaled parametric equation of state to describe and predict thermodynamic properties of supercooled water. The equation of state, built on the growing evidence that the critical point of supercooled liquid-liquid water separation exists, is universal in terms of theoretical scaling fields and is shown to belong to the Ising-model class of universality. The theoretical scaling fields are postulated to be analytical combinations of the physical fields, pressure and temperatu...

  1. Real Space Imaging of Nanoparticle Assembly at Liquid-Liquid Interfaces with Nanoscale Resolution.

    Science.gov (United States)

    Costa, Luca; Li-Destri, Giovanni; Thomson, Neil H; Konovalov, Oleg; Pontoni, Diego

    2016-09-14

    Bottom up self-assembly of functional materials at liquid-liquid interfaces has recently emerged as method to design and produce novel two-dimensional (2D) nanostructured membranes and devices with tailored properties. Liquid-liquid interfaces can be seen as a "factory floor" for nanoparticle (NP) self-assembly, because NPs are driven there by a reduction of interfacial energy. Such 2D assembly can be characterized by reciprocal space techniques, namely X-ray and neutron scattering or reflectivity. These techniques have drawbacks, however, as the structural information is averaged over the finite size of the radiation beam and nonperiodic isolated assemblies in 3D or defects may not be easily detected. Real-space in situ imaging methods are more appropriate in this context, but they often suffer from limited resolution and underperform or fail when applied to challenging liquid-liquid interfaces. Here, we study the surfactant-induced assembly of SiO2 nanoparticle monolayers at a water-oil interface using in situ atomic force microscopy (AFM) achieving nanoscale resolved imaging capabilities. Hitherto, AFM imaging has been restricted to solid-liquid interfaces because applications to liquid interfaces have been hindered by their softness and intrinsic dynamics, requiring accurate sample preparation methods and nonconventional AFM operational schemes. Comparing both AFM and grazing incidence X-ray small angle scattering data, we unambiguously demonstrate correlation between real and reciprocal space structure determination showing that the average interfacial NP density is found to vary with surfactant concentration. Additionally, the interaction between the tip and the interface can be exploited to locally determine the acting interfacial interactions. This work opens up the way to studying complex nanostructure formation and phase behavior in a range of liquid-liquid and complex liquid interfaces. PMID:27571473

  2. Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review

    Directory of Open Access Journals (Sweden)

    Rahul Antony

    2014-10-01

    Full Text Available Mass transfer is a basic phenomenon behind many processes like reaction, absorption, extraction etc. Mass transfer plays a significant role in microfluidic systems where the chemical / biological process systems are shrinkened down to a micro scale. Micro reactor system, with its high compatibility and performance, gains a wide interest among the researchers in the recent years. Micro structured reac-tors holds advantages over the conventional types in chemical processes. The significance of micro re-actor not limited to its scalability but to energy efficiency, on-site / on-demand production, reliability, safety, highly controlled outputs, etc. Liquid-liquid two phase reaction in a microreactor system is highly demandable when both reactants are liquids or when air medium cannot be suitable. This arti-cle overviews various liquid-liquid flow regimes in a microchannel. Discussions on the hydrodynamics of flow in micro scale are made. Considering the importance of mass transfer in liquid-liquid systems and the advantage of slug regime over other regimes, the article focuses especially on the mass trans-fer between two liquid phases in slug flow and the details of experimental studies carried out in this area. The advantages of slug flow over other flow regimes in micro structured reactor applications are showcased. © 2014 BCREC UNDIP. All rights reservedReceived: 31st May 2014; Revised: 6th August 2014; Accepted: 14th August 2014How to Cite: Antony, R., Giri Nandagopal, M.S., Sreekumar, N., Rangabhashiyam, S., Selvaraju, N. (2014. Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review. Bulletin of Chemical Reaction Engineering & Catalysis,9(3: 207-223. (doi:10.9767/bcrec.9.3.6977.207-223Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6977.207-223

  3. Process for the recovery of magnesium and/or nickel by liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Gabra, G.

    1984-02-14

    The recovery of substantially pure magnesium and/or nickel sulphite which is present in a solid starting meterial. The latter is treated with gaseous SO/sub 2/ in water, the solution obtained is treated by a liquid-liquid extraction, to give an aqueous phase and an organic phase and the magnesium and/or nickel sulphite is recovered from the aqueous phase. With this process, it is possible to obtain a magnesium salt of high purity.

  4. Thermokinetics of Liquid-Liquid Reaction of Dy(NO3)3 with Histidine

    Institute of Scientific and Technical Information of China (English)

    李仲谨; 陈三平; 房艳; 高胜利

    2003-01-01

    The thermokinetics of liquid-liquid reaction of dysprosium nitrate with histidine were studied using a microcalorimeter. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant, three kinetic parameters (the activation energy, the pre-exponential constant and the reaction order) were obtained. On the basis of thermodynamics and kinetics, the formation reaction of the complex was discussed.

  5. Liquid-liquid distribution of aromatic α-amino acids in multicomponent systems

    Science.gov (United States)

    Korenman, Ya. I.; Mokshina, N. Ya.; Pakhomova, O. A.

    2010-02-01

    Distribution coefficients and recovery factors of phenylalanine, tyrosine, and tryptophan are measured in extraction systems with butanol, pentanol, acetone, and ethyl acetate, their binary and ternary mixtures, and water-soluble polymers. Extraction conditions—extractant composition, salting-out agents, and pH—are optimized. Efficient systems providing maximum quantitative characteristics of the process of liquid-liquid distribution of aromatic α-amino acids are proposed.

  6. Real Space Imaging of Nanoparticle Assembly at Liquid-Liquid Interfaces with Nanoscale Resolution.

    Science.gov (United States)

    Costa, Luca; Li-Destri, Giovanni; Thomson, Neil H; Konovalov, Oleg; Pontoni, Diego

    2016-09-14

    Bottom up self-assembly of functional materials at liquid-liquid interfaces has recently emerged as method to design and produce novel two-dimensional (2D) nanostructured membranes and devices with tailored properties. Liquid-liquid interfaces can be seen as a "factory floor" for nanoparticle (NP) self-assembly, because NPs are driven there by a reduction of interfacial energy. Such 2D assembly can be characterized by reciprocal space techniques, namely X-ray and neutron scattering or reflectivity. These techniques have drawbacks, however, as the structural information is averaged over the finite size of the radiation beam and nonperiodic isolated assemblies in 3D or defects may not be easily detected. Real-space in situ imaging methods are more appropriate in this context, but they often suffer from limited resolution and underperform or fail when applied to challenging liquid-liquid interfaces. Here, we study the surfactant-induced assembly of SiO2 nanoparticle monolayers at a water-oil interface using in situ atomic force microscopy (AFM) achieving nanoscale resolved imaging capabilities. Hitherto, AFM imaging has been restricted to solid-liquid interfaces because applications to liquid interfaces have been hindered by their softness and intrinsic dynamics, requiring accurate sample preparation methods and nonconventional AFM operational schemes. Comparing both AFM and grazing incidence X-ray small angle scattering data, we unambiguously demonstrate correlation between real and reciprocal space structure determination showing that the average interfacial NP density is found to vary with surfactant concentration. Additionally, the interaction between the tip and the interface can be exploited to locally determine the acting interfacial interactions. This work opens up the way to studying complex nanostructure formation and phase behavior in a range of liquid-liquid and complex liquid interfaces.

  7. Review of algorithms for modeling metal distribution equilibria in liquid-liquid extraction processes

    Directory of Open Access Journals (Sweden)

    Lozano, L. J.

    2005-10-01

    Full Text Available This work focuses on general guidelines to be considered for application of least-squares routines and artificial neural networks (ANN in the estimation of metal distribution equilibria in liquid-liquid extraction process. The goal of the procedure in the statistical method is to find the values of the equilibrium constants (Kj for the reactions involved in the metal extraction which minimizes the differences between experimental distribution coefficient (Dexp and theoretical distribution coefficients according to the mechanism proposed (Dtheor- In the first part of the article, results obtained with the most frequently routine reported in the bibliography are compared with those obtained using the algorithms previously discussed. In the second part, the main features of a single back-propagation neural network for the same purpose are discussed, and the results obtained are compared with those obtained with the classical methods.

    El trabajo presenta las líneas generales a considerar para la estimación del equilibrio de distribución de metales en procesos de extracción líquido-líquido, según dos métodos: algoritmo clásico de mínimos cuadrados y redes neuronales artificiales. El objetivo del procedimiento, en el caso del método estadístico, es encontrar los valores de las constantes de equilibrio (Kj para las reacciones involucradas en la extracción del metal, que minimizan las diferencias entre el coeficiente de distribución experimental y el coeficiente de distribución teórico, de acuerdo al mecanismo propuesto. En la primera parte del artículo se comparan los resultados obtenidos a partir de los algoritmos usados más habitualmente en la bibliografía, con los datos obtenidos mediante el algoritmo previamente descrito. En la segunda parte, se presentan las características fundamentales para aplicar una red neuronal sencilla con algoritmo back-propagation y los

  8. 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. PMID:23381802

  9. C. elegans uses Liquid-Liquid Demixing for the Assembly of Non-Membrane-Bound Compartments

    Science.gov (United States)

    Weber, Christoph A.; Juelicher, Frank; Diaz Delgadillo, Andres Felipe; Jawerth, Louise; Hyman, Anthony A.; Department Biological Physics Team; Hyman Lab Collaboration

    2015-03-01

    P granules are liquid cytoplasmic RNA/Protein condensates known to determine the germ lineage in Caenorhabditis elegans. They resemble striking similarities with liquid droplets, such as dripping, shearing and wetting. Assuming that P granules are liquid-like we consider how they form in the crowded cytoplasm. Using confocal and light-sheet microscopy, P granule formation in-vivo and in-vitro is shown to share all hallmarks with a liquid-liquid phase-separation. Specifically, demixing is determined by temperature and concentration, the droplet formation is reversible with respect to temperature quenches and there is evidence for droplet growth due to coalescence and Ostwald-ripening. Liquid-liquid demixing in-vivo breaks the paradigmatic view that a molecular machinery is necessary to build up organelles through complex biological pathways. Instead we propose that P granules form following a Flory-Huggins model. Liquid-liquid demixing could also serve as a mechanism for the assembly of non-membrane-bound compartments in other living organisms.

  10. A microfluidic study of liquid-liquid extraction mediated by carbon dioxide.

    Science.gov (United States)

    Lestari, Gabriella; Salari, Alinaghi; Abolhasani, Milad; Kumacheva, Eugenia

    2016-07-01

    Liquid-liquid extraction is an important separation and purification method; however, it faces a challenge in reducing the energy consumption and the environmental impact of solvent (extractant) recovery. The reversible chemical reactions of switchable solvents (nitrogenous bases) with carbon dioxide (CO2) can be implemented in reactive liquid-liquid extraction to significantly reduce the cost and energy requirements of solvent recovery. The development of new effective switchable solvents reacting with CO2 and the optimization of extraction conditions rely on the ability to evaluate and screen the performance of switchable solvents in extraction processes. We report a microfluidic strategy for time- and labour-efficient studies of CO2-mediated solvent extraction. The platform utilizes a liquid segment containing an aqueous extractant droplet and a droplet of a solution of a switchable solvent in a non-polar liquid, with gaseous CO2 supplied to the segment from both sides. Following the reaction of the switchable solvent with CO2, the solvent becomes hydrophilic and transfers from the non-polar solvent to the aqueous droplet. By monitoring the time-dependent variation in droplet volumes, we determined the efficiency and extraction time for the CO2-mediated extraction of different nitrogenous bases in a broad experimental parameter space. The platform enables a significant reduction in the amount of switchable solvents used in these studies, provides accurate temporal characterization of the liquid-liquid extraction process, and offers the capability of high-throughput screening of switchable solvents. PMID:27327198

  11. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

    Science.gov (United States)

    Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases. PMID:25149798

  12. On the phase-field modelling of a miscible liquid/liquid boundary.

    Science.gov (United States)

    Xie, Ruilin; Vorobev, Anatoliy

    2016-02-15

    Mixing of miscible liquids is essential for numerous processes in industry and nature. Mixing, i.e. interpenetration of molecules through the liquid/liquid boundary, occurs via interfacial diffusion. Mixing can also involve externally or internally driven hydrodynamic flows, and can lead to deformation or disintegration of the liquid/liquid boundary. At the moment, the mixing dynamics remains poorly understood. The classical Fick's law, generally accepted for description of the diffusion process, does not explain the experimental observations, in particular, the recent experiments with dissolution of a liquid solute by a liquid solvent within a horizontal capillary (Stevar and Vorobev, 2012). We present the results of the numerical study aimed at development of an advanced model for the dissolution dynamics of liquid/liquid binary mixtures. The model is based on the phase-field (Cahn-Hilliard) approach that is used as a physics-based model for the thermo- and hydrodynamic evolution of binary mixtures. Within this approach, the diffusion flux is defined through the gradient of chemical potential, and, in particular, includes the effect of barodiffusion. The dynamic interfacial stresses at the miscible interface are also taken into account. The simulations showed that such an approach can accurately reproduce the shape of the solute/solvent boundary, and some aspects of the diffusion dynamics. Nevertheless, all experimentally-observed features of the diffusion motion of the solute/solvent boundary, were not reproduced. PMID:26609922

  13. Removal of nitrogen compounds from Brazilian petroleum samples by oxidation followed by liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, L.; Pergher, S.B.C. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Quimica], E-mail: pergher@uricer.edu.br; Oliveira, J.V. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Engenharia dos Alimentos; Souza, W.F. [Petroleo Brasileiro S.A. (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2009-10-15

    This work reports liquid-liquid extraction of nitrogen compounds from oxidized and non-oxidized Brazilian petroleum samples. The experiments were accomplished in a laboratory-scale liquid-liquid apparatus in the temperature range of 303 K-323 K, using methanol, n-methyl-2-pyrrolidone (NMP) and N,Ndimethylformamide (DMF), and their mixtures as extraction solvents, employing solvent to sample volume ratios of 1:2, 1:1 and 2:1, exploring up to three separation stages. Results show that an increase in temperature, solvent to oil ratio, and number of equilibrium stages greatly improves the nitrogen removal from the oxidized sample (from 2600 to 200 ppm). The employed oxidation scheme is thus demonstrated to be an essential and efficient step of sample preparation for the selective liquid-liquid removal of nitrogen compounds. It is shown that the use of mixtures of DMF and NMP as well their use as co-solvents with methanol did not prove to be useful for selective nitrogen extraction since great oil losses were observed in the final process. (author)

  14. Microsystems for liquid-liquid extraction of radionuclides in the analytical protocols

    International Nuclear Information System (INIS)

    Radiochemical analyses are necessary to numerous steps for nuclear wastes management and for the control of the environment. An analytical protocol generally includes different steps of chemical separations which are lengthy, manual and complicated to implement because of their confinement in glove boxes and because of the hostile chemical and radiochemical media. Thus there is a huge importance to propose innovative and robust solutions to automate these steps but also to reduce the volumes of the radioactive and chemical wastes at the end of the analytical cycle. One solution consists in the miniaturization of the analyses through the use of lab-on-chip. The objective of this thesis work was to propose a rational approach to the conception of separative microsystems for the liquid-liquid extraction of radionuclides. To achieve this, the hydrodynamic behavior as well as the extraction performances have been investigated in one chip for three different chemical systems: Eu(III)-HNO3/DMDBTDMA, Eu(III)-AcO(H,Na)-HNO3/HDEHP and U(VI)-HCl/Aliquat336. A methodology has been developed for the implementation of the liquid-liquid extraction in micro-system for each chemical system. The influence of various geometric parameters such as channel length or specific interfacial area has been studied and the comparison of the liquid-liquid extraction performances has led to highlight the influence of the phases viscosities ratio on the flows. Thanks to the modeling of both hydrodynamics and mass transfer in micro-system, the criteria related to physical and kinetic properties of the chemical systems have been distinguished to propose a rational conception of tailor-made chips. Finally, several examples of the liquid-liquid extraction implementation in micro-system have been described for analytical applications in the nuclear field: U/Co separation by Aliquat336, Eu/Sm separation by DMDBTDMA or even the coupling between a liquid-liquid extraction chip and the system of detection

  15. Determination of Organic Pollutants in Small Samples of Groundwaters by Liquid-Liquid Extraction and Capillary Gas Chromatography

    DEFF Research Database (Denmark)

    Harrison, I.; Leader, R.U.; Higgo, J.J.W.;

    1994-01-01

    A method is presented for the determination of 22 organic compounds in polluted groundwaters. The method includes liquid-liquid extraction of the base/neutral organics from small, alkaline groundwater samples, followed by derivatisation and liquid-liquid extraction of phenolic compounds after...... neutralisation. The extracts were analysed by capillary gas chromatography. Dual detection by flame Ionisation and electron capture was used to reduce analysis time....

  16. STUDY ON ENRICHMENT AND SEPARATION OF TRACE Pd(Ⅱ) WHITH SILICA GEL BONDED BY (BENZOYLAZO—ARSENAZO I)—AMINOPROPYL

    Institute of Scientific and Technical Information of China (English)

    LIUFeng; LIKean; 等

    1992-01-01

    This Paper reports enrichment and sepqration of trace Pd(Ⅱ)with silica gel bonded by (benzolyazo-arsenazo I)-aminopropyl(BAAI·SG).BAAI·SG is stable in solution between 6 mol/L HCl and pH 9.0.The maximum adsorptive capacities of BAAI·SG and SG are 52.7,23.5μmol/g respectively.After preconcentration through BAII·SG column,Pd(Ⅱ)of ppb level in artificial water samples can be measured by spectrophotometry.

  17. Direct determination of chlorophenols in water samples through ultrasound-assisted hollow fiber liquid-liquid-liquid microextraction on-line coupled with high-performance liquid chromatography.

    Science.gov (United States)

    Chao, Yu-Ying; Tu, Yi-Ming; Jian, Zhi-Xuan; Wang, Hsaio-Wen; Huang, Yeou-Lih

    2013-01-01

    In this study we on-line coupled hollow fiber liquid-liquid-liquid microextraction (HF-LLLME), assisted by an ultrasonic probe, with high-performance liquid chromatography (HPLC). In this approach, the target analytes - 2-chlorophenol (2-CP), 3-chlorophenol (3-CP), 2,6-dichlorophenol (2,6-DCP), and 3,4-dichlorophenol (3,4-DCP) - were extracted into a hollow fiber (HF) supported liquid membrane (SLM) and then back-extracted into the acceptor solution in the lumen of the HF. Next, the acceptor solution was withdrawn on-line into the HPLC sample loop connected to the HF and then injected directly into the HPLC system for analysis. We found that the chlorophenols (CPs) could diffuse quickly through two sequential extraction interfaces - the donor phase - SLM and the SLM - acceptor phase - under the assistance of an ultrasonic probe. Ultrasonication provided effective mixing of the extracted boundary layers with the bulk of the sample and it increased the driving forces for mass transfer, thereby enhancing the extraction kinetics and leading to rapid enrichment of the target analytes. We studied the effects of various parameters on the extraction efficiency, viz. the nature of the SLM and acceptor phase, the compositions of the donor and acceptor phases, the fiber length, the stirring rate, the ion strength, the sample temperature, the sonication conditions, and the perfusion flow rate. This on-line extraction method exhibited linearity (r(2)≥0.998), sensitivity (limits of detection: 0.03-0.05 μg L(-1)), and precision (RSD%≤4.8), allowing the sensitive, simple, and rapid determination of CPs in aqueous solutions and water samples with a sampling time of just 2 min. PMID:23237709

  18. 偶氮胂-Ⅲ光度法测定烟草中的钙%Spectrophotometric Determination of Calcium in Tobacco with Arsenazo-Ⅲ

    Institute of Scientific and Technical Information of China (English)

    刘巍; 李忠; 刘思远; 王岚; 杨光宇

    2001-01-01

    本文研究了偶氮胂-Ⅲ与钙的显色反应,在pH=8.5氯化铵-氨水缓冲液介质中,乳化剂-OP存在下,偶氮胂-Ⅲ与钙反应生成1∶1稳定络合物,λmax=680nm,ε=2.13×104L*mol-1*cm-1。钙含量在0—30μg/25mL范围内符合比耳定律,该方法用于烟草样品中钙含量的测定,结果令人满意。%Color reaction of calcium(Ⅱ) with arsenazo-Ⅲ was studied.In the presence of pH=8.5 buffer solution and emulgent-OP medium arsenazo-Ⅲ can react with calcium(Ⅱ) to form a stable 1∶1 complex.The molar absorptivity is 2.13×104L*mol-1*cm-1 at 680nm.Beer's law is obeyed in the range of 0—30μg/25mL.This method can be applied to the determination of calcium in tobacco with satisfactory results.

  19. Investigation of the oxidation of hydroquinone at the liquid/liquid interface

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The oxidation of hydroquinone(QH_2) was investigated for the first time at liquid/liquid(L/L) interface by scanning electrochemical microscopy(SECM).In this study,electron transfer(ET) from QH_2 in aqueous to ferrocene(Fc) in nitrobenzene (NB) was probed.The apparent heterogeneous rate constants for ET reactions were obtained by fitting the experimental approach curves to the theoretical values.The results showed that the rate constants for oxidation reaction of QH_2 were sensitive to the changes of the ...

  20. Liquid - liquid equilibria of the water + butyric acid + decanol ternary system

    Directory of Open Access Journals (Sweden)

    S.I. Kirbaslar

    2006-09-01

    Full Text Available Liquid-liquid equilibrium (LLE data for the water + butyric acid + decanol ternary system were determined experimentally at temperatures of 298.15, 308.15 and 318.15 K. Complete phase diagrams were obtained by determining the solubility curve and the tie lines. The reliability of the experimental tie line data was confirmed with the Othmer-Tobias correlation. The UNIFAC method was used to predict the phase equilibrium of the system using the interaction parameters for groups CH3, CH2, COOH, OH and H2O determined experimentally. Distribution coefficients and separation factors were evaluated for the immiscibility region.

  1. In Situ Fluorescence Microscopic Measurements of Complexation Reactions at Liquid/Liquid Interface

    OpenAIRE

    TSUKAHARA, Satoshi

    2005-01-01

    In situ microscopic measurement is a novel approach to clarify the intrinsic mechanism of complexation reactions occurring at liquid/liquid interfaces. The present review was mainly focused on recent three topics of methodology of in situ fluorescence microscopic observation and measurement of interfacial complexation reactions: (1) two kinds of self-assemblies of Pd2+ and 5,10,15,20-tetra(4-pyridyl)-21H, 23H-porphine complexes formed at the toluene/water interface, (2) microextraction of Eu3...

  2. Liquid-Liquid Extraction-Chromogenic Systems Containing Iron(III), 4-Nitrocatechol and Tetrazolium Salts

    OpenAIRE

    Galya K. Toncheva; Teodora S. Stefanova; Gavazov, Kiril B.

    2015-01-01

    Complex formation and liquid-liquid extraction were studied in systems containing iron(III), 4-nitrocatechol (4NC),tetrazolium salt (TZS), water and organic solvent. Three different TZS were used: 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT), 3-(2-naphtyl)-2,5-diphenyl-2H-tetrazolium chloride (Tetrazolium violet, TV) and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT).The cations of the first two TZSs (TZ+: MTT+ and TV+) form intensively color...

  3. Ternary (liquid + liquid) equilibria of {trifluorotris(perfluoroethyl)phosphate based ionic liquids + thiophene + heptane}: Part 2

    International Nuclear Information System (INIS)

    Highlights: • Ternary (liquid + liquid) equilibria for 3 ionic liquid + thiophene + heptane systems. • The influence of ionic liquid structure on phase diagrams is discussed. • Influence of IL structure on S and β for heptane/thiophene separation is discussed. - Abstract: Ternary (liquid + liquid) equilibria for 3 systems containing ionic liquids {(1-ethyl-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, 1-(2-hydroxyethyl)-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, ethyl-dimethyl-(2-methoxyethyl)ammonium trifluorotris(perfluoroethyl)phosphate) + thiophene + heptane} have been determined at T = 298.15 K. The selectivity and solute distribution ratio were calculated for investigated systems and compared with literature values obtained for other systems containing ionic liquids with [FAP]− anions and [emim]+ cations. In each system, high solubility of thiophene and low solubility of heptane in the ionic liquid are observed. The experimental results have been correlated using NRTL model. The influence of the structure of ionic liquid on phase equilibria, selectivity and solute distribution ratio is discussed

  4. Indication of liquid-liquid phase transition in CuZr-based melts

    DEFF Research Database (Denmark)

    Zhou, C.; Hu, L.N.; Sun, Q.J.;

    2013-01-01

    We study the dynamic behavior of CuZr-based melts well above the liquidus temperature. The results show a discontinuous change in viscosity during cooling, which is attributed to an underlying liquid-liquid phase transition (LLPT) in these melts. The LLPT is further verified by thermodynamic resp...... liquids to the weakly ordered low-density liquids upon cooling.......We study the dynamic behavior of CuZr-based melts well above the liquidus temperature. The results show a discontinuous change in viscosity during cooling, which is attributed to an underlying liquid-liquid phase transition (LLPT) in these melts. The LLPT is further verified by thermodynamic...... response in the same superheated region. We find that the LLPT in the Cu46Zr46Al8 melt is reversible above 1350 K upon repeated heating and cooling. Based on the concept of fluid clustering in metallic melts, the reversible LLPT is attributed to the structural transition from the strongly ordered high-density...

  5. Thermodynamic precursors, liquid-liquid transitions, dynamic and topological anomalies in densified liquid germania

    International Nuclear Information System (INIS)

    The thermodynamic, dynamic, structural, and rigidity properties of densified liquid germania (GeO2) have been investigated using classical molecular dynamics simulation. We construct from a thermodynamic framework an analytical equation of state for the liquid allowing the possible detection of thermodynamic precursors (extrema of the derivatives of the free energy), which usually indicate the possibility of a liquid-liquid transition. It is found that for the present germania system, such precursors and the possible underlying liquid-liquid transition are hidden by the slowing down of the dynamics with decreasing temperature. In this respect, germania behaves quite differently when compared to parent tetrahedral systems such as silica or water. We then detect a diffusivity anomaly (a maximum of diffusion with changing density/volume) that is strongly correlated with changes in coordinated species, and the softening of bond-bending (BB) topological constraints that decrease the liquid rigidity and enhance transport. The diffusivity anomaly is finally substantiated from a Rosenfeld-type scaling law linked to the pair correlation entropy, and to structural relaxation

  6. (Liquid + liquid) equilibrium for the system (hydrolyzed palm oil + ethanol + water) for diacylglycerol enrichment

    International Nuclear Information System (INIS)

    Highlights: ► We measured LLE for the system (hydrolyzed palm oil + ethanol + water). ► The experimental data were well correlated with UNIQUAC and NRTL models. ► Gibbs free energy minimization was used. ► Hydrolyzed palm oil can be diacylglycerol-enriched from a LL extraction process. -- Abstract: This work reports experimental results and the thermodynamic modelling of the (liquid + liquid) equilibrium of hydrolyzed palm oil (which contains triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids in its composition) with water and ethanol. The LLE values were obtained with the aim of enriching the palm oil diacylglycerol content by LLE extraction. The LLE experimental data were used to estimate UNIQUAC and NRTL parameters, which were used for (liquid + liquid) calculations employing the Gibbs free energy minimization approach. Experimental data were well correlated using UNIQUAC and NRTL models, in which the maximum value of root mean square deviation maximum of 0.75 wt.% was obtained. From the results obtained in this study, it was possible to demonstrate the feasibility of the palm oil diacylglycerol enrichment through liquid–liquid phase separation following the esterification procedure

  7. Predicting apparent slip at liquid-liquid interfaces without an interface slip condition

    Science.gov (United States)

    Poesio, Pietro; Damone, Angelo; Matar, Omar

    2015-11-01

    We show that if we include a density-dependent viscosity into the Navier-Stokes equations then we can describe, naturally, the velocity profile in the interfacial region, as we transition from one fluid to another. This requires knowledge of the density distribution (for instance, via Molecular Dynamics [MD] simulations, a diffuse-interface approach, or Density Functional Theory) everywhere in the fluids, even at liquid-liquid interfaces where regions of rapid density variations are possible due to molecular interactions. We therefore do not need an artificial interface condition that describes the apparent velocity slip. If the results are compared with the computations obtained from MD simulations, we find an almost perfect agreement. The main contribution of this work is to provide a simple way to account for the apparent slip at liquid-liquid interfaces without relying upon an additional boundary condition, which needs to be calculated separately using MD simulations. Examples are provided involving two immiscible fluids of varying average density ratios, undergoing simple Couette and Poisseuille flows. MIUR through PRIN2012-NANOBridge; Royal Society International Exchange Scheme (IE141486).

  8. Thermophysical properties of biodiesel and related systems: (Liquid + liquid) equilibrium data for soybean biodiesel

    International Nuclear Information System (INIS)

    Highlights: ► (Liquid + liquid) equilibrium data for the systems of biodiesel production. ► LLE data for multicomponent FAME and FAEE from (303.15 to 333.15) K. ► Experimental data correlated using the UNIQUAC model. -- Abstract: This work reports (liquid + liquid) equilibrium (LLE) data for the systems of interest in soybean biodiesel production. Numerical data for LLE were obtained for binary, ternary and quaternary systems comprising fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE) from soybean oil, water, glycerol, methanol, and ethanol at temperatures of (303.15, 318.15, and 333.15) K. Quantification of compounds in equilibrium in both phases was determined by analytical methods whereas solubility curves (binodal) were obtained by the cloud-point method. For all systems investigated, good alignments were obtained between phase compositions and the initial as well as overall compositions hence indicating low deviations from the mass balance. Experimental results were correlated using the UNIQUAC model with satisfactory agreement between experiment and theory

  9. (Liquid + liquid) equilibrium for the system {ethyl stearate(1) + ethanol(2) + glycerol(3)}

    International Nuclear Information System (INIS)

    Highlights: ► We measured LLE for the ternary system (ethyl stearate + ethanol + glycerol) with and without NaCl. ► Phase equilibrium data for the biodiesel separation process are presented. ► The experimental data were modelled using NRTL, UNIQUAC and UNIFAC models. - Abstract: This paper reports the results of a new experimental study on the (liquid + liquid) equilibrium of the system {ethyl stearate(1) + ethanol(2) + glycerol(3)} at atmospheric pressure and at T = (313.15 and 323.15) K. The equilibrium compositions were measured by gas chromatography. Ternary diagrams were obtained for each temperature and the equilibrium data were compared to the system in the presence of salt (NaCl) at T = 323.15 K. The experimentally determined (liquid + liquid) equilibrium data were satisfactorily correlated with NRTL and UNIQUAC equations. A comparative analysis was performed using the UNIFAC-LLE group contribution method. From the results presented herein good predictions were obtained for this ternary system.

  10. Liquid-liquid extraction for the enrichment of edible oils with phenols from olive leaf extracts.

    Science.gov (United States)

    Japón-Luján, R; Luque de Castro, M D

    2008-04-01

    A liquid-liquid extraction method to enrich edible oils--olive, sunflower, and soy oils--with phenols from olive leaf extracts is proposed. After microwave assistance to remove the phenols from three varieties of olive leaves, concentrations in the extracts between 12921 and 5173 mg/L of oleuropein, between 488 and 192 mg/L of apigenin-7-glucoside, between 444 and 219 mg/L of luteolin-7-glucoside, and between 501 and 213 mg/L of verbascoside were obtained, which clearly depended on the target variety. After optimization of the liquid-liquid extraction step, the concentrations in oils were 442, 162, and 164 mg/L of oleuropein, respectively, which were also enriched in apigenin-7-glucoside (between 8 and 15 mg/L, depending of the oil), lutelin-7-glucoside (between 11 and 12 mg/L), and verbascoside (between 11 and 13 mg/L). The oil-extract distribution factor of these compounds was also calculated for all olive leaf varieties and edible oils using different extracts concentrations and also different oil-extract volume ratios. Thus, a door is open to enrichment of any oil with olive phenols at preset concentrations using extracts preconcentrated as required and taking into account the distribution factor of the target compounds between the oil and the extracts. PMID:18324773

  11. Thermodynamic precursors, liquid-liquid transitions, dynamic and topological anomalies in densified liquid germania

    Energy Technology Data Exchange (ETDEWEB)

    Pacaud, F.; Micoulaut, M. [Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4 Place Jussieu, F-75252 Paris Cedex 05 (France)

    2015-08-14

    The thermodynamic, dynamic, structural, and rigidity properties of densified liquid germania (GeO{sub 2}) have been investigated using classical molecular dynamics simulation. We construct from a thermodynamic framework an analytical equation of state for the liquid allowing the possible detection of thermodynamic precursors (extrema of the derivatives of the free energy), which usually indicate the possibility of a liquid-liquid transition. It is found that for the present germania system, such precursors and the possible underlying liquid-liquid transition are hidden by the slowing down of the dynamics with decreasing temperature. In this respect, germania behaves quite differently when compared to parent tetrahedral systems such as silica or water. We then detect a diffusivity anomaly (a maximum of diffusion with changing density/volume) that is strongly correlated with changes in coordinated species, and the softening of bond-bending (BB) topological constraints that decrease the liquid rigidity and enhance transport. The diffusivity anomaly is finally substantiated from a Rosenfeld-type scaling law linked to the pair correlation entropy, and to structural relaxation.

  12. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    International Nuclear Information System (INIS)

    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

  13. Solution processing of polymer semiconductor: Insulator blends-Tailored optical properties through liquid-liquid phase separation control

    KAUST Repository

    Hellmann, Christoph

    2014-12-17

    © 2014 Wiley Periodicals, Inc. It has been demonstrated that the 0-0 absorption transition of poly(3-hexylthiophene) (P3HT) in blends with poly(ethylene oxide) (PEO) could be rationally tuned through the control of the liquid-liquid phase separation process during solution deposition. Pronounced J-like aggregation behavior, characteristic for systems of a low exciton band width, was found for blends where the most pronounced liquid-liquid phase separation occurred in solution, leading to domains of P3HT and PEO of high phase purity. Since liquid-liquid phase separation could be readily manipulated either by the solution temperature, solute concentration, or deposition temperature, to name a few parameters, our findings promise the design from the out-set of semiconductor:insulator architectures of pre-defined properties by manipulation of the interaction parameter between the solutes as well as the respective solute:solvent system using classical polymer science principles.

  14. Using cyclic liquid-liquid extraction method for isolation and identification of relative compounds during lignin biodegradation

    Institute of Scientific and Technical Information of China (English)

    黄峰; 高培基; 陈嘉翔

    1999-01-01

    By using the cyclic liquid-liquid extraction method the lignin biodegradated derivatives can be effectively extracted from the effluent liquors in ligninolytic enzymes treated kraft pulps. More than forty compounds were identified from the extractives by gas chromatography-mass spectrometry analysis. The result showed that lignin is treated with different ligninolytic enzymes, and the composition and content of the extractives differ obviously. These results suggest that the cyclic liquid-liquid extraction method can be used effectively as one new technique for the study of lignin biodegrada-tion mechanisms.

  15. (Ternary liquid + liquid) equilibria for (water + acetone + {alpha}-pinene, or {beta}-pinene, or limonene) mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaoli [Department of Chemistry and Chemical Engineering, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Tamura, Kazuhiro, E-mail: tamura@t.kanazawa-u.ac.j [Department of Chemistry and Chemical Engineering, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)

    2010-11-15

    (Ternary liquid + liquid) equilibria (tie-lines) of (water + acetone + {alpha}-pinene) at T = (288.15, 298.15, and 308.15) K and (water + acetone + {beta}-pinene, or limonene) at T = 298.15 K have been measured. The experimental (ternary liquid + liquid) equilibrium data have been correlated successfully by the original UNIQUAC and modified UNIQUAC models. The modified UNIQUAC model reproduced accurately the experimental results for the (water + acetone + {alpha}-pinene) system at all the temperatures but fairly agreed with the experimental data for the (water + acetone + {beta}-pinene, or limonene) systems.

  16. Liquid/liquid metal extraction: Phase diagram topology resulting from molecular interactions between extractant, ion, oil and water

    Science.gov (United States)

    Bauer, C.; Bauduin, P.; Dufrêche, J. F.; Zemb, T.; Diat, O.

    2012-11-01

    We consider the class of surfactants called "extractants" since they specifically interact with some cations and are used in liquid-liquid separation processes. We review here features of water-poor reverse micelles in water/oil/ extractant systems as determined by combined structural studies including small angle scattering techniques on absolute scale. Origins of instabilities, liquid-liquid separation as well as emulsification failure are detected. Phase diagrams contain the same multi-phase domains as classical microemulsions, but special unusual features appear due to the high spontaneous curvature directed towards the polar cores of aggregates as well as rigidity of the film made by extracting molecules.

  17. A review of the isobaric (vapor + liquid + liquid) equilibria of multicomponent systems and the experimental methods used in their investigation

    Energy Technology Data Exchange (ETDEWEB)

    Gomis, Vicente, E-mail: vgomis@ua.e [Departamento de Ingenieria Quimica, Universidad de Alicante, Ap. 99, E-03080 Alicante (Spain); Pequenin, Ana; Asensi, Juan Carlos [Departamento de Ingenieria Quimica, Universidad de Alicante, Ap. 99, E-03080 Alicante (Spain)

    2010-07-15

    An overview of the multicomponent systems for which isobaric (vapor + liquid + liquid) equilibrium (VLLE) data has been published, is presented. This overview comprises 36 ternary and three quaternary systems. For each one of these systems is specified a reference, pressure range, experimental method and the amount of equilibrium data determined. This is followed by a brief description for each experimental method of the specific procedure carried out to determine the (vapor + liquid) equilibrium in the case where the liquid is heterogeneous. Lastly, a final assessment is presented of the experimental procedures used to determine the (vapor + liquid + liquid) equilibria (VLLE).

  18. Temperature dependence on mutual solubility of binary (methanol + limonene) mixture and (liquid + liquid) equilibria of ternary (methanol + ethanol + limonene) mixture

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Kazuhiro [Department of Chemistry and Chemical Engineering, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)], E-mail: tamura@t.kanazawa-u.ac.jp; Li Xiaoli; Li Hengde [Department of Chemistry and Chemical Engineering, Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)

    2009-04-15

    Mutual solubility data of the binary (methanol + limonene) mixture at the temperatures ranging from 288.15 K close to upper critical solution temperature, and ternary (liquid + liquid) equilibrium (tie-lines) of the (methanol + ethanol + limonene) mixture at the temperatures (288.15, 298.15, and 308.15) K have been obtained. The experimental results have been represented accurately in terms of the extended and modified UNIQUAC models with binary parameters, compared with the UNIQUAC model. The temperature dependence of binary and ternary (liquid + liquid) equilibrium for the binary (methanol + limonene) and ternary (methanol + ethanol + limonene) mixtures could be calculated successfully using the extended and modified UNIQUAC model.

  19. Statistical thermodynamics of liquid-liquid phase separation in ternary systems during complex coacervation

    Science.gov (United States)

    Pawar, Nisha; Bohidar, H. B.

    2010-09-01

    Liquid-liquid phase separation leading to complex coacervation in a ternary system (oppositely charged polyion and macroion in a solvent) is discussed within the framework of a statistical thermodynamics model. The polyion and the macroion in the ternary system interact to form soluble aggregates (complexes) in the solvent, which undergoes liquid-liquid phase separation. Four necessary conditions are shown to drive the phase separation: (i) (σ23)3r/Φ23c≥((64)/(9α2))(χ23Φ3)2 , (ii) r≥[(64(χ23Φ3)2)/(9α2σ233)]1/2 , (iii) χ23≥((2χ231-1))/(Φ23cΦ3) , and (iv) (σ23)2/I≥(8)/(3α)(2χ231-1) (where σ23 is the surface charge on the complex formed due to binding of the polyelectrolyte and macroion, Φ23c is the critical volume fraction of the complex, χ23 is the Flory interaction parameter between polyelectrolyte and macroion, χ231 is the same between solvent and the complex, Φ3 is the volume fraction of the macroions, I is the ionic strength of the solution, α is electrostatic interaction parameter and r is typically of the order of molecular weight of the polyions). It has been shown that coacervation always requires a hydrated medium. In the case of a colloidal macroion and polyelectrolyte coacervation, molecular weight of polyelectrolyte must satisfy the condition r≥103Da to exhibit liquid-liquid phase separation. This model has been successfully applied to study the coacervation phenomenon observed in aqueous Laponite (macroion)-gelatin (polyion) system where it was found that the coacervate volume fraction, δΦ23˜χ2312 (where δΦ23 is the volume fraction of coacervates formed during phase separation). The free energy and entropy of this process have been evaluated, and a free-energy landscape has been drawn for this system that maps the pathway leading to phase separation.

  20. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain)

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related

  1. 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). PMID:26920309

  2. Computer modelling of the surface tension of the gas-liquid and liquid-liquid interface.

    Science.gov (United States)

    Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J

    2016-03-01

    This review presents the state of the art in molecular simulations of interfacial systems and of the calculation of the surface tension from the underlying intermolecular potential. We provide a short account of different methodological factors (size-effects, truncation procedures, long-range corrections and potential models) that can affect the results of the simulations. Accurate calculations are presented for the calculation of the surface tension as a function of the temperature, pressure and composition by considering the planar gas-liquid interface of a range of molecular fluids. In particular, we consider the challenging problems of reproducing the interfacial tension of salt solutions as a function of the salt molality; the simulations of spherical interfaces including the calculation of the sign and size of the Tolman length for a spherical droplet; the use of coarse-grained models in the calculation of the interfacial tension of liquid-liquid surfaces and the mesoscopic simulations of oil-water-surfactant interfacial systems.

  3. Liquid-Liquid Extraction-Chromogenic Systems Containing Iron(III, 4-Nitrocatechol and Tetrazolium Salts

    Directory of Open Access Journals (Sweden)

    Galya K. Toncheva

    2015-03-01

    Full Text Available Complex formation and liquid-liquid extraction were studied in systems containing iron(III, 4-nitrocatechol (4NC,tetrazolium salt (TZS, water and organic solvent. Three different TZS were used: 3-(4,5-dimethyl-2-thiazol-2,5-diphenyl-2H-tetrazolium bromide (MTT, 3-(2-naphtyl-2,5-diphenyl-2H-tetrazolium chloride (Tetrazolium violet, TV and 2-(4-iodophenyl-3-(4-nitrophenyl-5-phenyl-2H-tetrazolium chloride (INT.The cations of the first two TZSs (TZ+: MTT+ and TV+ form intensively colored (molar absorptivity of 4.6´104 L mol–1 cm–1 and 4.4´104 L mol–1 cm–1, respectively chloroform extractable ion-associates with the FeIII-4NC anionic chelate. These ternary complexes can be represented with the following general formula: (TZ+3[FeIII(4NC3]3−.

  4. The Liquid-Liquid Extraction of Toxic Metals (Cd, Hg and Pb by Calixarenes

    Directory of Open Access Journals (Sweden)

    D. Max Roundhill

    2009-12-01

    Full Text Available Toxic metals (Cd, Hg and Pb are mostly present in the environment due to natural phenomenon and human activities as well. Exposure of these non-essential elements in the environment causes severe effects. They are known to cause problems in humans as well as in aquatic life. In this work, we demonstrate various studies regarding liquid-liquid extraction of selected ions with different functionalized calixarenes. This review article briefly discusses several molecular designs of calixarenes for divalent ion (Cd2+, Hg2+ and Pb2+ recognition; as well as the relationship between structure and selectivity of the macrocycles is elaborated. The article does not, however, attempt to cover all of the different approaches to these toxic metal ions extraction.

  5. Prediction of Liquid-Liquid Equilibrium Using the Group Solubility Parameter Model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Mo; CHEN Fuming

    2005-01-01

    The group solubility parameter (GSP) model was used to analyze the liquid-liquid equilibrium (LLE) of ternary and quaternary systems. The GSP parameters are divided into four dimensions representing the four major intermolecular forces. The values of the parameters were determined by regression using the nonlinear SIMPLEX optimization method to fit the LLE data of 548 ternary and 26 quaternary systems selected from the literature. LLE predictions of 8 ternary systems were then made using the fit parameters. Comparison of the results with predictions using the modified UNIFAC model shows that the GSP model has less adjustable parameters to achieve a similar accuracy and that the parameter values are easily acquired by analysis of available data.

  6. (Liquid + liquid) equilibria of {l_brace}heptane + xylene + N-formylmorpholine{r_brace} ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dongchu [College of Chemistry and Chemical Engineering, Central South University, ChangSha 410083 (China)], E-mail: dcchen@hnust.edu.cn; Ye Hongqi; Hao Wu [College of Chemistry and Chemical Engineering, Central South University, ChangSha 410083 (China)

    2007-12-15

    (Liquid + liquid) equilibrium (LLE) data for ternary system {l_brace}heptane (1) + m-xylene (2) + N-formylmorpholine (3){r_brace} have been determined experimentally at temperatures ranging from 298.15 K to 353.15 K. Complete phase diagrams were obtained by determining solubility and tie-line data. Tie-line compositions were correlated by Othmer-Tobias and Bachman methods. The universal quasichemical activity coefficient (UNIQUAC) and The non-random two liquids equation (NRTL) were used to correlate the phase equilibrium in the system using the interaction parameters determined from experimental data. It is found that UNIQUAC and NRTL used for LLE could provide a good correlation. Distribution coefficients, separation factors, and selectivity were evaluated for the immiscibility region.

  7. Separation of phosphorous by liquid-liquid extraction for the measurement of 32P

    International Nuclear Information System (INIS)

    Phosphorous containing radioisotope waste was separated and determined by liquid-liquid extraction method through liquid scintillation counter (LSC). In this process, ammonium phosphate was converted to phosphomolybdate (PMo) by the reaction of ammonium molybdate (Mo) in HCl solution (0.02 M) and maximum UV/VIS absorbance (λmax) 218 nm was observed. The PMo solution was extracted with TOA (Tri-n-Octylamine)/xylene mixture and λmax 290 nm was found for this organic layer. Absorbance of aqueous and organic layer was linear through concentration. The impurities such as Co, Cr, Gd, etc. remain in aqueous layer by treating with Mo which was determined by ICP-AES and AAS. The quenching correction curve for 32P was calculated using LSC results. No counting change was observed as the volume of quenchers increased. The recovery was 98% and 81% for the extraction and separation process from the test using H332PO4 as standard tracer. (author)

  8. Generalized breakup and coalescence models for population balance modelling of liquid-liquid flows

    CERN Document Server

    Traczyk, Marcin; Thompson, Chris

    2015-01-01

    Population balance framework is a useful tool that can be used to describe size distribution of droplets in a liquid-liquid dispersion. Breakup and coalescence models provide closures for mathematical formulation of the population balance equation (PBE) and are crucial for accu- rate predictions of the mean droplet size in the flow. Number of closures for both breakup and coalescence can be identified in the literature and most of them need an estimation of model parameters that can differ even by several orders of magnitude on a case to case basis. In this paper we review the fundamental assumptions and derivation of breakup and coalescence ker- nels. Subsequently, we rigorously apply two-stage optimization over several independent sets of experiments in order to identify model parameters. Two-stage identification allows us to estab- lish new parametric dependencies valid for experiments that vary over large ranges of important non-dimensional groups. This be adopted for optimization of parameters in breakup...

  9. Effect of liquid-liquid structure transition on solidification of Sn-Bi alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of the liquid-liquid structure transition(L-LST) on the solidification behaviors and morphologies of Sn-Bi alloys was studied further. The results show that the undercooling of the primary and eutectic phase increases and the microstructure becomes finer after solidifying from the melt experiencing the L-LST. In the meantime, in hypoeutectic alloy, when solidifying from the melt experiencing the L-LST, the morphology of primary phase changes from the fir-tree crystal into the equiaxed crystal, and less primary phase and more eutectic structure are observed. Moreover, in eutectic alloy, the spacing of eutectic phase decreases markedly. These investigations would be beneficial to further exploration of the correlation between the melt structure and the micro mechanism of solidification.

  10. Liquid-liquid phase separation in highly undercooled Ni-Pb hypermonotectic alloys

    Institute of Scientific and Technical Information of China (English)

    YANG Gen-cang; XIE Hui; HAO Wei-xin; ZHANG Zhong-ming; GUO Xue-feng

    2006-01-01

    Liquid-liquid phase separation in the undercooled Ni-20%Pb(mole fraction, the same below if not mentioned)hypermonotectic melts was investigated by the observation of the water-quenched structure and DTA analysis. The results indicate that the number of spherical cells in the water-quenched microstructure increases with dropping temperature, and the cells gather and grow up obviously. The spherical cell origins from L1 phase separated from homogeneous melt, and is the product of monotectic reaction. Both results of the water-quenched structures and DTA analysis prove that liquid phase separation still occurs in the highly undercooled Ni-Pb hypermonotectic alloy melts, and liquid phase separation in the immiscible gap can not be fully inhibited by high undercooling and rapid solidification.

  11. CFD simulation on the turbulent mixing flow performance of the liquid-liquid ejector

    Science.gov (United States)

    An, W. Z.; Bie, H. Y.; Liu, C. C.; Hao, Z. R.

    2016-05-01

    In order to study the flow performance of the liquid-liquid ejector, 3D ejector simulation models were established to investigate the influences of suction angle, suction number and working condition on the ejector performance. The simulation results showed that when the suction angle was 60°, the total pressure was in equilibrium state. The double suction ejector would induced more vortexes in the suction chamber than that of the single suction ejector, and the turbulent intensity of the fluid inside the ejector was bigger, however, it also caused much more loss in energy. When the working pressure was lower than 0.6 MPa, the liquid entrainment ratio increased rapidly. Once the working pressure reached 0.6 MPa, the liquid entrainment ratio basically remained unchanged. The mass flow rate of the suction medium increased with the increasing of suction pressure, and the differential pressure between the suction pressure and the working pressure at the nozzle also increased simultaneously.

  12. Synergism by co-assembly at the origin of ion selectivity in liquid-liquid extraction

    International Nuclear Information System (INIS)

    In liquid-liquid extraction, synergism emerges when for a defined formulation of the solvent phase, there is an increase of distribution coefficients for some cations in a mixture. To characterize the synergistic mechanisms, we determine the free energy of mixed co-assembly in aggregates. Aggregation in any point of a phase diagram can be followed not only structurally by SANS, SAXS, and SLS, but also thermodynamically by determining the concentration of monomers coexisting with reverse aggregates. Using the industrially used couple HDEHP/TOPO forming mixed reverse aggregates, and the representative couple U/Fe, we show that there is no peculiarity in the aggregates microstructure at the maximum of synergism. Nevertheless, the free energy of aggregation necessary to form mixed aggregates containing extracted ions in their polar core is comparable to the transfer free energy difference between target and nontarget ions, as deduced from the synergistic selectivity peak. (authors)

  13. Measurement of vapor-liquid-liquid phase equilibrium-Equipment and results

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; von Solms, Nicolas; Richon, Dominique;

    2015-01-01

    There exists a need for new accurate and reliable experimental data, preferably with full characterization of all the phases present in equilibrium. The need for high-quality experimental phase equilibrium data is the case for the chemical industry in general. All areas deal with processes whose...... optimization is dependent on phase equilibrium data.The objective of this work is to provide experimental data for hydrocarbon systems with polar chemicals such as alcohols, glycols and water. A new experimental equipment was designed and constructed for measurement of multi-phase equilibrium in hydrocarbon......-water-gas hydrate inhibitor systems, at temperatures ranging from 283 to 353 K and at pressures up to 40 MPa. The core of the equipment is an equilibrium cell, equipped with sapphire windows and connected to an analytical system by capillary samplers.New vapor-liquid-liquid equilibrium data are reported for methane...

  14. Liquid-liquid equilibria for polymer solutions and blends, including copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Song, Y.; Hino, T.; Lambert, S.M.; Prausnitz, J.M.

    1995-02-01

    A simplified perturbed hard-sphere-chain (PHSC) theory is applied to interpret, correlate, and (in part) predict liquid-liquid equilibria (LLE) for polymer solutions and blends, including copolymers. The PHSC equation of state uses a hard-sphere-chain reference system plus a van der Waals attractive perturbation. Three pure-component parameters are obtained from readily available thermodynamic properties. Mixture parameters are obtained using pure-component parameters, conventional combining rules, and one or two binary constants. Theoretical and experimental coexistence curves and miscibility maps show good agreement for selected blends containing polymers and copolymers. For LLE of dilute or semi-dilute solvent/polymer solutions, it is necessary to decrease the pure-component polymer chain length, probably because the mean-field approximation is not suitable for such solutions.

  15. Tilt dynamics of an electrostatically actuated microoscillator at a liquid-liquid interface

    International Nuclear Information System (INIS)

    We investigate the time-domain tilt response of an electrostatically actuated mechanical microoscillator positioned at a liquid-liquid interface. An analytical model is presented to simulate the microoscillator's rotational motion inside a microchannel completely filled with two immiscible liquids. The model considers two coupled ordinary differential equations; one simulates the mechanical response of the microplate-microbeam assembly making-up the mi-crooscillator and the other provides the behaviour of the electrical charge responsible for the electrostatic moment that tilts the microplate. Results show that remarkable improvements in sampling time and sensitivity can be obtained using a bi-liquid configuration versus its single-liquid counterpart. Therefore, enhanced performance of mechanical microsensors for liquids could be achieved.

  16. Instability due to interfacial tension in parallel liquid-liquid flow

    Science.gov (United States)

    Rodriguez, Oscar M. H.

    2016-06-01

    The frequent occurrence of multiphase flows in pipes has motivated a great research interest over the last decades. The particular case of liquid-liquid flow is commonly encountered in the petroleum industry, where a number of applications involve oil-water flow such as crude oil production in directional wells. However, it has not received the same attention when compared to gas-liquid flow. In addition, most of the available information has to do with flow in pipes. When it comes to flows in annular ducts the data are scanty. A general transition criterion has been recently proposed in order to obtain the stratified and core-annular flow-pattern transition boundaries in viscous oil-water flow. The proposed criterion was based on an one-dimensional two-fluid model of liquid-liquid two-phase flow. A stability analysis was carried out and interfacial tension is considered. A new destabilizing term arises, which is a function of the cross-section curvature of the interface. It is well accepted that interfacial tension favors the stable condition. However, the analysis of the new interfacial-tension term shows that it can actually destabilize the basic flow pattern, playing an important role in regions of extreme volumetric fractions. Such an interesting effect seems to be more pronounced in flows of viscous fluids and in annular-duct flow. The effect of interfacial tension is explored and the advantages of using a more complete model are discussed and illustrated through comparisons with experimental data from the literature. The evaluation of the effects of fluid viscosity and interfacial tension allows the correction and enhancement of transition models based essentially on data of pipe flow of low viscosity fluids.

  17. Removal of non-ionic organic pollutants from water via liquid-liquid extraction.

    Science.gov (United States)

    López-Montilla, Juan C; Pandey, Samir; Shah, Dinesh O; Crisalle, Oscar D

    2005-05-01

    The removal of model pollutants bromocresol green (BG) and phenol from water is demonstrated via two liquid-liquid extraction methods. Both methods exploit selective interactions established by the pollutant molecule with a surfactant, oil, or alcohol, and are variants of the more general Winsor systems where the phases are in contact along an extremely large interfacial area. In the first method the surfactant and the co-surfactant move from a predominantly oil-in-water microemulsion (Winsor I), to a middle phase microemulsion (Winsor III), and finally to a water-in-oil microemulsion (Winsor II), as the physicochemical conditions of salinity, temperature or hydrophilic-lipophilic balance of the surfactant system are varied. This method achieves better than 99% removal of the pollutant BG from water. It is argued that the removal is produced upon increasing the salinity of the system because the interaction of BG with a medium chain-length alcohol drives it to move along with the alcohol to another phase. The second method, which is scalable to industrial levels, uses a spontaneously produced water-in-oil microemulsion with large interfacial area that appears after bringing in contact water and a pre-formed Winsor II or Winsor III microemulsion system containing different surfactants and oils. The method is applied to the removal of phenol from water, and it is found that systems with polar oils such as ethyl butyrate or with cationic surfactants such as stearyl trimethylammonium chloride are more efficient in removing phenol than systems with normal alkanes or anionic surfactants. It is also shown that a microemulsion formed using a polar oil performs better than using only the polar oil as the extraction solvent. Finally, the efficiency of the second liquid-liquid extraction method can be increased from 69% in a single-stage process to 83% in a two-stage process, using the same total amount of extraction solvent. PMID:15899289

  18. Binary, ternary and quaternary liquid-liquid equilibria in 1-butanol, oleic acid, water and n-heptane mixtures

    NARCIS (Netherlands)

    Winkelman, J. G. M.; Kraai, G. N.; Heeres, H. J.

    2009-01-01

    This work reports on liquid-liquid equilibria in the system 1-butanol, oleic acid, water and n-heptane used for biphasic, lipase catalysed esterifications. The literature was studied on the mutual solubility in binary systems of water and each of the organic components. Experimental results were obt

  19. Antioxidant and antimicrobial properties of essential oil constituents encapsulated in zein nanoparticles prepared by liquid-liquid dispersion method

    Science.gov (United States)

    Thymol and carvacrol, two isomeric terpenoids found in the essential oil of thyme, were encapsulated in nanoparticles of the corn protein zein using a liquid-liquid dispersion method. The morphology, antioxidant properties, and antimicrobial activity were determined for nanaparticles formed under ac...

  20. Analysis of the transient rotating cylinder apparatus for the measurement of liquid-liquid interface shear viscosity

    DEFF Research Database (Denmark)

    Hassager, Ole; Westborg, H

    1987-01-01

    An analysis of the transient rotating cylinder apparatus for the measurement of liquid-liquid interface viscosity is given. An analytical expression that allows the determination of the interfacial viscosity from observations of the interface movement is given. The expression is presented...... in tabular form for selected values of the physical parameters of the two phases, and suggestions for apparatus design are given....

  1. Formation of Au nanoparticle-doped PVK microcapsules and foam-like structures at the liquid/liquid interface

    Energy Technology Data Exchange (ETDEWEB)

    Chu Chunxiao; Yang Dan; Wang Di; Ma Huihui [Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100 (China); Liu Hongguo, E-mail: hgliu@sdu.edu.cn [Key Laboratory for Colloid and Interface Chemistry of Education Ministry, Shandong University, Jinan 250100 (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Au nanoparticle-doped microcapsule and foamlike film of PVK formed at the liquid/liquid interface. Black-Right-Pointing-Pointer These composites formed due to self-assembly of polymer molecules at the interface. Black-Right-Pointing-Pointer Au nanoparticles were produced simultaneously and doped in the films. Black-Right-Pointing-Pointer The composite films exhibited effective catalytic properties. Black-Right-Pointing-Pointer Durable catalytic activity was achieved after the second cycle. - Abstract: Gold nanoparticle-doped microcapsules and foamlike films of poly(N-vinylcarbazole) (PVK) were prepared through a self-assembly process at a liquid/liquid interface. The liquid/liquid interface was formed by an aqueous solution of HAuCl{sub 4} and a chloroform solution of PVK. The composite structures were characterized using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and UV-vis spectroscopy. The results revealed that microcapsules with the size of several hundreds of nanometers and foamlike thin films were formed, and small gold nanoclusters and nanoparticles embedded in the walls. The formation of these composite nanostructures was the result of the adsorption and combination of PVK molecules with AuCl{sub 4}{sup -} ions, self-assembly of the composite molecules, and reduction of the complex ions at the liquid/liquid interface. The composite structures exhibited effective catalytic activity for the reduction of 4-nitrophenol (4-NP) by KBH{sub 4} in aqueous solutions.

  2. 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 = ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Zeini Jahromi, Elham [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Bidari, Araz [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Assadi, Yaghoub [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of) and Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)]. E-mail: y_assadi@iust.ac.ir; Milani Hosseini, Mohammad Reza [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jamali, Mohammad Reza [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2007-03-07

    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 {mu}L methanol (disperser solvent) containing 34 {mu}L 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 {mu}L). Then a 20 {mu}L 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{sup -1} with detection limit of 0.6 ng L{sup -1}. The relative standard deviation (R.S.D.s) for ten replicate measurements of 20 ng L{sup -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{sup -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

  4. Understanding voltage-induced localization of nanoparticles at a liquid-liquid interface

    International Nuclear Information System (INIS)

    Functionalization of liquid-liquid interfaces is a hot area, driven by aspirations to build self-assembled interfacial structures with unique properties, in particular accessible to light from both sides of the interface. Adsorption of nanoparticles is an example of such functionalization. Interesting new developments take place in electrochemical liquid-liquid systems, consisting of two immiscible electrolytic solutions that form an interface impermeable to ions until a sufficiently high voltage is applied across the interface. The voltage drops across a nanoscale region near the interface due to the formation of two back-to-back electrical double layers on the two sides of the interface. This highly localized voltage drop opens a new possibility for the stabilization and control of interfacial architectures. This appears to be particularly important for metal and even semiconductor nanoparticles, because they are, in turn, 'functionalized'. They are covered by surfactants with acidic groups, some of which dissociate in water. Coverage with surfactants is required to avoid particle-particle agglomeration in the bulk. An electric field can push such nanoparticles to the interface or move them away, depending on the direction of the field. This, together with the change of the free energy of solvation of nanoparticles when they move from the bulk to the surface, are the two new decisive factors affecting their adsorption and desorption. We discuss these effects together with the more familiar ones that are known to determine interfacial localization of uncharged nanoparticles. The presented critical analysis is qualitative. Although we will try to rationalize the main effects by some simplified formulae, they should not be taken literally: they pave the way towards understanding of nanoparticle localization in these systems, rather than give exact answers. These equations will, however, help us to 'visualize' how a properly applied electric field, assisted by the

  5. Spectroscopic analysis of bosentan in biological samples after a liquid-liquid microextraction

    Science.gov (United States)

    Sajedi-Amin, Sanaz; Assadpour-Zeynali, Karim; Panahi-Azar, Vahid; Kebriaeezadeh, Abbas; Khoubnasabjafari, Maryam; Ansarin, Khalil; Jouyban-Gharamaleki, Vahid; Jouyban, Abolghasem

    2015-01-01

    Introduction:Microextraction processes with UV-Vis measurement have been developed and validated for analysis of bosentan in biological samples. Methods:In this work, liquid–liquid microextraction procedures (DLLME & USAEME) were employed for cleanup, pre-concentration, and determination of bosentan in biological samples by UV-Vis spectroscopy at 270 nm. The method was validated and applied to the determination of bosentan in spiked serum, exhaled breath condensate and urine samples. Results:Various experimental factors including type of extraction and dispersive solvents and their volumes, pH, sonication time and centrifuging time were investigated. Under the optimum conditions, the method was linear in the range of 1.0–5.0 μg.mL-1, with coefficient of determination (R2) of > 0.998. The limit of detection (LOD) was 0.07 mg.L-1. Recovery of the target analyte in biological samples was 106.2%. The method could be easily applied for higher concentration of bosentan and needs more improvement for application in the pharmacokinetic investigations where more sensitive methods are required. Conclusion:A simple, low cost, precise and accurate spectrophotometric analysis of bosentan in biological samples after liquid-liquid microextraction were developed and validated for routine analyses. PMID:26929923

  6. Sequential dispersive liquid-liquid microextraction for the determination of aryloxyphenoxy-propionate herbicides in water.

    Science.gov (United States)

    Li, Songqing; Gao, Peng; Zhang, Jiaheng; Li, Yubo; Peng, Bing; Gao, Haixiang; Zhou, Wenfeng

    2012-12-01

    A novel dispersive liquid-liquid microextraction (DLLME) method followed by HPLC analysis, termed sequential DLLME, was developed for the preconcentration and determination of aryloxyphenoxy-propionate herbicides (i.e. haloxyfop-R-methyl, cyhalofop-butyl, fenoxaprop-P-ethyl, and fluazifop-P-butyl) in aqueous samples. The method is based on the combination of ultrasound-assisted DLLME with in situ ionic liquid (IL) DLLME into one extraction procedure and achieved better performance than widely used DLLME procedures. Chlorobenzene was used as the extraction solvent during the first extraction. Hydrophilic IL 1-octyl-3-methylimidazolium chloride was used as a dispersive solvent during the first extraction and as an extraction solvent during the second extraction after an in situ chloride exchange by bis[(trifluoromethane)sulfonyl]imide. Several experimental parameters affecting the extraction efficiency were studied and optimized with the design of experiments using MINITAB® 16 software. Under the optimized conditions, the extractions resulted in analyte recoveries of 78-91%. The correlation coefficients of the calibration curves ranged from 0.9994 to 0.9997 at concentrations of 10-300, 15-300, and 20-300 μg L(-1). The relative SDs (n = 5) ranged from 2.9 to 5.4%. The LODs for the four herbicides were between 1.50 and 6.12 μg L(-1). PMID:23109344

  7. Growth Kinetics of Intracellular RNA/Protein Droplets: Signature of a Liquid-Liquid Phase Transition?

    Science.gov (United States)

    Berry, Joel; Weber, Stephanie C.; Vaidya, Nilesh; Zhu, Lian; Haataja, Mikko; Brangwynne, Clifford P.

    2015-03-01

    Nonmembrane-bound organelles are functional, dynamic assemblies of RNA and/or protein that can self-assemble and disassemble within the cytoplasm or nucleoplasm. The possibility that underlying intracellular phase transitions may drive and mediate the morphological evolution of some membrane-less organelles has been supported by several recent studies. In this talk, results from a collaborative experimental-theoretical study of the growth and dissolution kinetics of nucleoli and extranucleolar droplets (ENDs) in C. elegans embryos will be presented. We have employed Flory-Huggins solution theory, reaction-diffusion kinetics, and quantitative statistical dynamic scaling analysis to characterize the specific growth mechanisms at work. Our findings indicate that both in vivo and in vitro droplet scaling and growth kinetics are consistent with those resulting from an equilibrium liquid-liquid phase transition mediated by passive nonequilibrium growth mechanisms - simultaneous Brownian coalescence and Ostwald ripening. This supports a view in which cells can employ phase transitions to drive structural organization, while utilizing active processes, such as local transcriptional activity, to fine tune the kinetics of these phase transitions in response to given conditions.

  8. Thermodynamics of mixtures containing alkoxyethanols. XXVIII: Liquid-liquid equilibria for 2-phenoxyethanol + selected alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Victor; Garcia, Mario [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain); Gonzalez, Juan Antonio, E-mail: jagl@termo.uva.es [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain); Garcia De La Fuente, Isaias; Cobos, Jose Carlos [G.E.T.E.F., Grupo Especializado en Termodinamica de Equilibrio entre Fases, Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, E-47071 Valladolid (Spain)

    2011-07-10

    Highlights: {yields} LLE coexistence curves were determined for mixtures of 2PhEE with alkanes. {yields} UCST values are higher for n-alkane systems than for solutions with cyclic alkanes. {yields} For the latter mixtures, UCST increases with the size of the alkyl group attached. {yields} Alkoxyethanol-alkoxyethanol interactions are enhanced by aromatic group in cellosolve. - Abstract: The coexistence curves of the liquid-liquid equilibria (LLE) for systems of 2-phenoxyethanol (2PhEE) with heptane, octane, cyclohexane, methylcyclohexane or ethylcyclohexane have been determined by the method of the critical opalescence using a laser scattering technique. All the curves show an upper critical solution temperature (UCST), have a rather horizontal top and their symmetry depends on the relative size of the mixture compounds. UCST values are higher for systems with linear alkanes than for solutions including cyclic alkanes. For these mixtures, the UCST increases with the size of the alkyl group attached to the cyclic part of the molecule. It is shown that interactions between alkoxyethanol molecules are stronger when the hydroxyether contains an aromatic group. Data are used to determine the critical exponent for the order parameter mole fraction. Values obtained are consistent with those provided by the Ising model or by the renormalization group theory.

  9. Determination of phenolic compounds in honey using dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Campone, Luca; Piccinelli, Anna Lisa; Pagano, Imma; Carabetta, Sonia; Di Sanzo, Rosa; Russo, Mariateresa; Rastrelli, Luca

    2014-03-21

    Honey is a valuable functional food rich in phenolic compounds with a broad spectrum of biological activities. Analysis of the phenolic compounds in honey is a very promising tool for the quality control, the authentication and characterization of botanical origin, and the nutraceutical research. This work describes a novel approach for the rapid analysis of five phenolic acids and 10 flavonoids in honey. Phenolic compounds were rapidly extracted and concentrated from diluted honey by dispersive liquid-liquid microextraction (DLLME) and then analyzed using high performance liquid chromatography with UV absorbance detection (HPLC-UV). Some important parameters, such as the nature and volume of extraction and dispersive solvents, pH and salt effect were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, an exhaustive extraction for twelve of the investigated analytes (recoveries >70%), with a precision (RSDhoney, provided similar or higher extraction efficiency, except in the case of the most hydrophilic phenolic acids. The capability of DLLME to the extraction of other honey phytochemicals, such as abscisic acid, was also demonstrated. The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost. PMID:24565235

  10. The removal of dinitrochlorobenzene from industrial residuals by liquid-liquid extraction with chemical reaction

    Directory of Open Access Journals (Sweden)

    G. C. M. Ferreira

    2007-09-01

    Full Text Available Nitrochlorobenzenes (NCBs are very important in the chemical industry since they have been used as raw material for the manufacture of crop protection products, as active ingredients in the pharmaceutical industry, as pigments and as antioxidants as well as for other uses. In industrial processes, NCBs are produced by monochlorobenzene (MCB nitration reactions and one of the main residuals formed is dinitrochlorobenzene (DNCB, which is mainly composed of the isomer 2,4DNCB. This subproduct, although of commercial interest when in its pure state, is generally incinerated due to the high costs of recovery treatment and purification. The objective of this study is to present an alternative to the treatment of industrial residuals containing DNCB. The technique consists of converting DNCB into sodium dinitrophenolate, which is very soluble in water and is also easy to reuse. For this purpose, liquid-liquid extraction with chemical reaction (alkaline hydrolysis with a rotating disc contactor (RDC is used. Experimental data on MCB nitration reactions as well as alkaline hydrolysis using a rotating disc contactor are presented.

  11. Computer modelling of the surface tension of the gas-liquid and liquid-liquid interface.

    Science.gov (United States)

    Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J

    2016-03-01

    This review presents the state of the art in molecular simulations of interfacial systems and of the calculation of the surface tension from the underlying intermolecular potential. We provide a short account of different methodological factors (size-effects, truncation procedures, long-range corrections and potential models) that can affect the results of the simulations. Accurate calculations are presented for the calculation of the surface tension as a function of the temperature, pressure and composition by considering the planar gas-liquid interface of a range of molecular fluids. In particular, we consider the challenging problems of reproducing the interfacial tension of salt solutions as a function of the salt molality; the simulations of spherical interfaces including the calculation of the sign and size of the Tolman length for a spherical droplet; the use of coarse-grained models in the calculation of the interfacial tension of liquid-liquid surfaces and the mesoscopic simulations of oil-water-surfactant interfacial systems. PMID:26744846

  12. Ionic liquid based dispersive liquid-liquid microextraction of aromatic amines in water samples

    Institute of Scientific and Technical Information of China (English)

    Yun Chang Fan; Zheng Liang Hu; Mei Lan Chen; Chao Shen Tu; Yan Zhu

    2008-01-01

    In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid (IL) phase was injected directly into the high performance liquid chromatography (HPLC) system for determination. Some parameters that might affect the extraction efficiency were optimized. Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained. The limits of detection (LOD, S/N = 3) for the four analytes were in the range of 0.45-2.6 μg L-1. The relative standard deviations (R.S.D., n = 6) were in the range of 6.2-9.8%. This method was applied for the analysis of the real water samples. The recoveries ranged from 93.4 to 106.4%. The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.

  13. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    International Nuclear Information System (INIS)

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al2O3 substrates indicated polycrystalline films with a LiAlO2 secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides

  14. Determination of four heterocyclic insecticides by ionic liquid dispersive liquid-liquid microextraction in water samples.

    Science.gov (United States)

    Liu, Yu; Zhao, Ercheng; Zhu, Wentao; Gao, Haixiang; Zhou, Zhiqiang

    2009-02-01

    A novel microextraction method termed ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) combining high-performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of insecticides in water samples. Four heterocyclic insecticides (fipronil, chlorfenapyr, buprofezin, and hexythiazox) were selected as the model compounds for validating this new method. This technique combines extraction and concentration of the analytes into one step, and the ionic liquid was used instead of a volatile organic solvent as the extraction solvent. Several important parameters influencing the IL-DLLME extraction efficiency such as the volume of extraction solvent, the type and volume of disperser solvent, extraction time, centrifugation time, salt effect as well as acid addition were investigated. Under the optimized conditions, good enrichment factors (209-276) and accepted recoveries (79-110%) were obtained for the extraction of the target analytes in water samples. The calibration curves were linear with correlation coefficient ranged from 0.9947 to 0.9973 in the concentration level of 2-100 microg/L, and the relative standard deviations (RSDs, n=5) were 4.5-10.7%. The limits of detection for the four insecticides were 0.53-1.28 microg/L at a signal-to-noise ratio (S/N) of 3.

  15. Influence of microwave heating on liquid-liquid phase inversion and temperature rates for immiscible mixtures.

    Science.gov (United States)

    Kennedy, Alvin; Tadesse, Solomon; Nunes, Janine; Reznik, Aron

    2011-01-01

    Time dependencies of component temperatures for mixtures of immiscible liquids during microwave heating were studied for acetonitrile-cyclohexane and water-toluene. For the first time, we report microwave induced liquid-liquid phase inversion for acetonitrile-cyclohexane mixture: acetonitrile layer was initially at the bottom of the mixture, after 10 sec of microwave heating its density decreased and it inverted to the top of the mixture for the remainder of the microwave heating. This phase inversion could not be achieved by conventional radiant heating. The maximum rate of temperature growth for the polar component of the mixtures was 2 - 5 times larger than for the non-polar component. This suggests that microwave energy is absorbed by polar liquids (water or acetonitrile) and heat is transferred into the non-polar liquid (toluene or cyclohexane) in the mixture by conduction (in case of cyclohexane) or conduction and convection (in case of toluene). Comparison between experimental data and semi-empirical mathematical models, proposed in [Kennedy et at., 2009] showed good correlation. Average relative error between theoretical and experimental results did not exceed 7%. These results can be used to model the temperature kinetics of components for other multiphase mixtures.

  16. OIL/WATER SEPARATION IN A LIQUID-LIQUID CYLINDRICAL CYC-LONE

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-fei; XU Jing-yu; ZHANG Jun; SUN Huan-qiang; ZHANG Jian; WU Ying-xiang

    2012-01-01

    The oil/water separation in a liquid-liquid cylindrical cyclone is experimentally studied in this article.The effects of the flow split-ratio and the flow rate on the oil/water separation performance are determined.From the experimental results,it is shown that with the increase of the flow split-ratio,the oil/water separation efficiency is enhanced at first,and an optimal flow split-ratio exists,beyond that optimal split-ratio,the watercut in the underflow keeps constant,while the oil content in the overflow begins to decrease.The process of the oil core structure formation and the phase distribution in the cyclone are determined by numerical simulations.Furthermore,the dependence of the separation efficiency on the Reynolds number and the flow split-ratio is investigated based on a dimensional analysis.A comparison between the predicted values and the experimental data shows a good agreement.

  17. Stabilization of Pickering emulsions by generating complex colloidal layers at liquid-liquid interfaces.

    Science.gov (United States)

    Lee, Geun Ju; Son, Han Am; Cho, Jang Woo; Choi, Sang Koo; Kim, Hyun Tae; Kim, Jin Woong

    2014-01-01

    Typical Pickering emulsions accumulate particles to form a robust colloidal layer at an immiscible liquid-liquid interface. However, if the particles are smaller than tens of nanometers, they have a tendency toward coming off from the interface, thereby destabilizing emulsion drops. To solve this problem, a technique that can make the adsorbed nanoparticles stay at the interface should be developed. This study introduces a practical method that allows us to obtain a mechanically stable Pickering emulsions; n-decane was emulsified to form an oil-in-water emulsion of which interface was stabilized with a complex colloidal layer consisting of 12 nm-sized silica nanoparticles, a poly(vinyl alcohol) binder, and an alkyl-chained silane coupling agent. We have found that in the conditions of high salinity, the emulsion drops attract each other and form an emulsion gel phase. However, even in such harsh conditions, the complex silica layer maintains its original structure at the interface, thus stabilizing the emulsion drop against coalescence. PMID:24183436

  18. Epitaxial thin film growth of LiH using a liquid-Li atomic template

    Energy Technology Data Exchange (ETDEWEB)

    Oguchi, Hiroyuki, E-mail: oguchi@nanosys.mech.tohoku.ac.jp [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan); Micro System Integration Center (muSIC), Tohoku University, Sendai 980-0845 (Japan); Ikeshoji, Tamio; Orimo, Shin-ichi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Ohsawa, Takeo; Shiraki, Susumu; Hitosugi, Taro [Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Kuwano, Hiroki [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan)

    2014-11-24

    We report on the synthesis of lithium hydride (LiH) epitaxial thin films through the hydrogenation of a Li melt, forming abrupt LiH/MgO interface. Experimental and first-principles molecular dynamics studies reveal a comprehensive microscopic picture of the crystallization processes, which sheds light on the fundamental atomistic growth processes that have remained unknown in the vapor-liquid-solid method. We found that the periodic structure that formed, because of the liquid-Li atoms at the film/MgO-substrate interface, serves as an atomic template for the epitaxial growth of LiH crystals. In contrast, films grown on the Al{sub 2}O{sub 3} substrates indicated polycrystalline films with a LiAlO{sub 2} secondary phase. These results and the proposed growth process provide insights into the preparation of other alkaline metal hydride thin films on oxides. Further, our investigations open the way to explore fundamental physics and chemistry of metal hydrides including possible phenomena that emerge at the heterointerfaces of metal hydrides.

  19. Liquid-liquid phase separation in aerosol particles: imaging at the nanometer scale.

    Science.gov (United States)

    O'Brien, Rachel E; Wang, Bingbing; Kelly, Stephen T; Lundt, Nils; You, Yuan; Bertram, Allan K; Leone, Stephen R; Laskin, Alexander; Gilles, Mary K

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission X-ray microscopy (STXM) to investigate the LLPS of micrometer-sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), α, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH's above the deliquescence point and that the majority of the organic component was located in the outer phase. The outer phase composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 70:30% organic to inorganic mix in the outer phase. These two chemical imaging techniques are well suited for in situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  20. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  1. An Experimental Study of Liquid-Liquid Microflow Pattern Maps Accompanied with Mass Transfer

    Institute of Scientific and Technical Information of China (English)

    邵华伟; 吕阳成; 王凯; 骆广生

    2012-01-01

    This paper presents the experimental results of liquid-liquid microflows in a coaxial microfluidic device with mass transfer. Three working systems were n-butanol + phosphoric acid (PA) + water, methyl isobutyl ketone (MIBK) + PA + water, 30% kerosene in tri-n-butylphosphate (TBP)+ PA + water. The direction and intensity of mass transfer were adjusted by adding PA in one of two phases mutual saturated in advance. When PA transferred from the organic phase to the aqueous phase, tiny aqueous droplets may generate inside the organic phase by mass transfer inducement to form a new W/O/W flow pattern directly on some special cases. Once the PA concentration was very high, violent Marangoni effect could be observed to throw part of organic phase out of droplets as tail. The interphase transfer of PA could expand the jetting flow region, in particular for systems with low or medium interfacial tension and when the mass transfer direction was from the aqueous phase to the organic phase.

  2. Identification of chemical compounds in a liquid-liquid extraction system

    International Nuclear Information System (INIS)

    The objective of the present work is to identify the chemical compounds that are distributed in a liquid-liquid extraction system in which the third phase is observed; for this purpose the FeCl3 (0.12M) - HCl (8.43M) - Diisopropilic ether - system was used, for the quantitative determination of the chemical compounds, FeCl3 solutions labelled with 59Fe or witH 38Cl were used; the Karl Fischer method for the determination of the water concentration at the organic phases was used, the obtained data was used for the calculations of the H+ distribution in each phase. The results are that when the distribution equilibrium is reached, the aqueous phase is a 7.5M HCl solution; the light organic phase contains 2 H[FeCl4].6H2O and the dense organic phase contains 2 H[FeCl4].6H2O.3HCl.12H2O. The differences between these compounds are due to a high concentration of water and the HCl in the organic solvent. This causes a heterogeneous physic field, and then the third phase formation. (author)

  3. A technical review of liquid/liquid and solid/liquid separation equipment in the field of nuclear-fuel reprocessing

    International Nuclear Information System (INIS)

    Liquid/liquid extraction is generally accepted as the preferred method in nuclear-fuel reprocessing. However, although many types of liquid/liquid contactors are available, only a few meet the stringent specifications set by the nuclear industry. This report discusses the criteria for contactor selection and then reviews the most important types, namely packed columns, pulsed columns, mixer-setters and centrifugal contactors. Finally, a short section concerned with solid/liquid separations is included because of the possible deleterious effects caused by solids in liquid/liquid contactors

  4. Isolating Reactions at the Picoliter Scale: Parallel Control of Reaction Kinetics at the Liquid-Liquid Interface.

    Science.gov (United States)

    Phan-Quang, Gia Chuong; Lee, Hiang Kwee; Ling, Xing Yi

    2016-07-11

    Miniaturized liquid-liquid interfacial reactors offer enhanced surface area and rapid confinement of compounds of opposite solubility, yet they are unable to provide in situ reaction monitoring at a molecular level at the interface. A picoreactor operative at the liquid-liquid interface is described, comprising plasmonic colloidosomes containing Ag octahedra strategically assembled at the water-in-decane emulsion interface. The plasmonic colloidosomes isolate ultrasmall amounts of solutions (<200 pL), allowing parallel monitoring of multiple reactions simultaneously. Using the surface-enhanced Raman spectroscopy (SERS) technique, in situ monitoring of the interfacial protonation of dimethyl yellow (p-dimethylaminoazobenzene (DY)) is performed, revealing an apparent rate constant of 0.09 min(-1) for the first-order reaction. The presence of isomeric products with similar physical properties is resolved, which would otherwise be indiscernible by other analytical methods. PMID:27239973

  5. Anomalous effect of flow rate on the electrochemical behavior at a liquid|liquid interface under microfluidic conditions.

    Science.gov (United States)

    Kaluza, Dawid; Adamiak, Wojciech; Kalwarczyk, Tomasz; Sozanski, Krzysztof; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2013-12-23

    We have investigated the oxidation of ferrocene at a flowing organic solvent|aqueous electrolyte|solid electrode junction in a microfluidic setup using cyclic voltammetry and fluorescent laser scanning confocal microscopy. At low flow rates the oxidation current decreases with increasing flow, contrary to the Levich equation, but at higher flow rates the current increases linearly with the cube root of the flow rate. This behavior is explained using a simple model postulating a smallest effective width of the three-phase junction, which after fitting to the data comes to be ca. 20 μm. The fluorescence microscopy reveals mixing of the two phases close to the PDMS cover, but the liquid|liquid junction is stable close to the glass support. This study shows the importance of the solid|liquid|liquid junctions for the behavior of multiphase systems under microfluidic conditions.

  6. Anomalous effect of flow rate on the electrochemical behavior at a liquid|liquid interface under microfluidic conditions.

    Science.gov (United States)

    Kaluza, Dawid; Adamiak, Wojciech; Kalwarczyk, Tomasz; Sozanski, Krzysztof; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2013-12-23

    We have investigated the oxidation of ferrocene at a flowing organic solvent|aqueous electrolyte|solid electrode junction in a microfluidic setup using cyclic voltammetry and fluorescent laser scanning confocal microscopy. At low flow rates the oxidation current decreases with increasing flow, contrary to the Levich equation, but at higher flow rates the current increases linearly with the cube root of the flow rate. This behavior is explained using a simple model postulating a smallest effective width of the three-phase junction, which after fitting to the data comes to be ca. 20 μm. The fluorescence microscopy reveals mixing of the two phases close to the PDMS cover, but the liquid|liquid junction is stable close to the glass support. This study shows the importance of the solid|liquid|liquid junctions for the behavior of multiphase systems under microfluidic conditions. PMID:24328179

  7. CONTRIBUTION TO THE DEVELOPMENT OF A SIMULATION SOFTWARE PERFORMANCE AND SHARING RATIO IN LIQUID-LIQUID EXTRACTION

    Directory of Open Access Journals (Sweden)

    A. Hadj Seyd

    2015-07-01

    Full Text Available The present work is to develop software to predict the value yield and the distribution coefficient in the process of liquid-liquid extraction of components of a mixture, from mathematical models expressing these entities, based on equations equilibrium between liquid-liquid phases, and predict the conditions under which the extraction operation is favorable, unfavorable or impossible to realize, by studying the variation of the entities cited, based on the parameters influencing the extraction, which are: initial concentrations, rate of solvent and pH, in the case of a simple extraction (extraction of neutral products or when it is reactive (extraction of complex acids or bases for one or more components.The programming language used is "Delphi" which is a very powerful oriented object programming under Windows.

  8. Stopped-flow injection liquid-liquid extraction spectrophotometric determination of palladium in airborne particulate matter and automobile catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anthemidis, A.N.; Themelis, D.G.; Stratis, J.A. [Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54006 Thessaloniki (Greece)

    2001-03-30

    A stopped-flow injection liquid-liquid extraction (SF-EX-FIA) spectrophotometric method is reported for the determination of palladium(II), using the 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) as a color forming reagent. The colored complex Pd(II)-DPPH was extracted in CHCl{sub 3} and the absorbance was monitored at 560 nm. An injection valve was used as a commutator in order to combine the stopped-flow technique with liquid-liquid extraction FI system. The calibration graph was linear up to 12 mg l{sup -1} (s{sub r}=0.27%; r=0.9999) with a detection limit of c{sub L}=0.007 mg l{sup -1}. The sampling rate was 20 injections per hour. The proposed method has been successfully applied to the determination of palladium in airborne particulate matter (APM) and in automobile exhaust gas converter catalysts.

  9. Dynamic Modelling and Simulation of (Pulsed and Stirred) Liquid-Liquid Extraction Columns using the Population Balance Equation

    OpenAIRE

    Jaradat, Moutasem

    2012-01-01

    The discrete nature of the dispersed phase (swarm of droplet) in stirred and pulsed liquid-liquid extraction columns makes its mathematical modelling of such complex system a tedious task. The dispersed phase is considered as a population of droplets distributed randomly with respect to their internal properties (such as: droplet size and solute concentration) at a specific location in space. Hence, the population balance equation has been emerged as a mathematical tool to model and describe ...

  10. A novel liquid/liquid extraction process composed of surfactant and acetonitrile for purification of polygalacturonase enzyme from Durio zibethinus.

    Science.gov (United States)

    Amid, Mehrnoush; Manap, Yazid; Azmira, Farhana; Hussin, Muhaini; Sarker, Zaidul Islam

    2015-07-01

    Polygalacturonase is one of the important enzymes used in various industries such as food, detergent, pharmaceutical, textile, pulp and paper. A novel liquid/liquid extraction process composed of surfactant and acetonitrile was employed for the first time to purify polygalacturonase from Durio zibethinus. The influences of different parameters such as type and concentration of surfactants, concentrations of acetonitrile and composition of surfactant/acetonitrile on partitioning behavior and recovery of polygalacturonase was investigated. Moreover, the effect of pH of system and crude load on purification fold and yield of purified polygalacturonase were studied. The results of the experiment indicated the polygalacturonase was partitioned into surfactant top rich phase with impurities being partitioned into acetonitrile bottom rich phase in the novel method of liquid/liquid process composed of 23% (w/w) Triton X-100 and 19% (w/w) acetonitrile, at 55.6% of TLL (tie line length) crude load of 25% (w/w) at pH 6.0. Recovery and recycling of components also was measured in each successive step of liquid/liquid extraction process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 97.3% while phase components were also recovered and recycled above 95%. This study demonstrated that the novel method of liquid/liquid extraction process can be used as an efficient and economical extraction method rather than the traditional methods of extraction for the purification and recovery of the valuable enzyme.

  11. Study on Osmotic Pressure and Liquid-Liquid Equilibria for Micelle, Colloid and Microemulsion Systems by Yukawa Potential

    Institute of Scientific and Technical Information of China (English)

    FU,Dong(付东); LU,Jiu-Fang(陆九芳); WU,Wei(吴畏); Li,Yi-Gui(李以圭)

    2004-01-01

    An equation of state (EOS) was established to study the osmotic pressure and liquid-liquid equilibria for micelle,colloid and microemulsion systems. The Carnahan-Starling equation was used for the hard sphere repulsion. The Yukawa potential was used to describe both the attractive dispersion and the double-layer repulsion. By using the established EOS, the osmotic pressures for charged colloid, uncharged micelle, uncharged and weakly charged microemuslion, the phase equilibria for uncharged micelle and charged colloid systems were studied.

  12. Anti-cancer efficacy of nonthermal plasma dissolved in a liquid, liquid plasma in heterogeneous cancer cells

    OpenAIRE

    Ngoc Hoan Nguyen; Hyung Jun Park; Sang Sik Yang; Kyeong Sook Choi; Jong-Soo Lee

    2016-01-01

    The therapeutic potential of nonthermal plasma for cancer treatment has been reported recently. The heterogeneity of cancer cells need to be addressed to design effective anticancer treatments. Here, we show that treatment with nonthermal atmospheric-pressure plasma dissolved in a liquid (liquid plasma) induces oxidative stress in heterogeneous populations of cancer cells and ultimately kills these cells via apoptosis, regardless of genetic status, e.g., mutations in p53 and other DNA-damage-...

  13. Validation of a Liquid-liquid Extraction Method for Analysis of Wine Aroma Compounds with GC-MS

    OpenAIRE

    Ivanova, Violeta; Stefova, Marina; Stafilov, Trajče; Vojnoski, Borimir; Bíró, Ildiko; Bufa, Anita; Kilár, Ferenc

    2012-01-01

    A validated method for identification and quantification of volatile compounds in wine was developed using liquid-liquid extraction followed by gas chromatography coupled to mass spectrometry (Ivanova et al., 2012a, 2012b). Dichloromethane was used as an extraction solvent, with good repeatability and reproducibility (RSD < 10%). The correlation coefficients (R2) ranged from 0.9951 to 0.9992, showing linear calibration curves of the used reference compounds (2-phenyl ethanol, ethyl nonanoate,...

  14. Binary, ternary and quaternary liquid-liquid equilibria in 1-butanol, oleic acid, water and n-heptane mixtures

    OpenAIRE

    Winkelman, J.G.M.; Kraai, G. N.; Heeres, H. J.

    2009-01-01

    This work reports on liquid-liquid equilibria in the system 1-butanol, oleic acid, water and n-heptane used for biphasic, lipase catalysed esterifications. The literature was studied on the mutual solubility in binary systems of water and each of the organic components. Experimental results were obtained on the composition of the coexisting phases of a series of ternary and quaternary mixtures of the components at 301,308 and 313 K. The data were correlated successfully with the UNIQUAC model...

  15. Optimized determination of polybrominated diphenyl ethers by ultrasound-assisted liquid-liquid extraction and high-performance liquid chromatography.

    Science.gov (United States)

    He, Kuang; Lv, YuanCai; Chen, YuanCai

    2014-10-01

    A method based on ultrasound-assisted liquid-liquid extraction and high-performance liquid chromatography has been optimized for the determination of six polybrominated diphenyl ether congeners. The optimal condition relevant to the extraction was first investigated, more than 98.7 ± 0.7% recovery was achieved with dichloromethane as extractant, 5 min extraction time, and three cycles of ultrasound-assisted liquid-liquid extraction. Then multiple function was employed to optimize polybrominated diphenyl ether detection conditions with overall resolution and chromatography signal area as the responses. The condition chosen in this experiment was methanol/water 93:7 v/v, flow rate 0.80 mL/min, column temperature 30.0°C. The optimized technique revealed good linearity (R(2) > 0.9962 over a concentration range of 1-100 μg/L) and repeatability (relative standard deviation ultrasound-assisted liquid-liquid extraction coupled with high-performance liquid chromatography was effective to identify and quantify the complex polybrominated diphenyl ethers in effluent samples. PMID:25142014

  16. Ionic-liquid-based dispersive liquid-liquid microextraction for high-throughput multiple food contaminant screening.

    Science.gov (United States)

    Ho, Yee-Man; Tsoi, Yeuk-Ki; Leung, Kelvin Sze-Yin

    2013-12-01

    This paper describes an innovation of dispersive liquid-liquid microextraction enabling multiple-component analysis of eight high-priority food contaminants in two chemically distinctive families: Sudan dyes and phthalate plasticizers. To provide convenient sample handling for solid and solid-containing matrices, a modified dispersive liquid-liquid microextraction procedure used an extractant precoated frit to perform simultaneous filtration, solvent mixing, and phase dispersion in one simple step. A binary ionic liquid extractant system was carefully tuned to deliver high quality analysis based only on affordable LC with diode array detector instrumentation. The method is comprehensively validated for robust quantification with good precision (6.9-9.8% RSD) in a linear 2-1000 μg/L range. Having accomplished enrichment factors up to 451, the treatment enables sensitive detection at 0.09-1.01 μg/L levels. Analysis of six high-risk solid condiments and sauces further verified its practical applicability within a 70-120% recovery range. Compared to other approaches, the current dispersive liquid-liquid microextraction treatment offers major advantages in terms of minimal solvent (1.5 mL) and sample (0.1 g) consumption, ultra-high analytical throughput (6 min), and the ability to handle complex solid matrices. The idea of performing simultaneous analysis for multiple contaminants presented here fosters a more effective mode of operation in food control routines.

  17. Analysis of aflatoxins in nonalcoholic beer using liquid-liquid extraction and ultraperformance LC-MS/MS.

    Science.gov (United States)

    Khan, Mohammad R; Alothman, Zeid A; Ghfar, Ayman A; Wabaidur, Saikh M

    2013-02-01

    Aflatoxins AFB1, AFB2, AFG1, and AFG2 are toxic secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus and posses a potential threat to food safety. In the present work, liquid-liquid extraction and ultraperformance LC-MS/MS method has been applied for the determination of four naturally occurring aflatoxins AFB1, AFB2, AFG1, and AFG2 in nonalcoholic beer. Aflatoxins extraction from nonalcoholic beer was carried out using liquid-liquid extraction procedure. The effects of solvent-types were studied to obtain maximum recovery of the target analytes with minimum contamination. Among different solvents, the aflatoxins extraction was best achieved using ethyl acetate. The obtained recoveries were ranged from 85 to 96% with good quality parameters: LOD values between 0.001 and 0.003 ng/mL, linearity of the calibration curve (r(2) > 0.999), and repeatability (run-to-run) and reproducibility (day-to-day) precisions with RSDs lower than 5% (n = 5) achieved at 0.50 ng/mL concentration. The optimized liquid-liquid extraction in combination with ultraperformance LC-MS/MS was applied successfully to the analysis of AFB1, AFB2, AFG1, and AFG2 aflatoxins in 11 nonalcoholic beers and were detected up to 15.31 ng/L in some of the samples.

  18. Theoretical and Computational Studies of Condensed-Phase Phenomena: The Origin of Biological Homochirality, and the Liquid-Liquid Phase Transition in Network-Forming Fluids

    Science.gov (United States)

    Ricci, Francesco

    ) model of silicon. A similar analysis is also presented for the generalized SW family of models by varying the "tetrahedrality" of the potential. Contrary to previously published findings, we do not find any evidence of the existence of an LLPT for SW silicon, nor for the generalized family of SW models over the range of parameters studied. Our results for the original parameterization of SW silicon are in semi-quantitative agreement with previous free energy calculations for this model, which were only provided at three state points. Explanations for the discrepancies between previous independent studies are provided, along with explicit demonstrations of how these discrepancies may have occurred. Finally, in the fourth part of this dissertation, we perform free energy calculations to demonstrate the existence of an LLPT in the Jagla potential. We also utilize finite-size scaling analysis to calculate the surface tension associated with the LLPT. In addition to the thermodynamics of the model, we investigate the relaxation times for density and bond-orientational order and show that, contrary to assertions in the literature, the characteristic relaxation time of bond-orientational order is not orders of magnitude slower than that of density. We compare our results for the Jagla model with those found in the literature for the ST2 model of water (which has also been rigorously shown to exhibit an LLPT) in order to emphasize key similarities and differences between two models that exhibit pure-component liquid-liquid phase separation.

  19. Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

    Science.gov (United States)

    Xing, Han-Zhu; Wang, Xia; Chen, Xiang-Feng; Wang, Ming-Lin; Zhao, Ru-Song

    2015-05-01

    A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.

  20. Modeling the liquid-liquid interface and the transfer of a solute by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Molecular Dynamics method and Lennard-Jones potential functions have been employed to model Liquid-Liquid Interfaces. The variation of the miscibilities between the two liquids is obtained by changing the interaction between the two atomic species. The resulting interfaces have a thickness of about three atomic diameters and are stable on the time scale of the simulation. They have been characterized by the density and pressure profiles. The interfacial tension has also been computed and is of the order of magnitude of experimental values. The diffusion process is anisotropic in the interfacial region: the transverse diffusion coefficient (parallelly to the interface) is higher than the normal one. A qualitative explanation of this behaviour is suggested by considering the pressure tensor. The second part of this work, performed by Molecular Dynamics in the canonical ensemble, is devoted to the kinetic study of the transfer of a solute through the interface. A model of a symmetric interface with an atomic solute has been used. The interaction potential between the solute and the solvents has been built in order to obtain an activation barrier to the transfer. We have computed the mean force exerted by the solvent on the solute as a function of its distance to the interface. The resulting mean force potential corresponds to a free energy difference. The height of the energy barrier involved is about 4 kT. The potential energy and entropy profiles have also been calculated and discussed. The diffusion coefficient of the solute has been computed by equilibrium and non-equilibrium methods. We deduced the friction coefficient of the solvent, which is essential to determine the Kramers transmission coefficient. This coefficient is compared to the one obtained by simulation. Finally, the solute transfer rate constant has been calculated. (author)

  1. Exploring the nature of the liquid-liquid transition in silicon: a non-activated transformation.

    Science.gov (United States)

    Lü, Y J; Zhang, X X; Chen, M; Jiang, Jian-Zhong

    2015-10-28

    In contrast to other glass formers, silicon exhibits a thermodynamic discontinuity between its liquid and amorphous solid states. Some researchers have conjectured that a first-order phase transition occurs between two forms of liquid silicon: the high-density liquid (HDL) and the low-density liquid (LDL). Despite the fact that several computer simulations have supported a liquid-liquid phase transition (LLPT) in silicon, recent work based on surface free energy calculations contradicts its existence and the authors of this work have argued that the proposed LLPT has been mistakenly interpreted [J. Chem. Phys., 2013, 138, 214504]. A similar controversy has also arisen in the case of water because of discrepancies in the calculation of its free energy surface [Nature, 2014, 510, 385; J. Chem. Phys., 2013, 138, 214504]. Current evidence supporting or not supporting the LLPT is mostly derived from the thermodynamic stability of the LDL phase. Provided that the HDL-LDL transition is a first-order transition, the formation of LDL silicon should be an activated process. Following this idea, the nature of the LLPT should be clarified by tracing the kinetic path toward LDL silicon. In this work, we focus on the transformation process from HDL to LDL phases and use the mean first passage time (MFPT) method to examine thermodynamic and dynamic trajectories. The MFPT results show that the presumed HDL-LDL transition is not characterized by a thermodynamic activated process but by a continuous dynamic transformation. LDL silicon is actually a mixture of the high-density liquid and a low-density tetrahedral network. We show that the five-membered Si-Si rings in the LDL network play a critical role in stabilizing the low-density network and suppressing the crystallization. PMID:26415631

  2. 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. PMID:19700165

  3. 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). PMID:19779926

  4. Successive pH- and heat-induced homogenous liquid-liquid extraction.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Feriduni, Behruz

    2016-08-12

    A simple and efficient analytical method known as pH- and heat-induced homogenous liquid-liquid extraction combined with high-performance liquid chromatography has been successfully developed for the extraction and determination of neonicotinoid pesticides in aqueous samples. In this method, a few mL of a water-miscible basic extraction solvent is mixed with a high volume of an aqueous phase containing the analytes and passed through a tube which a portion of the tube is filled with sodium carbonate as a separating agent. By passing the solution, salt is dissolved and the fine droplets of the extraction solvent are formed. The produced droplets go up through the remained solution and collect as a separated layer. In the following, the collected organic phase is removed and placed into a micro tube. Then it is heated in a water bath to form two phases. Several experimental parameters that influence extraction efficiency such as type and volume of extraction solvent, type of phase separation agent, temperature, and extraction time were investigated. Under the optimum conditions, the extraction recoveries and enrichment factors ranged between 51 and 81% and 680 and 1080, respectively. Calibration curves showed a high-level of linearity for all target analytes with coefficients of determination ranging between 0.997 and 0.999. The repeatability of the proposed method expressed as relative standard deviation varied between 3 and 5% (n=6, C=50μgL(-1)), and the detection limits were in the range of 0.52-1.0μgL(-1). Finally, the performance of the method was evaluated by analyzing the selected pesticides in different fruit juice and vegetable samples. PMID:27394088

  5. Electrostatic Assembly of Polymers and Nanoparticles at Liquid-Liquid Interfaces

    Science.gov (United States)

    Hoagland, David

    The electrostatic attraction between charged solutes on opposite sides of the interface between immiscible liquids offers an efficient route to the self-assembly of two-dimensional films. As implemented by us, a hydrophobic polymer with amine end(s) or block(s) is presented in an oil phase, and a negatively charged nanoparticle is presented in an aqueous phase; both solutes are insoluble in the opposite phase but efficiently driven to the liquid-liquid interface by mutual electrostatically attraction to the solute in the opposite phase. Depending on experimental conditions (salt concentration, pH, solute concentrations, etc.), a continuous, nanoscopically thin composite film builds at the oil-water interface over the timescale of minutes, often accompanied by a dramatic reduction of interfacial tension akin to that observed for a surfactant. Film formation and properties by the new route will be discussed, as principally probed through pendant drop interfacial tensiometry and pendant drop interfacial rheometry. Components of model system are toluene-dissolved amine end-capped polystyrene and water-dispersed acid-treated carbon nanotubes or citrate-treated gold nanospheres. Film structures are complicated, as are crucial electrostatic interactions near the interface. With amine end-capped polystyrene partnered with acid-treated carbon nanotubes, high pH (above 5) and high polystyrene molecular weight (above 5000 g/mol) strongly hinder film formation. These films, which are liquid-like, show two viscoelastic relaxations, a fast relaxation (about 10 s) associated with polystyrene chain rearrangements (slightly impacted by carbon nanotube association) and a slow relaxation (about 20 min) associated with polystyrene adsorption/desorption; at intermediate times (or frequencies), the two-dimensional storage and loss moduli follow approximately the same power law dependences. Support by NSF through the Univ. of Massachusetts MRSEC.

  6. Modeling of Ultrasonically Generated Liquid-Liquid Dispersions During Controlled Directional Solidification

    Science.gov (United States)

    Grugel, R. N.; Fedoseyev, A. I.

    2000-01-01

    There are innumerable two-component systems in which two very different liquid phases co-exist in equilibrium over a range of temperature and composition, e.g., oil and water, salt fluxes and solders, aluminum and lead. Often it is of practical concern to fabricate a solid component consisting of a uniform dispersion of one phase in the other. Unfortunately, uniform microstructural development during solidification of two immiscible liquids is hampered by inherent, often large, density differences between the phases that lead to severe segregation. Uniformity is also compromised by preferential wetting and coalescence phenomena. It is, however, well known that ultrasonic energy can initiate and maintain a fine liquid-liquid dispersion. The work presented here extends that observation by application of ultrasonic energy to promote uniform phase incorporation during controlled directional solidification. To this end experiments with the transparent organic, immiscible, succinonitrile-glycerol system were conducted and the numerous processing parameters associated with this technique were evaluated in view of optimizing dispersion uniformity. In view of the initial experimental results a model that predicts the dispersed liquid droplet size as a function of material properties, sample geometry, and applied energy has been developed. In the mathematical model we consider the ultrasonic field in an experimental ampoule of length L and diameter D induced by a probe having a vibration frequency of f=2OKhz (circular frequency omega = 2 pi f). The amplitude is adjustable from A=65 to 13Omicrons. The probe tip diameter is d, the liquid has a density of p, in which the speed of sound and surface tension are, respectively, c and sigma. The mathematical model and numerical investigation for the experiments [1] is done using the following assumptions: (i) The droplet size is small in comparison to the sound wave length; (ii) The forces between droplets are neglected (relative

  7. Speciation analysis of mercury in sediments using ionic-liquid-based vortex-assisted liquid-liquid microextraction combined with high-performance liquid chromatography and cold vapor atomic fluorescence spectrometry.

    Science.gov (United States)

    Leng, Geng; Chen, Wenjin; Wang, Yong

    2015-08-01

    An improved novel method based on ionic liquid vortex-assisted liquid-liquid microextraction has been developed for the extraction of methylmercury, ethylmercury and inorganic mercury in sediment samples prior to analysis by high-performance liquid chromatography with cold vapor atomic fluorescence spectrometry. In this work, mercury species were firstly complexed with dithizone, and the complexes were extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate. Key factors that affect the extraction efficiency of mercury species, such as type and amount of ionic liquid and chelatants, extraction time, sample pH, salt effect and matrix effect were investigated. Under the optimum conditions, linearity was found in the concentration range from 0.1-70 ng/g. Limits of detection ranged from 0.037-0.061 ng/g. Reproducibility and recoveries were assessed by extracting a series of six independent sediment samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied in analysis of real sediment samples. In this work, ionic liquids vortex-assisted liquid-liquid microextraction was for the first time used for the extraction of mercury species in sediment samples. The proposed method was proved to be much simpler and more rapid, as well as more environmentally friendly and efficient compared with the previous methods. PMID:25998155

  8. Tandem dispersive liquid-liquid microextraction as an efficient method for determination of basic drugs in complicated matrices.

    Science.gov (United States)

    Bazregar, Mohammad; Rajabi, Maryam; Yamini, Yadollah; Saffarzadeh, Zahra; Asghari, Alireza

    2016-01-15

    A simple and efficient approach is introduced for the improvement of the clean-up and applicability of the dispersive liquid-liquid microextraction (DLLME) method in complicated matrices. For this purpose, two dispersive microextraction methods were combined, and the tandem dispersive liquid-liquid microextraction (TDLLME) method was provided. At first, using the ultrasound-assisted emulsification microextraction (USAEME) method, the tricyclic anti-depressant (TCA) drugs nortriptyline, imipramine, and amitriptyline, as the model compounds, contained in an aqueous sample solution (8.0 mL), were extracted into an organic solvent (35 μL). Then by utilizing the air-agitated liquid-liquid microextraction (AALLME) method, these analytes were simply back-extracted into 50 μL of an aqueous acceptor phase. By performing this convenient extraction method, a high sample clean-up was obtained; the overall extraction time was 7 min. The back-extraction step could be performed in less than 2 min, and very simple tools were required for this purpose. The response surface methodology (RSM) was used for the optimization of the experimental parameters so that the volumes 95 and 50 μL were obtained for the organic solvent and the acceptor phase, respectively, and the pH values of 11.25 and 1.75 were obtained for the donor and acceptor phases, respectively, as the optimal extraction conditions. Under the optimized conditions, TDLLME-HPLC-UV provided a good linearity in the range of 2.5-5000 ng mL(-1), low limits of detection (0.7-1.0 ng mL(-1)), good extraction repeatabilities (relative standard deviations below 6.2%, n=5), and enrichment factors (EFs) of 50-101. Finally, the developed method was successfully used for the determination of the mentioned drugs in the wastewater and human plasma samples. PMID:26711155

  9. Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for determination of benzoate and sorbate in yogurt drinks and method optimization by central composite design.

    Science.gov (United States)

    Kamankesh, Marzieh; Mohammadi, Abdorreza; Tehrani, Zohreh Modarres; Ferdowsi, Roohallah; Hosseini, Hedayat

    2013-05-15

    A new method based on dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography (HPLC) for determination of benzoate and sorbate salts in yogurt drinks was developed. The effective parameters in DLLME process, including volume of extraction and disperser solvents, pH and salt effect, were optimized using response surface methodology (RSM) based on central composite design. The yogurt drink samples were extracted using NaOH and Carrez solutions (potassium hexaferrocyanide and zinc acetate) were used for sedimentation of proteins. For DLLME, a mixture of extraction solvent (1-octanol) and disperser solvent (ethanol) was rapidly injected into the sample solution by syringe and cloudy solution is formed. Subsequently, the upper 1-octanol layer was analyzed by HPLC. The detection limits for benzoate and sorbate were 0.06 ng mL(-1) and 0.15 ng mL(-1), respectively. The relative standard deviations (RSD) for seven analyses were 4.96% for benzoate and 4.58% for sorbate. The proposed method demonstrated good linearity and high enrichment factor. A clean separation and good chromatogram is readily achieved without the presence of matrix interference. A comparison of this method with previous methods demonstrated that the proposed method is an accurate, rapid and reliable sample-pretreatment method that gives very good enrichment factors and detection limits for extracting and determining sorbate and benzoate in yogurt drink samples. PMID:23618139

  10. APPLICATION OF A GENERALIZED MAXIMUM LIKELIHOOD METHOD IN THE REDUCTION OF MULTICOMPONENT LIQUID-LIQUID EQUILIBRIUM DATA

    Directory of Open Access Journals (Sweden)

    L. STRAGEVITCH

    1997-03-01

    Full Text Available The equations of the method based on the maximum likelihood principle have been rewritten in a suitable generalized form to allow the use of any number of implicit constraints in the determination of model parameters from experimental data and from the associated experimental uncertainties. In addition to the use of any number of constraints, this method also allows data, with different numbers of constraints, to be reduced simultaneously. Application of the method is illustrated in the reduction of liquid-liquid equilibrium data of binary, ternary and quaternary systems simultaneously

  11. Salt effect of KBr on the liquid-liquid equilibrium of the water/ethanol/1-pentanol system

    Directory of Open Access Journals (Sweden)

    G.R. Santos

    2000-12-01

    Full Text Available Liquid-liquid equilibrium data for the water/ethanol/1-pentanol/potassium bromide systems were experimentally determined at 25° C and 40ºC. The experimental data were correlated through the NRTL and UNIFAC-Dortmund models for the activity coefficient, with the estimation of new binary interaction parameters for both models, corresponding to the salt-solvent and solvent-solvent interactions for the NRTL model and the ion-ion and solvent-ion interactions for the UNIFAC-Dortmund model. The results obtained have shown that the NRTL model was more able to represent equilibrium data for the studied systems.

  12. Combination of corona discharge ion mobility spectrometry with a novel reagent gas and two immiscible organic solvent liquid-liquid-liquid microextraction for analysis of clomipramine in biological samples.

    Science.gov (United States)

    Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari; Khayamian, Taghi; Moradmand, Ali

    2011-12-01

    A novel and sensitive method based on combination of two immiscible organic solvents hollow fiber-based liquid-liquid-liquid microextraction and corona discharge ion mobility spectrometry (HF-LLLME-CD-IMS) was employed for the analysis of clomipramine in human urine and plasma. The effect of formic, acetic and propionic acid as the reagent gas (dopant) on the corona discharge ion mobility signal was investigated. The influence of dopant amount was also studied. Optimum mass flow rates of the dopants were 3.7, 1.1 and 1.0 μmol min(-1) for formic, acetic and propionic acid, respectively. Experimental parameters influencing the extraction efficiency of HF-LLLME, such as NaOH concentration as donor solution, ionic strength of the sample, stirring rate, and extraction time were investigated and optimized. Under the optimum conditions, analytical parameters such as linearity, precision and limit of detection were also evaluated. The linear dynamic range was from 1 to 100 μg L(-1) (r(2)=0.9980) and the limit of detection was 0.35 μg L(-1). Intra- and inter-day precisions were satisfactory with a relative standard deviation (RSD) of 5.9 and 6.7%, respectively. The proposed method was satisfactorily applied for the determination of clomipramine in human plasma and urine. PMID:22041141

  13. Three-phase slug flow in microchips can provide beneficial reaction conditions for enzyme liquid-liquid reactions.

    Science.gov (United States)

    Cech, Jiří; Přibyl, Michal; Snita, Dalimil

    2013-01-01

    Here, we introduce a solution to low stability of a two-phase slug flow with a chemical reaction occurring at the phase interface in a microfluidic reactor where substantial merging of individual reacting slugs results in the loss of uniformity of the flow. We create a three-phase slug flow by introducing a third fluid phase into the originally two-phase liquid-liquid slug flow, which generates small two-phase liquid slugs separated by gas phase. Introduction of the third phase into our system efficiently prevents merging of slugs and provides beneficial reaction conditions, such as uniform flow pattern along the whole reaction capillary, interfacial area with good reproducibility, and intensive water-oil interface renewal. We tested the three-phase flow on an enzyme hydrolysis of soybean oil and compared the reaction conversion with those from unstable two-phase slug flows. We experimentally confirmed that the three-phase slug flow arrangement provides conversions and pressure drops comparable or even better with two-phase liquid-liquid arrangements.

  14. Determination of fenvalerate in tomato by ultrasound-assisted solvent extraction combined with dispersive liquid-liquid microextraction.

    Science.gov (United States)

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

    2014-09-01

    Ultrasound-assisted solvent extraction (UASE) combined with dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) has been developed for extraction and determination of fenvalerate from tomato samples. Fenvalerate was determined by high-performance liquid-liquid chromatography-ultraviolet detector. Effects of parameters such as type and volume of extraction solvent in the UASE stage, sonication time, type and volume of extraction solvent and disperser solvent in the DLLME-SFO stage, salt addition and pH effect on extraction were studied and optimized. Under the optimum conditions, the calibration graph was linear in the range of 5-500 µg kg(-1) with a detection limit of 0.6 µg kg(-1). The relative standard deviation for five replicate measurements of 100 µg kg(-1) of fenvalerate was 6.5%. The relative recovery of fenvalerate in different tomato samples at a spiking level of 10, 20 and 50 µg kg(-1) is in the range of 93.5-108%. The obtained results show that UASE-DLLME-SFO is a sensitive, fast and simple method for the determination of fenvalerate in tomato samples. PMID:24025187

  15. Determination of abamectin in citrus fruits using SPE combined with dispersive liquid-liquid microextraction and HPLC-UV detection.

    Science.gov (United States)

    Rezaee, Mohammad; Mashayekhi, Hossein Ali; Saleh, Abolfazl; Abdollahzadeh, Yaser; Naeeni, Mohammad Hosein; Fattahi, Nazir

    2013-08-01

    A new pretreatment method, SPE combined with dispersive liquid-liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound-assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid-liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B1a and from 0.05 to 10.0 mg/kg for B1b with correlation coefficient (r(2)) of 0.998 for B1a and 0.991 for B1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B1a and B1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples. PMID:23913592

  16. Studies of extractant molecules in solution and at liquid-liquid interfaces: structural and mechanistic aspects of synergy effects

    International Nuclear Information System (INIS)

    Molecular dynamics simulations reported herein provide new important insights into cation recognition and complexation in solution as well as liquid-liquid extraction, with a particular focus on the microscopic events taking place at the interface between two immiscible liquids. Preliminary studies concerned the representation of the trivalent rare earth cations La3+, Eu3+ and Yb3+ in force field simulations, probing structural and energetic features on an experimentally characterized model system based on substituted pyridine dicarboxamide ligands. Complexation of such cations by a novel calixarene derivative was investigated showing unexpected features, such as the position of the cation in the complex. Independent experimental studies published subsequently support these findings. Another part of the work is related to industrial liquid-liquid extraction systems using tri-n-butyl phosphate (TBP) as co-solvent, extractant, surfactant and synergist. We investigate 1) concentration effects simulating up to 60 TBP at a water/chloroform interface, 2) acidity using a neutral and ionic model of HNO3 and 3) synergistic aspects of mixed TBP/calixarene extraction systems. These simulations provide the first microscopic insights into such issues. We finally addressed the topic of solute transfer across the water/chloroform interface. The potential of mean force for such a process has been calculated by both standard methods and novel approaches

  17. Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid-liquid ultrasonic extraction

    Science.gov (United States)

    Xia, Qinghai; Yang, Yaling; Liu, Mousheng

    2012-10-01

    An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al3+) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N) = 3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.

  18. Detection of melamine in feed using liquid-liquid extraction treatment combined with surface-enhanced Raman scattering spectroscopy.

    Directory of Open Access Journals (Sweden)

    Jie Cheng

    Full Text Available A rapid, selective, and sensitive method to determine the melamine content in animal feeds was developed using surface-enhanced Raman scattering spectroscopy on aggregated 55 nm Au nanoparticles with liquid-liquid extraction sample preparation. Butyl alcohol was used as the initial extraction solvent, and liquid-liquid extraction was performed twice using HCl (pH 3-4 and 6:1 (v/v n-butyl alcohol/ethyl acetate. The intensity of the matrix-based peak at 731 cm⁻¹ was set at 100 as a basis for the feeds, and the peak at 707 cm-1 was the characteristic peak of melamine used in the calculations. Sufficient linearity was obtained in the range 2-10 µg·g⁻¹ (R² = 0.991. Limits of detection and quantification in the feeds were 0.5 and 2 µg·g⁻¹, respectively. The recovery rates were 82.5-90.2% with coefficients of variation below 4.02%. This new protocol could be easily developed for the routine monitoring of on-site feed quality and market surveillance.

  19. Two-phase stopped-flow measurement of the protonation of tetraphenylporphyrin at the liquid-liquid interface.

    Science.gov (United States)

    Nagatani, H; Watarai, H

    1996-04-01

    The formation rate of the protonated form of tetraphenylporphyrin (TPP) in a dispersed two-phase system composed of dodecane and aqueous trichloroacetic acid (TCA) was studied by means of a stopped-flow method. The protonation reaction took place at the liquid-liquid interface, and the diprotonated TPP (H(2)TPP(2+)) formed was adsorbed there. In order to determine the rate-determining process, changes in absorbance at the absorption maximum wavelengths of TPP and H(2)TPP(2+) were analyzed. The obtained rate constant for the decrease of TPP in the organic phase, 21 ± 2 s(-1), was in agreement with that for the increase of diprotonated TPP at the interface, 20 ± 3 s(-1). The observed rate constants did not show any dependence on concentrations of both TPP and the acid. The experimental results suggested the rate-determining step to be the molecular diffusion process of TPP in the stagnant layer in the organic phase side at the liquid-liquid interface, and the thickness of the stagnant layer was estimated as 1.4 × 10(-4) cm. PMID:21619156

  20. Acidic ionic liquids for n-alkane isomerization in a liquid-liquid or slurry-phase reaction mode

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.; Hager, V.; Geburtig, D.; Kohr, C.; Wasserscheid, P. [Erlangen-Nuernberg Univ. (Germany). Lehrstuhl fuer Chemische Reaktionstechnik; Haumann, M. [Chemical Reaction Engineering, FAU Busan Campus, Korea (Korea, Republic of)

    2011-07-01

    Highly acidic ionic liquid (IL) catalysts offer the opportunity to convert n-alkanes at very low reaction temperatures. The results of IL catalyzed isomerization and cracking reactions of pure n-octane are presented. Influence of IL composition, [C{sub 4}C{sub 1}Im]Cl / AlCl{sub 3} / H{sub 2}SO{sub 4} and [C{sub 4}C{sub 1}Im]Cl / AlCl{sub 3} / 1-chlorooctane, on catalyst activity and selectivities to branched alkanes was investigated. Acidic chloroaluminate IL catalysts form liquid-liquid biphasic systems with unpolar organic product mixtures. Thus, recycling of the acidic IL is enabled by simple phase separation in the liquid-liquid biphasic reaction mode or the IL can be immobilized on an inorganic support with a large specific surface area. These supported ionic liquid phase (SILP) catalysts offer the advantage to get a macroscopically heterogeneous system while still preserving all benefits of the homogeneous catalyst which can be used for the slurry-phase n-alkane isomerization. The interaction of the solid support and acidic IL influences strongly the catalytic activity. (orig.)

  1. Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.

    Science.gov (United States)

    Hatami, Mehdi; Farhadi, Khalil; Abdollahpour, Assem

    2011-11-01

    A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers. PMID:21972192

  2. A Robust Computational Method for Coupled Liquid-liquid Phase Separation and Gas-particle Partitioning Predictions of Multicomponent Aerosols

    Science.gov (United States)

    Zuend, A.; Di Stefano, A.

    2014-12-01

    Providing efficient and reliable model predictions for the partitioning of atmospheric aerosol components between different phases (gas, liquids, solids) is a challenging problem. The partitioning of water, various semivolatile organic components, inorganic acids, bases, and salts, depends simultaneously on the chemical properties and interaction effects among all constituents of a gas + aerosol system. The effects of hygroscopic particle growth on the water contents and physical states of potentially two or more liquid and/or solid aerosol phases in turn may significantly affect multiphase chemistry, the direct effect of aerosols on climate, and the ability of specific particles to act as cloud condensation or ice nuclei. Considering the presence of a liquid-liquid phase separation in aerosol particles, which typically leads to one phase being enriched in rather hydrophobic compounds and the other phase enriched in water and dissolved electrolytes, adds a high degree of complexity to the goal of predicting the gas-particle partitioning of all components. Coupled gas-particle partitioning and phase separation methods are required to correctly account for the phase behaviour of aerosols exposed to varying environmental conditions, such as changes to relative humidity. We present new theoretical insights and a substantially improved algorithm for the reliable prediction of gas-particle partitioning at thermodynamic equilibrium based on the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. We introduce a new approach for the accurate prediction of the phase distribution of multiple inorganic ions between two liquid phases, constrained by charge balance, and the coupling of the liquid-liquid equilibrium model to a robust gas-particle partitioning algorithm. Such coupled models are useful for exploring the range of environmental conditions leading to complete or incomplete miscibility of aerosol constituents which will affect

  3. Hollow fiber liquid-liquid-liquid microextraction followed by solid-phase microextraction and in situ derivatization for the determination of chlorophenols by gas chromatography-electron capture detection.

    Science.gov (United States)

    Saraji, Mohammad; Ghani, Milad

    2015-10-30

    A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis.

  4. Hollow fiber liquid-liquid-liquid microextraction followed by solid-phase microextraction and in situ derivatization for the determination of chlorophenols by gas chromatography-electron capture detection.

    Science.gov (United States)

    Saraji, Mohammad; Ghani, Milad

    2015-10-30

    A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis. PMID:26411480

  5. Membrane supported liquid-liquid-liquid microextraction combined with field-amplified sample injection CE-UV for high-sensitivity analysis of six cardiovascular drugs in human urine sample.

    Science.gov (United States)

    Zhou, Xiaoqing; He, Man; Chen, Beibei; Yang, Qing; Hu, Bin

    2016-05-01

    An effective dual preconcentration method involving off-line membrane supported liquid-liquid-liquid microextraction (MS-LLLME) and on-line field-amplified sample injection (FASI) was proposed for the extraction of six cardiovascular drugs, including mexiletine, xylocaine, propafenone, propranolol, metoprolol, and carvedilol from aqueous solution prior to CE-UV. In MS-LLLME, the analytes were extracted from 9 mL sample solution into toluene, and then back extracted into a drop of acceptor phase of 10 μL 20 mmol/L acetic acid. After that, the acceptor phase was directly introduced into CE for FASI without any modification. In FASI process, water plug was hydrodynamically injected (50 mbar, 3 s) into the capillary prior to sample injection (+6 kV, 18 s). Six target analytes were separated in less than 10 min at 25°C with a BGE consisting of 70 mmol/L Tris-H3 PO4 (pH 2.2) containing 10% v/v methanol. Under the optimized conditions, LODs obtained by the proposed MS-LLLME-FASI-CE-UV method were in the range of 0.02-0.82 μg/L (based on S/N = 3) with enrichment factors of 546- to 7300-fold for the target analytes. The RSDs of the developed method were in the range of 6.7-12.9% (n = 7). Good linearity (R(2) = 0.9928-0.9997) was obtained in concentration range of 0.1-100 μg/L for mexiletine and propranolol, 0.2-100 μg/L for xylocaine and metoprolol, 0.5-100 μg/L for propafenone and 2.0-100 μg/L for carvedilol, respectively. The developed method was successfully applied for real-time determination of metoprolol in human urine samples within 26 h after uptake. PMID:26763094

  6. Evaluation of the combination of a dispersive liquid-liquid microextraction method with micellar electrokinetic chromatography coupled to mass spectrometry for the determination of estrogenic compounds in milk and yogurt.

    Science.gov (United States)

    D'Orazio, Giovanni; Asensio-Ramos, María; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Ángel; Fanali, Salvatore

    2015-02-01

    In this work, the suitability of a methodology based on dispersive liquid-liquid microextraction (DLLME) has been evaluated for the extraction of four endoestrogens (estriol, 17α-estradiol, 17β-estradiol, and estrone), an exoestrogen (17α-etynylestradiol), and a mycotoxin (zearalenone), together with some of their major metabolites (2-methoxyestradiol, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol) from different types of milk (whole and skimmed cow milk and semiskimmed goat milk) and whole natural yogurt. The methodology includes a previous protein precipitation with acidified ACN and a defatting step with n-hexane. Separation of the analytes, determination, and quantification were developed by MEKC coupled to ESI-MS using a BGE containing an aqueous solution of ammonium perfluorooctanoate as MS friendly surfactant. Calibration, precision, and accuracy studies of the described DLLME-MEKC-MS/MS method were evaluated obtaining a good linearity and LODs in the low micrograms per liter range.

  7. RECOVERY OF CARBOXYLIC ACIDS FROM AQUEOUS SOLUTIONS BY LIQUID-LIQUID EXTRACTION WITH A TRIISOOCTYLAMINE DILUENT SYSTEM

    Directory of Open Access Journals (Sweden)

    G. Malmary

    2001-12-01

    Full Text Available Tertiary alkylamines in solution with organic diluents are attractive extractants for the recovery of carboxylic acids from dilute aqueous phases. The aim of this study was to investigate the mechanism for extraction of organic acids from water by a long-chain aliphatic tertiary amine. In order to attain this objective, we studied the liquid-liquid equilibria between the triisooctylamine + 1-octanol + n-heptane system as solvent and an aqueous solution of an individual carboxylic acid such as citric, lactic and malic acids. The experiments showed that the partition coefficient for a particular organic acid depends on the kind of solute, notably when the acid concentration in the aqueous phase is low. A mathematical model, where both chemical association and physical distribution are taken into consideration, is proposed. The model suggests that the various complexes obtained between amine and organic acids contribute to the distribution of the solute between the coexisting phases in equilibrium.

  8. Salt effect on (liquid + liquid) equilibrium of (water + tert-butanol + 1-butanol) system: Experimental data and correlation

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Milton A.P. [School of Chemical Engineering, State University of Campinas, P.O. Box 6066, Campinas-SP 13081-970 (Brazil); Aznar, Martin [School of Chemical Engineering, State University of Campinas, P.O. Box 6066, Campinas-SP 13081-970 (Brazil)]. E-mail: maznar@feq.unicamp.br

    2006-01-15

    (Liquid + liquid) equilibrium data for the quaternary systems (water + tert-butanol + 1-butanol + KBr) and (water + tert-butanol + 1-butanol + MgCl{sub 2}) were experimentally determined at T = 293.15 K and T = 313.15 K. For mixtures with KBr, the overall salt concentrations were 5 and 10 mass percent; for mixtures with MgCl{sub 2}, the overall salt concentrations were 2 and 5 mass percent. The experimental results were used to estimate molecular interaction parameters for the NRTL activity coefficient model, using the Simplex minimization method and a concentration-based objective function. The correlation results are extremely satisfactory, with deviations in phase compositions below 1.7%.

  9. Determination of trace amount of lead in industrial and municipal effluent water samples based on dispersive liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Shirkhanloo, H. [Iranian Petroleum Industry Health Research Institute, Occupational and Environmental Health Research Center, Tehran (Iran, Islamic Republic of); Sedighi, K.; Mousavi, H. Z., E-mail: hzmousavi@semnan.ac.ir [Semnan University, College of Science, Department of Chemistry, Semnan (Iran, Islamic Republic of)

    2014-10-01

    In this study, a simple, sensitive and accurate method was developed for the determination of lead ion by combining ionic liquid dispersive liquid-liquid extraction (Il-DLL E) with flame atomic absorption spectrometry. Tetraethyl thiuram disulfide (Tetd), acetone and 1-octyl-3m ethylimidazolium hexafluorophosphate [(C{sub 8}MIM) (PF{sub 6})] were used as the chelating agent, dispersive and extraction solvent, respectively. Under the optimal conditions, the calibration graph was linear in the range of 5-190 μg L{sup -1} of lead and the detection limit was 0.8 μg L{sup -1} with a sample volume of 200 ml. The proposed method was validated by the analysis of one certified reference material and applied successfully to the determination of lead in real water samples. (Author)

  10. Development of dispersive liquid-liquid microextraction based on solidification of floating organic drop for the determination of trace nickel.

    Science.gov (United States)

    Wang, Yukun; Zhang, Jingwen; Zhao, Bin; Du, Xin; Ma, Jingjun; Li, Jingci

    2011-12-01

    A liquid-phase microextraction technique was developed using dispersive liquid-liquid microextraction based on solidification of floating organic drop combined with flame atomic absorption spectrometry, for the extraction and determination of trace amounts of nickel in water samples. Microextraction efficiency factors, such as the type and volume of extraction and dispersive solvents, pH, extraction time, the chelating agent amount, and ionic strength, were investigated and optimized. Under optimum conditions, the calibration graph was linear in the range of 4.23-250 μg L(-1) with a detection limit of 1.27 μg L(-1). The relative standard deviation for ten replicate measurements of 10 and 100 μg L(-1) of nickel were 3.21% and 2.55%, respectively. The proposed method was assessed through the analysis of certified reference water or recovery experiments. PMID:21598026

  11. A microfluidic platform for the rapid determination of distribution coefficients by gravity assisted droplet-based liquid-liquid extraction

    DEFF Research Database (Denmark)

    Poulsen, Carl Esben; Wootton, Robert C. R.; Wolff, Anders;

    2015-01-01

    The determination of pharmacokinetic properties of drugs, such as the distribution coefficient, D, is a crucial measurement in pharmaceutical research. Surprisingly, the conventional (gold standard) technique used for D measurements, the shake-flask method, is antiquated and unsuitable for the te......The determination of pharmacokinetic properties of drugs, such as the distribution coefficient, D, is a crucial measurement in pharmaceutical research. Surprisingly, the conventional (gold standard) technique used for D measurements, the shake-flask method, is antiquated and unsuitable...... for the testing of valuable and scarce drug candidates. Herein we present a simple micro fluidic platform for the determination of distribution coefficients using droplet-based liquid-liquid extraction. For simplicity, this platform makes use of gravity to enable phase separation for analysis and is 48 times...

  12. Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements. Predictions properly give the flow behavior observed in experiments, such as the Rankine-vortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocyclones is inhomogeneous and anisotropic.

  13. A Liquid-Liquid Thermoelectric Heat Exchanger as a Heat Pump for Testing Phase Change Material Heat Exchangers

    Science.gov (United States)

    Sheth, Rubik B.; Makinen, Janice; Le, Hung V.

    2016-01-01

    The primary objective of the Phase Change HX payload on the International Space Station (ISS) is to test and demonstrate the viability and performance of Phase Change Material Heat Exchangers (PCM HX). The system was required to pump a working fluid through a PCM HX to promote the phase change material to freeze and thaw as expected on Orion's Multipurpose Crew Vehicle. Due to limitations on ISS's Internal Thermal Control System, a heat pump was needed on the Phase Change HX payload to help with reducing the working fluid's temperature to below 0degC (32degF). This paper will review the design and development of a TEC based liquid-liquid heat exchanger as a way to vary to fluid temperature for the freeze and thaw phase of the PCM HX. Specifically, the paper will review the design of custom coldplates and sizing for the required heat removal of the HX.

  14. (Liquid + liquid) equilibria in ternary aqueous mixtures of phosphoric acid with organic solvents at T = 298.2 K

    Energy Technology Data Exchange (ETDEWEB)

    Ghanadzadeh, H., E-mail: hggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Department of Chemical Engineering, University of Guilan, Rasht (Iran, Islamic Republic of); Ghanadzadeh, A., E-mail: aggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Aghajani, Z.; Abbasnejad, S.; Shekarsaraee, S. [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of)

    2010-06-15

    (Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of left bracewater (1) + phosphoric acid (2) + organic solvents (3)right brace were determined at T = 298.2 K and atmospheric pressure. The organic solvents were cyclohexane, 2-methyl-2-butanol (tert-amyl alcohol), and isobutyl acetate. All the investigated systems exhibit Type-1 behaviour of LLE. The immiscibility region was found to be larger for the (water + phosphoric acid + cyclohexane) ternary system. The experimental LLE results were correlated with the NRTL model, and the binary interaction parameters were obtained. The reliability of the experimental tie-line results was tested through the Othmer-Tobias and Bachman correlation equations. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to these factors. The experimental results indicate the superiority of cyclohexane as the preferred solvent for the extraction of phosphoric acid from its aqueous solutions.

  15. Synthesis of Ag-Au bimetallic film at liquid-liquid interface and its application in vapor sensing

    Energy Technology Data Exchange (ETDEWEB)

    Pasricha, Renu, E-mail: pasrichar@mail.nplindia.ernet.i [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Gupta, Shweta [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Sastry, M. [Tata Chemical Innovation Center, Anmol Pride, Baner Road, Pune-45 (India); Singh, Nahar; Gupta, Prabhat [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India)

    2010-11-30

    We demonstrate a novel process for preparing densely packed film of silver nanoparticles at the liquid-liquid interface followed by a transmetallation reaction with gold ion to yield a film of bimetallic nanoparticles. Films of assembled silver as well as Ag-Au bimetallic were characterized by UV-vis-spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. I-V measurement shows linear behavior for both the films with ca. five orders of magnitude drop in resistance for the Ag-Au bimetallic film. Temperature dependent I-V measurement revealed a semiconductor to metal transition after transmetallation reaction. The films where checked for their potential application in chemical vapor sensing to ammonia vapors.

  16. Liquid-liquid extraction of ion-association complexes of cobalt(II-4-(2-pyridylazoresorcinol with ditetrazolium salts

    Directory of Open Access Journals (Sweden)

    Divarova Vidka V.

    2015-01-01

    Full Text Available The formation and liquid-liquid extraction of ion-association complexes between Co(II-4-(2-Pyridylazoresorcinol (PAR anionic chelates and cations of three ditetrazolium chlorides were studied: Blue Tetrazolium chloride (BTC, Neotetrazolium chloride (NTC and Nitro Blue Tetrazolium chloride (NBT. The optimum conditions for the formation and solvent extraction of the ion-association comlpex chelates were determined. It has been found that in the systems of Co(II-PAR-DTS, the reactants are reacted in molar ratios 1:2:1 and the general formula of complexes was suggested. The extraction equilibria were investigated and quantitatively characterized by the equilibrium constants and the recovery factors. The analytical characteristics of the complexes were calculated.

  17. Facilitated Ion Transfer Across the Micro-liquid/Liquid Interface Supported at the Tip of a Silanized Micropipette

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Glass micropipettes with silanized inner walls can be filled with an organic solvent for voltammetric measurements in an aqueous solution. This arrangement was employed to investigate systematically the mechanism of facilitated potassium ion transfer by an ionophore dibenzo-18-crown-6(DB18C6) across a micro-water/1,2-dichloroethane(W/DCE) interface supported at the tip of a silanized micropipette. Our experimental results verify that this facilitated ion transfer across the liquid/liquid interface did occur by an interfacial complexation-dissociation process(TIC-TID mechanism). The ratio of the diffusion coefficient of DB18C6 to that of its complexed ion in the DCE phase was calculated to be 1.74±0.07.

  18. Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

    Institute of Scientific and Technical Information of China (English)

    陆耀军; 周力行; 沈熊

    2000-01-01

    The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements . Predictions properly give the flow behavior observed in experiments, such as the Rankine-vortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocy-clones is inhomogeneous and anisotropic.

  19. Trace recovery of uranium and rare earth contained in phosphates by liquid-liquid extraction in sulfuric attack liquor

    International Nuclear Information System (INIS)

    Uranium and rare earths can be recovered in sedimentary phosphates during the wet processing of the ore by sulfuric acid giving raw phosphoric acid at 30 per cent of P2O5. Practically all the uranium contained and only part of rare earths are put into solution in this treatment. Separation of these elements in the phosphoric solution is obtained by liquid-liquid extraction with alkylphosphoric acids and especially with their mono and di esters. Partition isotherms are determined and counter-current tests are effected. Uranium and rare earths reextraction from these solvents can be simultaneous or separate with aqueous solutions alkaline or containing HF or by antisynergism. Pros and cons of each reextraction process are discussed. In conclusion HDEHP or OPPA are recommended because of availability, stability and hydrodynamic, OPPA less selective with rare earths allows the recovery with uranium of ceric earths, yttrium and yttric earths

  20. The status of research on CFD-PBM simulation of liquid-liquid two-phase flow in extraction columns

    International Nuclear Information System (INIS)

    Computational fluid dynamics (CFD) simulation has gained more and more interest in the chemical engineering researchers and is becoming a useful tool for the chemical engineering research. The research on liquid-liquid two-phase flow CFD simulation in extraction columns is now in its initial stage. There is much work to do for the developing of this research field. The purpose of this article is to review the CFD simulation methods for two-phase flow in extraction column. The population balance model (PBM) is detailedly described in this article because it is the main method used in the two-phase flow CFD simulation currently. Then some examples for the two-phase flow simulation in extraction columns are briefly introduced. The strategy for the research on CFD simulation of two-phase flow in extraction columns is suggested at last. (authors)

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

    International Nuclear Information System (INIS)

    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 13C12-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 cm2 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 13C12-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

  2. Optimization of ultrasound assisted dispersive liquid-liquid microextraction of six antidepressants in human plasma using experimental design.

    Science.gov (United States)

    Fernández, P; Taboada, V; Regenjo, M; Morales, L; Alvarez, I; Carro, A M; Lorenzo, R A

    2016-05-30

    A simple Ultrasounds Assisted-Dispersive Liquid Liquid Microextraction (UA-DLLME) method is presented for the simultaneous determination of six second-generation antidepressants in plasma by Ultra Performance Liquid Chromatography with Photodiode Array Detector (UPLC-PDA). The main factors that potentially affect to DLLME were optimized by a screening design followed by a response surface design and desirability functions. The optimal conditions were 2.5mL of acetonitrile as dispersant solvent, 0.2mL of chloroform as extractant solvent, 3min of ultrasounds stirring and extraction pH 9.8.Under optimized conditions, the UPLC-PDA method showed good separation of antidepressants in 2.5min and good linearity in the range of 0.02-4μgmL(-1), with determination coefficients higher than 0.998. The limits of detection were in the range 4-5ngmL(-1). The method precision (n=5) was evaluated showing relative standard deviations (RSD) lower than 8.1% for all compounds. The average recoveries ranged from 92.5% for fluoxetine to 110% for mirtazapine. The applicability of DLLME/UPLC-PDA was successfully tested in twenty nine plasma samples from antidepressant consumers. Real samples were analyzed by the proposed method and the results were successfully submitted to comparison with those obtained by a Liquid Liquid Extraction-Gas Chromatography - Mass Spectrometry (LLE-GC-MS) method. The results confirmed the presence of venlafaxine in most cases (19 cases), followed by sertraline (3 cases) and fluoxetine (3 cases) at concentrations below toxic levels. PMID:26955756

  3. Quaternary liquid/liquid equilibria of sodium sulfate, sodium sulfite and water with two solvents: Acetone and 2-propanol

    Energy Technology Data Exchange (ETDEWEB)

    Schiozer, A.L.

    1994-03-01

    Aqueous solutions of sodium sulfate and sodium sulfite are produced from sodium carbonate in flue-gas scrubbers; recovery of these salts often requires multi-effect evaporators; however, a new energy-efficient unit operation called extractive crystallization has been shown to have reduced energy costs. In this process, an organic solvent is added to the aqueous salt solution to precipitate salt. Acetone is a suitable solvent for this process, better than 2-propanol. Liquid/liquid/solid equilibria for ternary systems containing a salt, water, and an organic solvent were measured. Systems investigated were sodium sulfite/water/acetone and sodium sulfite/water/2-propanol. Experiments were conducted at salt saturation covering a temperature range between the lower consolute temperature and 48.6{degrees}C. In the attempt to improve the extractive crystallization process for recovery of sodium sulfate from flue-gas scrubbers, attention was given to a feed containing a mixture of sodium sulfite and sodium sulfate. Liquid-liquid equilibria for quaternary systems containing two salts, water, and an organic solvent were experimentally determined at 35{degrees}C. The systems investigated were sodium sulfate/sodium sulfite/water/acetone and sodium sulfate/sodium sulfite/water/2propanol. The systems were studied at three salt ratios. For each salt ratio, experiments were conducted starting at saturation, water was then added until the one-phase region was reached. Mixtures of the two salts proved to have a small disadvantage relative to the 100 % sulfate feed process. Therefore, a sulfate-based extractive crystallization process is recommended.

  4. Simulations of electrolytes at the liquid-liquid interface and of lanthanide cations complexes in gas phase

    International Nuclear Information System (INIS)

    Two processes related to liquid/liquid extraction of ions by extractant molecules were studied: the ion approach at the interface and the ion complexation by ligands. In the first part, the behaviour of salts at the chloroform/water interface was simulated by molecular dynamics. The aim was to understand the way these salts ions approach the interface in order to be extracted. Some ions are repelled by the interface (K+, Cl-, UO22+, Na+, NO3-) whereas others adsorb (amphiphilic molecules and also ClO4-, SCN-, guanidinium Gu+ and picrate Pic-). The surface-active counter-ions make the ion approach at the interface easier. In a perfectly homogeneous mixture of the two solvents (water and chloroform) de-mixing, the ions seem to influence the phases separation rate. Nitric acid which is known to favour liquid/liquid extraction reveals strong adsorption at the interface in its neutral form and a smaller one in its ionic form (H3O+/NO3-). HNO3 and H3O+ display particular orientations at the interface: hydrogen atoms are pointing in the direction of the water slab. The nature of the organic phase can also influence the ion approach at the interface. For example, Gu+ and Pic- adsorb much less at the supercritical CO2/water interface than at the chloroform/water interface. In the second part, complexes of La3+, Eu3+ and Yb3+ with ligands such as amide, urea, thio-amide, thiourea were studied by quantum mechanics. Our calculations show that cation-ligand interactions depend on the nature of substituents on ligands, on the presence of counter-ions or on the number of ligands in the complex. Sulfur compounds seem to less interact with cations than oxygen compounds. Ureas interact as much as amides and are potentially good ligands. (author)

  5. Techno-economic analysis for incorporating a liquid-liquid extraction system to remove acetic acid into a proposed commercial scale biorefinery.

    Science.gov (United States)

    Aghazadeh, Mahdieh; Engelberth, Abigail S

    2016-07-01

    Mitigating the effect of fermentation inhibitors in bioethanol plants can have a great positive impact on the economy of this industry. Liquid-liquid extraction (LLE) using ethyl acetate is able to remove fermentation inhibitors-chiefly, acetic acid-from an aqueous solution used to produce bioethanol. The fermentation broth resulting from LLE has higher performance for ethanol yield and its production rate. Previous techno-economic analyses focused on second-generation biofuel production did not address the impact of removing the fermentation inhibitors on the economic performance of the biorefinery. A comprehensive analysis of applying a separation system to mitigate the fermentation inhibition effect and to provide an analysis on the economic impact of removal of acetic acid from corn stover hydrolysate on the overall revenue of the biorefinery is necessary. This study examines the pros and cons associated with implementing LLE column along with the solvent recovery system into a commercial scale bioethanol plant. Using details from the NREL-developed model of corn stover biorefinery, the capital costs associated with the equipment and the operating cost for the use of solvent were estimated and the results were compared with the profit gain due to higher ethanol production. Results indicate that the additional capital will add 1% to the total capital and manufacturing cost will increase by 5.9%. The benefit arises from the higher ethanol production rate and yield as a consequence of inhibitor extraction and results in a $0.35 per gallon reduction in the minimum ethanol selling price (MESP). © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:971-977, 2016. PMID:27390294

  6. Determination of geosmin and 2-methylisoborneol in water and wine samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cortada, Carol; Vidal, Lorena; Canals, Antonio

    2011-01-01

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USADLLME) procedure has been developed to preconcentrate geosmin and 2-methylisoborneol (MIB) from water and wine samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). 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 USADLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: solvent volume, 8μL; solvent type: tetrachloroethylene; sample volume, 12 mL; centrifugation speed, 2300 rpm; extraction temperature 20 °C; extraction time, 3 min; and centrifugation time, 3 min. Under the optimized experimental conditions the method gave good levels of repeatability with coefficient of variation under 11% (n=10). Limits of detection were 2 and 9 ng L⁻¹ for geosmin and MIB, respectively. Calculated calibration curves gave high levels of linearity with correlation coefficient values of 0.9988 and 0.9994 for geosmin and MIB, respectively. Finally, the proposed method was applied to the analysis of two water (reservoir and tap) samples and three wine (red, rose and white) samples. The samples were previously analyzed and confirmed free of target analytes. Recovery values ranged between 70 and 113% at two spiking levels (0.25 μg L⁻¹ and 30 ng L⁻¹) showing that the matrix had a negligible effect upon extraction. Only red wine showed a noticeable matrix effect (70-72% recovery). Similar conclusions have been obtained from an uncertainty budget evaluation study.

  7. Development and validation of an automated liquid-liquid extraction GC/MS method for the determination of THC, 11-OH-THC, and free THC-carboxylic acid (THC-COOH) from blood serum.

    Science.gov (United States)

    Purschke, Kirsten; Heinl, Sonja; Lerch, Oliver; Erdmann, Freidoon; Veit, Florian

    2016-06-01

    The analysis of Δ(9)-tetrahydrocannabinol (THC) and its metabolites 11-hydroxy-Δ(9)-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THC-COOH) from blood serum is a routine task in forensic toxicology laboratories. For examination of consumption habits, the concentration of the phase I metabolite THC-COOH is used. Recommendations for interpretation of analysis values in medical-psychological assessments (regranting of driver's licenses, Germany) include threshold values for the free, unconjugated THC-COOH. Using a fully automated two-step liquid-liquid extraction, THC, 11-OH-THC, and free, unconjugated THC-COOH were extracted from blood serum, silylated with N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and analyzed by GC/MS. The automation was carried out by an x-y-z sample robot equipped with modules for shaking, centrifugation, and solvent evaporation. This method was based on a previously developed manual sample preparation method. Validation guidelines of the Society of Toxicological and Forensic Chemistry (GTFCh) were fulfilled for both methods, at which the focus of this article is the automated one. Limits of detection and quantification for THC were 0.3 and 0.6 μg/L, for 11-OH-THC were 0.1 and 0.8 μg/L, and for THC-COOH were 0.3 and 1.1 μg/L, when extracting only 0.5 mL of blood serum. Therefore, the required limit of quantification for THC of 1 μg/L in driving under the influence of cannabis cases in Germany (and other countries) can be reached and the method can be employed in that context. Real and external control samples were analyzed, and a round robin test was passed successfully. To date, the method is employed in the Institute of Legal Medicine in Giessen, Germany, in daily routine. Automation helps in avoiding errors during sample preparation and reduces the workload of the laboratory personnel. Due to its flexibility, the analysis system can be employed for other liquid-liquid extractions as

  8. Development and validation of an automated liquid-liquid extraction GC/MS method for the determination of THC, 11-OH-THC, and free THC-carboxylic acid (THC-COOH) from blood serum.

    Science.gov (United States)

    Purschke, Kirsten; Heinl, Sonja; Lerch, Oliver; Erdmann, Freidoon; Veit, Florian

    2016-06-01

    The analysis of Δ(9)-tetrahydrocannabinol (THC) and its metabolites 11-hydroxy-Δ(9)-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THC-COOH) from blood serum is a routine task in forensic toxicology laboratories. For examination of consumption habits, the concentration of the phase I metabolite THC-COOH is used. Recommendations for interpretation of analysis values in medical-psychological assessments (regranting of driver's licenses, Germany) include threshold values for the free, unconjugated THC-COOH. Using a fully automated two-step liquid-liquid extraction, THC, 11-OH-THC, and free, unconjugated THC-COOH were extracted from blood serum, silylated with N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and analyzed by GC/MS. The automation was carried out by an x-y-z sample robot equipped with modules for shaking, centrifugation, and solvent evaporation. This method was based on a previously developed manual sample preparation method. Validation guidelines of the Society of Toxicological and Forensic Chemistry (GTFCh) were fulfilled for both methods, at which the focus of this article is the automated one. Limits of detection and quantification for THC were 0.3 and 0.6 μg/L, for 11-OH-THC were 0.1 and 0.8 μg/L, and for THC-COOH were 0.3 and 1.1 μg/L, when extracting only 0.5 mL of blood serum. Therefore, the required limit of quantification for THC of 1 μg/L in driving under the influence of cannabis cases in Germany (and other countries) can be reached and the method can be employed in that context. Real and external control samples were analyzed, and a round robin test was passed successfully. To date, the method is employed in the Institute of Legal Medicine in Giessen, Germany, in daily routine. Automation helps in avoiding errors during sample preparation and reduces the workload of the laboratory personnel. Due to its flexibility, the analysis system can be employed for other liquid-liquid extractions as

  9. Ternary and quaternary (liquid + liquid) equilibria for (water + ethanol + {alpha}-pinene, +{beta}-pinene, or +limonene) and (water + ethanol + {alpha}-pinene + limonene) at the temperature 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Li Hengde [Department of Chemistry and Chemical Engineering, Division of Material Engineering and Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Tamura, Kazuhiro [Department of Chemistry and Chemical Engineering, Division of Material Engineering and Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)]. E-mail: tamura@t.kanazawa-u.ac.jp

    2006-08-15

    (Liquid + liquid) equilibria and tie-lines for the ternary (water + ethanol + {alpha}-pinene, or {beta}-pinene or limonene) and quaternary (water + ethanol + {alpha}-pinene + limonene) mixtures have been measured at T = 298.15 K. The experimental multicomponent (liquid + liquid) equilibrium data have been successfully represented in terms of the modified UNIQUAC model with binary parameters.

  10. Liquid-liquid equilibria for binary and ternary systems containing glycols, aromatic hydrocarbons, and water: Experimental measurements and modeling with the CPA EoS

    DEFF Research Database (Denmark)

    Folas, Georgios; Kontogeorgis, Georgios; Michelsen, Michael Locht;

    2006-01-01

    Liquid-liquid equilibrium data of four binary glycol + aromatic hydrocarbon systems and three ternary systems containing water have been measured at atmospheric pressure. The measured systems are monoethylene glycol (MEG) + benzene or toluene, triethylene glycol (TEG) + benzene or toluene, MEG + ...

  11. Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

    Science.gov (United States)

    Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

    2016-01-01

    Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

  12. In situ liquid-liquid extraction as a sample preparation method for matrix-assisted laser desorption/ionization MS analysis of polypeptide mixtures

    DEFF Research Database (Denmark)

    Kjellström, Sven; Jensen, Ole Nørregaard

    2003-01-01

    A novel liquid-liquid extraction (LLE) procedure was investigated for preparation of peptide and protein samples for matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). LLE using ethyl acetate as the water-immiscible organic solvent enabled segregation of hydrophobic...

  13. The effect of the interaction between the minority phase droplets on the nucleation behavior during the liquid-liquid phase transformation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The microstructure evolution during the liquid-liquid phase transformation of Al-Pb alloy was calculated. The numerical results indicate that the interaction between the minority phase droplets has effect on the nucleation process of the droplets, and the effect increases with the cooling rate and the content of Pb.

  14. Changing Hydrogen-Bond Structure during an Aqueous Liquid-Liquid Transition Investigated with Time-Resolved and Two-Dimensional Vibrational Spectroscopy

    NARCIS (Netherlands)

    J.R. Bruijn; T.H. van der Loop; S. Woutersen

    2016-01-01

    We investigate the putative liquid-liquid phase transition in aqueous glycerol solution, using the OD-stretch mode in dilute OD/OH isotopic mixtures to probe the hydrogen-bond structure. The conversion exhibits Avrami kinetics with an exponent of n = 2.9 +/- 0.1 (as opposed to n = 1.7 observed upon

  15. Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2010-05-01

    Full Text Available Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008. This model allows the reliable computation of the liquid-liquid coexistence curve (binodal, corresponding tie-lines, the limit of stability/metastability (spinodal, and further thermodynamic properties of the phase diagram. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six

  16. Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2010-08-01

    Full Text Available Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008. This model allows the reliable computation of the liquid-liquid coexistence curve (binodal, corresponding tie-lines, the limit of stability/metastability (spinodal, and further thermodynamic properties of multicomponent systems. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six

  17. Electro-oxidative leaching of pitchblende for uranium determination by arsenazo III spectrophotometry using fluid injection analysis system; Lixiviacao eletro-oxidativa de pechblenda para determinacao de uranio por espectrofotometria com arsenazo III empregando um sistema de analises por injecao em fluxo

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Alvaro Serafim Ferreira de

    2006-07-01

    In this work two different electro dissolution cells were projected and tested in order to solubilize pitchblende minerals aiming to posterior on line association to a flow injection system for the spectrophotometric determination of uranium leachate. The influence of current density, time, temperature, the electrolyte concentration nature, and the particle suspension density, were studied. Hydrodynamic and chemical parameters effects were evaluated to establish the best efficiency of the flow injection analysis system and to receive samples pretreated by electro oxidative leaching for the uranium determination. Arsenazo III was used as a colorimetric reagent and parameters such as acidity and reagents concentration, carrier and reagent flow rates, injection volume, reactor and reduction column size were studied and optimized. The calibration curves have showed a linear behavior (R{sup 2} = 0.9996) between the concentration range of 0.05 and 2.0 mgL{sup -1}. A relative deviation standard of 5.5 % (at 0.1 mgL{sup -1}) and a detection limit of 0.02 mgL{sup -1} were obtained, as well an analytical throughput of 60 sample determinations per hour. In the association of the flow injected analysis system with the electro-dissolution cells, values up to 98 % were obtained for the uranium extraction. The developed methodology for the electrooxidative extraction and on line spectrophotometric uranium determination in pitchblende samples, showed agreement with the reference method (ICP-MS), with a deviation between the results of less than 3.5 %. The proposal system showed advantages in relation to the conventional technique, like: automation of all analytical process, less quantities and more swiftness in the sample dissolution, less volume and acid concentration and reduction of the matrix effect. (author)

  18. Simulations of electrolytes at the liquid-liquid interface and of lanthanide cations complexes in gas phase; Simulations d'electrolytes a l'interface liquide/liquide et de complexes de cations lanthanides en phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Berny, F

    2000-07-01

    Two processes related to liquid/liquid extraction of ions by extractant molecules were studied: the ion approach at the interface and the ion complexation by ligands. In the first part, the behaviour of salts at the chloroform/water interface was simulated by molecular dynamics. The aim was to understand the way these salts ions approach the interface in order to be extracted. Some ions are repelled by the interface (K{sup +}, Cl{sup -}, UO{sub 2}{sup 2+}, Na{sup +}, NO{sub 3}{sup -}) whereas others adsorb (amphiphilic molecules and also ClO{sub 4}{sup -}, SCN{sup -}, guanidinium Gu{sup +} and picrate Pic{sup -}). The surface-active counter-ions make the ion approach at the interface easier. In a perfectly homogeneous mixture of the two solvents (water and chloroform) de-mixing, the ions seem to influence the phases separation rate. Nitric acid which is known to favour liquid/liquid extraction reveals strong adsorption at the interface in its neutral form and a smaller one in its ionic form (H{sub 3}O{sup +}/NO{sub 3}{sup -}). HNO{sub 3} and H{sub 3}O{sup +} display particular orientations at the interface: hydrogen atoms are pointing in the direction of the water slab. The nature of the organic phase can also influence the ion approach at the interface. For example, Gu{sup +} and Pic{sup -} adsorb much less at the supercritical CO{sub 2}/water interface than at the chloroform/water interface. In the second part, complexes of La{sup 3+}, Eu{sup 3+} and Yb{sup 3+} with ligands such as amide, urea, thio-amide, thiourea were studied by quantum mechanics. Our calculations show that cation-ligand interactions depend on the nature of substituents on ligands, on the presence of counter-ions or on the number of ligands in the complex. Sulfur compounds seem to less interact with cations than oxygen compounds. Ureas interact as much as amides and are potentially good ligands. (author)

  19. 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. PMID:26695329

  20. Ultrafast magnetic-resonance-imaging velocimetry of liquid-liquid systems: overcoming chemical-shift artifacts using compressed sensing.

    Science.gov (United States)

    Tayler, Alexander B; Benning, Martin; Sederman, Andrew J; Holland, Daniel J; Gladden, Lynn F

    2014-06-01

    We present simultaneous measurement of dispersed and continuous phase flow fields for liquid-liquid systems obtained using ultrafast magnetic resonance imaging. Chemical-shift artifacts, which are otherwise highly problematic for this type of measurement, are overcome using a compressed sensing based image reconstruction algorithm that accounts for off-resonant signal components. This scheme is combined with high-temporal-resolution spiral imaging (188 frames per second), which is noted for its robustness to flow. It is demonstrated that both quantitative signal intensity and phase preconditioning are preserved throughout the image reconstruction algorithm. Measurements are acquired of oil droplets of varying viscosity rising through stagnant water. From these data it is apparent that the internal droplet flow fields are heavily influenced by the droplet shape oscillations, and that the accurate modeling of droplet shape is of critical importance in the modeling of droplet-side hydrodynamics. The application of the technique to three-component systems is also demonstrated, as is the measurement of local concentration maps of a mutually soluble species (acetone in polydimethylsiloxane-water).

  1. Dual dispersive liquid-liquid microextraction for determination of phenylpropenes in oils by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Tsai, Chia-Ju; Li, Jih-Heng; Feng, Chia-Hsien

    2015-09-01

    A novel, simple and quick sample preparation method was developed and used for pre-concentration and extraction of six phenylpropenes, including anethole, estragole, eugenol, methyl eugenol, safrole and myristicin, from oil samples by dual dispersive liquid-liquid microextraction. Gas chromatography-mass spectrometry was used for determination and separation of compounds. Several experimental parameters affecting extraction efficiency were evaluated and optimized, including forward-extractant type and volume, surfactant type and concentration, water volume, and back-extractant type and volume. For all analytes (10-1000ng/mL), the limits of detection (S/N≧3) ranged from 1.0 to 3.0ng/mL; the limits of quantification (S/N≧10) ranged from 2.5 to 10.0ng/mL; and enrichment factors ranged from 3.2 to 37.1 times. Within-run and between-run relative standard deviations (n=6) were less than 2.61% and less than 4.33%, respectively. Linearity was excellent with determination coefficients (r(2)) above 0.9977. The experiments showed that the proposed method is a simple, effective, and environmentally friendly method of analyzing phenylpropenes in oil samples.

  2. Rapid removal of nitrobenzene in a three-phase ozone loaded system with gas-liquid-liquid

    Science.gov (United States)

    Li, Shiyin; Zhu, Jiangpeng; Wang, Guoxiang; Ni, Lixiao; Zhang, Yong; Green, Christopher T.

    2015-01-01

    This study explores the removal rate of nitrobenzene (NB) using a new gas-liquid-liquid (G-L-L) three-phase ozone loaded system consisting of a gaseous ozone, an aqueous solvent phase, and a fluorinated solvent phase (perfluorodecalin, or FDC). The removal rate of NB was quantified in relation to six factors including 1) initial pH, 2) initial NB dosage, 3) gaseous ozone dosage, 4) free radical scavenger, 5) FDC pre-aerated gaseous ozone, and 6) reuse of FDC. The NB removal rate is positively affected by the first three factors. Compared with the conventional gas-liquid (water) (G-L) two-phase ozonation system, the free radical scavenger (tertiary butyl alcohol) has much less influence on the removal rate of NB in the G-L-L system. The FDC loaded ozone acts as an ozone reservoir and serves as the main reactive phase in the G-L-L three-phase system. The reuse of FDC has little influence on the removal rate of NB. These experimental results suggest that the oxidation efficiency of ozonation in the G-L-L three-phase system is better than that in the conventional G-L two-phase system.

  3. Estrogens determination in wastewater samples by automatic in-syringe dispersive liquid-liquid microextraction prior silylation and gas chromatography.

    Science.gov (United States)

    González, Alba; Avivar, Jessica; Cerdà, Víctor

    2015-09-25

    A new procedure for the extraction, preconcentration and simultaneous determination of the estrogens most used in contraception pharmaceuticals (estrone, 17β-estradiol, estriol, and 17α-ethynylestradiol), cataloged as Contaminants of Emergent Concern by the Environmental Protection Agency of the United States (US-EPA), is proposed. The developed system performs an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction (in-syringe-MSA-DLLME) prior derivatization and gas chromatography (GC-MS). Different extraction (carbon tetrachloride, ethyl acetate, chloroform and trichloroethylene) and disperser solvents (acetone, acetonitrile and methanol) were tested. Chloroform and acetone were chosen as extraction and disperser solvent, respectively, as they provided the best extraction efficiency. Then, a multivariate optimization of the extraction conditions was carried out. Derivatization conditions were also studied to ensure the conversion of the estrogens to their respective trimethylsilyl derivatives. Low LODs and LOQs were achieved, i.e. between 11 and 82ngL(-1), and 37 and 272ngL(-1), respectively. Good values for intra and inter-day precision were obtained (RSDs≤7.06% and RSD≤7.11%, respectively). The method was successfully applied to wastewater samples.

  4. Determination of calcium stearate in polyolefin samples by gas chromatographic technique after performing dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Ranji, Ali; Ghorbani Ravandi, Mahboobeh; Farajzadeh, Mir Ali

    2008-05-01

    In this study, a gas chromatographic method is presented for the determination of calcium stearate after its conversion to stearic acid in a polymeric matrix. A solution of hydrochloric acid in 2-propanol is used as an extracting solvent of calcium stearate and its converter to stearic acid. For stearic acid preconcentration before its injection to a separation system, a recently presented extraction method, dispersive liquid-liquid microextraction, using carbon tetrachloride as an extracting solvent is used. Finally, 1 microL of the organic phase collected at the bottom of a conical test tube after centrifuging is injected into a gas chromatograph (GC) for quantification. This method has a relatively broad linear dynamic range (50 - 2000 mg/L) with a limit of detection (LOD) of 15 mg/L for stearic acid in solution. The LOD of the proposed method in a polymeric sample using 10 mg of polymer is 60 ppm as calcium stearate. Some effective parameters, such as the time and temperature of heating, the concentration of hydrochloric acid and the volume of distilled water, were studied. PMID:18469468

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Qingxiang, E-mail: zhouqx@cup.edu.cn [School of Chemistry and Environmental Sciences, Henan Normal University, Henan Key Laboratory for Environmental Pollution Control, Key Laboratory for Yellow River and Huaihe River Water Environment and Pollution Control, Ministry of Education, Xinxiang 453007 (China); State Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum Beijing, Beijing 102249 (China); Zhao, Na [State Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum Beijing, Beijing 102249 (China); Xie, Guohong [College of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003 (China)

    2011-05-15

    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{sup -1} (r{sup 2} = 0.9990). The precision was 2.12% (RSD, n = 7) and the detection limit was 0.95 ng L{sup -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%.

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

    Science.gov (United States)

    Zhou, Qingxiang; Zhao, Na; Xie, Guohong

    2011-05-15

    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%. PMID:21398026

  7. 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. PMID:27374593

  8. A new coupling of spectrophotometric determination with ultrasound-assisted emulsification dispersive liquid-liquid microextraction of trace silver

    Science.gov (United States)

    Wen, Xiaodong; Kong, Lamei; Chen, Meihui; Deng, Qingwen; Zhao, Xia; Guo, Jie

    2012-11-01

    In this work, a new coupling of spectrophotometric determination with preconcentration method named as ultrasound-assisted emulsification dispersive liquid-liquid microextraction (UAE-DLLME) for trace silver was firstly established. Disperser solvent in traditional DLLME was substituted by ultrasound-assisted emulsification, which could afford more effective emulsification and make the extraction method greener. The extraction was accomplished efficiently in only 3 min during ultrasound-assisted emulsification. Compared to traditional DLLME, the established pretreatment was simpler, greener and more effective. The UAE-DLLME technique was effectively coupled with ordinary spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The factors influencing UAE-DLLME, such as concentration of chelating agent, kind and volume of extractant, pH, conditions of phase separation, ultrasound extraction time and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for silver was 0.45 μg L-1, with sensitivity enhancement factor (EF) of 35. The established method was applied to the determination of trace silver in real and certified reference samples with satisfactory analytical results.

  9. Response surface methodology for the optimization of dispersive liquid-liquid microextraction of chloropropanols in human plasma.

    Science.gov (United States)

    Gonzalez-Siso, Paula; Lorenzo, Rosa A; Regenjo, María; Fernández, Purificación; Carro, Antonia M

    2015-10-01

    Chloropropanols are processing toxicants with a potential risk to human health due to the increased intake of processed foods. A rapid and efficient method for the determination of three chloropropanols in human plasma was developed using ultrasound-assisted dispersive liquid-liquid microextraction. The method involved derivatization and extraction in one step followed by gas chromatography with tandem mass spectrometry analysis. Parameters affecting extraction, such as sample pH, ionic strength, type and volume of dispersive and extraction solvents were optimized by response surface methodology using a pentagonal design. The linear range of the method was 5-200 ng/mL for 1,3-dichloro-2-propanol, 10-200 ng/mL for 2,3-dichloro-2-propanol and 10-400 ng/mL for 3-chloropropane-1,2-diol with the determination coefficients between 0.9989 and 0.9997. The limits of detection were in the range of 0.3-3.2 ng/mL. The precision varied from 1.9 to 10% relative standard deviation (n = 9). The recovery of the method was between 91 and 101%. Advantages such as low consumption of organic solvents and short time of analysis make the method suitable for the biomonitoring of chloropropanols. PMID:26205350

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

    Science.gov (United States)

    Di Napoli-Davis, Gina; Owens, Janel E

    2013-09-01

    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)C12-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. PMID:23792388

  11. Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid-liquid extraction.

    Science.gov (United States)

    Armenta, Sergio; Garrigues, Salvador; de la Guardia, Miguel; Brassier, Judit; Alcalà, Manel; Blanco, Marcelo

    2015-03-01

    We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid-liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160μgL(-1), requires adding 0.2M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spectroscopy after LLME provides an LOD of 11μgL(-1) with the former technique and 800μgL(-1) with the latter, in addition to a limit of confirmation (LOC) of 1.5mgL(-1). Using IMS after thermal desorption simplifies the operational procedure, and using it jointly with IR spectroscopy after LLME allows double confirmation of MDMA abuse with two techniques based on different principles (viz., IMS drift times and IR spectra). Also, it affords on-site analyses, albeit at a lower throughput.

  12. Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K2CO3 Systems

    Institute of Scientific and Technical Information of China (English)

    XU Wen-you; JI Min

    2005-01-01

    KF or K2CO3 was added into the 1-butanol-water system and two phases were formed: water-rich phase (water phase) and 1-butanol-rich phase (1-butanol phase). The liquid-liquid equilibrium (LLE) data for 1-butanol-water-KF and 1-butanol-water-K2 CO3 systems were measured at 25 C and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27. 11% and 31. 68%, respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase.For 1-butanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equation, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC equation.

  13. Temperature-Induced Liquid-Liquid Transition in Metallic Melts: A Brief Review on the New Physical Phenomenon

    Directory of Open Access Journals (Sweden)

    Fang-Qiu Zu

    2015-03-01

    Full Text Available Understanding the nature of liquid structures and properties remains an open problem for many fundamental and applied fields. It is well known that there is no other defined phase line above liquidus (TL in phase diagrams of ordinary alloys. However, via resorts of internal friction, electric resistivity, thermal analysis, X-ray diffraction, solidification, etc., the results of our research on lots of single- and multiple-component melts show a novel physical image: temperature induced liquid-liquid structure transition (TI-LLST can occur above TL. Moreover, the solidification behaviors and structures out of the melts that experienced TI-LLST are distinct from those out of the melts before TI-LLST. In this paper, some typical examples of TI-LLST and characteristic aspects of the TI-LLST are briefly reviewed, in which the main contents are limited in our own achievements, although other groups have also observed similar phenomena using different methods. In the sense of phenomenology, TI-LLST reported here is quite different from other recognized liquid transitions, i.e., there are only a few convincing cases of liquid P, Si, C, H2O, Al2O3-Y2O3, etc. in which the transition occurs, either induced by pressure or at a supercooled state and near liquidus.

  14. A novel procedure for phase separation in dispersive liquid-liquid microextraction based on solidification of the aqueous phase.

    Science.gov (United States)

    March, J G; Cerdà, V

    2016-08-15

    In this paper, an alternative for handling the organic phase after a dispersive liquid-liquid microextraction using organic solvents lighter than water is presented. It is based on solidification (at -18°C) of the aqueous phase obtained after centrifugation, and the decantation, collection and analysis of the liquid organic layer. The extraction of nicotine in toluene, and its determination in eggplant samples was conducted as a proof of concept. The study has been carried out using standards prepared in water and the formation of the dispersion was assisted by sonication. The organic extract was analysed using gas chromatography coupled to mass spectrometry. Satisfactory analytical figures of merit as: limit of detection (0.4µgL(-1), 2ngg(-1) wet sample), limit of quantification (1.2µgL(-1), 6.5ngg(-1) wet sample), within-day precision (RSD=7%), and linearity interval (up to 384µgL(-1) nicotine) were achieved. It constituted a contribution to the handling of organic extracts after microextraction processes. PMID:27260454

  15. Research On The Purification Of Zirconium From Zirconium Dioxide By Liquid-Liquid Extraction Method With Tributyl Phosphate Solvent

    International Nuclear Information System (INIS)

    The study of hafnium separation from zirconium and purification of zirconium by liquid-liquid solvent extraction method bases on the selective extraction, capacity and high stability of tributyl phosphate solvent (TBP). Technical grade ZrO2 powder, imported product (about 2% Hf content), is mixed with NaOH by 1:6 mole ratio, baked at 700oC in 2 hours. The mixture of zirconate and hafnate Na2Zr(Hf)O3 was dissolved in water, acidified by HNO3 to transfer to Zr(Hf)O(NO3)2. The obtained solution is used for the hafnium separation and purification of zirconium investigation. The influence of acid concentration (HNO3) in initial solution (feed solution) on the efficiency of zirconium extraction, the effect of the extraction solvent concentration (TBP) to zirconium distribution ratio and the effect of concentrations of mixture of components (Zr and Hf) in initial solution on zirconium extraction performance and also effect of the ratio between organic and aqueous phase to zirconium distribution coefficient were carried out in this paper. Established optimum conditions of the interruptive solvent extraction in experimental scale including metal contents in initial solution CHf/Zr is 30 g/L; TBP concentration in kerosene is 60% by volume; the acid (HNO3) concentration in initial solution [H+] = 6 M; and organic : aqueous phases rate equal by 1:1. Conditions of the extracted scrubbing and extracted tripping also the continuous extraction process were studied as a first step. (author)

  16. An automatic countercurrent liquid-liquid micro-extraction system coupled with atomic absorption spectrometry for metal determination.

    Science.gov (United States)

    Mitani, Constantina; Anthemidis, Aristidis N

    2015-02-01

    A novel and versatile automatic sequential injection countercurrent liquid-liquid microextraction (SI-CC-LLME) system coupled with atomic absorption spectrometry (FAAS) is presented for metal determination. The extraction procedure was based on the countercurrent flow of aqueous and organic phases which takes place into a newly designed lab made microextraction chamber. A noteworthy feature of the extraction chamber is that it can be utilized for organic solvents heavier or lighter than water. The proposed method was successfully demonstrated for on-line lead determination and applied in environmental water samples using an amount of 120 μL of chloroform as extractant and ammonium diethyldithiophosphate as chelating reagent. The effect of the major experimental parameters including the volume of extractant, as well as the flow rate of aqueous and organic phases were studied and optimized. Under the optimum conditions for 6 mL sample consumption an enhancement factor of 130 was obtained. The detection limit was 1.5 μg L(-1) and the precision of the method, expressed as relative standard deviation (RSD) was 2.7% at 40.0 μg L(-1) Pb(II) concentration level. The proposed method was evaluated by analyzing certified reference materials and spiked environmental water samples. PMID:25435230

  17. 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. PMID:24742534

  18. Estrogens determination in wastewater samples by automatic in-syringe dispersive liquid-liquid microextraction prior silylation and gas chromatography.

    Science.gov (United States)

    González, Alba; Avivar, Jessica; Cerdà, Víctor

    2015-09-25

    A new procedure for the extraction, preconcentration and simultaneous determination of the estrogens most used in contraception pharmaceuticals (estrone, 17β-estradiol, estriol, and 17α-ethynylestradiol), cataloged as Contaminants of Emergent Concern by the Environmental Protection Agency of the United States (US-EPA), is proposed. The developed system performs an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction (in-syringe-MSA-DLLME) prior derivatization and gas chromatography (GC-MS). Different extraction (carbon tetrachloride, ethyl acetate, chloroform and trichloroethylene) and disperser solvents (acetone, acetonitrile and methanol) were tested. Chloroform and acetone were chosen as extraction and disperser solvent, respectively, as they provided the best extraction efficiency. Then, a multivariate optimization of the extraction conditions was carried out. Derivatization conditions were also studied to ensure the conversion of the estrogens to their respective trimethylsilyl derivatives. Low LODs and LOQs were achieved, i.e. between 11 and 82ngL(-1), and 37 and 272ngL(-1), respectively. Good values for intra and inter-day precision were obtained (RSDs≤7.06% and RSD≤7.11%, respectively). The method was successfully applied to wastewater samples. PMID:26319623

  19. Detection of sulfonamide drug in urine using liquid-liquid extraction and surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Markina, Natalia E.; Shalabay, Victoria V.; Zakharevich, Andrey M.; Markin, Alexey V.

    2016-04-01

    In this article we have applied liquid-liquid extraction (LLE) as a sample preparation technique for detection of sulfadimethoxine (one of sulfonamide drugs) in urine using surface-enhanced Raman spectroscopy (SERS). SERS substrate based on silver nanoparticles has been prepared by citrate reduction of silver nitrate. Obtained calibration curve (SERS intensity vs. sulfadimethoxine concentration) has been used for detection of sulfadimethoxine in human urine samples artificially contaminated by sulfadimethoxine. Three different solvents (ethyl acetate, diethyl ether, chloroform) have been used for LLE performance tests. Chloroform being found as the most effective one based on calculation of recoveries after SERS measurements. Thus we would like to propose fast (less than 20 minutes), simple and sensitive (detection limit up to 1 μg/ml) test for detecting sulfa drugs in urine using a combination of SERS with LLE with sample volume as low as 100 μL. Such test can be applied for evaluation of the degree of drug extraction from human body and half-life of such drug applied in the course of therapeutic treatments of certain diseases.

  20. Vortex-assisted liquid-liquid microextraction of bisphenol S prior to its determination by HPLC with UV detection

    International Nuclear Information System (INIS)

    Vortex-assisted liquid-liquid microextraction (VALLME) for the rapid extraction of trace bisphenol S (BPS) in environmental water is presented. In order to simplify the procedure, an in-house fabricated glass dropper with different internal diameters of the two ends is exploited. The solidification-melt step was cut in VALLME by means of the in-house fabricated glass dropper. After extraction with 2-ethylhexanol, BPS was detected by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Factors such as type and volume of extraction solvent, extraction time, sample pH and ionic strength were evaluated. Under optimized conditions, the linearity range varied from 0.10 to 50 μg L−1 with a squared regression coefficient r2 of 0.9995. The relative standard deviation (RSD) is 2.3 % (n = 7). The limit of detection (LOD) and limit of quantification (LOQ) are 0.02 and 0.06 μg L−1, respectively. The presented method was employed for the determination of BPS in real water samples. The relative recoveries are 81.8–87.3 % for the two real water samples. The method is shown to be economical, fast and can be routinely performed. (author)

  1. Optimization and validation of liquid-liquid extraction with low temperature partitioning for determination of carbamates in water

    Energy Technology Data Exchange (ETDEWEB)

    Machado Goulart, Simone; Domingos Alves, Renata; Neves, Antonio Augusto; Queiroz, Jose Humberto de; Conde de Assis, Tamires [Departamento de Quimica, Universidade Federal de Vicosa, Vila Gianetti, Casa 24, 36 570-000 Vicosa, MG (Brazil); Queiroz, Maria Eliana L.R. de, E-mail: meliana@ufv.br [Departamento de Quimica, Universidade Federal de Vicosa, Vila Gianetti, Casa 24, 36 570-000 Vicosa, MG (Brazil)

    2010-06-25

    Using a 2{sup 3} experimental design, liquid-liquid extraction with low temperature partitioning (LLE-LTP) was optimized and validated for analysis of three carbamates (aldicarb, carbofuran and carbaryl) in water samples. In this method, 2.0 mL of sample is placed in contact with 4.0 mL of acetonitrile. After agitation, the sample is placed in a freezer for 3 h for phase separation. The organic extract is analyzed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). For validation of the technique, the following figures of merit were evaluated: accuracy, precision, detection and quantification limits, linearity, sensibility and selectivity. Extraction recovery percentages of the carbamates aldicarb, carbofuran and carbaryl were 90%, 95% and 96%, respectively. Even though extremely low volumes of sample and solvent were used, the extraction method was selective and the detection and quantification limits were between 5.0 and 10.0 {mu}g L{sup -1}, and 17.0 and 33.0 {mu}g L{sup -1}, respectively.

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

    International Nuclear Information System (INIS)

    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 Fe2O3(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)

  3. Anti-cancer efficacy of nonthermal plasma dissolved in a liquid, liquid plasma in heterogeneous cancer cells

    Science.gov (United States)

    Nguyen, Ngoc Hoan; Park, Hyung Jun; Yang, Sang Sik; Choi, Kyeong Sook; Lee, Jong-Soo

    2016-01-01

    The therapeutic potential of nonthermal plasma for cancer treatment has been reported recently. The heterogeneity of cancer cells need to be addressed to design effective anticancer treatments. Here, we show that treatment with nonthermal atmospheric-pressure plasma dissolved in a liquid (liquid plasma) induces oxidative stress in heterogeneous populations of cancer cells and ultimately kills these cells via apoptosis, regardless of genetic status, e.g., mutations in p53 and other DNA-damage-response genes. We found that liquid plasma markedly increased the concentration of intracellular and mitochondrial reactive oxygen species (ROS), reflecting an influx from the extracellular milieu. Liquid plasma contributed to mitochondrial accumulation of ROS and depolarization of mitochondrial membrane potential with consequent cell death. Healthy normal cells, however, were hardly affected by the liquid-plasma treatment. The antioxidant N-acetylcysteine blocked liquid-plasma-induced cell death. A knockdown of CuZn-superoxide dismutase or Mn-SOD enhanced the plasma-induced cell death, whereas expression of exogenous CuZn-SOD, Mn-SOD, or catalase blocked the cell death. These results suggest that the mitochondrial dysfunction mediated by ROS production is a key contributor to liquid-plasma-induced apoptotic cell death, regardless of genetic variation. Thus, liquid plasma may have clinical applications, e.g., the development of therapeutic strategies and prevention of disease progression despite tumor heterogeneity. PMID:27364630

  4. Optimization and validation of liquid-liquid extraction with low temperature partitioning for determination of carbamates in water

    International Nuclear Information System (INIS)

    Using a 23 experimental design, liquid-liquid extraction with low temperature partitioning (LLE-LTP) was optimized and validated for analysis of three carbamates (aldicarb, carbofuran and carbaryl) in water samples. In this method, 2.0 mL of sample is placed in contact with 4.0 mL of acetonitrile. After agitation, the sample is placed in a freezer for 3 h for phase separation. The organic extract is analyzed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). For validation of the technique, the following figures of merit were evaluated: accuracy, precision, detection and quantification limits, linearity, sensibility and selectivity. Extraction recovery percentages of the carbamates aldicarb, carbofuran and carbaryl were 90%, 95% and 96%, respectively. Even though extremely low volumes of sample and solvent were used, the extraction method was selective and the detection and quantification limits were between 5.0 and 10.0 μg L-1, and 17.0 and 33.0 μg L-1, respectively.

  5. Preparation of high purification and food grade phosphoric acid from technical grade phosphoric acid by liquid-liquid detraction method

    International Nuclear Information System (INIS)

    Pay attention to increasing consumption of high purification and food grade phosphoric acid in various industries and food industries and on in on hand and lack of preparation between production and distribution of this products its purification is so vital. In this article of liquid-liquid extraction method with normal hexane-mixture of ammonia and acetone-diisopropyl alcohol and normal butanol solvents and these determination of distribution coefficient each one with ph-me try titration we can evaluate effectiveness and sufficiency each one. Because of proper coefficient distribution and its local production of normal butanol solvent and low price is the best solvent. To phosphoric acid modifying coefficient distribution for extraction of phosphoric acid we can add a little value sulfuric acid to the mixture and to remove flouride impurity we add a little Na2O. After extraction stage extracted phosphoric acid in the normal strips by evaluating with distilled water and then by passing the carbon active bed and following passes of cationic resine column and concentrated with vacuum distillation. Conclusion of this article is produce of phosphoric acid 85% w/w and food grade from impure phosphoric acid 52% w/w with technical grade

  6. Dispersive Liquid-Liquid Microextraction of Bismuth in Various Samples and Determination by Flame Atomic Absorption Spectrometry

    Directory of Open Access Journals (Sweden)

    Teslima Daşbaşı

    2016-01-01

    Full Text Available A dispersive liquid-liquid microextraction method for the determination of bismuth in various samples by flame atomic absorption spectrometry is described. In this method, crystal violet was used as counter positive ion for BiCl4- complex ion, chloroform as extraction solvent, and ethanol as disperser solvent. The analytical parameters that may affect the extraction efficiency like acidity of sample, type and amount of extraction and disperser solvents, amount of ligand, and extraction time were studied in detail. The effect of interfering ions on the analyte recovery was also investigated. The calibration graph was linear in the range of 0.040–1.00 mg L−1 with detection limit of 4.0 μg L−1 (n=13. The precision as relative standard deviation was 3% (n=11, 0.20 mg L−1 and the enrichment factor was 74. The developed method was applied successfully for the determination of bismuth in various water, pharmaceutical, and cosmetic samples and the certified reference material (TMDA-64 lake water.

  7. Ionic liquid-based dispersive liquid-liquid microextraction for the determination of formaldehyde in wastewaters and detergents.

    Science.gov (United States)

    Arvand, Majid; Bozorgzadeh, Elahe; Shariati, Shahab; Zanjanchi, Mohammad Ali

    2012-12-01

    Spectrophotometry in combination with ionic liquid-based dispersive liquid-liquid microextraction (DLLME) was applied for the extraction and determination of formaldehyde in real samples. The method is based on the reaction of formaldehyde with methyl acetoacetate in the presence of ammonia. The variation in the absorbance of the reaction product was measured at 375 nm. An appropriate mixture of ethanol (disperser solvent) and ionic liquid, 1-hexyl-3-methylimidazoliumhexafluoro-phosphate [C(6)MIM][PF(6)] (extraction solvent) was rapidly injected into a water sample containing formaldehyde. After extraction, sedimented phase was analyzed by spectrophotometry. Under the optimum conditions, the calibration graph was linear in the range of 0.1-20 ng mL(-1) with the detection limit of 0.02 ng mL(-1) and limit of quantification of 0.08 ng mL(-1) for formaldehyde. The relative standard deviation (RSD%, n = 5) for the extraction and determination of 0.8 ng mL(-1) of formaldehyde in the aqueous samples was 2.5%. The results showed that DLLME is a very simple, rapid, sensitive, and efficient analytical method for the determination of trace amounts of formaldehyde in wastewaters and detergents, and suitable results were obtained.

  8. Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water.

    Science.gov (United States)

    Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

    2015-01-01

    Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, T(g) . Here we report a universal water-content, X(aqu) , dependence of T(g) for aqueous solutions. Solutions with X(aqu)>X(cr)(aqu)vitrify/devitrify at a constant temperature, ~T(g) , referring to freeze-concentrated phase with X(aqu)left behind ice crystallization. Those solutions with X(aqu)recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of T(g) by annealing is attributable to freeze-concentrated phase of solutions instead of 'liquid II phase of water'. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution.

  9. Analysis of captan, folpet, and captafol in apples by dispersive liquid-liquid microextraction combined with gas chromatography.

    Science.gov (United States)

    Zang, Xiaohuan; Wang, Juntao; Wang, Ou; Wang, Mingzhao; Ma, Jingjun; Xi, Guohong; Wang, Zhi

    2008-10-01

    A novel method was developed for the determination of captan, folpet, and captafol in apples by dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-electron capture detection (GC-ECD). Some experimental parameters that influence the extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, and addition of salt, were studied and optimized to obtain the best extraction results. Under the optimum conditions, high enrichment factors for the compounds were achieved ranging from 824 to 912. The recoveries of fungicides in apples at spiking levels of 20.0 microg kg(-1) and 70.0 microg kg(-1) were 93.0-109.5% and 95.4-107.7%, respectively. The relative standard deviations (RSDs) for the apple samples at 30.0 microg kg(-1) of each fungicide were in the range from 3.8 to 4.9%. The limits of detection were between 3.0 and 8.0 microg kg(-1). The linearity of the method ranged from 10 to 100 microg kg(-1) for the three fungicides, with correlation coefficients (r (2)) varying from 0.9982 to 0.9997. The obtained results show that the DLLME combined with GC-ECD can satisfy the requirements for the determination of fungicides in apple samples.

  10. Mapping Liquid-liquid protein phase separation using ultra-fast-scanning fluorescence correlation spectroscopy

    Science.gov (United States)

    Wei, Ming-Tzo; Elbaum-Garfinkle, Shana; Arnold, Craig B.; Priestley, Rodney D.; Brangwynne, Clifford P.

    Intrinsically disordered proteins (IDPs) are an understudied class of proteins that play important roles in a wide variety of biological processes in cells. We've previously shown that the C. elegans IDP LAF-1 phase separates into P granule-like droplets in vitro. However, the physics of the condensed phase remains poorly understood. Here, we use a novel technique, ultra-fast-scanning fluorescence correlation spectroscopy, to study the nano-scale rheological properties of LAF-1 droplets. Ultra-fast-scanning FCS uses a tunable acoustic gradient index of refraction (TAG) lens with an oil immersion objective to control axial movement of the focal point over a length of several micrometers at frequencies of 70kHz. Using ultra-fast-scanning FCS allows for the accurate determination of molecular concentrations and their diffusion coefficient, when the particle is passing through an excitation volume. Our work reveals an asymmetric LAF-1 phase diagram, and demonstrates that LAF-1 droplets are purely viscous phases which are highly tunable by salt concentration.

  11. (Liquid + liquid) equilibria of (water + linalool + limonene) ternary system at T = (298.15, 308.15, and 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Gramajo de Doz, Monica B. [Departamento de Fisica, Facultad de Ciencias Exactas y Tecnologia, Universidad Nacional de Tucuman, Avenida Independencia 1800, 4000 Tucuman (Argentina)], E-mail: mgramajo@herrera.unt.edu.ar; Cases, Alicia M.; Solimo, Horacio N. [Departamento de Fisica, Facultad de Ciencias Exactas y Tecnologia, Universidad Nacional de Tucuman, Avenida Independencia 1800, 4000 Tucuman (Argentina)

    2008-11-15

    (Liquid + liquid) equilibrium (LLE) data for {l_brace}water (1) + linalool (2) + limonene (3){r_brace} ternary system at T = (298.15, 308.15, and 318.15 {+-} 0.05) K are reported. The organic chemicals were quantified by gas chromatography using a flame ionisation detector while water was quantified using a thermal conductivity detector. The effect of the temperature on (liquid + liquid) equilibrium is determined and discussed. Experimental data for the ternary mixture are compared with values calculated by the NRTL and UNIQUAC equations, and predicted by means of the UNIFAC group contribution method. It is found that the UNIQUAC and NRTL models provide a good correlation of the solubility curve at these three temperatures, while comparing the calculated values with the experimental ones, the best fit is obtained with the NRTL model. Finally, the UNIFAC model provides poor results, since it predicts a greater heterogeneous region than experimentally observed.

  12. Measurement and Correlation of Liquid-Liquid Equilibrium Data for Ethanol-Water-KF and Ethanol-Water-K2CO3 Systems

    Institute of Scientific and Technical Information of China (English)

    许文友; 袁希纲

    2002-01-01

    The liquid-liquid equilibrium data for two ternary systems, ethanol-water-KF and ethanol- water-K2CO3, were determined at 25oC. Experiments show that by adding KF or K2CO3 into the ethanol-water system two phases are formed: an ethanol-rich phase with negligible salt and a water-rich phase with negligible ethanol, thus water can be separated out easily. A mathematical calculation of the liquid-liquid equilibrium data was carried out with the Pitzer theory on water activity in the aqueous phase, and with the Wilson or NRTL or UNIQUAC equations for that in the ethanol phase, which is in good agreement with experimental data.

  13. (Liquid + liquid) equilibrium of (water + 2-propanol + 1-butanol + salt) systems at T = 313.15 K and T = 353.15 K: Experimental data and correlation

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Milton A.P. [School of Chemical Engineering, State University of Campinas, P.O. Box 6066, 13081-970 Campinas-SP (Brazil); Aznar, Martin [School of Chemical Engineering, State University of Campinas, P.O. Box 6066, 13081-970 Campinas-SP (Brazil)]. E-mail: maznar@feq.unicamp.br

    2006-06-15

    (Liquid + liquid) equilibrium data for the quaternary systems (water + 2-propanol + 1-butanol + potassium bromide) and (water + 2-propanol + 1-butanol + magnesium chloride) were measured at T = 313.15 K and T = 353.15 K. The overall salt concentrations were 5 and 10 mass percent. Ternary (liquid + liquid) equilibrium data for the salt-free system (water + 2-propanol + 1-butanol) were also determined and found to be in good agreement with data from the literature. The NRTL model for the activity coefficient was used to correlate the data. New interaction parameters were estimated, using the Simplex minimization method and a concentration-based objective function. The results are very satisfactory, with root mean square deviations between experimental and calculated compositions of both phases being less than 0.5%.

  14. Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model

    Directory of Open Access Journals (Sweden)

    Pessôa Filho P. A.

    2004-01-01

    Full Text Available Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.

  15. Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

    Directory of Open Access Journals (Sweden)

    B. D. Castro

    2005-09-01

    Full Text Available Liquid-liquid extraction using aqueous two-phase systems is a highly efficient technique for separation and purification of biomolecules due to the mild properties of both liquid phases. Reliable data on the phase behavior of these systems are essential for the design and operation of new separation processes; several authors reported phase diagrams for polymer-polymer systems, but data on polymer-salt systems are still relatively scarce. In this work, experimental liquid-liquid equilibrium data on water + polyethylene glycol 8000 + magnesium sulfate and water + polyethylene glycol 8000 + sodium sulfate aqueous two-phase systems were obtained at 35°C. Both equilibrium phases were analyzed by lyophilization and ashing. Experimental results were correlated with a mass-fraction-based NRTL activity coefficient model. New interaction parameters were estimated with the Simplex method. The mean deviations between the experimental and calculated compositions in both equilibrium phases is about 2%.

  16. Determination of some B Vitamins in Sour Cherry Juice Using Dispersive Liquid-liquid Microextraction Followed by High-performance Liquid Chromatography

    OpenAIRE

    Parsaei, Parvin; Bahmaei, Manouchehr; Ghannadi, Alireza

    2014-01-01

    Dispersive liquid-liquid microextraction method (DLLME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine thiamine (B1), nicotinamide (B3) and pyridoxine (B6) in sour cherry juice. This method was rapid, simple and sensitive. Separation was accomplished using a C18 column. The optimum chromatographic conditions were found to be: mobile phase consisted of 8% methanol and 92% aqueous phase (1% (V/V) acetic acid water solution); flow rate,...

  17. Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry

    OpenAIRE

    Cortada Cortés, Carolina; Costa dos Reis, Luciana; Vidal Martínez, Lorena; Llorca, Julio; Canals Hernández, Antonio

    2013-01-01

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was la...

  18. A phase separation method for analyses of fluoroquinones in meats based on ultrasound-assisted salt-induced liquid-liquid microextraction and a new integrated device

    OpenAIRE

    Wang, H; Gao, M.; Xu, Y; W. Wang; Zheng, L; Dahlgren, RA; Wang, X.

    2015-01-01

    © 2015 Elsevier Ltd. Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted, salt-induced, liquid-liquid microextraction for determination of five fluoroquinones in meats by HPLC analysis. The novel integrated device consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surfa...

  19. Integration of phase separation with ultrasound-assisted salt-induced liquid-liquid microextraction for analyzing the fluoroquinones in human body fluids by liquid chromatography

    OpenAIRE

    Wang, H; Gao, M.; Wang, M.; Zhang, R.; W. Wang; Dahlgren, RA; Wang, X.

    2015-01-01

    © 2015 Elsevier B.V. Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted salt-induced liquid-liquid microextraction for determination of five fluoroquinones (FQs) in human body fluids. The integrated device consisted of three simple HDPE components used to separate the extraction solvent from the aqueous phase prior to retrieving the extractant. A series of extraction parameters were optimized using the response surface method based on centr...

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

    OpenAIRE

    Mohammad Rezaee; Reyhaneh Shadaniyan; Majid Haji Hosseini; Faezeh Khalilian

    2015-01-01

    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...

  1. Determination of Gemfibrozil (Lipitor and Lopid) in Water, Biological Fluids and Drug Matrix by Dispersive Liquid-Liquid micro Extraction (DLLME) and Liquid Chromatography

    OpenAIRE

    Ghorbani A.; Dayani M.

    2014-01-01

    In this study Dispersive liquid-liquid micro extraction (DLLME) coupled with High performance liquid chromatography was applied for the determination of Gemfibrozil in water, drug`s matrix and biological liquids (human plasma and urine). In this method, the appropriate mixture of extraction solvent (200 μl chlorophorm) and disperser solvent (1 ml methanol) are injected rapidly into the aqueous sample (10.0 ml) by syringe, cloudy solution is formed that consisted of fine particles of extractio...

  2. Local viscosity of binary water+glycerol mixtures at liquid/liquid interfaces probed by time-resolved surface second harmonic generation

    OpenAIRE

    Fita, Piotr; Punzi, Angela; Vauthey, Eric

    2009-01-01

    The excited-state relaxation of malachite green and brilliant green in solvents of various viscosity has been investigated at liquid/liquid interfaces and in bulk solutions by surface second harmonic generation and transient absorption spectroscopy. Mixtures of water and glycerol in various proportions have been used as solvents of variable viscosity. Transient absorption measurements in bulk revealed that both dyes are suitable as a probe of local viscosity for water+glycerol mixtures and th...

  3. Recovery of aromatic aglycones from grape pomace winemaking by-products by using liquid-liquid and pressurized-liquid extraction

    OpenAIRE

    Muñoz-González, Carolina; Rodríguez-Bencomo, Juan José; Martín-Álvarez, Pedro J.; Moreno-Arribas, M. Victoria; Pozo-Bayón, Mª Ángeles

    2014-01-01

    The potential of winemaking grape pomace by-products as a source of glycosidic aroma precursors that under enzymatic hydrolysis might release aroma compounds has been evaluated. Two different extraction methodologies, liquid-liquid and pressurized liquid extraction (LLE and PLE) were employed. Solid phase extraction (SPE)-GC-MS analysis of the hydrolyzed LLE glycosidic extract revealed 22 aroma compounds belonging to different chemical families (terpenes, C13 norisoprenoids, vanillines, etc.)...

  4. Screening and quantitative determination of twelve acidic and neutral pharmaceuticals in whole blood by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Simonsen, Kirsten Wiese; Steentoft, Anni; Buck, Maike;

    2010-01-01

    . The method was fully validated for salicylic acid, paracetamol, phenobarbital, carisoprodol, meprobamate, topiramate, etodolac, chlorzoxazone, furosemide, ibuprofen, warfarin, and salicylamide. The method also tentatively includes thiopental, theophylline, piroxicam, naproxen, diclophenac, and modafinil......We describe a multi-method for simultaneous identification and quantification of 12 acidic and neutral compounds in whole blood. The method involves a simple liquid-liquid extraction, and the identification and quantification are performed using liquid chromatography-tandem mass spectrometry...

  5. Comparison of air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction for polycyclic aromatic hydrocarbons determination in hookah water.

    Science.gov (United States)

    Rajabi, Maryam; Bazregar, Mohammad; Daneshfar, Ali; Asghari, Alireza

    2015-07-01

    In this work, two disperser-free microextraction methods, namely, air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction are compared for the determination of a number of polycyclic aromatic hydrocarbons in aqueous samples, followed by gas chromatography with flame ionization detection. The effects of various experimental parameters upon the extraction efficiencies of both methods are investigated. Under the optimal conditions, the enrichment factors and limits of detection were found to be in the ranges of 327-773 and 0.015-0.05 ng/mL for air-agitated liquid-liquid microextraction and 406-670 and 0.015-0.05 ng/mL for ultrasound-assisted emulsification microextraction, respectively. The linear dynamic ranges and extraction recoveries were obtained to be in the range of 0.05-120 ng/mL (R(2) ≥ 0.995) and 33-77% for air-agitated liquid-liquid microextraction and 0.05-110 ng/mL (R(2) ≥ 0.994) and 41-67% for ultrasound-assisted emulsification microextraction, respectively. To investigate this common view among some people that smoking hookah is healthy due to the passage of smoke through the hookah water, samples of both the hookah water and hookah smoke were analyzed. PMID:25989415

  6. 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.

  7. Ultrapreconcentration and determination of organophosphorus pesticides in water by solid-phase extraction combined with dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Chen, Junhua; Zhou, Guangming; Deng, Yongli; Cheng, Hongmei; Shen, Jie; Gao, Yi; Peng, Guilong

    2016-01-01

    Solid-phase extraction coupled with dispersive liquid-liquid microextraction was developed as an ultra-preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion-methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid-phase extraction coupled with dispersive liquid-liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid-phase extraction coupled with dispersive liquid-liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9-6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.

  8. Rapid analysis of aflatoxins B1, B2, and ochratoxin A in rice samples using dispersive liquid-liquid microextraction combined with HPLC.

    Science.gov (United States)

    Lai, Xian-Wen; Sun, Dai-Li; Ruan, Chun-Qiang; Zhang, He; Liu, Cheng-Lan

    2014-01-01

    A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China.

  9. Rapid analysis of aflatoxins B1, B2, and ochratoxin A in rice samples using dispersive liquid-liquid microextraction combined with HPLC.

    Science.gov (United States)

    Lai, Xian-Wen; Sun, Dai-Li; Ruan, Chun-Qiang; Zhang, He; Liu, Cheng-Lan

    2014-01-01

    A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China. PMID:24243826

  10. Self-healing gold mirrors and filters at liquid-liquid interfaces

    Science.gov (United States)

    Smirnov, Evgeny; Peljo, Pekka; Scanlon, Micheál D.; Gumy, Frederic; Girault, Hubert H.

    2016-03-01

    The optical and morphological properties of lustrous metal self-healing liquid-like nanofilms were systematically studied for different applications (e.g., optical mirrors or filters). These nanofilms were formed by a one-step self-assembly methodology of gold nanoparticles (AuNPs) at immiscible water-oil interfaces, previously reported by our group. We investigated a host of experimental variables and herein report their influence on the optical properties of nanofilms: AuNP mean diameter, interfacial AuNP surface coverage, nature of the organic solvent, and nature of the lipophilic organic molecule that caps the AuNPs in the interfacial nanofilm. To probe the interfacial gold nanofilms we used in situ (UV-vis-NIR spectroscopy and optical microscopy) as well as ex situ (SEM and TEM of interfacial gold nanofilms transferred to silicon substrates) techniques. The interfacial AuNP surface coverage strongly influenced the morphology of the interfacial nanofilms, and in turn their maximum reflectance and absorbance. We observed three distinct morphological regimes; (i) smooth 2D monolayers of ``floating islands'' of AuNPs at low surface coverages, (ii) a mixed 2D/3D regime with the beginnings of 3D nanostructures consisting of small piles of adsorbed AuNPs even under sub-full-monolayer conditions and, finally, (iii) a 3D regime characterised by the 2D full-monolayer being covered in significant piles of adsorbed AuNPs. A maximal value of reflectance reached 58% in comparison with a solid gold mirror, when 38 nm mean diameter AuNPs were used at a water-nitrobenzene interface. Meanwhile, interfacial gold nanofilms prepared with 12 nm mean diameter AuNPs exhibited the highest extinction intensities at ca. 690 nm and absorbance around 90% of the incident light, making them an attractive candidate for filtering applications. Furthermore, the interparticle spacing, and resulting interparticle plasmon coupling derived optical properties, varied significantly on replacing

  11. Investigation and development of liquid-liquid extraction systems for the removal of pertechnetate from aqueous nuclear waste stream simulants

    Science.gov (United States)

    Gansle, Kristina Marie Rohal

    1998-11-01

    The solvent extraction behavior of perrhenate (ReO 4-) and pertechnetate (TcO4- ) from aqueous nuclear waste stream simulants was examined using the anion-exchange reagent Aliquat-336 nitrate. The extraction tendencies of ReO 4- followed those of TcO4- from both acidic and basic media, demonstrating that ReO4 - was a suitable nonradioactive surrogate for TcO4 -. For ICP-AES analysis of Re in high salt solutions, a V-groove nebulizer and 1:1 dilution of the sample and standards with 0.1% Triton X-100 surfactant reduced deposition of solids within the sample introduction system, thus minimizing memory effects. A new approach to waste remediation technology, Redox-Recyclable Extraction and Recovery (R2ER), was also studied. The redox-active species 1,1',3,3'-tetrakis(2-methyl-2-hexyl)ferrocene (HEP) was oxidized to its cationic form for extraction of TcO4 - or ReO4- from aqueous waste and reduced to its neutral form for recovery of the anion. The thermodynamics of liquid-liquid interfacial electron transfer for the oxidation/activation of HEP were shown to be controlled by three factors: the reduction potentials of the redox-active species in the aqueous and organic phases and the transfer of an ion across the liquid-liquid interface. The deactivation/reduction rate of HEP+NO3- by iron was affected by organic solvent diluent and improved by treating the iron with hexanes and 1 M HCl. The volume of solid secondary-waste in the R2ER cycle was reduced by a factor of 3000. In complete extraction/recovery cycles, HEP+NO3- in 2-nonanone removed greater than 99% TcO4- from the 101-SY, 103-SY, 1 M HCl and 1 M NaOH/1.5 M NaNO3 Hanford Tank waste simulants. Another redox-active extractant, bis(hydridotris(1-pyrazolyl)borato)iron(III) nitrate (FeTp2+NO3-), was also selective for ReO4- remediation from simulated aqueous waste. Organic solutions of the alkyl substituted ferricenium extractants were not stable in the presence of nucleophilic anions and/or reducing agents. HEP+NO3

  12. Laser induced-thermal lens spectrometry in combination with dispersive liquid-liquid microextraction for trace analysis.

    Science.gov (United States)

    Shokoufi, Nader; Hamdamali, Amir

    2010-11-29

    A new combination method including laser induced-thermal lens spectrometry (LI-TLS) and dispersive liquid-liquid micro extraction (DLLME) was developed and used for determination and preconcentration of trace amount of lead in liquid samples. Thermal lens spectrometry is suitable for determination of analyte after DLLME because of the low volume of the remained phase after DLLME and increasing of the enhancement factor for the non polar organic solvents. Non polar organic solvents have the ideal conditions for this combination because of low thermal conductivity and large variation in refractive index with temperature. In this method; ethanol, carbon tetrachloride and 1,5-diphenyl thiocarbazone (dithizone), were used as disperser solvent, extraction solvent and chelating agent, respectively. Some effective parameters on the micro extraction, complex formation and combination were selected and optimized. Under optimum conditions, the calibration graphs were linear in the range of 0.1-75 μg L(-1) with the detection limit of 0.01 μg L(-1). The relative standard deviation (RSD) for 5 and 50 μg L(-1) of lead was 3.2 and 2.5, respectively. The enhancement factor of 1000 was obtained from a sample volume of 10.0 mL and determination volume of 25 μL. DLLME/LI-TLS method was applied to the analysis of human blood serums and real water samples. Accuracy of the method was proved by using of standard reference materials. Also, the proposed method was compared with other trace analysis methods. PMID:21035603

  13. Speciation analysis of mercury in water samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography.

    Science.gov (United States)

    Gao, Zhongben; Ma, Xiaoguo

    2011-09-19

    A novel approach for preconcentration and speciation analysis of trace amount of mercury from water samples was proposed by dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with diode array detection (HPLC-DAD). Mercury species (Hg(2+), methylmercury (MeHg(+)) and phenylmercury (PhHg(+))) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of extraction solvent dispersed in the aqueous sample by dispersive solvent. After extraction, the sedimented phase was analyzed by HPLC-DAD. Some important parameters affecting the DLLME such as extraction solvent and dispersive solvent type and volume, concentration of dithizone solution, sample pH, extraction time and salt effect were investigated. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]) was found to be a suitable extractant for the chelates. Under the optimized conditions (extraction solvent: 70 μL of ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]); dispersive solvent: 0.75 mL of methanol containing dithizone (0.02%, m/v); pH: 4; extraction time: 5 min; and without salt addition), the limits of detection for Hg(2+), MeHg(+) and PhHg(+) were 0.32, 0.96 and 1.91 μg L(-1) (SN(-1)=3) respectively, and the relative standard deviation (RSD) was between 4.1 and 7.3% (n=5). Three real water samples (tap water, river water and lake water) spiked with mercury species were detected by the developed method, and the relative recoveries obtained for Hg(2+), MeHg(+) and PhHg(+) were 89.6-101.3%, 85.6-102.0% and 81.3-97.6%, respectively. PMID:21819859

  14. Recovery of Acetic Acid from An Ethanol Fermentation Broth by Liquid-Liquid Extraction (LLE) Using Various Solvents

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thi Thu Huong; Kim, Tae Hyun [Kongju National University, Cheonan (Korea, Republic of); Um, Byung Hwan [Hankyong National University, Anseong (Korea, Republic of)

    2015-12-15

    Liquid-liquid extraction (LLE) using various solvents was studied for recovery of acetic acid from a synthetic ethanol fermentation broth. The microbial fermentation of sugars presented in hydrolyzate gives rise to acetic acid as a byproduct. In order to obtain pure ethanol for use as a biofuel, fermentation broth should be subjected to acetic acid removal step and the recovered acetic acid can be put to industrial use. Herein, batch LLE experiments were carried out at 25°C using a synthetic fermentation broth comprising 20.0 g l{sup -1} acetic acid and 5.0 g l{sup -1} ethanol. Ethyl acetate (EtOAc), tri-n-octylphosphine oxide (TOPO), tri-n-octylamine (TOA), and tri-n-alkylphosphine oxide (TAPO) were utilized as solvents, and the extraction potential of each solvent was evaluated by varying the organic phase-to-aqueous phase ratios as 0.2, 0.5, 1.0, 2.0, and 4.0. The highest acetic acid extraction yield was achieved with TAPO; however, the lowest ethanol-to-acetic acid extraction ratio was obtained using TOPO. In a single-stage batch extraction, 97.0 % and 92.4 % of acetic acid could be extracted using TAPO and TOPO when the ratio of organic-to-aqueous phases is 4:1 respectively. A higher solvent-to-feed ratio resulted in an increase in the ethanol-to-acetic acid ratio, which decreased both acetic acid purity and acetic acid extraction yield.

  15. Automated on-line liquid-liquid extraction system for temporal mass spectrometric analysis of dynamic samples.

    Science.gov (United States)

    Hsieh, Kai-Ta; Liu, Pei-Han; Urban, Pawel L

    2015-09-24

    Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid-liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 min. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053-2.000 mM; LOD for ibuprofen, ∼0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h(-1)). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment. PMID:26423626

  16. Exploitation of pulsed flows for on-line dispersive liquid-liquid microextraction: Spectrophotometric determination of formaldehyde in milk.

    Science.gov (United States)

    Nascimento, Carina F; Brasil, Marcos A S; Costa, Susana P F; Pinto, Paula C A G; Saraiva, Maria Lúcia M F S; Rocha, Fábio R P

    2015-11-01

    Formaldehyde is often added to foods as a preservative, but it is highly toxic to humans, having been identified as a carcinogenic substance. It has also been used for the adulteration of milk in order to diminish the bacteria count and increase the shelf life of the product. Herein, we present a green dispersive liquid-liquid microextraction procedure in a flow-batch system for the determination of formaldehyde in milk. Pulsed flows were exploited for the first time to improve the dispersion of the extractant in the aqueous phase. The Hantzsch reaction was used for the derivatization of formaldehyde and the product was extracted with the ionic liquid (IL) trihexyltetradecylphosphonium chloride with methanol as the disperser. The flow-batch chamber was made of stainless steel with the facility for resistive heating to speed up the derivatization reaction. Spectrophotometric measurements were directly carried out in the organic phase using an optical fiber spectrophotometer. The limit of detection and coefficient of variation were 100 μg L(-1) and 3.1% (n=10), respectively, with a linear response from 0.5 to 5.0 mg L(-1), described by the equation A=0.088+0.116CF (mg L(-1)) in which A is absorbance and CF is formaldehyde concentration in mg L(-1). The estimated recoveries of formaldehyde from spiked milk samples ranged from 91% to 106% and the slopes of the analytical curves obtained with reference solutions in water or milk were in agreement, thus indicating the absence of matrix effects. Accuracy was demonstrated by the agreement of the results with those achieved by the reference fluorimetric procedure at the 95% confidence level. The proposed procedure allows for 10 extractions per hour, with minimized reagent consumption (120 μL of IL and 3.5 μL acetylacetone) and generation of only 6.7 mL waste per determination, which contribute to the eco-friendliness of the procedure.

  17. Magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction of selenium for speciation in foods and beverages.

    Science.gov (United States)

    Wang, Xiaojun; Wu, Long; Cao, Jiaqi; Hong, Xincheng; Ye, Rui; Chen, Weiji; Yuan, Ting

    2016-07-01

    A novel, simple and rapid method based on magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction (MEA-IL-DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) determination was established for the speciation of selenium in various food and beverage samples. In the procedure, a special magnetic effervescent tablet containing CO2 sources (sodium carbonate and sodium dihydrogenphosphate), ionic liquids and Fe3O4 magnetic nanoparticles (MNPs) was used to combine extractant dispersion and magnetic recovery procedures into a single step. The parameters influencing the microextraction efficiency, such as pH of the sample solution, volume of ionic liquid, amount of MNPs, concentration of the chelating agent, salt effect and matrix effect were investigated and optimised. Under the optimised conditions, the limits of detection (LODs) for Se(IV) were 0.021 μg l(-)(1) and the linear dynamic range was 0.05-5.0 μg l(-)(1). The relative standard deviation for seven replicate measurements of 1.0 μg l(-)(1) of Se(IV) was 2.9%. The accuracy of the developed method was evaluated by analysis of the standard reference materials (GBW10016 tea, GBW10017 milk powder, GBW10043 Liaoning rice, GBW10046 Henan wheat, GBW10048 celery). The proposed method was successfully applied to food and beverage samples including black tea, milk powder, mushroom, soybean, bamboo shoots, energy drink, bottled water, carbonated drink and mineral water for the speciation of Se(IV) and Se(VI) with satisfactory relative recoveries (92.0-108.1%). PMID:27181611

  18. Liquid-liquid extraction of molybdenum and its ultra-trace determination by graphite furnace atomic absorption spectrophotometry

    International Nuclear Information System (INIS)

    A highly sensitive and reliable method for the determination of molybdenum at nanogram level in rocks, ores, minerals, soils and hydrogeochemical samples has been developed by liquid-liquid extraction of the metal into a suitable organic solvent, followed by its measurement by Graphite Furnace Atomic Absorption Spectrophotometer. Molybdenum in the sample (∼200 mesh) was opened by NH4HF2 and H2SO4 dissolution. At pH 4-6, major matrix elements like Fe, Ti, Nb, Cu, Th, REEs etc are removed by the solvent extraction of the complexes of these elements with the, O-O' type of ligand, 2,3 dihydroxynaphthalene (2,3 H2ND) leaving Mo (VI) in aqueous solution. Subsequently, Mo (VI) was reduced with hydroxylamine hydrochloride to Mo (V) which was allowed to form a 1:2 complex with the cited ligand, 2,3 H2ND at pH 2-4. At this very pH, the Mo (V)-2,3 H2ND neutral complex was readily extracted in ethyl or butyl acetate. Then Mo (V) was stripped off into aqueous solution (minimum volume). This solution was fed into the graphite furnace through an auto sampler. The concentration of the analyte in the sample was found out/read from the calibration curve prepared against known standards. The method was validated by applying it on a host of rock samples including Geological Reference Materials and water samples. Molybdenum can be estimated up to 1 μg per gram rock sample with a precision of 2.0% and 2 ppb in water samples with a precision of ±5%. (author)

  19. Turbulence in microfluidics: Cleanroom-free, fast, solventless, and bondless fabrication and application in high throughput liquid-liquid extraction.

    Science.gov (United States)

    de Camargo, Camila L; Shiroma, Letícia S; Giordano, Gabriela F; Gobbi, Angelo L; Vieira, Luis C S; Lima, Renato S

    2016-10-12

    This paper addresses an important breakthrough in the deployment of ultra-high adhesion strength microfluidic technologies to provide turbulence at harsh flow rate conditions. This paper is only, to our knowledge, the second reporting on the generation of high flow rate-assisted turbulence in microchannels. This flow solves a crucial bottleneck in microfluidics: the generation of high throughput homogeneous mixings. We focused on the fabrication of bulky polydimethylsiloxane (PDMS) microchips (without any interfaces) rather than the laborious surface modifications that were employed in the first reporting about turbulence-assisted microfluidics. The fabrication is cleanroom-free, simple, low-cost, fast, solventless, and bondless requiring only a laboratory oven. More specifically, our method relies on the shaping of a nylon scaffold, cure of PDMS with embedded nylon, and removal of this scaffold. The scaffold was obtained by manually wrapping nylon threads. The withdrawing out of the scaffold was completed in few seconds using only a plier. Such microchannels endured flow rates of up to 60.0 mL min(-1) with a strikingly low elastic deformation. The importance in producing turbulence into microscale channels was successfully shown in liquid-liquid extractions. The great energy dissipation rate relative to the turbulence created high throughput and efficient extractions in microfluidics for the first time. The residence time was only 0.01 s at 25.0 mL min(-1) (total flow rate of the immiscible phases). In addition, the partition coefficient determined in a single run was similar to that obtained by the conventional batch shake-flask method that was realized in triplicate.

  20. 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

    2015-01-01

    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.

  1. Turbulence in microfluidics: Cleanroom-free, fast, solventless, and bondless fabrication and application in high throughput liquid-liquid extraction.

    Science.gov (United States)

    de Camargo, Camila L; Shiroma, Letícia S; Giordano, Gabriela F; Gobbi, Angelo L; Vieira, Luis C S; Lima, Renato S

    2016-10-12

    This paper addresses an important breakthrough in the deployment of ultra-high adhesion strength microfluidic technologies to provide turbulence at harsh flow rate conditions. This paper is only, to our knowledge, the second reporting on the generation of high flow rate-assisted turbulence in microchannels. This flow solves a crucial bottleneck in microfluidics: the generation of high throughput homogeneous mixings. We focused on the fabrication of bulky polydimethylsiloxane (PDMS) microchips (without any interfaces) rather than the laborious surface modifications that were employed in the first reporting about turbulence-assisted microfluidics. The fabrication is cleanroom-free, simple, low-cost, fast, solventless, and bondless requiring only a laboratory oven. More specifically, our method relies on the shaping of a nylon scaffold, cure of PDMS with embedded nylon, and removal of this scaffold. The scaffold was obtained by manually wrapping nylon threads. The withdrawing out of the scaffold was completed in few seconds using only a plier. Such microchannels endured flow rates of up to 60.0 mL min(-1) with a strikingly low elastic deformation. The importance in producing turbulence into microscale channels was successfully shown in liquid-liquid extractions. The great energy dissipation rate relative to the turbulence created high throughput and efficient extractions in microfluidics for the first time. The residence time was only 0.01 s at 25.0 mL min(-1) (total flow rate of the immiscible phases). In addition, the partition coefficient determined in a single run was similar to that obtained by the conventional batch shake-flask method that was realized in triplicate. PMID:27662761

  2. Two-state thermodynamics and the possibility of a liquid-liquid phase transition in supercooled TIP4P/2005 water

    Science.gov (United States)

    Singh, Rakesh S.; Biddle, John W.; Debenedetti, Pablo G.; Anisimov, Mikhail A.

    2016-04-01

    Water shows intriguing thermodynamic and dynamic anomalies in the supercooled liquid state. One possible explanation of the origin of these anomalies lies in the existence of a metastable liquid-liquid phase transition (LLPT) between two (high and low density) forms of water. While the anomalies are observed in experiments on bulk and confined water and by computer simulation studies of different water-like models, the existence of a LLPT in water is still debated. Unambiguous experimental proof of the existence of a LLPT in bulk supercooled water is hampered by fast ice nucleation which is a precursor of the hypothesized LLPT. Moreover, the hypothesized LLPT, being metastable, in principle cannot exist in the thermodynamic limit (infinite size, infinite time). Therefore, computer simulations of water models are crucial for exploring the possibility of the metastable LLPT and the nature of the anomalies. In this work, we present new simulation results in the NVT ensemble for one of the most accurate classical molecular models of water, TIP4P/2005. To describe the computed properties and explore the possibility of a LLPT, we have applied two-structure thermodynamics, viewing water as a non-ideal mixture of two interconvertible local structures ("states"). The results suggest the presence of a liquid-liquid critical point and are consistent with the existence of a LLPT in this model for the simulated length and time scales. We have compared the behavior of TIP4P/2005 with other popular water-like models, namely, mW and ST2, and with real water, all of which are well described by two-state thermodynamics. In view of the current debate involving different studies of TIP4P/2005, we discuss consequences of metastability and finite size in observing the liquid-liquid separation. We also address the relationship between the phenomenological order parameter of two-structure thermodynamics and the microscopic nature of the low-density structure.

  3. Two-state thermodynamics and the possibility of a liquid-liquid phase transition in supercooled TIP4P/2005 water.

    Science.gov (United States)

    Singh, Rakesh S; Biddle, John W; Debenedetti, Pablo G; Anisimov, Mikhail A

    2016-04-14

    Water shows intriguing thermodynamic and dynamic anomalies in the supercooled liquid state. One possible explanation of the origin of these anomalies lies in the existence of a metastable liquid-liquid phase transition (LLPT) between two (high and low density) forms of water. While the anomalies are observed in experiments on bulk and confined water and by computer simulation studies of different water-like models, the existence of a LLPT in water is still debated. Unambiguous experimental proof of the existence of a LLPT in bulk supercooled water is hampered by fast ice nucleation which is a precursor of the hypothesized LLPT. Moreover, the hypothesized LLPT, being metastable, in principle cannot exist in the thermodynamic limit (infinite size, infinite time). Therefore, computer simulations of water models are crucial for exploring the possibility of the metastable LLPT and the nature of the anomalies. In this work, we present new simulation results in the NVT ensemble for one of the most accurate classical molecular models of water, TIP4P/2005. To describe the computed properties and explore the possibility of a LLPT, we have applied two-structure thermodynamics, viewing water as a non-ideal mixture of two interconvertible local structures ("states"). The results suggest the presence of a liquid-liquid critical point and are consistent with the existence of a LLPT in this model for the simulated length and time scales. We have compared the behavior of TIP4P/2005 with other popular water-like models, namely, mW and ST2, and with real water, all of which are well described by two-state thermodynamics. In view of the current debate involving different studies of TIP4P/2005, we discuss consequences of metastability and finite size in observing the liquid-liquid separation. We also address the relationship between the phenomenological order parameter of two-structure thermodynamics and the microscopic nature of the low-density structure. PMID:27083735

  4. 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.

  5. Vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria calculations for polystyrene plus methyleyclohexane and polystyrene plus cyclohexane solutions

    DEFF Research Database (Denmark)

    Wilczura-Wachnik, H.; Jonsdottir, Svava Osk

    2006-01-01

    This paper presents the vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria predictions for polystyrene in two theta solvents: cyclohexane and methylcyclohexane. VLE calculations were performed with the Elbro free volume method and a modified version of the PC-SAFT method, as well...... as with three UNIFAC type group contribution models: Entropic Free Volume + UNIFAC VLE 1 coeff., Entropic Free Volume + UNIFAC VLE 2coeff., and Oishi-Prausnitz + UNIFAC VLE 2coeff. Solvent activities were calculated for the polystyrene + cyclohexane and polystyrene + methylcyclohcxane solutions, and compared...

  6. 水-丁酸-壬醇三相系统的液液平衡%Liquid-Liquid Equilibria of Water + Butyric Acid + Nonanol Ternary System

    Institute of Scientific and Technical Information of China (English)

    S.üsmail K1rbaslar; Sema Yüksel; Erol ínce; ísmail Boz

    2004-01-01

    Liquid-liquid equilibrium (LLE) data for the water + butyric acid + nonanol system have been determined experimentally at the temperatures of 298.15 K, 308.15 K and 318.15 K. Tie-line compositions were correlated by Othmer-Tobias method. The universal quasichemical functional group activity coefficient (UNIFAC) and modified UNIFAC methods were used to predict the phase equilibrium in the system using the interaction parameters between CH3, CH2, COOH, OH and H2O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region.

  7. (Liquid + liquid) equilibrium of {l_brace}water + phenol + (1-butanol, or 2-butanol, or tert-butanol){r_brace} systems

    Energy Technology Data Exchange (ETDEWEB)

    Hadlich de Oliveira, Leonardo [School of Chemical Engineering, State University of Campinas, UNICAMP, P.O. Box 6066, 13083-970 Campinas-SP (Brazil); Aznar, Martin, E-mail: maznar@feq.unicamp.b [School of Chemical Engineering, State University of Campinas, UNICAMP, P.O. Box 6066, 13083-970 Campinas-SP (Brazil)

    2010-11-15

    (Liquid + liquid) equilibrium (LLE) and binodal curve data were determined for the systems (water + phenol + tert-butanol) at T = 298.15 K, (water + phenol + 2-butanol) and (water + phenol + 1-butanol) at T = 298.15 K and T = 313.15 K by the combined techniques of densimetry and refractometry. Type I curve (for tert-butanol) and Type II curves (for 1- and 2-butanol) were found. The data were correlated with the NRTL model and the parameters estimated present root mean square deviations below 2% for the system with tert-butanol and lower than 0.8% for the other systems.

  8. Unique self-assembly behavior of a triblock copolymer and fabrication of catalytically active gold nanoparticle/polymer thin films at the liquid/liquid interface

    International Nuclear Information System (INIS)

    Gold nanoparticle-doped poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) thin films were prepared at the planar liquid/liquid interface between the chloroform solution of the polymer and aqueous solution of HAuCl4. Transmission electron microscopic (TEM) investigations revealed that foam films composed of microcapsules as well as one-dimensional belts were formed, and numerous Au nanoparticles were incorporated in the walls of the microcapsules and the nanobelts. The walls and the belts have layered structure. The formation mechanism of the foams and the belts was attributed to adsorption of the polymer molecules, combination of the polymer molecules with AuCl4− ions, microphase separation and self-assembly of the composite molecules at the interface. This microstructure is different apparently from those formed in solutions, in casting or spin-coating thin films and at the air/water interface of this triblock copolymer, reflecting unique self-assembly behavior at the liquid/liquid interface. This microstructure is also different from those formed by homo-P2VP and P4VP-b-PS-b-P4VP at the liquid/liquid interface, indicating the effects of molecular structures on the self-assembly behaviors of the polymers. After further treatment by UV-light irradiation and KBH4 aqueous solution, the gold species were reduced completely, as indicated by UV–vis spectra and X-ray photoelectron spectra (XPS). Thermogravimetric analysis indicated that the composite films have high thermal stability, and the content of gold was estimated to be about 9.1%. These composite films exhibited high catalytic activity for the reduction of 4-nitrophenol by KBH4 in aqueous solutions. - Highlights: • P2VP-b-PS-b-P2VP formed microcapsules and nanobelts at the liquid/liquid interface. • Its self-assembly behavior differs from P4VP-b-PS-b-P4VP at the interface. • This behavior also differs from those in solution, in film and at air/water interface.

  9. (Liquid + liquid) phase equilibria for (water + 2,3-butanediol + oleyl alcohol) at T = (300.2, 307.2, and 314.2) K

    Energy Technology Data Exchange (ETDEWEB)

    Khayati, Gholam [Department of Chemical Engineering, Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143 Tehran (Iran, Islamic Republic of); Pahlavanzadeh, Hassan [Department of Chemical Engineering, Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143 Tehran (Iran, Islamic Republic of)], E-mail: pahlavzh@modares.ac.ir; Vasheghani-Farahani, Ebrahim [Department of Chemical Engineering, Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143 Tehran (Iran, Islamic Republic of); Ghaemi, Nasser [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of)

    2009-02-15

    (Liquid + liquid equilibrium) (LLE) data for ternary system: (water + 2,3-butanediol + oleyl alcohol) has been measured at T = (300.2, 307.2, and 314.2) K. Complete phase diagrams were obtained by determining solubility and tie-line data. Tie-line compositions were correlated by Othmer-Tobias and Bachman methods. The nonrandom two liquids equation (NRTL) was used to correlate the phase equilibrium in the system using the interaction parameters determined from experimental data. It is found that NRTL could give a good correlation for the LLE data. Distribution coefficients and separation factors were evaluated for the immiscibility region.

  10. Liquid-liquid extraction and separation of VIII group elements, especially ruthenium, by synergic combinations or aromatic polyimines and micellar cationic exchangers

    International Nuclear Information System (INIS)

    This thesis aims to characterize and to quantify the chemical equilibria involved in d-elements liquid-liquid extraction systems, especially elements belonging to the VIII group (Fe, Ni, Co, Ru, Rh, Pd, Pt). These systems are composed of synergic combination of aromatic polyimines and micellar cationic exchangers. Substitutions are first performed in aqueous acidic media by aromatic polyimines; then extractions are operated using micellic canionic exchangers. Chemical equilibria, selectivity effects, especially those due to ion-pair formations, kinetics, extractant behaviour are analysed and quantified

  11. MicroSISAK. Continuous liquid-liquid extractions of radionuclides at {>=} 0.2 mL/min

    Energy Technology Data Exchange (ETDEWEB)

    Hild, D.; Eberhardt, K.; Kratz, J.V.; Wiehl, N. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Even, J. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Helmholtz-Institut Mainz, Mainz (Germany); Loeb, P.; Werner, B.; Hofmann, C. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany)

    2013-07-01

    Continuous liquid-liquid extraction of short-lived radionuclides has traditionally been performed with the SISAK system consisting of static mixers and H-centrifuges for phase separation. SISAK operates at flow rates of typically 1 mL/s. Thus, it produces large volumes of radioactive liquid waste that is difficult to dispose of. Therefore, it has been aimed to develop and use a further miniaturised extraction unit based on microtechnology and precision engineering to reduce the flow rate by at least two orders of magnitude. The accordingly developed MicroSISAK device is a micro membrane extractor in which a micromixer element with 2 x 16 feed channels of 30 {mu}m width followed by a 60 {mu}m high mixing chamber is used for intimately contacting the aqueous and organic phase. Subsequent phase separation is achieved via hydrophobic Teflon membranes with a pore size of 1 {mu}m. The MicroSISAK device has been tested and optimized with radiotracers of the group-4 elements Zr and Hf in the system H{sub 2}SO{sub 4}/trioctyl amine (TOA) in toluene. At a temperature of 58 C and a flow rate of 0.2 mL/min of both phases, extraction yields of 87 {+-} 3% were achieved. The transport time from the micromixer to the first Teflon membrane was in this case 3.9s. It can be shortened to 1.56s at a flow rate of 0.5 mL/min. Under similar conditions, the extraction yield of {sup 99m}Tc milked from a {sup 99}Mo generator in the system HNO{sub 3}/tetraphenyl arsonium chloride (TPAC) in chloroform was 83 {+-} 3%. In an on-line experiment at the TRIGA Mainz reactor, short-lived Tc isotopes produced in the fission of {sup 235}U with thermal neutrons were transported by a He/KCl gas-jet to the chemistry apparatus, deposited by impaction, dissolved in 0.01 mol/L HNO{sub 3}/KBrO{sub 3}, and extracted into 10{sup -4} mol/L TPAC in chloroform in MicroSISAK. The separated phases were transported via capillaries to two separate flow-through cells positioned in front of two Ge detectors. The

  12. PEG-salt aqueous two-phase systems: an attractive and versatile liquid-liquid extraction technology for the downstream processing of proteins and enzymes.

    Science.gov (United States)

    Glyk, Anna; Scheper, Thomas; Beutel, Sascha

    2015-08-01

    Nowadays, there is an increasing demand to establish new feasible, efficient downstream processing (DSP) techniques in biotechnology and related fields. Although several conventional DSP technologies have been widely employed, they are usually expensive and time-consuming and often provide only low recovery yields. Hence, the DSP is one major bottleneck for the commercialization of biological products. In this context, polyethylene glycol (PEG)-salt aqueous two-phase systems (ATPS) represent a promising, efficient liquid-liquid extraction technology for the DSP of various biomolecules, such as proteins and enzymes. Furthermore, ATPS can overcome the limitations of traditional DSP techniques and have gained importance for applications in several fields of biotechnology due to versatile advantages over conventional DSP methods, such as biocompatibility, technical simplicity, and easy scale-up potential. In the present review, various practical applications of PEG-salt ATPS are presented to highlight their feasibility to operate as an attractive and versatile liquid-liquid extraction technology for the DSP of proteins and enzymes, thus facilitating the approach of new researchers to this technique. Thereby, single- and multi-stage extraction, several process integration methods, as well as large-scale extraction and purification of proteins regarding technical aspects, scale-up, recycling of process chemicals, and economic aspects are discussed.

  13. Suitability of dispersive liquid-liquid microextraction for the in situ silylation of chlorophenols in water samples before gas chromatography with mass spectrometry.

    Science.gov (United States)

    Saraji, Mohammad; Ghambari, Hoda

    2015-10-01

    Trace analysis of chlorophenols in water was performed by simultaneous silylation and dispersive liquid-liquid microextraction followed by gas chromatography with mass spectrometry. Dispersive liquid-liquid microextraction was carried out using an organic solvent lighter than water (n-hexane). The effect of different silylating reagents on the method efficiency was investigated. The influence of derivatization reagent volume, presence of catalyst and derivatization/extraction time on the yield of the derivatization reaction was studied. Different parameters affecting extraction efficiency such as kind and volume of extraction and disperser solvents, pH of the sample and addition of salt were also investigated and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 0.05-100 ng/mL and the limit of detection was 0.01 ng/mL. The enrichment factors were 242, 351, and 363 for 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol, respectively. The values of intra- and inter-day relative standard deviations were in the range of 3.0-6.4 and 6.1-9.9%, respectively. The applicability of the method was investigated by analyzing water and wastewater samples.

  14. Sensitive quantitation of polyamines in plant foods by ultrasound-assisted benzoylation and dispersive liquid-liquid microextraction with the aid of experimental designs.

    Science.gov (United States)

    Pinto, Edgar; Melo, Armindo; Ferreira, Isabel M P L V O

    2014-05-14

    A new method involving ultrasound-assisted benzoylation and dispersive liquid-liquid microextraction was optimized with the aid of chemometrics for the extraction, cleanup, and determination of polyamines in plant foods. Putrescine, cadaverine, spermidine, and spermine were derivatized with 3,5-dinitrobenzoyl chloride and extracted by dispersive liquid-liquid microextraction using acetonitrile and carbon tetrachloride as dispersive and extraction solvents, respectively. Two-level full factorial design and central composite design were applied to select the most appropriate derivatization and extraction conditions. The developed method was linear in the 0.5-10.0 mg/L range, with a R(2) ≥ 0.9989. Intra- and interday precisions ranged from 0.8 to 6.9% and from 3.0 to 10.3%, respectively, and the limit of detection ranged between 0.018 and 0.042 μg/g of fresh weight. This method was applied to the analyses of six different types of plant foods, presenting recoveries between 81.7 and 114.2%. The method is inexpensive, versatile, simple, and sensitive. PMID:24773181

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

    International Nuclear Information System (INIS)

    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 μL 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-1, the detection limit was 0.37 ng mL-1 (3Sb/m, n = 7) and the relative standard deviation was ±1.63% (n = 7, C = 200 ng mL-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.

  16. Suitability of dispersive liquid-liquid microextraction for the in situ silylation of chlorophenols in water samples before gas chromatography with mass spectrometry.

    Science.gov (United States)

    Saraji, Mohammad; Ghambari, Hoda

    2015-10-01

    Trace analysis of chlorophenols in water was performed by simultaneous silylation and dispersive liquid-liquid microextraction followed by gas chromatography with mass spectrometry. Dispersive liquid-liquid microextraction was carried out using an organic solvent lighter than water (n-hexane). The effect of different silylating reagents on the method efficiency was investigated. The influence of derivatization reagent volume, presence of catalyst and derivatization/extraction time on the yield of the derivatization reaction was studied. Different parameters affecting extraction efficiency such as kind and volume of extraction and disperser solvents, pH of the sample and addition of salt were also investigated and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 0.05-100 ng/mL and the limit of detection was 0.01 ng/mL. The enrichment factors were 242, 351, and 363 for 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol, respectively. The values of intra- and inter-day relative standard deviations were in the range of 3.0-6.4 and 6.1-9.9%, respectively. The applicability of the method was investigated by analyzing water and wastewater samples. PMID:26257251

  17. Assessment of dispersive liquid-liquid microextraction conditions for gas chromatography time-of-flight mass spectrometry identification of organic compounds in honey.

    Science.gov (United States)

    Moniruzzaman, M; Rodríguez, I; Rodríguez-Cabo, T; Cela, R; Sulaiman, S A; Gan, S H

    2014-11-14

    The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas. PMID:25441341

  18. Interfacial-tension-force model for the wavy stratified liquid-liquid flow pattern transition: The usage of two different approaches

    Science.gov (United States)

    de Castro, Marcelo Souza; Rodriguez, Oscar Mauricio Hernandez

    2016-06-01

    The study of the hydrodynamic stability of flow patterns is important in the design of equipment and pipelines for multiphase flows. The maintenance of a particular flow pattern becomes important in many applications, e.g., stratified flow pattern in heavy oil production avoiding the formation of emulsions because of the separation of phases and annular flow pattern in heat exchangers which increases the heat transfer coefficient. Flow maps are drawn to orientate engineers which flow pattern is present in a pipeline, for example. The ways how these flow maps are drawn have changed from totally experimental work, to phenomenological models, and then to stability analysis theories. In this work an experimental liquid-liquid flow map, with water and viscous oil as work fluids, drawn via subjective approach with high speed camera was used to compare to approaches of the same theory: the interfacial-tension-force model. This theory was used to drawn the wavy stratified flow pattern transition boundary. This paper presents a comparison between the two approaches of the interfacial-tension-force model for transition boundaries of liquid-liquid flow patterns: (i) solving the wave equation for the wave speed and using average values for wave number and wave speed; and (ii) solving the same equation for the wave number and then using a correlation for the wave speed. The results show that the second approach presents better results.

  19. [Determination of five triazine herbicides in infant milk powder by high performance liquid chromatography coupled with ionic liquid-based homogeneous liquid-liquid microextraction].

    Science.gov (United States)

    Zhang, Liyuan; Yao, Di; Li, Na; Zhang, Hanqi; Yu, Aimin

    2015-07-01

    A high performance liquid chromatography coupled with homogeneous liquid-liquid microextraction was developed for the determination of five triazine herbicides in infant milk powders. The ionic liquid was used as microextraction solvent. The separation of the herbicides was performed on an Eclipse XDB-C18 column using acetonitrile and water as mobile phases in gradient mode. The effects of homogeneous liquid-liquid extraction conditions on the experimental results were investigated in detail. Under the optimized experimental conditions, the calibration curves for determining the analytes were linear and the correlation coefficients were ≥ 0.9992. The limits of detection for cyanazine, desmetryn, terbumeton, terbuthylazine and dimethametryn were 12.1, 13.8, 11.8, 14.6 and 13.7 μg/kg, respectively. The recoveries of the analytes spiked in four infant milk powders ranged from 92.2% to 103.2% and the relative standard deviations were lower than 6%. This method is sensitive, simple, and suitable for the determination of triazine herbicides in milk powder samples.

  20. a System which Uses a Continuous Optimization Approach for the Design of AN Optimum Extractant Molecule for Use in Liquid-Liquid Extraction.

    Science.gov (United States)

    Naser, Samer Fahim

    The design of an extractant molecule for use in liquid-liquid extraction, traditionally a combinatorial optimization problem, has been solved using continuous optimization. UNIFAC, a thermodynamic group contribution method which allows the calculation of an activity coefficient of a component from its chemical structure, was used as the basis for all calculations. A computer system was developed which employs a three step procedure. First, the error in the liquid-liquid equilibrium relations resulting from the specification of a target separation criteria is minimized by continuously varying the functional groups in the design group pool. Second, the theoretical molecule obtained from the first step is used as a starting point to optimize up to seven separation criteria by variation of functional groups and mole fractions to obtain the optimum theoretical extractant molecule which satisfies the equilibrium relations. Third, the theoretical molecule is used to generate alternative extractant molecules which contain integer functional group values only. Numeric molecular structure constraints were developed which help maintain the feasibility of molecules in the first two steps, and allow the rejection of infeasible molecules in the third step. These constraints include limits on boiling point and molecular weight. The system developed was successfully tested on several separation problems and has suggested extractants as good or better than ones currently in use. This is the first reported use of continuous optimization in molecular design. For large design pools, this approach, as opposed to combinatorial optimization, is several orders of magnitude faster.

  1. Ion-transfer voltammetric determination of the beta-blocker propranolol in a physiological matrix at silicon membrane-based liquid|liquid microinterface arrays.

    Science.gov (United States)

    Collins, Courtney J; Arrigan, Damien W M

    2009-03-15

    In this work, the ion-transfer voltammetric detection of the protonated beta-blocker propranolol in artificial saliva is presented. Cyclic voltammetry, differential pulse voltammetry, and differential pulse stripping voltammetry (DPSV) were employed in the detection of the cationic drug based on ion-transfer voltammetry across arrays of microinterfaces between artificial saliva and an organogel phase. It was found that the artificial saliva matrix decreased the available potential window for ion-transfer voltammetry at this liquid|liquid interface but transfer of protonated propranolol was still achieved. The DPSV method employed a preconditioning step as well as a preconcentration step followed by analytical signal generation based on the back-transfer of the drug across the array of microinterfaces. The DPSV peak current response was linear with drug concentration in the artificial saliva matrix over the concentration range of 0.05-1 microM (i(p) = -8.13 (nA microM(-1))(concentration) + 0.07 (nA), R = 0.9929, n = 7), and the calculated detection limit (3s(b)) was 0.02 microM. These results demonstrate that DPSV at arrays of liquid|liquid microinterfaces is a viable analytical approach for pharmaceutical determinations in biomimetic matrixes.

  2. Development of a dispersive liquid-liquid microextraction method with a new sequence of steps and its comparison with a conventional method.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Asghari, Azam; Feriduni, Behruz

    2016-08-01

    In this paper, a dispersive liquid-liquid microextraction method with a new sequence of steps from the view of salt addition has been developed for the extraction and preconcentration of some organophosphorous pesticides from aqueous samples before analysis by gas chromatography with flame ionization detection. In this method, an appropriate mixture of extraction and disperser solvents is rapidly injected by a syringe into the aqueous sample. Then, sodium chloride is added into the solution to increase its ionic strength. The obtained results by the proposed method are compared with those of the conventional dispersive liquid-liquid microextraction in which the salt is added into the aqueous phase before dispersion of the extraction solvent. Some effective parameters on the method efficiency including type and volume of extraction and disperser solvents, type and percent of salt, etc. are investigated. Under the optimal conditions, limits of detection and quantification of the proposed method compared to conventional one were improved by a factor between 1.4-2.2 and 1.3-2.3, respectively. Extraction recoveries and enrichment factors of the proposed method with respect to conventional one enhanced from 43-60 to 72-99% and 1433-2000 to 2404-3285, respectively. PMID:27311791

  3. Development of an ionic liquid based dispersive liquid-liquid microextraction method for the analysis of polycyclic aromatic hydrocarbons in water samples.

    Science.gov (United States)

    Pena, M Teresa; Casais, M Carmen; Mejuto, M Carmen; Cela, Rafael

    2009-09-01

    A simple, rapid and efficient method, ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME), has been developed for the first time for the determination of 18 polycyclic aromatic hydrocarbons (PAHs) in water samples. The chemical affinity between the ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate) and the analytes permits the extraction of the PAHs from the sample matrix also allowing their preconcentration. Thus, this technique combines extraction and concentration of the analytes into one step and avoids using toxic chlorinated solvents. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, extraction time, dispersion stage, centrifuging time and ionic strength, were optimised. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection (Flu). The optimised method exhibited a good precision level with relative standard deviation values between 1.2% and 5.7%. Quantification limits obtained for all of these considered compounds (between 0.1 and 7 ng L(-1)) were well below the limits recommended in the EU. The extraction yields for the different compounds obtained by IL-DLLME, ranged from 90.3% to 103.8%. Furthermore, high enrichment factors (301-346) were also achieved. The extraction efficiency of the optimised method is compared with that achieved by liquid-liquid extraction. Finally, the proposed method was successfully applied to the analysis of PAHs in real water samples (tap, bottled, fountain, well, river, rainwater, treated and raw wastewater). PMID:19646707

  4. (Liquid + liquid) equilibria for the ternary mixtures (alkane + toluene + ionic liquid) at T = 298.15 K: Influence of the anion on the phase equilibria

    International Nuclear Information System (INIS)

    Highlights: ► [BMpyr][NTF2] and [BMpyr][TFO] were studied as solvents to extract aromatics from alkanes. ► (Liquid + liquid) equilibrium data were measured at 298.15 K for six ternary systems. ► Selectivity and solute distribution ratio were calculated and compared. ► The influence of the structure of anion of the ionic liquid was analyzed. ► Experimental data were satisfactorily correlated using NRTL model. - Abstract: (Liquid + liquid) equilibrium data for the ionic liquids 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMpyr][NTf2], and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMpyr][TFO], with toluene, and heptane or cyclohexane were determined at T = 298.15 K and atmospheric pressure. In order to check if these ILs can be used as potential solvents for the extraction of toluene from aliphatic compounds, the ability of the ILs as solvents was evaluated in terms of selectivity and solute distribution ratio. The experimental data were correlated accurately with the Non Random Two-Liquid model.

  5. A new liquid-liquid extraction method for determination of montelukast in small volume human plasma samples using HPLC with fluorescence detector

    Directory of Open Access Journals (Sweden)

    Chauhan B

    2006-01-01

    Full Text Available Montelukast is a potent orally active cysteinyl leukotriene receptor antagonist that significantly improves parameters of asthmatics. A new liquid-liquid extraction based reverse phase liquid chromatography method has been developed and subsequently validated for the determination of montelukast in human plasma. The separation was achieved with C8 column (150x4.6 mm, 5 micron and a mobile phase comprising of a mixture of 10 mM ammonium acetate buffer (pH 3.0 and acetonitrile in a ratio of 35:65 v/v. Montelukast was extracted from human plasma using a liquid-liquid extraction technique with ter-butylmethylether. The limit of detection and lowest limit of quantification were 5 and 10 ng/ml respectively. This method was found to be linear over the range of 10 to 1000 ng/ml with a recovery of 53 to 62%. Intraday and interday precision (% CV was < 15% and accuracy ranged from 96.23 to 108.39%. Stability studies showed that montelukast in human plasma is stable during the short-term period of sample preparation and analysis. This method can be used with small volume sample during pharmacokinetic studies.

  6. Changing Hydrogen-Bond Structure during an Aqueous Liquid-Liquid Transition Investigated with Time-Resolved and Two-Dimensional Vibrational Spectroscopy.

    Science.gov (United States)

    Bruijn, Jeroen R; van der Loop, Tibert H; Woutersen, Sander

    2016-03-01

    We investigate the putative liquid-liquid phase transition in aqueous glycerol solution, using the OD-stretch mode in dilute OD/OH isotopic mixtures to probe the hydrogen-bond structure. The conversion exhibits Avrami kinetics with an exponent of n = 2.9 ± 0.1 (as opposed to n = 1.7 observed upon inducing ice nucleation and growth in the same sample), which indicates a transition from one liquid phase to another. Two-dimensional infrared (2D-IR) spectroscopy shows that the initial and final phases have different hydrogen-bond structures: the former has a single Gaussian distribution of hydrogen-bond lengths, whereas the latter has a bimodal distribution consisting of a broad distribution and a narrower, ice-like distribution. The 2D-IR spectrum of the final phase is identical to that of ice/glycerol at the same temperature. Combined with the kinetic data this suggests that the liquid-liquid transformation is immediately followed by a rapid formation of small (probably nanometer-sized) ice crystals. PMID:26891098

  7. SBA-15分子筛用于组装二溴对氯偶氮胂%USE OF MOLECULAR SIEVE SBA - 15 FOR INCORPORATION OF DIBROMOCHLORO-ARSENAZO

    Institute of Scientific and Technical Information of China (English)

    翟庆洲; 于辉; 蔡建岩; 秦亮

    2006-01-01

    Molecular sieve (SBA - 15)-(dibromochloro-arsenazo, DBC-ASA) host-guest composite materials were prepared by a liquid-phase grafting method using the calcined SBA- 15 molecular sieve as the host material, the DBC-ASA solution as the guest material, and water as the medium. The composite materials (SBA- 15)-(DBC-ASA) were characterized by X-ray diffraction(XRD), Fourier transform infrared(FTIR)spectra, solid state diffuse reflectance absorption spectra, and luminescence studies. The XRD results show that the molecular sieve framework in the (SBA- 15)-(DBC-ASA) host-guest composite materials is retained, and is highly ordered. The FTIR spectra indicate that the framework of the SBA- 15 molecular sieve is retained when a small amount of DBC-ASA is incorporated into it, the order degree of the molecular sieve decreases when a large amount of DBC-ASA is incorporated into it. The solid state diffuse reflectance absorption spectra show that DBC-ASA is located in the channel of the SBA - 15 molecular sieve, and the channel of SBA - 15 has stereoconfinment. The luminescence spectra show a strong non-radiation transition processes in the prepared samples, and this results in very strong electron-photon interaction causing a charge transfer transition. The Stokes displacement takes place and the spectrum bands broaden.%以煅烧的分子筛SBA-15为主体材料,二溴对氯偶氮胂(dibromochloro-arsenazo,DBC-ASA)作客体材料,以水为介质,用液相移植法制备了(SBA-15)-(DBC-ASA)主客体复合材料.用粉末X射线衍射、Fourier变换红外光谱、固体扩散漫反射吸收光谱及发光研究表征了所制得的复合材料(SBA-15)-(DBC-ASA)的性质.X射线衍射结果表明:(SBA-15)-(DBC-ASA)主客体复合材料分子筛骨架存在且有序度高.红外光谱分析表明:较低量的DBC-ASA引入SBA-15分子筛中,分子筛骨架结构仍然存在,但引入量较大时,分子筛的骨架有序度明显降低.固体扩散漫反射吸收光谱研

  8. Application of elevated temperature-dispersive liquid-liquid microextraction for determination of organophosphorus pesticides residues in aqueous samples followed by gas chromatography-flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Rezaee Aghdam, Samaneh; Nouri, Nina; Bamorrowat, Mahdi

    2016-12-01

    In the present study, an elevated temperature, dispersive, liquid-liquid microextraction/gas chromatography-flame ionization detection was investigated for the determination, pre-concentration, and extraction of six organophosphorus pesticides (malathion, phosalone, dichlorvos, diazinon, profenofos, and chlorpyrifos) residues in fruit juice and aqueous samples. A mixture of 1,2-dibromoethane (extraction solvent) and dimethyl sulfoxide (disperser solvent) was injected rapidly into the sample solution heated at an elevated temperature. Analytical parameters, including enrichment factors (1600-2075), linearity (r>0.994), limits of detection (0.82-2.72ngmL(-1)) and quantification (2.60-7.36ngmL(-1)), relative standard deviations (<7%) and extraction recoveries (64-83%), showed the high efficiency of the method developed for analysis of the target analytes. The proposed procedure was used effectively to analyse selected analytes in river water and fruit juice, and diazinon was found at ngmL(-1) concentrations in apple juice.

  9. The Study of a New Method to Determine Copper Ion by Square-Wave Voltammetry-Extraction Iodometry at the Liquid/Liquid Interfaces

    OpenAIRE

    Jinping Jia; Shaoai Xie; Changyan Shi

    2008-01-01

    A new method of indirect determination of Cu2+ was developed based on square-wave voltammetry by the oxidation of iodide in organic solvent at the liquid/liquid (L/L) interface. The limit of detection for the determination of Cu2+ in this method was found to be 5×10−4 mol/L, and the concentration ranged up to 1×10−2 mol/L gave a linear limiting current versus concentration response. For the same simulated wastewater, this method showed high accuracy compared with the...

  10. Determination of volatile components of green, black, oolong and white tea by optimized ultrasound-assisted extraction-dispersive liquid-liquid microextraction coupled with gas chromatography.

    Science.gov (United States)

    Sereshti, Hassan; Samadi, Soheila; Jalali-Heravi, Mehdi

    2013-03-01

    Ultrasound assisted extraction (UAE) followed by dispersive liquid-liquid microextraction (DLLME) was used for extraction and preconcentration of volatile constituents of six tea plants. The preconcentrated compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Totally, 42 compounds were identified and caffeine was quantitatively determined. The main parameters (factors) of the extraction process were optimized by using a central composite design (CCD). Methanol and chloroform were selected as the extraction solvent and preconcentration solvent, respectively .The optimal conditions were obtained as 21 in for sonication time; 32°C for temperature; 27 L for volume of extraction solvent and 7.4% for salt concentration (NaCl/H(2)O). The determination coefficient (R(2)) was 0.9988. The relative standard deviation (RSD %) was 4.8 (n=5), and the enhancement factors (EFs) were 4.0-42.6. PMID:23375769

  11. Screening and quantitative determination of twelve acidic and neutral pharmaceuticals in whole blood by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Simonsen, Kirsten Wiese; Steentoft, Anni; Buck, Maike; Hansen, Lene; Linnet, Kristian

    2010-09-01

    We describe a multi-method for simultaneous identification and quantification of 12 acidic and neutral compounds in whole blood. The method involves a simple liquid-liquid extraction, and the identification and quantification are performed using liquid chromatography-tandem mass spectrometry. The method was fully validated for salicylic acid, paracetamol, phenobarbital, carisoprodol, meprobamate, topiramate, etodolac, chlorzoxazone, furosemide, ibuprofen, warfarin, and salicylamide. The method also tentatively includes thiopental, theophylline, piroxicam, naproxen, diclophenac, and modafinil, but these drugs were not included in the full validation program and are not described in detail here. Limit of quantitation was 1 mg/kg for the compounds with coefficients of variation of < 20%, except for furosemide, which had a coefficient of variation of 32% at limit of quantitation. The measuring interval was wide for most components. Extraction efficiencies were high, reflecting the high-yield capacity of the method. PMID:20822673

  12. Baseline-Corrected Second-Order Derivative Electroanalysis Combined With Ultrasound-Assisted Liquid-Liquid Microextraction: Simultaneous Quantification of Fluoroquinolones at Low Levels.

    Science.gov (United States)

    de Oliveira, Luiz Henrique; Trindade, Magno Aparecido Gonçalves

    2016-06-21

    A baseline-corrected second-order derivative procedure and a miniaturized sample preparation based on low-density solvent and ultrasound-assisted liquid-liquid microextraction (LDS-UA-LLME) was combined to provide the simultaneous electroanalysis of three fluoroquinolones (FQ) as emerging contaminants (ECs). The enhanced mathematical processing provided the best separation with an accurate measurement of the overlapping peaks during the simultaneous electro-oxidation of target FQs that were directly dropped on the surface of carbon nanofiber-modified screen-printed electrodes. The adapted LDS-UA-LLME protocol was the key step involved in the sample preparation, which preconcentrate target analytes from diluted tap water samples with an enrichment factor of around 80×, allowing their quantification at trace levels. This combined feature demonstrated the unique application of an electroanalytical technique for the simultaneous electroanalysis of three FQs in spiked tap water samples, with recovery values remarkably close to 100%. PMID:27249314

  13. Comparison of ultrasound-assisted cloud point extraction and ultrasound-assisted dispersive liquid liquid microextraction for copper coupled with spectrophotometric determination

    Science.gov (United States)

    Yang, Shengchun; Fang, Xiang; Duan, Liju; Yang, Shu; Lei, Zirong; Wen, Xiaodong

    2015-09-01

    In this work, ultrasound-assisted cloud point extraction (UA-CPE) and ultrasound-assisted dispersive liquid liquid microextraction (UA-DLLME) were investigated and compared firstly as ultrasound-assisted liquid phase microextraction methods, which were coupled with spectrophotometer for copper preconcentration and detection. Compared to conventional CPE and DLLME, the extraction patterns were changed and improved by the effect of ultrasound. As novel methods, their applications were expanded and the analytical performance of spectrophotometric determination for copper was considerably improved. The influence factors of UA-CPE and UA-DLLME were studied in detail. Under the optimal conditions, the limits of detection (LODs) for copper were 0.7 μg L-1 of UA-CPE and 0.8 μg L-1 of UA-DLLME with sensitivity enhancement factors (EFs) of 17 and 16. The developed methods were applied to the determination of trace copper in real water samples with satisfactory analytical results.

  14. Determination of Macrolide Antibiotics Using Dispersive Liquid-Liquid Microextraction Followed by Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

    Science.gov (United States)

    Chen, Kuan-Yu; Yang, Thomas C.; Chang, Sarah Y.

    2012-06-01

    A novel method for the determination of macrolide antibiotics using dispersive liquid-liquid microextraction coupled to surface-assisted laser desorption/ionization mass spectrometric detection was developed. Acetone and dichloromethane were used as the disperser solvent and extraction solvent, respectively. A mixture of extraction solvent and disperser solvent were rapidly injected into a 1.0 mL aqueous sample to form a cloudy solution. After the extraction, macrolide antibiotics were detected using surface-assisted laser desorption/ionization mass spectrometry (SALDI/MS) with colloidal silver as the matrix. Under optimum conditions, the limits of detection (LODs) at a signal-to-noise ratio of 3 were 2, 3, 3, and 2 nM for erythromycin (ERY), spiramycin (SPI), tilmicosin (TILM), and tylosin (TYL), respectively. This developed method was successfully applied to the determination of macrolide antibiotics in human urine samples.

  15. Vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction for the determination of carbamates in juices by micellar electrokinetic chromatography tandem mass spectrometry.

    Science.gov (United States)

    Moreno-González, David; Huertas-Pérez, José F; García-Campaña, Ana M; Gámiz-Gracia, Laura

    2015-07-01

    A new method based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction has been developed for the extraction of carbamate pesticides in juice samples prior to their determination by micellar electrokinetic chromatography coupled to tandem mass spectrometry. This sample treatment allowed the satisfactory extraction and the extract clean-up of 25 carbamates from different fruit and vegetal juices (banana, tomato, and peach). In this study, the addition of ammonium perfluorooctanoate in the aqueous sample in combination with vortex agitation, provided very clean extracts with short extraction times. Under optimized conditions, recoveries of the proposed method for these pesticides from fortified juice samples ranged from 81% to 104%, with relative standard deviations lower than 15%. Limits of quantification were between 2.3µgkg(-)(1) and 4.7µgkg(-)(1), showing the high sensitivity of this fast and simple method. PMID:25882424

  16. (Liquid + liquid) equilibrium for ternary mixtures of {l_brace}heptane + aromatic compounds + [EMpy][ESO{sub 4}]{r_brace} at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Mirkhani, S.A. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Vossoughi, M., E-mail: vosoughi@sharif.edu [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Pazuki, G.R. [Department of Chemical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Safekordi, A.A. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Heydari, A.; Akbari, J. [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Yavari, M. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2011-10-15

    Highlights: > This paper reports the LLE data of ternary systems {l_brace}heptane (1) + aromatic compounds (2) + [EMpy][ESO{sub 4}] (3){r_brace}. > The distribution coefficient and the selectivity were obtained from the experimental data. > The consistency of LLE data was successfully correlated with Othmer-Tobias and Hand equation. - Abstract: (Liquid + liquid) equilibrium (LLE) data for the ternary systems (heptane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate) and (heptane + benzene + 1-ethyl-3-methylpyridinium ethylsulfate) were measured at T = 298.15 K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of aromatic compounds from heptane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations.

  17. Ternary liquid-liquid equilibria of dimethyl carbonate + 2-propanol + water system at 303.15 and 313.15 K

    Science.gov (United States)

    Ginting, Rizqy Romadhona; Mustain, Asalil; Tetrisyanda, Rizki; Gunardi, Ignatius; Wibawa, Gede

    2015-12-01

    In this work, liquid-liquid equilibria data of dimethyl carbonate (DMC) + 2-propanol + water system were accurately determined at 303.15 and 313.15 K using stirred and jacketed equilibrium cell under atmospheric pressure. The reliabilities of the experimental data were confirmed using Bachman-Brown correlation giving r-squared value of 0.9993 and 0.9983 at 303.15 and 313.15 K, respectively. Experimental data obtained in this work exhibit Treybal's Type I ternary phase behavior. The selectivity and distribution coefficient of DMC increases with addition of DMC concentration in the organic phase. On the other hand, the effect of temperature to phase boundary was found to be not significant. The data were correlated well using the Non-Random Two Liquid (NRTL) and Universal Quasi-Chemical (UNIQUAC) activity coefficient models with root-mean-square deviation of 1.5% and 1.3%, respectively.

  18. Determination of aflatoxin B1 in cereals by homogeneous liquid-liquid extraction coupled to high performance liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Sheijooni-Fumani, Neda; Hassan, Jalal; Yousefi, Seyed R

    2011-06-01

    A simple and rapid method based on homogeneous liquid-liquid extraction coupled to HPLC with fluorescence detection was developed for the determination of aflatoxin B1 (AFB1) in the rice and grain samples after post-column derivatization. The proposed method eliminated the use of immunoaffinity columns for clean-up in the determination of AFB1. The parameters affecting recovery and preconcentration such as type and volume of organic solvent, volume ratio of water/methanol, concentration of phase separator reagent and extraction time were optimized. Under the optimized conditions, the calibration graph was linear in the concentration range of 0.01-1.0 ng/g with the detection limit of 0.003 ng/g. This method was successfully applied for the analysis of AFB1 in different cereal samples. PMID:21491592

  19. Ternary Liquid-Liquid Equilibrium for Systems of Fatty Acid Methyl Ester(Methyl Palmitate/Methyl Stearate)+Ethanol+Glycerol at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    夏淑倩; 罗慧娟; 马沛生

    2015-01-01

    Liquid-liquid equilibrium data of two ternary systems methyl palmitate+ethanol+glycerol and methyl stearate+ethanol+glycerol at(318.2 and 333.2)K and atmospheric pressure were measured. The values of distri-bution coefficient and selectivity were calculated, which indicates that glycerol can be separated from fatty acid ester by using ethanol as an extraction solvent. The consistency of the isothermal tie-line data were checked by the Othmer-Tobias equation. The correlation coefficients R2 are higher than 0.993,9 for all the fitted curves. The NRTL activity coefficient model was applied to the correlation of the measured tie-line data. The root mean square devia-tion(RMSD)values are less than 0.007 for all the systems, which shows a good predictive capability of this model for such systems.

  20. Liquid-liquid transition in supercooled aqueous solution involving a low-temperature phase similar to low-density amorphous water

    CERN Document Server

    Woutersen, Sander; Zhao, Zuofeng; Angell, C Austen

    2016-01-01

    The striking anomalies in physical properties of supercooled water that were discovered in the 1960-70s, remain incompletely understood and so provide both a source of controversy amongst theoreticians, and a stimulus to experimentalists and simulators to find new ways of penetrating the "crystallization curtain" that effectively shields the problem from solution. Recently a new door on the problem was opened by showing that, in ideal solutions, made using ionic liquid solutes, water anomalies are not destroyed as earlier found for common salt and most molecular solutes, but instead are enhanced to the point of precipitating an apparently first order liquid-liquid transition. The evidence was a spike in apparent heat capacity during cooling that could be fully reversed during reheating before any sign of ice crystallization appeared. Here, we use decoupled-oscillator infrared spectroscopy to define the structural character of this phenomenon using similar down and upscan rates as in the calorimetric study. Th...

  1. Baseline-Corrected Second-Order Derivative Electroanalysis Combined With Ultrasound-Assisted Liquid-Liquid Microextraction: Simultaneous Quantification of Fluoroquinolones at Low Levels.

    Science.gov (United States)

    de Oliveira, Luiz Henrique; Trindade, Magno Aparecido Gonçalves

    2016-06-21

    A baseline-corrected second-order derivative procedure and a miniaturized sample preparation based on low-density solvent and ultrasound-assisted liquid-liquid microextraction (LDS-UA-LLME) was combined to provide the simultaneous electroanalysis of three fluoroquinolones (FQ) as emerging contaminants (ECs). The enhanced mathematical processing provided the best separation with an accurate measurement of the overlapping peaks during the simultaneous electro-oxidation of target FQs that were directly dropped on the surface of carbon nanofiber-modified screen-printed electrodes. The adapted LDS-UA-LLME protocol was the key step involved in the sample preparation, which preconcentrate target analytes from diluted tap water samples with an enrichment factor of around 80×, allowing their quantification at trace levels. This combined feature demonstrated the unique application of an electroanalytical technique for the simultaneous electroanalysis of three FQs in spiked tap water samples, with recovery values remarkably close to 100%.

  2. Comparison of ultrasound-assisted cloud point extraction and ultrasound-assisted dispersive liquid liquid microextraction for copper coupled with spectrophotometric determination.

    Science.gov (United States)

    Yang, Shengchun; Fang, Xiang; Duan, Liju; Yang, Shu; Lei, Zirong; Wen, Xiaodong

    2015-09-01

    In this work, ultrasound-assisted cloud point extraction (UA-CPE) and ultrasound-assisted dispersive liquid liquid microextraction (UA-DLLME) were investigated and compared firstly as ultrasound-assisted liquid phase microextraction methods, which were coupled with spectrophotometer for copper preconcentration and detection. Compared to conventional CPE and DLLME, the extraction patterns were changed and improved by the effect of ultrasound. As novel methods, their applications were expanded and the analytical performance of spectrophotometric determination for copper was considerably improved. The influence factors of UA-CPE and UA-DLLME were studied in detail. Under the optimal conditions, the limits of detection (LODs) for copper were 0.7 μg L(-1) of UA-CPE and 0.8 μg L(-1) of UA-DLLME with sensitivity enhancement factors (EFs) of 17 and 16. The developed methods were applied to the determination of trace copper in real water samples with satisfactory analytical results.

  3. Rapid and sensitive determination of benzaldehyde arising from benzyl alcohol used as preservative in an injectable formulation solution using dispersive liquid-liquid microextraction followed by gas chromatography.

    Science.gov (United States)

    Mashayekhi, Hossein Ali; Rezaee, Mohammad; Garmaroudi, Shirin Sadeghi; Montazeri, Naser; Ahmadi, Seyed Javad

    2011-01-01

    A rapid and sensitive method has been developed for the determination of benzaldehyde, a toxic oxidation product of the widely used preservative and co-solvent benzyl alcohol in injectable formulations of non-steroidal anti-inflammatory drugs, diclofenac, vitamin B-complex and Voltaren injection solutions by using dispersive liquid-liquid microextraction followed by gas chromatography. This method involves the use of an appropriate mixture of extraction solvent (43.0 µL 1,2-dichloroethane) and disperser solvent (1.0 mL acetonitrile) for the formation of a cloudy solution in a 5.0-mL aqueous sample containing benzaldehyde. The linear range was 1.0-1000 µg L(-1), and the limit of detection was 0.2 µg L(-1) for benzaldehyde.

  4. Toxicological evaluation of liquids proposed for use in direct contact liquid--liquid heat exchangers for solar heated and cooled buildings

    Energy Technology Data Exchange (ETDEWEB)

    Buchan, R.M.; Majestic, J.R.; Billau, R.

    1976-09-01

    This report contains the results of the toxicological evaluation part of the project entitled, ''Direct Contact Liquid-Liquid Heat Exchangers for Solar Heated and Cooled Buildings.'' Obviously any liquid otherwise suitable for use in such a device should be subjected to a toxicological evaluation. 34 liquids (24 denser than water, 10 less dense) have physical and chemical properties that would make them suitable for use in such a device. In addition to the complexity involved in selecting the most promising liquids from the standpoint of their chemical and physical properties is added the additional difficulty of also considering their toxicological properties. Some of the physical and chemical properties of these liquids are listed. The liquids are listed in alphabetical order within groups, the denser than water liquids are listed first followed by those liquids less dense than water.

  5. [Determination of trichlorobenzenes in water-based cutting fluids and wastewater of machining using dispersive liquid-liquid microextraction-gas chromatography/mass spectrometry].

    Science.gov (United States)

    Shen, Haoyu; Zhao, Yonggang; Huai, Mingmin; Jiang, Hailiang

    2009-01-01

    The determination of trichlorobenzenes (TCBs) in water-based cutting fluids and wastewater of machining has been carried out. A gas chromatography/mass spectrometry (GC/ MS) method with selected ion monitoring (SIM) mode was employed. The target analyte was extracted from the matrix using dispersive liquid-liquid microextraction. Comparing with gas chromatography/electronic capture detection (GC/ECD) coupled with traditional sample preparation procedures, e.g. head-space extraction, liquid-liquid extraction and solid-phase extraction, the present method was accurate with broader linear range, better enrichment property, better replicability, easier to be operated and less interference. Overall recoveries were 94.7% - 104.3% with the relative standard deviations (RSDs) of at 2.3% - 7.8%. The detective limits for 1,3,5-, 1,2,4- and 1,2,3-trichlorobenzene were 2.0, 6.0 and 3.0 microg/L, respectively. The parameters, such as the nature and volume of extraction solvent, dispersive solvent, extraction time and salt effect, were studied and optimized. Some important factors, e.g., the concentration of common used additives in water-based cutting fluids, which may affect the recoveries and replicabilities for the determination of trichlorobenzenes, have been investigated. The result showed that no significant effects have been observed when the concentrations of NaNO2 and polyethylene glycol (PEG) were up to 1.0%. The present method has been applied for the determination of the trichlorobenzenes in 4 real samples. The result showed that two of them were found to contain these trichlorobenzenes. The TCBs in the samples were 0.15 - 1.67 mg/L.

  6. 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.

  7. Analyses of polychlorinated biphenyls in waters and wastewaters using vortex-assisted liquid-liquid microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Ozcan, Senar

    2011-03-01

    A method was developed for viable and rapid determination of seven polychlorinated biphenyls (PCBs) in water samples with vortex-assisted liquid-liquid microextraction (VALLME) using gas chromatography-mass spectrometry (GC-MS). At first, the most suitable extraction solvent and extraction solvent volume were determined. Later, the parameters affecting the extraction efficiency such as vortex extraction time, rotational speed of the vortex, and ionic strength of the sample were optimized by using a 2(3) factorial experimental design. The optimized extraction conditions for 5 mL water sample were as follows: extractant solvent 200 μL of chloroform; vortex extraction time of 2 min at 3000 rpm; centrifugation 5 min at 4000 rpm, and no ionic strength. Under the optimum condition, limits of detection (LOD) ranged from 0.36 to 0.73 ng/L. Mean recoveries of PCBs from fortified water samples are 96% for three different fortification levels and RSDs of the recoveries are below 5%. The developed procedure was successfully applied to the determination of PCBs in real water and wastewater samples such as tap, well, surface, bottled waters, and municipal, treated municipal, and industrial wastewaters. The performance of the proposed method was compared with traditional liquid-liquid extraction (LLE) of real water samples and the results show that efficiency of proposed method is comparable to the LLE. However, the proposed method offers several advantages, i.e. reducing sample requirement for measurement of target compounds, less solvent consumption, and reducing the costs associated with solvent purchase and waste disposal. It is also viable, rapid, and easy to use for the analyses of PCBs in water samples by using GC-MS. PMID:21280211

  8. CHEMOMETRICS IN BIOANALYTICAL SAMPLE PREPARATION - A FRACTIONATED COMBINED MIXTURE AND FACTORIAL DESIGN FOR THE MODELING OF THE RECOVERY OF 5 TRICYCLIC AMINES FROM PLASMA AFTER LIQUID-LIQUID-EXTRACTION PRIOR TO HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

    NARCIS (Netherlands)

    WIELING, J; MENSINK, CK; JONKMAN, JHG; COENEGRACHT, PMJ; DUINEVELD, CAA; DOORNBOS, DA

    1993-01-01

    A general systematic approach is described for the chemometric modelling of liquid-liquid extraction data of drugs from biological fluids. Extraction solvents were selected from Snyder's solvent selectivity triangle: methyl tert.-butyl ether, methylene chloride and chloroform. The composition of a m

  9. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    Emmerik, van P.T.; Smolders, C.A.

    1972-01-01

    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  10. Ionic liquid-based zinc oxide nanofluid for vortex assisted liquid liquid microextraction of inorganic mercury in environmental waters prior to cold vapor atomic fluorescence spectroscopic detection.

    Science.gov (United States)

    Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

    2016-03-01

    Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg(2+)) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1ng/mL of Hg(2+) in 10mL of sample solution was achieved using 50μL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg(2+) concentration of GBW08603 (9.6ng/mL) and GBW(E)080392 (8.9ng/mL) agreed well with their certified value (10ng/mL). The method was applied to the analysis of Hg(2+) in effluent, influent, lake and river water samples, with recoveries in the range of 79.8-92.8% and 83.6-106.1% at 1ng/mL and 5ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples. PMID:26717850

  11. Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of organochlorine pesticides in aqueous samples.

    Science.gov (United States)

    Li, Yee; Chen, Pai-Shan; Huang, Shang-Da

    2013-07-26

    A novel sample preparation method, "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)", coupled with gas chromatography using an electron capture detector (GC-ECD) was developed for the analysis of the organochlorine pesticides (OCPs), heptachlor, α-endosulfan, 4,4-DDE, 2,4-DDD and endrin, in aqueous samples. A microsyringe is used to withdrew and discharge 10-12μL of the extraction solvent and 60-120μL of water as the dispersed solvent (containing 1mgL(-1), Tween 80) 4 times within 10s to form a cloudy emulsified solution in the syringe. This is then injected into an 8mL aqueous sample spiked with all above OCPs. Dodecyl acetate and 2-dodecanol were both selected as extraction solvents to optimize their conditions separately. The total extraction time was about 0.5min. Under optimum conditions, using dodecyl acetate (12μL) as extraction solvent, the linear range of the method was 10-1000ngL(-1) for all OCPs, and the the limits of detection (LODs) ranged from 1 to 5ngL(-1). The absolute recoveries and relative recoveries were from 20.8 to 43.5% and 83.2 to 109.8% for lake water, and 19.9-49.2% and 85.4-115.9% for seawater respectively. In the second method, 2-dodecanol as extraction solvent, the linear range was from 5 to 5000ngL(-1) for the target compounds, and the LODs were between 0.5 and 2ngL(-1). The absolute recoveries and relative recoveries ranged from 25.7 to 42.2% and 96.3-111.2% for sea water, and 22.4-41.9% and 90.7-107.9% for stream water. This could solve several problems, which commonly occur in ultrasound-assisted emulsification micro-extraction (USAEME), dispersive liquid-liquid micro-extraction (DLLME) and other assisted emulsification methods. These problems include analyte degradation, increased solubility of the extraction solvent and analyte, and high toxicity and large volume of the organic solvent used. PMID:23566919

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

    Energy Technology Data Exchange (ETDEWEB)

    Naseri, Mohammad Taghi; Hemmatkhah, Payam; Hosseini, Mohammad Reza Milani [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Assadi, Yaghoub [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)], E-mail: y_assadi@iust.ac.ir

    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 {mu}L 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 {mu}g L{sup -1} with a detection limit of 0.5 {mu}g L{sup -1}. The relative standard deviation (R.S.D.) for seven replicate measurements of 5.0 and 50 {mu}g L{sup -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 {mu}g L{sup -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. Determination of Wastewater Compounds in Whole Water by Continuous Liquid-Liquid Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry

    Science.gov (United States)

    Zaugg, Steven D.; Smith, Steven G.; Schroeder, Michael P.

    2006-01-01

    A method for the determination of 69 compounds typically found in domestic and industrial wastewater is described. The method was developed in response to increasing concern over the impact of endocrine-disrupting chemicals on aquatic organisms in wastewater. This method also is useful for evaluating the effects of combined sanitary and storm-sewer overflow on the water quality of urban streams. The method focuses on the determination of compounds that are indicators of wastewater or have endocrine-disrupting potential. These compounds include the alkylphenol ethoxylate nonionic surfactants, food additives, fragrances, antioxidants, flame retardants, plasticizers, industrial solvents, disinfectants, fecal sterols, polycyclic aromatic hydrocarbons, and high-use domestic pesticides. Wastewater compounds in whole-water samples were extracted using continuous liquid-liquid extractors and methylene chloride solvent, and then determined by capillary-column gas chromatography/mass spectrometry. Recoveries in reagent-water samples fortified at 0.5 microgram per liter averaged 72 percent ? 8 percent relative standard deviation. The concentration of 21 compounds is always reported as estimated because method recovery was less than 60 percent, variability was greater than 25 percent relative standard deviation, or standard reference compounds were prepared from technical mixtures. Initial method detection limits averaged 0.18 microgram per liter. Samples were preserved by adding 60 grams of sodium chloride and stored at 4 degrees Celsius. The laboratory established a sample holding-time limit prior to sample extraction of 14 days from the date of collection.

  14. In situ ionic liquid dispersive liquid-liquid microextraction and direct microvial insert thermal desorption for gas chromatographic determination of bisphenol compounds.

    Science.gov (United States)

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2016-01-01

    A new procedure based on direct insert microvial thermal desorption injection allows the direct analysis of ionic liquid extracts by gas chromatography and mass spectrometry (GC-MS). For this purpose, an in situ ionic liquid dispersive liquid-liquid microextraction (in situ IL DLLME) has been developed for the quantification of bisphenol A (BPA), bisphenol Z (BPZ) and bisphenol F (BPF). Different parameters affecting the extraction efficiency of the microextraction technique and the thermal desorption step were studied. The optimized procedure, determining the analytes as acetyl derivatives, provided detection limits of 26, 18 and 19 ng L(-1) for BPA, BPZ and BPF, respectively. The release of the three analytes from plastic containers was monitored using this newly developed analytical method. Analysis of the migration test solutions for 15 different plastic containers in daily use identified the presence of the analytes at concentrations ranging between 0.07 and 37 μg L(-1) in six of the samples studied, BPA being the most commonly found and at higher concentrations than the other analytes.

  15. Rapid screening of haloacetamides in water using salt-assisted liquid-liquid extraction coupled injection-port silylation gas chromatography-mass spectrometry.

    Science.gov (United States)

    Chen, Tzu-Ling; Tzing, Shin-Hwa; Ding, Wang-Hsien

    2015-11-27

    The rapid screening of trace amounts of the nitrogenous disinfection by-products, haloacetamides (HAcAms), in drinking and swimming pool water was performed by a simple and reliable procedure based on salt-assisted liquid-liquid extraction (SALLE) combined with injection-port silylation gas chromatography-mass spectrometry (IPS-GC-MS) method. The optimal SALLE conditions involved the injection of 4-mL of ethyl acetate into a 10-mL water sample (pH 7) containing 3-g of sodium sulfate. After vortex extraction for 1min and centrifugation, 10μL of the extract (mixed with 1μL of MTBSTFA) was directly determined by IPS-GC-MS. The limits of quantitation (LOQs) were determined to be 0.03-0.3μg/L. Precision, as indicated by relative standard deviations (RSDs), was less than 10% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 76% and 94%. The SALLE plus IPS-GC-MS was successfully applied to quantitatively determine HAcAms from drinking and swimming pool water samples, and the total concentrations of the compounds ranged from 0.43 to 4.03μg/L.

  16. Dispersive liquid-liquid microextraction for the determination of nitrophenols in soils by microvial insert large volume injection-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

    2016-07-22

    A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC-MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an "in-situ" acetylation procedure, before being injected into the GC-MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86-111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg(-1), depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8-9.6ngg(-1) range.

  17. An in situ derivatization - dispersive liquid-liquid microextraction combined with gas-chromatography - mass spectrometry for determining biogenic amines in home-made fermented alcoholic drinks.

    Science.gov (United States)

    Płotka-Wasylka, Justyna; Simeonov, Vasil; Namieśnik, Jacek

    2016-07-01

    A novel dispersive liquid-liquid microextraction (DLLME) gas chromatography mass-spectrometry (GC-MS) method was developed for the determination of 13 biogenic amines in home-made wine samples. The method allows to simultaneous extraction and derivatization of the amines providing a simple and fast mode of extract enrichment. During the study, two different procedures were examined. Statistical analysis was performed to choose better procedure, as well as the conditions of derivatization reaction. At least, a mixture of methanol (dispersive solvent; 215μL), chloroform (extractive solvent; 400μL), and isobutyl choloroformate (derivatizing reagent; 90μL) was used as extractive/derivatizing reagent, added to 5mL of sample. The addition of mixture of pyridine and HCl was necessary to eliminate the by-products. The proposed method showed good linearity (correlation coefficients >0.9961), good recoveries (from 77 to 105%), and good intra-day precision (below 13%) and inter-day precision (below 10%). Moreover, detection limits were never over 4.1μg/L. The developed method was successfully applied to the analysis of 17 home-made wine samples not regulated by law. All of the biogenic amines analyzed were found in most of the wines.

  18. Simple field-based automated dispersive liquid-liquid microextraction of trace level phthalate esters in natural waters with gas chromatography and mass spectrometric analysis.

    Science.gov (United States)

    Leng, Geng; Chen, Wenjin; Wang, Yong

    2016-09-01

    A small, simple, and field-based automated dispersive liquid-liquid microextraction method followed by gas chromatography mass spectrometric analysis was developed for trace level phthalate esters analysis in natural waters. With a single syringe pump that is coupled with a multiposition valve, the whole extraction procedure including cleaning, sampling, mixing of extractant and disperser solvents, extraction, phase separation, and analytes collection was carried out in a totally automated way with a sample throughput of 21 h(-1) . Key factors, such as type and ratio of the extractant and disperser solvent, aspiration flow rate, extraction time, and matrix effect, were thoroughly investigated. Under the optimum conditions, linearity was found in the range from 0.03 to 60 μg/L. Limits of detection ranged from 0.0015 to 0.003 μg/L. Enrichment factors were in a range of 106-141. Reproducibility and recoveries were assessed by testing a series of three natural water samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied in analysis of real surface waters. The developed system is inexpensive, light (2.6 kg), simple to use, applicable in the field, with high sample throughput, and sensitive enough for trace level phthalate esters analysis in natural waters.

  19. Homogeneous Liquid-Liquid Microextraction for Determination of Organophosphorus Pesticides in Environmental Water Samples Prior to Gas Chromatography-Flame Photometric Detection.

    Science.gov (United States)

    Berijani, Sana; Sadigh, Mirhanif; Pournamdari, Elham

    2016-07-01

    In this study, homogeneous liquid-liquid microextraction (HLLME) was developed for preconcentration and extraction of 15 organophosphorus pesticides (OPPs) from water samples coupling with gas chromatography followed by a flame photometric detector (HLLME-GC-FPD). In this method, OPPs were extracted by the homogeneous phase in a ternary solvent system (water/acetic acid/chloroform). The homogeneous solution was excluded by the addition of sodium hydroxide as a phase separator reagent and a cloudy solution was formed. After centrifugation (3 min at 5,000 rpm), the fine particles of extraction solvent (chloroform) were sedimented at the bottom of the conical test tube (10.0 ± 0.5 µL). Furthermore, 0.5 µL of the sedimented phase was injected into the GC for separation and determination of OPPs. Optimal results were obtained under the following conditions: volume of the extracting solvent (chloroform), 53 µL; volume of the consolute solvent (acetic acid), 0.76 mL and concentration of sodium hydroxide, 40% (w/v). Under the optimum conditions, the enrichment factors of (260-665), the extraction percent of 75.8-104%, the dynamic linear range of 0.03-300 µg L(-1) and the limits of detection of 0.004-0.03 µg L(-1) were obtained for the OPPs. This method was successfully applied for the extraction and determination of the OPPs in environmental water samples.

  20. Up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry for the determination of fungicides in wine.

    Science.gov (United States)

    Chu, Shang-Ping; Tseng, Wan-Chi; Kong, Po-Hsin; Huang, Chun-Kai; Chen, Jung-Hsuan; Chen, Pai-Shan; Huang, Shang-Da

    2015-10-15

    An up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) method coupled with gas chromatography-mass spectrometry was developed for the determination of fungicides (cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole) in wine. The developed method requires 11 μL of 1-octanol without the need for dispersive solvents. The total extraction time was approximately 3 min. Under optimum conditions, the linear range of the method was 0.05-100 μg L(-1) for all fungicides and the limit of detection was 0.007-0.025 μg L(-1). The absolute and relative recoveries were 31-83% and 83-107% for white wine, respectively, and 32-85% and 83-108% for red wine, respectively. The intra-day and inter-day precision were 0.5-7.5% and 0.7-6.1%, respectively. Our developed method had good sensitivity and high extraction efficiency. UDSA-DLLME is a desirable method in terms of performance and speed.

  1. Simultaneous determination of polycyclic musks in blood and urine by solid supported liquid-liquid extraction and gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Liu, Hongtao; Huang, Liping; Chen, Yuxin; Guo, Liman; Li, Limin; Zhou, Haiyun; Luan, Tiangang

    2015-06-15

    A rapid, precise and accurate method for the simultaneous determination of 5 polycyclic musks (PCMs) in biological fluids was developed by solid supported liquid-liquid extraction (SLE) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). All parameters influencing SLE-GC-MS performance, including electron energy of electron-impact ionization source, collision energy for tandem mass spectrometer when operated in selected-reaction monitoring (SRM) mode, type and volume of elution reagent, nitrogen evaporation time, pH and salinity of sample have been carefully optimized. Eight milliliter of n-hexane was finally chosen as elution reagent. Blood and urine sample could be loaded into SLE cartridge without adjusting pH and salinity. Deuterated tonalide (AHTN-d3) was chosen as internal standard. The correlation coefficient (r(2)) of the calibration curves of target compounds ranged from 0.9996 to 0.9998. The dynamic range spanned over two orders of magnitude. The limit of detection (LOD) of target compounds in blood and urine ranged from 0.008 to 0.105μgL(-1) and 0.005 to 0.075μgL(-1), respectively. The developed procedure was successfully applied to the analysis of PCMs in human blood and urine obtaining satisfying recoveries on low, medium and high levels. The method was compared with SLE-GC-MS and shown one to two orders of magnitude improvement in sensitivity.

  2. (Liquid + liquid) equilibrium of (NaNO{sub 3} + PEG 4000 + H{sub 2}O) ternary system at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, Yecid P. [Departamento de Ingenieria Quimica, Universidad de Antofagasta, CICITEM (Chile); Galleguillos, Hector R., E-mail: hgalleguillos@uantof.cl [Departamento de Ingenieria Quimica, Universidad de Antofagasta, CICITEM (Chile)

    2011-11-15

    Highlights: > LLE data for the ATPS NaNO{sub 3} + PEG 4000 were determined at T = (288.15 and 308.15) K. > The experimental data shown that the temperature increases as STL and biphasic area increase. > The Chen-NRTL, modified Wilson and UNIQUAC models were used to correlate the experimental tie-line data. > The results show that the quality of fitting is better with the UNIQUAC model. - Abstract: Phase diagram and (liquid + liquid) equilibrium (LLE) data for the (NaNO{sub 3} + polyethylene glycol 4000 (PEG 4000) + H{sub 2}O) system have been determined experimentally at T = (288.15 and 308.15) K. The effects of temperature on the binodal curves and tie-lines have been studied and it was found that an increasing in temperature caused the expansion of two-phase region. The Chen-NRTL, modified Wilson and UNIQUAC models were used to correlate the experimental tie-line data. The results show that the quality of fitting is better with the UNIQUAC model.

  3. 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.

  4. 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.

  5. Ultrasound-assisted low-density solvent dispersive liquid-liquid extraction for the determination of alkanolamines and alkylamines in cosmetics with ion chromatography.

    Science.gov (United States)

    Zhong, Zhixiong; Li, Gongke; Zhong, Xiuhua; Luo, Zhibin; Zhu, Binghui

    2013-10-15

    A new one-step sample preparation technique termed ultrasound-assisted low-density solvent dispersive liquid-liquid extraction (UA-LDS-DLLE) coupled with ion chromatography (IC) was developed for the determination of three alkanolamines and two alkylamines in complex samples. Sample matrices were rapidly dissolved and dispersed to form cloudy solutions by using two solvents, where target analytes were transferred into acid solutions, while liposoluble substances were dissolved in cyclohexane. The obtained extracts could be used directly for injection analysis without any additional purification because the potential matrix interferences had been effectively eliminated in extraction process. The extraction efficiency could be markedly enhanced and the extraction could be quickly accomplished within 13 min under the synergistic effects of ultrasound radiation, vibration and heating. Various parameters influencing extraction efficiency were evaluated using orthogonal array experimental design. The extraction performance of the approach was demonstrated for the determination of target analytes in 15 commercial cosmetics covering very different matrices. Linearity ranges of 0.3-50 mg L(-1) and limits of detection varying from 0.072 to 0.12 mg L(-1) were achieved. The recoveries ranged from 86.9-108.5% with the relative standard deviations (RSDs) of 1.2-6.2%. The method was proved to be a simple and effective extraction technique that provided an attractive alternative to the analysis of trace amounts of target analytes in large numbers of cosmetics.

  6. 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. PMID:26041239

  7. Determination of 2-ethylhexyl 4-(dimethylamino) benzoate using membrane-assisted liquid-liquid extraction and gas chromatography-mass spectrometric detection.

    Science.gov (United States)

    March, J G; Genestar, C; Simonet, B M

    2009-06-01

    A flow-cell for micro-porous membrane liquid-liquid extraction with a sheet membrane was used to extract 2-ethylhexyl 4-(dimethylamino) benzoate (EDB) from urine of solar-cream users and spiked wine samples. The cell enabled the target analyte to be extracted from 7.9 mL of donor solution into 200 microL of acceptor solution (decane). After extraction, the acceptor solution was transferred to a micro-vial for GC-MS analysis without derivation. In this work, variables affecting the enrichment factor were also studied, such as organic solvent, extraction time, recirculation flow of the donor solution through the donor chamber, presence of potassium chloride and ethanol in the donor solution and pH. The method has been evaluated in terms of linearity, sensitivity, precision, limits of detection and quantification and extraction efficiency. Limits of quantification were 1 and 3 microg L(-1) EDB for urine and wine, respectively. Quantitative analysis has been carried out by applying the method of standard additions. Within- and between-day relative standard deviations were lower than 12% and 20%, respectively. EDB was found in the urine of users of cream containing EDB in the concentration interval 1.2-7.2 microg L(-1). Therefore, this provides evidence of EDB dermal absorption and subsequent excretion through the urinary tract. EDB was not found in the analysed wine samples. PMID:19347661

  8. 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)

    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)

  9. A phase separation method for analyses of fluoroquinones in meats based on ultrasound-assisted salt-induced liquid-liquid microextraction and a new integrated device.

    Science.gov (United States)

    Wang, Huili; Gao, Ming; Xu, Youqu; Wang, Wenwei; Zheng, Lian; Dahlgren, Randy A; Wang, Xuedong

    2015-08-01

    Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted, salt-induced, liquid-liquid microextraction for determination of five fluoroquinones in meats by HPLC analysis. The novel integrated device consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 589μL of acetone solvent, pH2.1, 4.1min extraction time and 3.5g of Na2SO4. The limits of detection were 0.056-0.64 μgkg(-1) and recoveries were 87.2-110.6% for the five fluoroquinones in muscle tissue from fish, chicken, pork and beef. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinones in meat samples. PMID:25885797

  10. Ultrasound-assisted ion-pair dispersive liquid-liquid microextraction of trace amounts of lead in water samples prior to graphite furnace atomic absorption spectrometry determination.

    Science.gov (United States)

    Afzali, Daryoush; Mohadesi, Ali Reza; Falahnejad, Masoumeh; Bahadori, Behnoosh

    2013-01-01

    A new ion-pair dispersive liquid-liquid microextraction method is described for separation and preconcentration of trace amounts of lead in different water samples. Graphite furnace atomic absorption spectrometry was used for determination of lead. The ion association complex between lead and iodide ions that forms is PbI4(-2)-tetradecyl-dimethylbenzylammonium, which is extracted into fine droplets of chlorobenzene. In order to reach the optimized experimental conditions, the influence of different parameters, such as concentration of KI, nature and volume of extraction solvents, pH effect, extraction time, and the period and speed of sonication and centrifugation, were optimized. The LOD was 0.08 ng/mL and the linear dynamic range was 0.20-8.0 ng/mL in initial solution with a correlation coefficient of 0.9985. Under the optimum conditions, the enrichment factor was 555.5. The proposed method was successfully applied for separation and determination of lead in sea, rain, river, and drinking water samples. PMID:23513972

  11. 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

    2015-07-01

    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. PMID:26043096

  12. 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

    2016-02-01

    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. PMID:26758524

  13. Trace analysis of some organophosphorus pesticides in rice samples using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography.

    Science.gov (United States)

    Sharafi, Kiomars; Fattahi, Nazir; Mahvi, Amir Hossein; Pirsaheb, Meghdad; Azizzadeh, Nahid; Noori, Masomeh

    2015-03-01

    An ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of a floating organic drop method followed by high-performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0-66.0%. The calibration graphs are linear in the range of 4-800 μg/kg and, limits of detection and limits of quantification are in the range of 1.5-3 and 4.2-8.5 μg/kg, respectively. The relative standard deviation for 50.0 μg/kg of organophosphorus pesticides in rice sample are in the range of 4.4-5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals. PMID:25641828

  14. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

    2014-01-15

    In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with dispersive liquid-liquid microextraction (DLLME) was applied to isolation and enrichment of saffron volatiles. The extracted components of the saffron were separated and determined by gas chromatography-mass spectrometry (GC-MS) technique. The mixture of methanol/acetonitrile was chosen for the extraction of the compounds and chloroform was used at the preconcentration stage. The important parameters, such as composition of extraction solvent, volume of preconcentration solvent, ultrasonic applying time, and salt concentration were optimised by using a half-fraction factorial central composite design (CCD). Under the optimal conditions, the linear dynamic ranges (LDRs) were 10-10,000mgL(-)(1). The determination coefficients (R(2)) were from 0.9990 to 0.9997. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 6-123mgL(-)(1) and 20-406mgL(-)(1), respectively. The relative standard deviations (RSDs) were 2.48-9.82% (n=3). The enhancement factors (EFs) were 3.6-41.3. PMID:24054273

  15. Ultrasound-assisted low-density solvent dispersive liquid-liquid extraction for the determination of alkanolamines and alkylamines in cosmetics with ion chromatography.

    Science.gov (United States)

    Zhong, Zhixiong; Li, Gongke; Zhong, Xiuhua; Luo, Zhibin; Zhu, Binghui

    2013-10-15

    A new one-step sample preparation technique termed ultrasound-assisted low-density solvent dispersive liquid-liquid extraction (UA-LDS-DLLE) coupled with ion chromatography (IC) was developed for the determination of three alkanolamines and two alkylamines in complex samples. Sample matrices were rapidly dissolved and dispersed to form cloudy solutions by using two solvents, where target analytes were transferred into acid solutions, while liposoluble substances were dissolved in cyclohexane. The obtained extracts could be used directly for injection analysis without any additional purification because the potential matrix interferences had been effectively eliminated in extraction process. The extraction efficiency could be markedly enhanced and the extraction could be quickly accomplished within 13 min under the synergistic effects of ultrasound radiation, vibration and heating. Various parameters influencing extraction efficiency were evaluated using orthogonal array experimental design. The extraction performance of the approach was demonstrated for the determination of target analytes in 15 commercial cosmetics covering very different matrices. Linearity ranges of 0.3-50 mg L(-1) and limits of detection varying from 0.072 to 0.12 mg L(-1) were achieved. The recoveries ranged from 86.9-108.5% with the relative standard deviations (RSDs) of 1.2-6.2%. The method was proved to be a simple and effective extraction technique that provided an attractive alternative to the analysis of trace amounts of target analytes in large numbers of cosmetics. PMID:24054627

  16. Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cortada, Carol; dos Reis, Luciana Costa; Vidal, Lorena; Llorca, Julio; Canals, Antonio

    2014-03-01

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: extractant solvent volume, 13 µL; solvent type, chlorobenzene; sample volume, 13 mL; centrifugation speed, 2300 rpm; centrifugation time, 5 min; and sonication time, 2 min. Under the optimized experimental conditions the method gave levels of repeatability with coefficients of variation between 10 and 24% (n=7). Limits of detection were between 0.002 and 1.4 µg L(-1). Calculated calibration curves gave high levels of linearity with correlation coefficient values between 0.991 and 0.9997. Finally, the proposed method was applied for the analysis of wastewater samples. Relative recovery values ranged between 71 and 116% showing that the matrix had a negligible effect upon extraction. To our knowledge, this is the first time that combines LLME and GC-MS for the analysis of methylsiloxanes in wastewater samples. PMID:24468359

  17. Integration of phase separation with ultrasound-assisted salt-induced liquid-liquid microextraction for analyzing the fluoroquinones in human body fluids by liquid chromatography.

    Science.gov (United States)

    Wang, Huili; Gao, Ming; Wang, Mei; Zhang, Rongbo; Wang, Wenwei; Dahlgren, Randy A; Wang, Xuedong

    2015-03-15

    Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted salt-induced liquid-liquid microextraction for determination of five fluoroquinones (FQs) in human body fluids. The integrated device consisted of three simple HDPE components used to separate the extraction solvent from the aqueous phase prior to retrieving the extractant. A series of extraction parameters were optimized using the response surface method based on central composite design. Optimal conditions consisted of 945μL acetone extraction solvent, pH 2.1, 4.1min stir time, 5.9g Na2SO4, and 4.0min centrifugation. Under optimized conditions, the limits of detection (at S/N=3) were 0.12-0.66μgL(-1), the linear range was 0.5-500μgL(-1) and recoveries were 92.6-110.9% for the five FQs extracted from plasma and urine. The proposed method has several advantages, such as easy construction from inexpensive materials, high extraction efficiency, short extraction time, and compatibility with HPLC analysis. Thus, this method shows excellent prospects for sample pretreatment and analysis of FQs in human body fluids. PMID:25660716

  18. A rapid ultrasound-assisted dispersive liquid-liquid microextraction followed by ultra-performance liquid chromatography for the simultaneous determination of seven benzodiazepines in human plasma samples.

    Science.gov (United States)

    Fernández, Purificación; González, Cristina; Pena, M Teresa; Carro, Antonia M; Lorenzo, Rosa A

    2013-03-12

    A simple and efficient ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) method has been developed for the determination of seven benzodiazepines (alprazolam, bromazepam, clonazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma samples. Chloroform and methanol were used as extractant and disperser solvents, respectively. The influence of several variables (e.g., type and volume of dispersant and extraction solvents, pH, ultrasonic time and ionic strength) was carefully evaluated and optimized, using an asymmetric screening design 3(2)4(2)//16. Analysis of extracts was performed by ultra-performance liquid chromatography coupled with photodiode array detection (UPLC-PDA). Under the optimum conditions, two reversed-phases, Shield RP18 and C18 columns were successfully tested, obtaining good linearity in a range of 0.01-5μgmL(-1), with correlation coefficients r>0.996. Quantification limits ranged between 4.3-13.2ngmL(-1) and 4.0-14.8ngmL(-1), were obtained for C18 and Shield RP18 columns, respectively. The optimized method exhibited a good precision level, with relative standard deviation values lower than 8%. The recoveries studied at two spiked levels, ranged from 71 to 102% for all considered compounds. The proposed method was successfully applied to the analysis of seven benzodiazepines in real human plasma samples. PMID:23452791

  19. Study on the determination of heavy metals in water samples with ultrasound-assisted dispersive liquid-liquid microextraction prior to FAAS.

    Science.gov (United States)

    Li, Zonghao; Yu, Gong; Song, Jun; Wang, Qi; Liu, Mousheng; Yang, Yaling

    2013-01-01

    A new, simple and rapid method based on dispersive liquid-liquid microextraction (DLLME) was developed for extracting and preconcentrating copper (Cu), nickel (Ni), lead (Pb) and cadmium (Cd) in water samples prior to flame atomic absorption spectrometry (FAAS) analysis. 1-(2-thiazolylazo)-naphthol (TAN) was used as chelating reagents, and non-ionic surfactant Triton X-114 and CCl(4) as disperser solvent and extraction solvent, respectively. Some influential factors relevant to DLLME, such as the concentration of TAN, type and volume of disperser and extraction solvent, pH and ultrasound time, were optimized. Under the optimal conditions, the calibration curve was linear in the range of 10-800 μg L(-1) for Cu and Ni, 10-500 μg L(-1) for Pb, and 10-1,000 μg L(-1) for Cd, respectively. The limits of detection for the four metal ions were below 0.5 μg L(-1), with the enhancement factors of 105, 66, 28 and 106 for Cu, Ni, Pb and Cd, respectively. The relative standard deviations (RSD, n = 6) were 2.6-4.1%. The proposed method was applied to determination of Cu, Ni, Pb and Cd in water samples and satisfactory relative recoveries (93.0-101.2%) were achieved. PMID:23168620

  20. Dispersive solvent-free ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction coupled with HPLC for determination of ulipristal acetate.

    Science.gov (United States)

    Gong, Aiqin; Zhu, Xiashi

    2015-01-01

    In this paper, a simple and efficient ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (UA IL-DLLME) coupled with high-performance liquid chromatography for the analysis of ulipristal acetate (UPA) was developed. UPA could be easily migrated into 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] IL phase without dispersive solvent. The research of extraction mechanism showed that hydrophobic interaction force played a key role in the IL-DLLME. Several important parameters affecting the extraction recovery were optimized. Under the optimized conditions, 25-fold enrichment factor was obtained and the limit of detection (LOD) was 6.8 ng mL(-1) (tablet) or 9.3 ng mL(-1) (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.03-6.0 µg mL(-1). The proposed method was successfully applied to the UPA tablets and the real mice serum samples. PMID:25281147

  1. [Simultaneous determination of four phthalate esters in water samples using ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography].

    Science.gov (United States)

    Ma, Yanling; Chen, Lingxin; Ding, Yangjun; Ming, Yongfei; Li, Jinhua

    2013-02-01

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography (UA-DLLME-HPLC) was developed for the determination of four typical phthalate esters (PAEs). The analyzed PAEs included dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di-n-octyl phthalate (DnOP). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time, were investigated. Enrichment factor (EF)was employed to evaluate the extraction efficiency. The conditions were finally chosen: CCl4 (40 microL)/ acetonitrile (1.0 mL) as extraction/dispersion solvents; 30 g/L NaCl; ultrasound/centrifugation of 5 min. Under the optimized extraction conditions, UA-DLLME exhibited strong enrichment ability for the four PAEs. The EFs for DMP, DEP, DBP and DnOP obtained were 71, 144, 169 and 159, respectively. The limits of detection were 3.78, 1.77, 3.07 and 3.30 microg/L for DMP, DEP, DBP and DnOP, respectively. The satisfactory recoveries for three water samples at three spiked levels ranged from 82.99%-114.47%, with the relative standard deviations of 1.93%-8.31%. It is a convenient, speedy, environmentally benign method for the routine analysis of PAEs in water samples. PMID:23697182

  2. Dispersive liquid-liquid microextraction for the determination of nitrophenols in soils by microvial insert large volume injection-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

    2016-07-22

    A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC-MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an "in-situ" acetylation procedure, before being injected into the GC-MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86-111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg(-1), depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8-9.6ngg(-1) range. PMID:27317004

  3. Homogeneous Liquid-Liquid Microextraction for Determination of Organophosphorus Pesticides in Environmental Water Samples Prior to Gas Chromatography-Flame Photometric Detection.

    Science.gov (United States)

    Berijani, Sana; Sadigh, Mirhanif; Pournamdari, Elham

    2016-07-01

    In this study, homogeneous liquid-liquid microextraction (HLLME) was developed for preconcentration and extraction of 15 organophosphorus pesticides (OPPs) from water samples coupling with gas chromatography followed by a flame photometric detector (HLLME-GC-FPD). In this method, OPPs were extracted by the homogeneous phase in a ternary solvent system (water/acetic acid/chloroform). The homogeneous solution was excluded by the addition of sodium hydroxide as a phase separator reagent and a cloudy solution was formed. After centrifugation (3 min at 5,000 rpm), the fine particles of extraction solvent (chloroform) were sedimented at the bottom of the conical test tube (10.0 ± 0.5 µL). Furthermore, 0.5 µL of the sedimented phase was injected into the GC for separation and determination of OPPs. Optimal results were obtained under the following conditions: volume of the extracting solvent (chloroform), 53 µL; volume of the consolute solvent (acetic acid), 0.76 mL and concentration of sodium hydroxide, 40% (w/v). Under the optimum conditions, the enrichment factors of (260-665), the extraction percent of 75.8-104%, the dynamic linear range of 0.03-300 µg L(-1) and the limits of detection of 0.004-0.03 µg L(-1) were obtained for the OPPs. This method was successfully applied for the extraction and determination of the OPPs in environmental water samples. PMID:26944949

  4. Dispersive liquid-liquid microextraction of lead(II) as 5-(4-dimethylaminobenzylidene) rhodanine chelates from food and water samples.

    Science.gov (United States)

    Alothman, Zeid A; Al-Shaalan, Nora H; Habila, Mohamed A; Unsal, Yunus E; Tuzen, Mustafa; Soylak, Mustafa

    2015-02-01

    A dispersive liquid-liquid microextraction procedure for lead(II) as its 5-(4-dimethylaminobenzylidene) rhodanine complex has been established prior to its microsampling flame atomic absorption spectrometric determination. The influences of various analytical parameters including pH, solvent type and volume, dispersive solvent type and volume, 5-(4-dimethylaminobenzylidene) rhodanine amount, salt effect, and centrifugation time and speed were investigated. The effects of certain alkali, alkaline earth, and transition metal ions on the quantitative extraction of lead(II) were also studied. Quantitative recoveries were obtained at pH 6. The enrichment factor was calculated as 125. The detection limit for lead is 1.1 μg/L. The accuracy of the method was tested with the additions recovery test and analysis of the standard reference materials (SPS-WW2 waste water, NIST SRM 1515 apple leaves, and TMDA-51.3 fortified water). Applications of the present procedure were tested by analyzing water and food samples. PMID:25618567

  5. Simple field-based automated dispersive liquid-liquid microextraction of trace level phthalate esters in natural waters with gas chromatography and mass spectrometric analysis.

    Science.gov (United States)

    Leng, Geng; Chen, Wenjin; Wang, Yong

    2016-09-01

    A small, simple, and field-based automated dispersive liquid-liquid microextraction method followed by gas chromatography mass spectrometric analysis was developed for trace level phthalate esters analysis in natural waters. With a single syringe pump that is coupled with a multiposition valve, the whole extraction procedure including cleaning, sampling, mixing of extractant and disperser solvents, extraction, phase separation, and analytes collection was carried out in a totally automated way with a sample throughput of 21 h(-1) . Key factors, such as type and ratio of the extractant and disperser solvent, aspiration flow rate, extraction time, and matrix effect, were thoroughly investigated. Under the optimum conditions, linearity was found in the range from 0.03 to 60 μg/L. Limits of detection ranged from 0.0015 to 0.003 μg/L. Enrichment factors were in a range of 106-141. Reproducibility and recoveries were assessed by testing a series of three natural water samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied in analysis of real surface waters. The developed system is inexpensive, light (2.6 kg), simple to use, applicable in the field, with high sample throughput, and sensitive enough for trace level phthalate esters analysis in natural waters. PMID:27377176

  6. Pipette vial dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    Science.gov (United States)

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

    2016-01-01

    A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%. PMID:26526571

  7. Dynamic crossover in deeply cooled water confined in MCM-41 at 4 kbar and its relation to the liquid-liquid transition hypothesis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe; Le, Peisi; Ito, Kanae; Chen, Sow-Hsin, E-mail: sowhsin@mit.edu [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Leão, Juscelino B. [National Institute of Standards and Technology Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Tyagi, Madhusudan [National Institute of Standards and Technology Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2015-09-21

    With quasi-elastic neutron scattering, we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure and find that (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. Especially, at temperatures below about 230 K, the relaxation time at 4 kbar is even smaller than that at ambient pressure. This feature is different from many other liquids. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis.

  8. Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE Using a pH-Responsive Fluorine-Based Surfactant

    Directory of Open Access Journals (Sweden)

    Shotaro Saito

    2015-08-01

    Full Text Available A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Re, Rh, Ru, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm, V, W, Y, Yb, Zn, and Zr were examined. By changing pH from a neutral or alkaline solution (pH ≥ 6.5 to that of an acidic solution (pH < 4.0, gallium, zirconium, palladium, silver, platinum, and rare earth elements were extracted at >90% efficiency into a sedimented Zonyl FSA® (CF3(CF2n(CH22S(CH22COOH, n = 6–8 liquid phase. Moreover, all rare earth elements were obtained with superior extraction and stripping percentages. In the recycling of rare earth elements, the sedimented phase was maintained using a filter along with a mixed solution of THF and 1 M sodium hydroxide aqueous solution. The Zonyl FSA® was filtrated and the rare earth elements were recovered on the filter as a hydroxide. Furthermore, the filtrated Zonyl FSA was reusable by conditioning the subject pH.

  9. Liquid-liquid Microextraction Based on Solidification of Floating Organic Drops Coupled with Gas Chromatography for Analyzing Trace Benzene, Toluene and Xylene in Water Samples

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mao-sheng; HUANG Jia-rong; ZHENG Xiang-hua; XIE Qiong-fang

    2011-01-01

    A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene,toluene and xylene(BTX)in water samples.In the microextraction procedure,a microdrop of n-decanol was delivered to the surface of the analytes' solution,and stirred for a desired time.Following the absolute extraction,the sample vial was cooled in an ice bath for 10 min.The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis.Factors relevant to the extraction efficiency were studied and optimized.The optimal experimental conditions were:15 μL of n-decanol as extractive solvent,30 mL of solution containing analytes,no salt,the stirring rate 400 r/min,the extraction temperature 30 ℃,and the extraction time 30 min.Under those optimized conditions,the detection limit(LOD)of analytes was in a range of 0.05-0.10 ng/mL by the developed method.A good linearity(r>0.99)in a calibration range of 0.01-100 μg/mL was obtained.The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.

  10. Quantification of tetramethyl-terephthalic acid in rat liver, spleen and urine matrices by liquid-liquid phase extraction and HPLC-photodiode array detection.

    Science.gov (United States)

    Baati, Tarek; Horcajada, Patricia; David, Olivier; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

    2012-01-01

    Tetramethyl-terephthalate (TMT) is the constitutive linker of the flexible porous iron(III) carboxylate Metal Organic Framework (MOF) MIL-88B_4CH₃ based drug nanocarrier (MIL stands for Material from Institut Lavoisier). A method for the determination of the concentration of tetramethyl-terephthalic acid has been developed in different biological rat matrices (liver, spleen and urine) using a liquid-liquid phase extraction and high-performance liquid chromatography (HPLC) coupled to photodiode array detection with 4-aminosalicylic acid as internal standard. The extraction conditions of TMT have been varied from urine to tissue depending on the complexity of the biological matrices. The chromatographic separation was performed with a gradient elution. In all matrices, the limits of detection and quantification of TMT was 0.01 and 0.05 μg ml⁻¹, respectively. The recovery of the TMT reached 86, 89 and 97% for urine, spleen and liver tissues, respectively. The linearity of the calibration curves in urine and tissues was satisfactory in all cases as evidenced by correlation coefficients >0.990. The within-day and between-day precisions were <15% (n=6) and the accuracy ranged in all cases between 86 and 103%. This method has finally allowed the quantification of TMT in rat urine and in tissue samples of rats administered intravenously with iron(III) tetramethyltherepthalate MIL-88B_4CH₃ nanoparticles.

  11. 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. PMID:24645524

  12. 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. PMID:20685458

  13. Determination of lead and cadmium using an ionic liquid and dispersive liquid-liquid microextraction followed by electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2013-06-15

    A procedure for the determination of ultratrace levels of lead and cadmium using dispersive liquid-liquid microextraction followed by electrothermal atomic absorption spectrometry (ETAAS) has been developed. The ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8MIm][NTf2]), is formed in situ and used to extract the lead and cadmium complexes with ammonium pyrrolidinedithiocarbamate. The very fine droplets of ([C8MIm][NTf2]) allow effective dispersion without the need for organic solvents. After centrifugation, the concentrations of lead and cadmium in the sedimented phase can be determined by ETAAS. Using a 10 mL aqueous sample, the enrichment factor of the procedure was 280 and detection limits of 0.2 and 3 ng L(-1) were obtained for cadmium and lead, respectively. The relative standard deviations for 10 replicates at the 10 ng L(-1) cadmium and 0.2 μg L(-1) lead levels were 6.5 and 7.3%, respectively. The method was successfully applied to the analysis of waters as well as to lixiviates obtained from toys made of plastic materials. PMID:23618174

  14. Liquid-liquid extraction to lithium isotope separation based on room-temperature ionic liquids containing 2,2'-binaphthyldiyl-17-crown-5

    International Nuclear Information System (INIS)

    A novel liquid-liquid extraction system was investigated for the selective separation of lithium isotopes using ionic liquids (ILs = C8mim+PF6-, C8mim+BF4-, and C8mim+NTf2-) as extraction solvent and 2,2'-binaphthyldiyl-17-crown-5 (BN-17-5) as extractant. The effects of the concentration of lithium salt, counter anion of lithium salt, initial pH of aqueous phase, extraction temperature, and time on the lithium isotopes separation were discussed. Under optimized conditions, the maximum single-stage separation factor α of 6Li/7Li obtained in the present study was 1.046 ± 0.002, indicating the lighter isotope 6Li was enriched in IL phase while the heavier isotope 7Li was concentrated in the solution phase. The formation of 1:1 complex Li(BN-17-5)+ in the IL phase was determined on the basis of slope analysis method. The large value of the free energy change (-ΔG° = 92.89 J mol-1) indicated the high separation capability of the Li isotopes by BN-17-5/IL system. Lithium in Li(BN-17-5)+ complex was stripped by 1 mol L-1 HCl solution. The extraction system offers high efficiency, simplicity, and green application prospect to lithium isotope separation. (author)

  15. (Liquid + liquid) equilibria for (benzene + cyclohexane + dimethyl sulfoxide) system at T = (298.15 or 303.15) K: Experimental data and correlation

    International Nuclear Information System (INIS)

    Graphical abstract: The selectivity of DMSO, is usually high. At 25 °C and atmospheric pressure, the selectivity coefficient can reach beyond 14, which means that DMSO can compete with some ionic liquids for extracting benzene from cyclohexane. So, DMSO has large potential to separate benzene from cyclohexane as a new extractant. - Highlights: • The highest selectivity coefficient is beyond 14 of DMSO at T = (298.15 or 303.15) K. • The data’s reliability is approved by the correlation of Othmer–Tobias equation. • NRTL model is in good agreement with the experimental data. - Abstract: (Liquid + liquid) equilibrium (LLE) data were measured experimentally at T = (298.15 or 303.15) K and atmospheric pressure for the (benzene + cyclohexane + dimethyl sulfone (DMSO)) system. The Othmer–Tobias equation was applied to verify the reliability of the data. Based on the data, the selectivity of DMSO was estimated and compared with that of ionic liquids. The highest selectivity coefficient of DMSO can reach beyond 14, which means it is able to compete with some ionic liquids and it would be a good extractant to separate benzene from cyclohexane. At the same time, the NRTL model was used to correlate the data and the results show that the model agrees on the experimental data very well

  16. Microextraction by packed sorbent and salting-out-assisted liquid-liquid extraction for the determination of aromatic amines formed from azo dyes in textiles.

    Science.gov (United States)

    Sánchez, Miguel del Nogal; Santos, Patricia Martín; Sappó, Cristina Pérez; Pavón, José Luis Pérez; Cordero, Bernardo Moreno

    2014-02-01

    EU legislation prohibits the use of certain azo dyes which, on reduction, form any of 22 aromatic amines listed in Regulation (EC) 1907/2006 at concentrations above the threshold limit of 30 mg Kg(-1). Two different extraction techniques for the determination of aromatic amines formed from azo dyes in textiles in combination with gas chromatography-mass spectrometry (GC-MS) are described. The first one is based on microextraction by packed sorbent (MEPS) and the other approach involves salting-out-assisted liquid-liquid extraction (SALLE). The influence of several parameters on the efficiency of the extraction using MEPS (sorbent material, sample volume, elution solvent, elution volume and washing steps, among others) and SALLE (extraction volume and amount of salt) were investigated. In addition, chromatographic separation was optimized and quadrupole mass spectrometry was evaluated using the synchronous SIM/scan data acquisition mode. The repeatability (n=8, S/N=3) of the methods, calculated as the relative standard deviation (RSD) was below 15 and 11% for all compounds when MEPS and SALLE were used, respectively. Standard additions procedure was used to quantify the aromatic amines in the textil samples. The detection limits in the samples for both methods were lower than the maximum value allowed by legislation. The results obtained in the analysis of textiles revealed the presence of o-anisidine, p-chloroaniline, 4-chloro-o-toluidine, 2-naphthylamine and 3,3'-dimethoxybenzidine in some of them. PMID:24401428

  17. Negative corona discharge-ion mobility spectrometry as a detection system for low density extraction solvent-based dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Ebrahimi, Amir; Jafari, Mohammad T

    2015-03-01

    This paper deals with a method based on negative corona discharge ionization ion mobility spectrometry (NCD-IMS) for the analysis of ethion (as an organophosphorus pesticide). The negative ions such as O2(-) and NO(x)(-) were eliminated from the background spectrum to increase the instrument sensitivity. The method was used to specify the sample extracted via dispersive liquid-liquid microextraction (DLLME) based on low density extraction solvent. The ion mobility spectrum of ethion in the negative mode and the reduced mobility value for its ion peak are firstly reported and compared with those of the positive mode. In order to combine the low density solvent DLLME directly with NCD-IMS, cyclohexane was selected as the extraction solvent, helping us to have a direct injection up to 20 µL solution, without any signal interference. The method was exhaustively validated in terms of sensitivity, enrichment factor, relative recovery, and repeatability. The linear dynamic range of 0.2-100.0 µg L(-1), detection limit of 0.075 µg L(-1), and the relative standard deviation (RSD) of about 5% were obtained for the analysis of ethion through this method. The average recoveries were calculated about 68% and 92% for the grape juice and underground water, respectively. Finally, some real samples were analyzed and the feasibility of the proposed method was successfully verified by the efficient extraction of the analyte using DLLME before the analysis by NCD-IMS. PMID:25618728

  18. Modeling of dispersive liquid-liquid microextraction for determination of essential oil from Borago officinalis L. by using combination of artificial neural network and genetic algorithm method.

    Science.gov (United States)

    Khajeh, Mostafa; Moghaddam, Zahra Safaei; Bohlooli, Mousa; Khajeh, Ahmad

    2015-01-01

    Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography was applied for the extraction and determination of essential oil constituents of the Borago officinalis L. In this study, an experimental data-based artificial neural network (ANN) model was constructed to describe the performance of DLLME method for various operating conditions. The volume of extraction and dispersive solvents, extraction time and salt effect were the input variables of this process, whereas the extraction efficiency was the output. The ANN method was found to be capable of modeling this procedure accurately. The overall agreement between the experimental data and ANN predictions was satisfactory showing a determination coefficient of 0.982. The optimum operating condition was then determined by the genetic algorithm method. The optimal conditions were 248 µL volume of extraction solvent, 260 µL volume of dispersive solvent, 2.5 min extraction time and 0.16 mol L(-1) of salt. The limit of detection and linear dynamic range were 0.15-24.0 and 1.2-1,800 ng mL(-1), respectively. The main components of the essential oil were δ-cadinene (31.02%), carvacrol (24.91%), α-pinene (20.89%) and α-cadinol (16.47%). PMID:26045584

  19. Experimental and Model Studies on Continuous Separation of 2-Phenylpropionic Acid Enantiomers by Enantioselective Liquid-Liquid Extraction in Centrifugal Contactor Separators.

    Science.gov (United States)

    Feng, Xiaofeng; Tang, Kewen; Zhang, Pangliang; Yin, Shuangfeng

    2016-03-01

    Multistage enantioselective liquid-liquid extraction (ELLE) of 2-phenylpropionic acid (2-PPA) enantiomers using hydroxypropyl-β-cyclodextrin (HP-β-CD) as extractant was studied experimentally in a counter-current cascade of centrifugal contactor separators (CCSs). Performance of the process was evaluated by purity (enantiomeric excess, ee) and yield (Y). A multistage equilibrium model was established on the basis of single-stage model for chiral extraction of 2-PPA enantiomers and the law of mass conservation. A series of experiments on the extract phase/washing phase ratio (W/O ratio), extractant concentration, the pH value of aqueous phase, and the number of stages was conducted to verify the multistage equilibrium model. It was found that model predictions were in good agreement with the experimental results. The model was applied to predict and optimize the symmetrical separation of 2-PPA enantiomers. The optimal conditions for symmetric separation involves a W/O ratio of 0.6, pH of 2.5, and HP-β-CD concentration of 0.1 mol L(-1) at a temperature of 278 K, where eeeq (equal enantiomeric excess) can reach up to 37% and Yeq (equal yield) to 69%. By simulation and optimization, the minimum number of stages was evaluated at 98 and 106 for eeeq > 95% and eeeq > 97%.

  20. Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

    Institute of Scientific and Technical Information of China (English)

    Zhi Mei Liu; Xiao Huan Zang; Wei Hua Liu; Chun Wang; Zhi Wang

    2009-01-01

    A novel method for the determination of five carbamate pesticides(metolcarb,carbofuran,carbaryl,isoprocard and diethofencard)in water samples was developed by dispersive liquid-liquid microextraction(DLLME)coupled with high performance liquid chromatography-diode array detector(HPLC-DAD).Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results.Under the optimum conditions for the method,the calibration curve was linear in the concentration range from 5 to I000 ng mL-1 for all the five carbamate pesticides,with the correlation coefficients(r2)varying from 0.9984 to 0.9994.Good enrichment factors were achieved ranging from 80 to 177-fold,depending on the compound.The limits of detection(LODs)(S/N = 3)were ranged from 0.1 to 0.5 ng mL-1.The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

  1. Dynamic crossover in deeply cooled water confined in MCM-41 at 4 kbar and its relation to the liquid-liquid transition hypothesis

    Science.gov (United States)

    Wang, Zhe; Le, Peisi; Ito, Kanae; Leão, Juscelino B.; Tyagi, Madhusudan; Chen, Sow-Hsin

    2015-09-01

    With quasi-elastic neutron scattering, we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure and find that (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. Especially, at temperatures below about 230 K, the relaxation time at 4 kbar is even smaller than that at ambient pressure. This feature is different from many other liquids. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis.

  2. Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

    Science.gov (United States)

    Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

    2016-09-01

    A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 μg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 μg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.

  3. 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.

  4. 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

    2016-06-01

    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.

  5. Pipette vial dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    Science.gov (United States)

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

    2016-01-01

    A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%.

  6. Up-and-down shaker-assisted ionic liquid-based dispersive liquid-liquid microextraction of benzophenone-type ultraviolet filters.

    Science.gov (United States)

    Ku, Yu-Chien; Leong, Mei-I; Wang, Wan-Ting; Huang, Shang-Da

    2013-04-01

    Sun protection is an important part of our lives. UV filters are widely used to absorb solar radiation in sunscreens. However, excess UV filters constitute persistent groups of organic micropollutants present in the environment. An environmentally friendly ionic-liquid-based up-and-down shaker-assisted dispersive liquid-liquid microextraction device combined with ultra-performance liquid chromatography coupled with photodiode-array detection has been developed to preconcentrate three UV filters (benzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone) from field water samples. In this method, the optimal conditions for the proposed extraction method were: 40 μL [C8MIM][PF6 ] as extraction solvent and 200 μL methanol as disperser solvent were used to extract the UV filters. After up-and-down shaking for 3 min, the aqueous solution was centrifuged at 5000 rpm speed, then using microtube to collect the settled extraction solvent and using ultra-performance liquid chromatography for further analysis. Quantification results indicated that the linear range was 2-1000 ng/mL. The LOD of this method was in the range 0.2-1.3 ng/mL with r(2) ≥ 0.9993. The relative recovery in studies of different types of field water samples was in the range 92-120%, and the RSD was 2.3-7.1%. The proposed method was also applied to the analysis of field samples. PMID:23495210

  7. 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.

  8. Determination of Earthy-musty Odorous Compounds in Drinking Water by Vortex Assisted Dispersive Liquid-Liquid Microextraction Combined with Gas Chromatography Tandem Mass Spectrometry.

    Science.gov (United States)

    Lu, Jian; Wu, Zhong-Ping; Che, Wen-Jun; Xian, Yan-Ping; Guo, Xin-Dong; Lv, Jia-Xin; Li, He

    2016-01-01

    A new method was developed for the determination of eight earthy-musty compounds in drinking water by gas chromatography tandem mass spectrometry (GC-MS/MS) combined with dispersive liquid-liquid microextraction (DLLME). In this work, the type and volume of extraction solvent and dispersion agent, and the amount of NaCl were optimized; the linearity, detection limit, recovery and precision of method were investigated. The results indicated that the target analytes were in the range of 0.2 - 100 μg/L with correlation coefficient (r) ranging from 0.9991 to 0.9999, the limit of detection (LOD, S/N = 3) of the analytes ranged from 0.2 to 1.0 ng/L with the enrichment factor of 320. The mean recoveries for drinking water at three spiked concentrations levels of 0.6 - 32 ng/L were in the range of 91.3 to 103%, the precision ranged from 3.1 to 7.5% (n = 6), and the inter-day precision was from 6.1 to 11.1% (n = 5). Only one of 15 selected real samples tested positive for GSM, and the concentration was 3 ng/L. This method was confirmed to be simple, fast, efficient, and accurate for the determination of earthy-musty compounds in aqueous samples.

  9. An in situ derivatization - dispersive liquid-liquid microextraction combined with gas-chromatography - mass spectrometry for determining biogenic amines in home-made fermented alcoholic drinks.

    Science.gov (United States)

    Płotka-Wasylka, Justyna; Simeonov, Vasil; Namieśnik, Jacek

    2016-07-01

    A novel dispersive liquid-liquid microextraction (DLLME) gas chromatography mass-spectrometry (GC-MS) method was developed for the determination of 13 biogenic amines in home-made wine samples. The method allows to simultaneous extraction and derivatization of the amines providing a simple and fast mode of extract enrichment. During the study, two different procedures were examined. Statistical analysis was performed to choose better procedure, as well as the conditions of derivatization reaction. At least, a mixture of methanol (dispersive solvent; 215μL), chloroform (extractive solvent; 400μL), and isobutyl choloroformate (derivatizing reagent; 90μL) was used as extractive/derivatizing reagent, added to 5mL of sample. The addition of mixture of pyridine and HCl was necessary to eliminate the by-products. The proposed method showed good linearity (correlation coefficients >0.9961), good recoveries (from 77 to 105%), and good intra-day precision (below 13%) and inter-day precision (below 10%). Moreover, detection limits were never over 4.1μg/L. The developed method was successfully applied to the analysis of 17 home-made wine samples not regulated by law. All of the biogenic amines analyzed were found in most of the wines. PMID:27237593

  10. Determination of Gemfibrozil (Lipitor and Lopid in Water, Biological Fluids and Drug Matrix by Dispersive Liquid-Liquid micro Extraction (DLLME and Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Ghorbani A.

    2014-07-01

    Full Text Available In this study Dispersive liquid-liquid micro extraction (DLLME coupled with High performance liquid chromatography was applied for the determination of Gemfibrozil in water, drug`s matrix and biological liquids (human plasma and urine. In this method, the appropriate mixture of extraction solvent (200 μl chlorophorm and disperser solvent (1 ml methanol are injected rapidly into the aqueous sample (10.0 ml by syringe, cloudy solution is formed that consisted of fine particles of extraction solvent which is dispersed entirely into aqueous phase. The mixture was centrifuged and the extraction solvent is sedimented on the bottom of the conical test tube. 50 μl of the sedimented phase is puted in a vial and it`s solvent is evaporated. Then 1ml methanol injected to vial and 20 μL of it injected into the HPLC for separation and determination of Gemfibrozil. Some important parameters, such as kind of extraction and disperser solvent, volume of them, extraction time, pH and ionic strength of the aqueous feed solution were optimized. Under the optimum conditions, the enrichment factors and extraction recoveries were 10 and 93.64%. The linear range was (0.1-100.0 mgl-1, limit of detection was 12.3 mgl-1. The relative standard deviations (RSD for 2 mgl-1 of Gemfibrozil in water were 1.3%, (n=10.

  11. 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. PMID:25711461

  12. 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

    2016-02-01

    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.

  13. Acid-base reaction-based dispersive liquid-liquid microextraction method for extraction of three classes of pesticides from fruit juice samples.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza

    2016-01-29

    A sample preparation method involving acid-base reaction-based dispersive liquid-liquid microextraction coupled with gas chromatography using nitrogen-phosphorous detection has been developed for the analysis of three classes of pesticides in juice samples. In this method, a basic organic solvent (p-chloroaniline) is used as an extraction solvent. It is dissolved in acidified deionized water and then injected into an alkaline aqueous sample solution. After injection, an acid-base reaction occurs and deprotonation of the organic solvent leads to formation of tiny droplets of the extractant and subsequent extraction of the analytes from sample solution. Under the optimum extraction conditions, the method showed low limits of detection and quantification in the range of 0.05-0.43ngmL(-1) and 0.17-1.43ngmL(-1), respectively. Extraction recoveries and enrichment factors were between 39.2 and 84.1% and between 548 and 1178, respectively. Relative standard deviations of less than 8.6% for the extraction of 2.0ngmL(-1) of each pesticide were obtained for intra- (n=6) and inter-day (n=4) precisions. Finally, different juice samples were successfully analyzed using the proposed method, and penconazole, diniconazole, triadimenol, and acetamiprid were determined in some samples at ngmL(-1) levels. PMID:26755415

  14. Fast, simple and efficient salting-out assisted liquid-liquid extraction of naringenin from fruit juice samples prior to their enantioselective determination by liquid chromatography.

    Science.gov (United States)

    Magiera, Sylwia; Kwietniowska, Ewelina

    2016-11-15

    In this study, an easy, simple and efficient method for the determination of naringenin enantiomers in fruit juices after salting-out-assisted liquid-liquid extraction (SALLE) and high-performance liquid chromatography (HPLC) with diode-array detection (DAD) was developed. The sample treatment is based on the use of water-miscible acetonitrile as the extractant and acetonitrile phase separation under high-salt conditions. After extraction, juice samples were incubated with hydrochloric acid in order to achieve hydrolysis of naringin to naringenin. The hydrolysis parameters were optimized by using a half-fraction factorial central composite design (CCD). After sample preparation, chromatographic separation was obtained on a Chiralcel® OJ-RH column using the mobile phase consisting of 10mM aqueous ammonium acetate:methanol:acetonitrile (50:30:20; v/v/v) with detection at 288nm. The average recovery of the analyzed compounds ranged from 85.6 to 97.1%. The proposed method was satisfactorily used for the determination of naringenin enantiomers in various fruit juices samples. PMID:27283626

  15. Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

    Science.gov (United States)

    Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

    2016-09-01

    A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 μg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 μg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption. PMID:27379391

  16. [Simultaneous determination of 23 ester compounds in cigarette water-borne adhesives by liquid-liquid extraction and gas chromatography-mass spectrometry].

    Science.gov (United States)

    Gong, Shuguo; Kong, Bo; Tuo, Suxing; Dai, Yunhui; Wu, Mingjian; Tan, Liquan; Liu, Wei

    2013-10-01

    A method of gas chromatography-mass spectrometry (GC-MS) with liquid-liquid extraction has been developed for the simultaneous determination of 23 ester compounds including acetate esters, acrylic esters, metacrylic acid esters and phthalate acid esters in cigarette water-borne adhesives. After dispersed in water, the sample was extracted by n-hexane solution containing phenyl ethyl propionate as internal standard substance. Then, the solution was centrifuged and filtrated through a 0.45 microm organic membrane filter. Finally, the solution was separated on a DB-WAXETR column (60 m x 0.25 mm x 0.25 microm), and detected with MS in selected ion monitoring mode, and quantified by internal standard method. The results showed a good linear correlation in the range of 0.4-50.0 mg/L. The recoveries of the ester compounds spiked in the sample were 81.8%-109.1%, and the relative standard deviations (RSDs, n = 5) were less than 4%. The limits of detection (LODs) and limits of quantification (LOQs were in the ranges of 0.02-0.76 mg/kg and 0.04-2.52 mg/kg, respectively. The method is simple, time-saving, and has high sensitivity and good reproducibility. It can be applied to the determination of the 23 ester compounds in cigarette water-borne adhesives.

  17. Determination of Haloacetic Acids in Bottled and Tap Water Sources by Dispersive Liquid-Liquid Microextraction and GC-MS Analysis

    Directory of Open Access Journals (Sweden)

    Mohsen A. Al-shatri

    2014-01-01

    Full Text Available Haloacetic acids are toxic organic pollutants that can be formed as by-products of disinfection of water by chlorination. In this study, we developed a fast and efficient method for the determination of six species of these compounds in water using dispersive liquid-liquid microextraction followed by GC-MS analysis. To be suitable for GC analysis, the acidic analytes were derivatized using n-octanol. One-factor-at-a-time optimization was carried out on several factors including temperature, extraction time, amount of catalyst, and dispersive solvent. The optimized conditions were then used to determine calibration parameters. Linearity, as demonstrated by coefficient of determination, ranged between 0.9900 and 0.9966 for the concentration range of 0.05–0.57 µg/L. The proposed method has good repeatability; intraday precision was calculated as %RSD of 2.38–9.34%, while interday precision was 4.69–8.06%. The method was applied to real samples in bottled water and tap water sources. Results indicated that the total concentrations of the analytes in these sources (2.97–5.30 µg/L were far below the maximum contaminant levels set by both the World Health Organization and the United States Environmental Protection Agency. The proposed method compared favorably with methods reported in the literature.

  18. Determination of six pyrethroid insecticides in fruit juice samples using dispersive liquid-liquid microextraction combined with high performance liquid chromatography.

    Science.gov (United States)

    Boonchiangma, Suthasinee; Ngeontae, Wittaya; Srijaranai, Supalax

    2012-01-15

    Dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography (HPLC) with UV detection was applied for the determination of six pyrethroids (tetramethrin, fenpropathrin, cypermethrin, deltamethrin, fenvalerate and permethrin) in various fruit juices including apple, red grape, orange, kiwi, passion fruit, pomegranate and guava juice. Six pyrethroids were separated within 30 min using a Waters Atlantis T3 column under an isocratic elution of acetonitrile-water (72:28). The parameters affecting extraction efficiency of the DLLME method such as type of disperser and extraction solvent, volume of disperser and extraction solvent and centrifugation time were investigated. Under the optimum conditions, 5.00 mL of sample solution, 300 μL of chloroform as extraction solvent and 1.25 mL of methanol as dispersive solvent gave high enrichment factor in the range of 62-84. Good linearity was obtained from 2 to 1,500 μg/L (r(2)>0.995). The mean recoveries of the pyrethroids evaluated by fortification of real samples were in the range of 84-94%. The limits of detection ranging from 2 to 5 μg/L are sufficient to analyze pyrethroid residues at the maximum residue limits (MRLs) established by the European Union (EU) in fruit juices. The proposed method can be applied to direct determination of pyrethroid residues in fruit juices.

  19. Determination of descriptors for polycyclic aromatic hydrocarbons and related compounds by chromatographic methods and liquid-liquid partition in totally organic biphasic systems.

    Science.gov (United States)

    Ariyasena, Thiloka C; Poole, Colin F

    2014-09-26

    Retention factors on several columns and at various temperatures using gas chromatography and from reversed-phase liquid chromatography on a SunFire C18 column with various mobile phase compositions containing acetonitrile, methanol and tetrahydrofuran as strength adjusting solvents are combined with liquid-liquid partition coefficients in totally organic biphasic systems to calculate descriptors for 23 polycyclic aromatic hydrocarbons and eighteen related compounds of environmental interest. The use of a consistent protocol for the above measurements provides descriptors that are more self consistent for the estimation of physicochemical properties (octanol-water, air-octanol, air-water, aqueous solubility, and subcooled liquid vapor pressure). The descriptor in this report tend to have smaller values for the L and E descriptors and random differences in the B and S descriptors compared with literature sources. A simple atom fragment constant model is proposed for the estimation of descriptors from structure for polycyclic aromatic hydrocarbons. The new descriptors show no bias in the prediction of the air-water partition coefficient for polycyclic aromatic hydrocarbons unlike the literature values.

  20. 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.

  1. Validation of method for determination of different classes of pesticides in aqueous samples by dispersive liquid-liquid microextraction with liquid chromatography-tandem mass spectrometric detection.

    Science.gov (United States)

    Caldas, Sergiane Souza; Costa, Fabiane Pinho; Primel, Ednei Gilberto

    2010-04-14

    In this study, a simple, rapid and efficient method has been developed for the extraction and preconcentration of different classes of pesticides, carbofuran (insecticide), clomazone (herbicide) and tebuconazole (fungicide) in aqueous samples by dispersive liquid-liquid microextraction (DLLME) coupled with liquid chromatography-tandem mass spectrometric detection. Some experimental parameters that influence the extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, speed of centrifugation, pH and addition of salt were examined and optimized. Under the optimum conditions, the recoveries of pesticides in water at spiking levels between 0.02 and 2.0 microg L(-1) ranged from 62.7% to 120.0%. The relative standard deviations varied between 1.9% and 9.1% (n=3). The limits of quantification of the method considering a 50-fold preconcentration step were 0.02 microg L(-1). The linearity of the method ranged from 1.0 to 1000 microg L(-1) for all compounds, with correlation coefficients varying from 0.9982 to 0.9992. Results show that the method we propose can meet the requirements for the determination of pesticides in water samples. The comparison of this method with solid-phase extraction indicates that DLLME is a simple, fast, and low-cost method for the determination of pesticides in natural waters.

  2. Simultaneous Distillation Extraction of Some Volatile Flavor Components from Pu-erh Tea Samples—Comparison with Steam Distillation-Liquid/Liquid Extraction and Soxhlet Extraction

    Directory of Open Access Journals (Sweden)

    Xungang Gu

    2009-01-01

    Full Text Available A simutaneous distillation extraction (SDE combined GC method was constructed for determination of volatile flavor components in Pu-erh tea samples. Dichloromethane and ethyl decylate was employed as organic phase in SDE and internal standard in determination, respectively. Weakly polar DB-5 column was used to separate the volatile flavor components in GC, 10 of the components were quantitatively analyzed, and further confirmed by GC-MS. The recovery covered from 66.4%–109%, and repeatability expressed as RSD was in range of 1.44%–12.6%. SDE was most suitable for the extraction of the anlytes by comparing with steam distillation-liquid/liquid extraction and Soxhlet extraction. Commercially available Pu-erh tea samples, including Pu-erh raw tea and ripe tea, were analyzed by the constructed method. the high-volatile components, such as benzyl alcohol, linalool oxide, and linalool, were greatly rich in Pu-erh raw teas, while the contents of 1,2,3-Trimethoxylbenzene and 1,2,4-Trimethoxylbenzene were much high in Pu-erh ripe teas.

  3. 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)

    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)

  4. Determination of estrogenic mycotoxins in environmental water samples by low-toxicity dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Emídio, Elissandro Soares; da Silva, Claudia Pereira; de Marchi, Mary Rosa Rodrigues

    2015-04-24

    A novel, simple, rapid and eco-friendly method based on dispersive liquid-liquid microextraction using a bromosolvent was developed to determine six estrogenic mycotoxins (zearalenone, zearalanone, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol) in water samples by liquid chromatography-electrospray ionization tandem mass spectrometry in the negative mode (LC-ESI-MS/MS). The optimal conditions for this method include the use of 100 μL bromocyclohexane as an extraction solvent (using a non-dispersion solvent), 10 mL of aqueous sample (adjusted to pH 4), a vortex extraction time of 2 min, centrifugation for 10 min at 3500 rpm and no ionic strength adjustment. The calibration function was linear and was verified by applying the Mandel fitting test with a 95% confidence level. No matrix effect was observed. According to the relative standard deviations (RSDs), the precision was better than 13% for the repeatability and intermediate precision. The average recoveries of the spiked compounds ranged from 81 to 118%. The method limits of detection (LOD) and quantification (LOQ) considering a 125-fold pre-concentration step were 4-20 and 8-40 ng L(-1), respectively. Next, the method was applied to the analysis of the environmental aqueous samples, demonstrating the presence of β-zearalanol and zearalanone in the river water samples.

  5. Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

    Science.gov (United States)

    Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

    2016-07-01

    Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser. PMID:27135774

  6. Ionic Liquid-based Microwave-assisted Liquid-liquid Microextraction and High Performance Liquid Chromatography Determination of Sulfonamides from Animal Oils

    Institute of Scientific and Technical Information of China (English)

    FENG Xu-dong; LIANG Fang-hui; SU Rui; WU Li-jie; LI Xue-yuan; WANG Xing-hua; ZHANG Han-qi

    2013-01-01

    The authors performed ionic liquid-based microwave-assisted liquid-liquid microextraction(IL-based MALLME) coupled with high performance liquid chromatographic separation for the determination of 6 sulfonamides (SAs) from animal oils.The target analytes were extracted from animal oil samples with sodium hydroxide solution containing 1-butyl-3-methylimidazolium tetrafluoroborateand as the extraction solvent under microwave irradiation.The experimental parameters of the IL-based MALLME,including types of ILs,volume of IL,amount of ion-pairing agent(NH4PF6),pH value of sample solution,and extraction temperature and time were evaluated.The limits of detection and quantification obtained were in a range of 0.4-0.5 μg/kg and a range of 1.2-1.8 μg/kg,respectively.The accuracy of the method was evaluated by analyzing five spiked animal oil samples at two fortified levels(5 and 50 μg/kg),and the recoveries of SAs varied from 81.4% to 114.5% with relative standard deviations ranging from 0.8% to 9.0%.

  7. 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. PMID:27334034

  8. 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)

    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)

  9. Monitoring of antifungal drugs in biological samples using ultrasonic-assisted supramolecular dispersive liquid-liquid microextraction based on solidification of a floating organic droplet.

    Science.gov (United States)

    Ezoddin, Maryam; Abdi, Khosrou

    2016-08-01

    A new method for the simultaneous determination of the three antifungal drugs using ultrasonic-assisted supramolecular dispersive liquid-liquid microextraction based on solidification of a floating organic droplet (UASMDLLME-SFO) was proposed. The supramolecular solvents produced from reversed micelles of 1-dodecanol (extraction solvent) in tetrahydrofuran (THF) were injected into the aqueous sample solution. Reverse micelle coacervates were produced in situ through self-assembly processes. The antifungal drugs were extracted from the aqueous sample into a supramolecular solvent. Sonication accelerated the mass transfer of the target analytes into the supramolecular solvent phase and enhanced the dispersion process. Some parameters affecting the extraction efficiency such as type and volume of the extraction solvent, pH, volume of the disperser solvent and ultrasound extraction time were investigated. Under optimum conditions, the limits of detections for ketoconazole, clotrimazole and miconazole ranged from 0.08 to 1.3μgL(-1) and the relative standard deviations (RSDs, n=5)<6% were obtained. The method was successfully applied for preconcentration of the three drugs in biological and water samples. PMID:27262083

  10. β-lactam antibiotics residues analysis in bovine milk by LC-ESI-MS/MS: a simple and fast liquid-liquid extraction method.

    Science.gov (United States)

    Jank, L; Hoff, R B; Tarouco, P C; Barreto, F; Pizzolato, T M

    2012-01-01

    This study presents the development and validation of a simple method for the detection and quantification of six β-lactam antibiotics residues (ceftiofur, penicillin G, penicillin V, oxacillin, cloxacillin and dicloxacillin) in bovine milk using a fast liquid-liquid extraction (LLE) for sample preparation, followed by liquid chromatography-electrospray-tandem mass spectrometry (LC-MS/MS). LLE consisted of the addition of acetonitrile to the sample, followed by addition of sodium chloride, centrifugation and direct injection of an aliquot into the LC-MS/MS system. Separation was performed in a C(18) column, using acetonitrile and water, both with 0.1% of formic acid, as mobile phase. Method validation was performed according to the criteria of Commission Decision 2002/657/EC. Limits of detection ranged from 0.4 (penicillin G and penicillin V) to 10.0 ng ml(-1) (ceftiofur), and linearity was achieved. The decision limit (CCα), detection capability (CCβ), accuracy, inter- and intra-day repeatability of the method are reported. PMID:21988179

  11. Vortex-assisted liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of furfurals and patulin in fruit juices.

    Science.gov (United States)

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

    2014-03-01

    A fast and simple solvent microextraction technique using salting out-vortex-assisted liquid-liquid microextraction (salting out-VALLME) was developed for the extraction of furfurals (2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF) and 5-hydroxymethylfurfural (5-HMF)) and patulin (PAT) in fruit juice samples. The optimum extraction conditions for 5 mL sample were: extraction solvent, 1-hexanol; volume of extractant, 200 µL; vortex time, 45 s; salt addition, 20%. The simultaneous determination of the furfurals and PAT were investigated using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). The separation was performed using ODS Hypersil C18 column (4.6 mm i.d × 250 mm, 5 μm) under gradient elution. The detection wavelengths used for all compounds were 280 nm except for 3-F (210 nm). The furfurals and PAT were successfully separated in less than 9 min. Good linearities (r(2)>0.99) were obtained within the range 1-5000 μg L(-1) for all compounds except for 3-F (10-5000 µg L(-1)) and PAT (0.5-100 μg L(-1)). The limits of detection (0.28-3.2 µg L(-1)) were estimated at S/N ratio of 3. The validated salting out-VALLME-HPLC method was applied for the analysis of furfurals and PAT in fruit juice samples (apple, mango and grape). PMID:24468341

  12. Application of elevated temperature-dispersive liquid-liquid microextraction for determination of organophosphorus pesticides residues in aqueous samples followed by gas chromatography-flame ionization detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Rezaee Aghdam, Samaneh; Nouri, Nina; Bamorrowat, Mahdi

    2016-12-01

    In the present study, an elevated temperature, dispersive, liquid-liquid microextraction/gas chromatography-flame ionization detection was investigated for the determination, pre-concentration, and extraction of six organophosphorus pesticides (malathion, phosalone, dichlorvos, diazinon, profenofos, and chlorpyrifos) residues in fruit juice and aqueous samples. A mixture of 1,2-dibromoethane (extraction solvent) and dimethyl sulfoxide (disperser solvent) was injected rapidly into the sample solution heated at an elevated temperature. Analytical parameters, including enrichment factors (1600-2075), linearity (r>0.994), limits of detection (0.82-2.72ngmL(-1)) and quantification (2.60-7.36ngmL(-1)), relative standard deviations (<7%) and extraction recoveries (64-83%), showed the high efficiency of the method developed for analysis of the target analytes. The proposed procedure was used effectively to analyse selected analytes in river water and fruit juice, and diazinon was found at ngmL(-1) concentrations in apple juice. PMID:27374524

  13. Speciation of very low amounts of arsenic and antimony in waters using dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, Ricardo E.; Lopez-Garcia, Ignacio [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain); Hernandez-Cordoba, Manuel [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain)], E-mail: hcordoba@um.es

    2009-04-15

    A new procedure for the determination of inorganic arsenic (III,V) and antimony (III,V) in water samples by dispersive liquid-liquid micro extraction separation and electrothermal atomic absorption spectrometry (ETAAS) is presented. At pH 1, As(III) and Sb(III) are complexed with ammonium pyrrolidine dithiocarbamate and extracted into the fine droplets formed when mixing carbon tetrachloride (extraction solvent), methanol (disperser solvent) and the sample solution. After extraction, the phases are separated by centrifugation, and As(III) and Sb(III) are determined in the organic phase. As(V) and Sb(V) remain in the aqueous layer. Total inorganic As and Sb are determined after the reduction of the pentavalent forms with sodium thiosulphate. As(V) and Sb(V) are calculated by difference. The detection limits are 0.01 and 0.05 {mu}g L{sup -1} for As(III) and Sb(III), respectively, with an enrichment factor of 115. The relative standard deviation is in the 2.9-4.5% range. The procedure has been applied to the speciation of inorganic As and Sb in bottled, tap and sea water samples with satisfactory results.

  14. QbD-oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid-liquid extraction and chromatographic separation.

    Science.gov (United States)

    Beg, Sarwar; Chaudhary, Vandna; Sharma, Gajanand; Garg, Babita; Panda, Sagar Suman; Singh, Bhupinder

    2016-06-01

    The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26352459

  15. 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

    2015-07-01

    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.

  16. Molecular dynamics simulations of hydrophobous ions at the liquid-liquid interfaces: case of dicarbollide anions as synergy agents and of ionic liquids as extracting medium; Simulations par dynamique moleculaire d'ions hydrophobes aux interfaces liquide - liquide: le cas des anions dicarbollides comme agents de synergie et celui des liquides ioniques comme milieu extractant

    Energy Technology Data Exchange (ETDEWEB)

    Chevrot, G

    2008-01-15

    Based on molecular dynamics simulations, we first describe the distribution of dicarbollide salts (CCD{sup -}, Mn{sup +}) in concentrated monophasic solutions (water, chloroform, octanol, nitrobenzene) and in the corresponding biphasic 'oil' - water solutions. We point to the importance of surface activity of the CCD{sup -}s and of their self-aggregation in water, with marked counterions effects, and we explain the synergistic effect of CCD{sup -}s in the Eu{sup 3+} extraction by BTP ligands. In the second part of the thesis we report exploratory simulations on the extraction of Sr{sup 2+} by 18-crown-6 to an hydrophobic ionic liquid ([BMI][PF6]), focusing on the liquid - liquid interface. Analogies and differences with a classical aqueous interface are outlined. (author)

  17. Theoretical study of closed-loop recycling liquid-liquid chromatography and experimental verification of the theory.

    Science.gov (United States)

    Kostanyan, Artak E; Erastov, Andrey A

    2016-09-01

    The non-ideal recycling equilibrium-cell model including the effects of extra-column dispersion is used to simulate and analyze closed-loop recycling counter-current chromatography (CLR CCC). Previously, the operating scheme with the detector located before the column was considered. In this study, analysis of the process is carried out for a more realistic and practical scheme with the detector located immediately after the column. Peak equation for individual cycles and equations describing the transport of single peaks and complex chromatograms inside the recycling closed-loop, as well as equations for the resolution between single solute peaks of the neighboring cycles, for the resolution of peaks in the recycling chromatogram and for the resolution between the chromatograms of the neighboring cycles are presented. It is shown that, unlike conventional chromatography, increasing of the extra-column volume (the recycling line length) may allow a better separation of the components in CLR chromatography. For the experimental verification of the theory, aspirin, caffeine, coumarin and the solvent system hexane/ethyl acetate/ethanol/water (1:1:1:1) were used. Comparison of experimental and simulated processes of recycling and distribution of the solutes in the closed-loop demonstrated a good agreement between theory and experiment.

  18. Theoretical study of closed-loop recycling liquid-liquid chromatography and experimental verification of the theory.

    Science.gov (United States)

    Kostanyan, Artak E; Erastov, Andrey A

    2016-09-01

    The non-ideal recycling equilibrium-cell model including the effects of extra-column dispersion is used to simulate and analyze closed-loop recycling counter-current chromatography (CLR CCC). Previously, the operating scheme with the detector located before the column was considered. In this study, analysis of the process is carried out for a more realistic and practical scheme with the detector located immediately after the column. Peak equation for individual cycles and equations describing the transport of single peaks and complex chromatograms inside the recycling closed-loop, as well as equations for the resolution between single solute peaks of the neighboring cycles, for the resolution of peaks in the recycling chromatogram and for the resolution between the chromatograms of the neighboring cycles are presented. It is shown that, unlike conventional chromatography, increasing of the extra-column volume (the recycling line length) may allow a better separation of the components in CLR chromatography. For the experimental verification of the theory, aspirin, caffeine, coumarin and the solvent system hexane/ethyl acetate/ethanol/water (1:1:1:1) were used. Comparison of experimental and simulated processes of recycling and distribution of the solutes in the closed-loop demonstrated a good agreement between theory and experiment. PMID:27492599

  19. Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum.

    Science.gov (United States)

    Chen, Tao; Liu, Yongling; Zou, Denglang; Chen, Chen; You, Jinmao; Zhou, Guoying; Sun, Jing; Li, Yulin

    2014-01-01

    This study presents an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid-liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe-emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high-speed counter-current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe-emodin, physcione, and chrysophanol.

  20. 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

    2014-06-01

    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.

  1. LIQUID-LIQUID EQUILIBRIA FOR MIXTURES OF WATER,DECANE and 1-ETHOXY-2-PROPANOL%1-乙氧基-2-丙醇/水/癸烷的液液平衡

    Institute of Scientific and Technical Information of China (English)

    陈瑶; 李任强; 田村和弘

    2003-01-01

    Experimental data of ternary liquid-liquid equilibria for mixtures of 1-ethoxy-2-propanol, water and decane were measured at 298.15K.Extended UNIQUAC model was empolyed to correlate those data. The extended UNIQUAC model successfully represented the thermodynamic properties for the ternary system of 1-ethoxy-2-propanol, water and decane. These experimental results are useful for designing the separation and extraction process.

  2. Optimization of an accelerated solvent extraction dispersive liquid-liquid microextraction method for the separation and determination of essential oil from Ligusticum chuanxiong Hort by gas chromatography with mass spectrometry.

    Science.gov (United States)

    Yang, Guang; Sun, Qiushi; Hu, Zhiyan; Liu, Hua; Zhou, Tingting; Fan, Guorong

    2015-10-01

    In this study, an accelerated solvent extraction dispersive liquid-liquid microextraction coupled with gas chromatography and mass spectrometry was established and employed for the extraction, concentration and analysis of essential oil constituents from Ligusticum chuanxiong Hort. Response surface methodology was performed to optimize the key parameters in accelerated solvent extraction on the extraction efficiency, and key parameters in dispersive liquid-liquid microextraction were discussed as well. Two representative constituents in Ligusticum chuanxiong Hort, (Z)-ligustilide and n-butylphthalide, were quantitatively analyzed. It was shown that the qualitative result of the accelerated solvent extraction dispersive liquid-liquid microextraction approach was in good agreement with that of hydro-distillation, whereas the proposed approach took far less extraction time (30 min), consumed less plant material (usually <1 g, 0.01 g for this study) and solvent (<20 mL) than the conventional system. To sum up, the proposed method could be recommended as a new approach in the extraction and analysis of essential oil.

  3. In-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction and silylation prior gas chromatography-mass spectrometry for ultraviolet filters determination in environmental water samples.

    Science.gov (United States)

    Clavijo, Sabrina; Avivar, Jessica; Suárez, Ruth; Cerdà, Víctor

    2016-04-22

    A novel online approach involving in-syringe magnetic stirring assisted dispersive liquid-liquid microextraction and derivatization coupled to gas chromatography-mass spectrometry has been developed for the determination of seven UV filters extensively used in cosmetic products in environmental water samples. The effect of parameters such as the type and volume of extraction solvent, dispersive solvent and derivatization agent, pH, ionic strength and stirring time, was studied using multivariate experimental design. Extraction, derivatization and preconcentration were simultaneously performed using acetone as dispersive solvent, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) as derivatization agent and trichloroethylene as extraction solvent. After stirring during 160s, the sedimented phase was transferred to a rotary micro-volume injection valve (3 μL) and introduced by an air stream into the injector of the GC through a stainless-steel tube used as interface. The detection limits were in the range of 0.023-0.16 μg L(-1) and good linearity was observed up to 500 μg L(-1) of the studied UV filters, with R(2) ranging between 0.9829 and 0.9963. The inter-day precision expressed as relative standard deviation (n=5) varied between 5.5 and 16.8%. Finally, the developed method was satisfactorily applied to assess the occurrence of the studied UV filters in seawater and pool water samples. Some of the studied UV filters were found in these samples and an add-recovery test was also successfully performed with recoveries between 82 and 111%.

  4. Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of synthetic musk fragrances in aqueous matrices by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Homem, Vera; Alves, Alice; Alves, Arminda; Santos, Lúcia

    2016-01-01

    A rapid and simple method for the simultaneous determination of twelve synthetic musks in water samples, using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was successfully developed. The influence of seven factors (volume of the extraction solvent and disperser solvent, sample volume, extraction time, ionic strength, type of extraction and disperser solvent) affecting the UA-DLLME extraction efficiency was investigated using a screening design. The significant factors were selected and optimised employing a central composite design: 80 μL of chloroform, 880 μL of acetonitrile, 6 mL of sample volume, 3.5% (wt) of NaCl and 2 min of extraction time. Under the optimised conditions, this methodology was successfully validated for the analysis of 12 synthetic musk compounds in different aqueous samples (tap, sea and river water, effluent and influent wastewater). The proposed method showed enrichment factors between 101 and 115 depending on the analyte, limits of detection in the range of 0.004-54 ng L(-1) and good repeatability (most relative standard deviation values below 10%). No significant matrix effects were found, since recoveries ranged between 71% and 118%. Finally, the method was satisfactorily applied to the analysis of five different aqueous samples. Results demonstrated the existence of a larger amount of synthetic musks in wastewaters than in other water samples (average concentrations of 2800 ng L(-1) in influent and 850 ng L(-1) in effluent). Galaxolide, tonalide and exaltolide were the compounds most detected.

  5. Salt-assisted dispersive liquid-liquid microextraction coupled with programmed temperature vaporization gas chromatography-mass spectrometry for the determination of haloacetonitriles in drinking water.

    Science.gov (United States)

    Ma, Huilian; Li, Yun; Zhang, Haijun; Shah, Syed Mazhar; Chen, Jiping

    2014-09-01

    We report here a new analytical method for the simultaneous determination of seven haloacetonitriles (HANs) in drinking water by coupling salt-assisted dispersive liquid-liquid microextraction (SADLLME) with programmed temperature vaporizer-gas chromatography-mass spectrometry (PTV-GC-MS). The newly developed method involves the dispersion of the extractant in aqueous sample by addition of a few grams of salt and no dispersion liquid was required as compared to the traditional DLLME methods. The extractant (CH2Cl2, 50μL) and the salt (Na2SO4, 2.4g) were successively added to water (8mL) in a conical centrifuge tube that was shaken for 1min and centrifuged (3500rpm, 3min). The aliquot of sedimented phase (4μL) was then directly injected into the PTV-GC-MS system. The limits of detection and quantification for the HANs were 0.4-13.2ngL(-1) and 1.2-43.9ngL(-1), respectively. The calibration curves showed good linearity (r(2)≥0.9904) over 3 orders of magnitude. The repeatability of the method was investigated by evaluating the intra- and inter-day precisions. The relative standard deviations (RSDs) obtained were lower than 10.2% and 7.8% at low and high concentration levels. The relative recoveries ranged from 79.3% to 105.1%. The developed methodology was applied for the analysis of seven HANs in several drinking water samples in coastal and inland cities of China. It was demonstrated to be a simple, sensible, reproducible and environment friendly method for the determination of trace HANs in drinking water samples.

  6. Large volume of water samples introduced in dispersive liquid-liquid microextraction for the determination of 15 triazole fungicides by gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Nie, Jing; Chen, Fujiang; Song, Zhiyu; Sun, Caixia; Li, Zuguang; Liu, Wenhan; Lee, Mawrong

    2016-10-01

    A novel method of large volume of water samples directly introduced in dispersive liquid-liquid microextraction was developed, which is based on ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas (CO2) breaking down the emulsion for the determination of 15 triazole fungicides by gas chromatography-tandem mass spectrometry. This technique makes low-density extraction solvent toluene (180 μL) dissolve in 200 mL of samples containing 0.05 mol L(-1) of HCl and 5 % of NaCl (w/v) to form a well emulsion by synergy of ultrasound and manual shaking, and injects NaHCO3 solution (1.0 mol L(-1)) to generate CO2 achieving phase separation with the assistance of ultrasound. The entire process is accomplished within 8 min. The injection of NaHCO3 to generate CO2 achieves phase separation that breaks through the centrifugation limited large volume aqueous samples. In addition, the device could be easily cleaned, and this kind of vessel could be reconfigured for any volume of samples. Under optimal conditions, the low limits of detection ranging from 0.7 to 51.7 ng L(-1), wide linearity, and enrichment factors obtained were in the range 924-3669 for different triazole fungicides. Southern end of the Beijing-Hangzhou Grand Canal water (Hangzhou, China) was used to verify the applicability of the developed method. Graphical Abstract Flow chart of ultrasound/manual shaking-synergy-assisted emulsification and self-generating carbon dioxide gas breaking down the emulsion.

  7. 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.

  8. Investigation of the ultrasound effect and target analyte selectivity of dispersive liquid-liquid microextraction and its application to a quinocetone pharmacokinetic study.

    Science.gov (United States)

    Zhang, Jiaheng; Li, Min; Li, Linxia; Li, Yubo; Peng, Bing; Zhang, Suxia; Gao, Haixiang; Zhou, Wenfeng

    2012-12-14

    An ultrasound-assisted dispersive liquid-liquid microextraction (UADLLME) was developed as a simple, sensitive, and robust method for the simultaneous determination of quinocetone (QCT) and three of its synthesized desoxy metabolites in swine urine samples via high-performance liquid chromatography (HPLC). Experimental parameters were optimized using the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicate that ultrasonic irradiation significantly affects the DLLME extraction efficiency. Moreover, the intermolecular binding energies and octanol-water partition ratio (K(ow)) of the target analytes were calculated using the density functional theory and the atom-additive method, respectively. A high correlation was found between the extraction efficiency and the calculated results, which may serve as a scientific guideline in the determination of the target analyte selectivity of DLLME. The feasibility of UADLLME with HPLC for the simultaneous determination of QCT and its desoxy metabolites in blank swine urine samples was then investigated. Higher enrichment factors (118-175), low limits of detection (0.06-0.12 ng mL(-1)), and high precisions (relative standard deviation < 2.5%) were obtained. Calibration curves were performed in the 0.5-500 ng mL(-1) range and displayed good linearity. In addition, the proposed method was successfully applied to the pharmacokinetic study of QCT and its desoxy metabolites in real urine samples. The results show that UADLLME has a potential application in the pharmacokinetic and residue studies of quinoxaline-N-dioxides derivatives in biological fluid samples. PMID:23122995

  9. Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of synthetic musk fragrances in aqueous matrices by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Homem, Vera; Alves, Alice; Alves, Arminda; Santos, Lúcia

    2016-02-01

    A rapid and simple method for the simultaneous determination of twelve synthetic musks in water samples, using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was successfully developed. The influence of seven factors (volume of the extraction solvent and disperser solvent, sample volume, extraction time, ionic strength, type of extraction and disperser solvent) affecting the UA-DLLME extraction efficiency was investigated using a screening design. The significant factors were selected and optimised employing a central composite design: 80 μL of chloroform, 880 μL of acetonitrile, 6 mL of sample volume, 3.5% (wt) of NaCl and 2 min of extraction time. Under the optimised conditions, this methodology was successfully validated for the analysis of 12 synthetic musk compounds in different aqueous samples (tap, sea and river water, effluent and influent wastewater). The proposed method showed enrichment factors between 101 and 115 depending on the analyte, limits of detection in the range of 0.004-54 ng L(-1) and good repeatability (most relative standard deviation values below 10%). No significant matrix effects were found, since recoveries ranged between 71% and 118%. Finally, the method was satisfactorily applied to the analysis of five different aqueous samples. Results demonstrated the existence of a larger amount of synthetic musks in wastewaters than in other water samples (average concentrations of 2800 ng L(-1) in influent and 850 ng L(-1) in effluent). Galaxolide, tonalide and exaltolide were the compounds most detected. PMID:26653427

  10. Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. root.

    Science.gov (United States)

    Wang, Zhibing; Cao, Bocheng; Yu, Aimin; Zhang, Hanqi; Qiu, Fangping

    2015-02-01

    The ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction has been developed and applied to the extraction of four tanshinones, including dihydrotanshinone, tanshinone I, cryptotanshinone and tanshinone IIA in Salvia miltiorrhiza Bge. root. High performance liquid chromatography was applied to the separation and determination of the analytes. The ionic liquid was used as extraction solvent and target analytes were extracted with help of ultrasound. Then, ion-pairing agent was added into the sample solution, which resulted in the formation of water-insoluble ionic liquid in the solution. The phase separation was performed by centrifugation. The extraction, concentration and purification of target analytes were performed simultaneously. The experimental parameters, including type and volume of ionic liquid, sample amount, the size of sample particle, pH value of extraction medium, extraction temperature, extraction time, amount of ion-pairing agent and centrifuging time, were investigated and optimized. The calibration curves showed good linear relationship (r>0.9997). The limits of detection and quantification were in the range of 0.052-0.093 and 0.17-0.31 μg mL(-1), respectively. The recoveries were between 70.45% and 94.23% with relative standard deviations lower than 5.31%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with UAE and HRE. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods. PMID:25497891

  11. 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)

    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 (HMIMPF6), 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 HMIMPF6. 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 HMIMPF6 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 (m0, 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%.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li Shengqing [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Supervision, Inspection and Testing Center of Microbial Products Quality (Wuhan), Ministry of Agriculture (China)], E-mail: sqingli@mail.hzau.edu.cn; Cai Shun; Hu Wei [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Chen Hao [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China)], E-mail: hchenhao@mail.hzau.edu.cn; Liu Hanlan [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China)

    2009-07-15

    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{sub 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{sub 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 {mu}L of HMIMPF{sub 6} as the extraction solvent. The enrichment factor of the method is 67. The detection limit was 7.4 ng L{sup - 1}, and the characteristic mass (m{sub 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{sup - 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%.

  13. Ultrasound-assisted dispersive liquid-liquid microextraction plus simultaneous silylation for rapid determination of salicylate and benzophenone-type ultraviolet filters in aqueous samples.

    Science.gov (United States)

    Wu, Jen-Wen; Chen, Hsin-Chang; Ding, Wang-Hsien

    2013-08-01

    A rapid procedure, using minimal amounts of solvent, for the reliable determination of five salicylate and benzophenone-type ultraviolet (UV) filters: ethylhexyl salicylate (EHS), 3,3,5-trimethyl-cyclohexyl salicylate (HMS), 2-hydroxy-4-methoxybenzophenone (BP-3), 2,4-dihydroxy-benzophenone (BP-1) and 2,2'-dihydroxy-4-methoxybenzophenone (BP-8), in aqueous samples is described. The method involves an ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) plus simultaneous silylation prior to their determination by gas chromatography-mass spectrometry (GC-MS). The parameters affecting the extraction and derivatization efficiency of the target UV filters from aqueous samples were systematically investigated and the conditions optimized. The optimal silylation and extraction conditions involved the rapid injection of a mixture of 750μL of acetone (as a dispersant), 15μL of tetrachloroethylene (as an extractant), and 20μL of BSTFA (as a derivatizing agent) into a 10-mL volume of aqueous samples (pH 7.0) containing 0.5g of sodium chloride in a glass tube with a conical bottom. After ultrasonication for 2.0min and centrifugation at 5000rpm (10min), the sedimented phase 5.0μL was directly introduced into the GC-MS. The limits of quantitation (LOQs) were less than 6ng/L. The precision for these analytes, as indicated by the relative standard deviations (RSDs), was less than 9% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 74 and 92%. The method was then applied to environmental aqueous samples, using a standard addition method, showing the occurrence of BP-3 in samples of both river water and municipal wastewater treatment plant (MWTP) effluents. PMID:23831000

  14. New method based on combining ultrasonic assisted miniaturized matrix solid-phase dispersion and homogeneous liquid-liquid extraction for the determination of some organochlorinated pesticides in fish

    International Nuclear Information System (INIS)

    Highlights: → Ultrasonic assisted miniaturized matrix solid-phase dispersion combined with HLLE was developed as a new method for the extraction of OCPs in fish. → The goal of this combination was to enhance the selectivity of HLLE procedure and to extend its application in biological samples. → This method proposed the advantages of good detection limits, lower consumption of reagents, and does not need any special instrumentation. - Abstract: In this study, ultrasonic assisted miniaturized matrix solid-phase dispersion (US-MMSPD) combined with homogeneous liquid-liquid extraction (HLLE) has been developed as a new method for the extraction of organochlorinated pesticides (OCPs) in fish prior to gas chromatography with electron capture detector (GC-ECD). In the proposed method, OCPs (heptachlor, aldrin, DDE, DDD, lindane and endrin) were first extracted from fish sample into acetonitrile by US-MMSPD procedure, and the extract was then used as consolute solvent in HLLE process. Optimal condition for US-MMSPD step was as follows: volume of acetonitrile, 1.5 mL; temperature of ultrasound, 40 deg. C; time of ultrasound, 10 min. For HLLE step, optimal results were obtained at the following conditions: volume of chloroform, 35 μL; volume of aqueous phase, 1.5 mL; volume of double distilled water, 0.5 mL; time of centrifuge, 10 min. Under the optimum conditions, the enrichment factors for the studied compounds were obtained in the range of 185-240, and the overall recoveries were ranged from 39.1% to 81.5%. The limits of detection were 0.4-1.2 ng g-1 and the relative standard deviations for 20 ng g-1 of the OCPs, varied from 3.2% to 8% (n = 4). Finally, the proposed method has been successfully applied to the analysis of the OCPs in real fish sample, and satisfactory results were obtained.

  15. New method based on combining ultrasonic assisted miniaturized matrix solid-phase dispersion and homogeneous liquid-liquid extraction for the determination of some organochlorinated pesticides in fish

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, Farahnaz [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846 (Iran, Islamic Republic of); Hosseini, Mohammad-Reza Milani, E-mail: drmilani@iust.ac.ir [Department of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846 (Iran, Islamic Republic of); Electroanalytical Chemistry Research Center, Iran University of Science and Technology, Narmak, Tehran 16846 (Iran, Islamic Republic of)

    2011-09-30

    Highlights: {yields} Ultrasonic assisted miniaturized matrix solid-phase dispersion combined with HLLE was developed as a new method for the extraction of OCPs in fish. {yields} The goal of this combination was to enhance the selectivity of HLLE procedure and to extend its application in biological samples. {yields} This method proposed the advantages of good detection limits, lower consumption of reagents, and does not need any special instrumentation. - Abstract: In this study, ultrasonic assisted miniaturized matrix solid-phase dispersion (US-MMSPD) combined with homogeneous liquid-liquid extraction (HLLE) has been developed as a new method for the extraction of organochlorinated pesticides (OCPs) in fish prior to gas chromatography with electron capture detector (GC-ECD). In the proposed method, OCPs (heptachlor, aldrin, DDE, DDD, lindane and endrin) were first extracted from fish sample into acetonitrile by US-MMSPD procedure, and the extract was then used as consolute solvent in HLLE process. Optimal condition for US-MMSPD step was as follows: volume of acetonitrile, 1.5 mL; temperature of ultrasound, 40 deg. C; time of ultrasound, 10 min. For HLLE step, optimal results were obtained at the following conditions: volume of chloroform, 35 {mu}L; volume of aqueous phase, 1.5 mL; volume of double distilled water, 0.5 mL; time of centrifuge, 10 min. Under the optimum conditions, the enrichment factors for the studied compounds were obtained in the range of 185-240, and the overall recoveries were ranged from 39.1% to 81.5%. The limits of detection were 0.4-1.2 ng g{sup -1} and the relative standard deviations for 20 ng g{sup -1} of the OCPs, varied from 3.2% to 8% (n = 4). Finally, the proposed method has been successfully applied to the analysis of the OCPs in real fish sample, and satisfactory results were obtained.

  16. Liquid-liquid electro-organo-synthetic processes in a carbon nanofibre membrane microreactor: Triple phase boundary effects in the absence of intentionally added electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, John D.; Ahn, Sunyhik D.; Taylor, James E.; Bull, Steven D. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank, E-mail: F.Marken@bath.ac.uk [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2011-07-30

    Graphical abstract: Display Omitted Highlights: > Amphiphilic carbon nanofiber membrane employed in electro-synthesis. > Triple phase boundary process within a carbon membrane. > Electrochemical deuteration in a liquid|liquid micro-reactor system. > Triple phase boundary reaction zone effects in electro-synthesis. - Abstract: An amphiphilic carbon nanofibre membrane electrode (ca. 50 nm fibre diameter, 50-100 {mu}m membrane thickness) is employed as an active working electrode and separator between an aqueous electrolyte phase (with reference and counter electrode) and an immiscible organic acetonitrile phase (containing only the redox active material). Potential control is achieved with a reference and counter electrode located in the aqueous electrolyte phase, but the electrolysis is conducted in the organic acetonitrile phase in the absence of intentionally added supporting electrolyte. For the one-electron oxidation of n-butylferrocene coupled to perchlorate anion transfer from aqueous to organic phase effective electrolysis is demonstrated with an apparent mass transfer coefficient of m = 4 x 10{sup -5} m s{sup -1} and electrolysis of typically 1 mg n-butylferrocene in a 100 {mu}L volume. For the two-electron reduction of tetraethyl-ethylenetetracarboxylate the apparent mass transfer coefficient m = 4 x 10{sup -6} m s{sup -1} is lower due to a less extended triple phase boundary reaction zone in the carbon nanofibre membrane. Nevertheless, effective electrolysis of up to 6 mg tetraethyl-ethylenetetracarboxylate in a 100 {mu}L volume is demonstrated. Deuterated products are formed in the presence of D{sub 2}O electrolyte media. The triple phase boundary dominated mechanism and future microreactor design improvements are discussed.

  17. Evaluation of dispersive liquid-liquid microextraction for the simultaneous determination of chlorophenols and haloanisoles in wines and cork stoppers using gas chromatography-mass spectrometry.

    Science.gov (United States)

    Campillo, Natalia; Viñas, Pilar; Cacho, Juan I; Peñalver, Rosa; Hernández-Córdoba, Manuel

    2010-11-19

    Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was evaluated for the simultaneous determination of five chlorophenols and seven haloanisoles in wines and cork stoppers. Parameters, such as the nature and volume of the extracting and disperser solvents, extraction time, salt addition, centrifugation time and sample volume or mass, affecting the DLLME were carefully optimized to extract and preconcentrate chlorophenols, in the form of their acetylated derivatives, and haloanisoles. In this extraction method, 1mL of acetone (disperser solvent) containing 30μL of carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5mL of sample solution containing 200μL of acetic anhydride (derivatizing reagent) and 0.5mL of phosphate buffer solution, thereby forming a cloudy solution. After extraction, phase separation was performed by centrifugation, and a volume of 4μL of the sedimented phase was analyzed by GC-MS. The wine samples were directly used for the DLLME extraction (red wines required a 1:1 dilution with water). For cork samples, the target analytes were first extracted with pentane, the solvent was evaporated and the residue reconstituted with acetone before DLLME. The use of an internal standard (2,4-dibromoanisole) notably improved the repeatability of the procedure. Under the optimized conditions, detection limits ranged from 0.004 to 0.108ngmL(-1) in wine samples (24-220pgg(-1) in corks), depending on the compound and the sample analyzed. The enrichment factors for haloanisoles were in the 380-700-fold range. PMID:20956005

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

    Science.gov (United States)

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

    2009-07-01

    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 ( m0, 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%.

  19. On-line sequential injection dispersive liquid-liquid microextraction system for flame atomic absorption spectrometric determination of copper and lead in water samples.

    Science.gov (United States)

    Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

    2009-06-30

    A simple, sensitive and powerful on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system was developed as an alternative approach for on-line metal preconcentration and separation, using extraction solvent at microlitre volume. The potentials of this novel schema, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace copper and lead determination in water samples. The stream of methanol (disperser solvent) containing 2.0% (v/v) xylene (extraction solvent) and 0.3% (m/v) ammonium diethyldithiophosphate (chelating agent) was merged on-line with the stream of sample (aqueous phase), resulting a cloudy mixture, which was consisted of fine droplets of the extraction solvent dispersed entirely into the aqueous phase. By this continuous process, metal chelating complexes were formed and extracted into the fine droplets of the extraction solvent. The hydrophobic droplets of organic phase were retained into a microcolumn packed with PTFE-turnings. A portion of 300 microL isobutylmethylketone was used for quantitative elution of the analytes, which transported directly to the nebulizer of FAAS. All the critical parameters of the system such as type of extraction solvent, flow-rate of disperser and sample, extraction time as well as the chemical parameters were studied. Under the optimum conditions the enhancement factor for copper and lead was 560 and 265, respectively. For copper, the detection limit and the precision (R.S.D.) were 0.04 microg L(-1) and 2.1% at 2.0 microg L(-1) Cu(II), respectively, while for lead were 0.54 microg L(-1) and 1.9% at 30.0 microg L(-1) Pb(II), respectively. The developed method was evaluated by analyzing certified reference material and applied successfully to the analysis of environmental water samples. PMID:19376348

  20. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    Science.gov (United States)

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples. PMID:25127592

  1. In-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction for automation and downscaling of methylene blue active substances assay.

    Science.gov (United States)

    Suárez, Ruth; Horstkotte, Burkhard; Cerdà, Victor

    2014-12-01

    A simple and rapid method for the determination of the methylene blue active substances assay based on in-syringe automation of magnetic stirring-assisted dispersive liquid-liquid microextraction was developed. The proposed method proved to be valid for the determination of anionic surfactant in waste, pond, well, tap, and drinking water samples. Sample mixing with reagents, extraction and phase separation were performed within the syringe of an automated syringe pump containing a magnetic stirring bar for homogenization and solvent dispersion. The syringe module was used upside-down to enable the use of chloroform as an extraction solvent of higher density than water. The calibration was found to be linear up to 0.3mg/L using only 200 µL of solvent and 4 mL of sample. The limits of detection (3σ) and quantification (10σ) were 7.0 µg/L and 22 µg/L, respectively. The relative standard deviation for 10 replicate determinations of 0.1mg/L SBDS was below 3%. Concentrations of anionic surfactants in natural water samples were in the range of 0.032-0.213 mg/L and no significant differences towards the standard method were found. Standard additions gave analyte recoveries between 95% and 106% proving the general applicability and adequateness of the system to MBSA index determination. Compared to the tedious standard method requiring up to 50 mL of chloroform, the entire procedure took only 345 s using 250-times less solvent.

  2. Fluorescent derivatization combined with aqueous solvent-based dispersive liquid-liquid microextraction for determination of butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma.

    Science.gov (United States)

    Chen, Yi-Ching; Tsai, Chia-Ju; Feng, Chia-Hsien

    2016-09-16

    A novel aqueous solvent-based dispersive liquid-liquid microextraction (AS-DLLME) method was combined with narrow-bore liquid chromatography and fluorescence detection for the determination of hydrophilic compounds. A remover (non-polar solvent) and extractant (aqueous solution) were introduced into the derivatization system (acetonitrile) to obtain a water-in-oil emulsion state that increased the mass transfer of analytes. As a proof of concept, three quaternary ammonium substances, including butyrobetaine, l-carnitine and acetyl-l-carnitine, were also used as analytes and determined in pharmaceuticals, personal care products, food and human plasma. The analytes were derivatized with 4-bromomethylbiphenyl for fluorescence detection and improved retention in the column. The linear response was 10-2000nM for l-carnitine and acetyl-l-carnitine with a good determination coefficient (r(2)>0.998) in the standard solution. The detection limit for l-carnitine and acetyl-l-carnitine was 4.5 fmol. The method was also successfully applied to a 1μL sample of human plasma. In the linearity calculations for determining butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma, the determination coefficients ranged from 0.996 to 0.999. Linear regression exhibited good reproducibility and a relative standard deviation better than 7.50% for the slope and 9.06% for the intercept. To characterize highly hydrophilic compounds in various samples, the proposed method provides good sensitivity for a small sample volume with a low consumption of toxic solvents.

  3. 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.

  4. A rapid and sensitive method to determine tacrolimus in rat whole blood using liquid-liquid extraction with mild temperature ultrasonication and LC-MS/MS.

    Science.gov (United States)

    Park, Jun Seo; Cho, Ha Ra; Kang, Myung Joo; Choi, Yong Seok

    2016-01-01

    Tacrolimus (TAC) is an immunosuppressant widely used in organ transplantation, but its extremely low aqueous solubility causes poor intestinal absorption. There have been efforts to develop an alternative TAC formulation with an improved dissolution rate and oral bioavailability (BA), and the development of a rapid and sensitive analytical method for its in vivo pharmacokinetic study is an essential prerequisite. Thus, here, we develop a novel method to determine TAC in rat whole blood based on liquid chromatography and tandem mass spectrometry, and liquid-liquid extraction (LLE) with mild temperature ultrasonication. For rapid and efficient separation of TAC from other hydrophobic compounds, a C8 column was chosen with isocratic mobile phase elution. With the help of the high specificity and the high sensitivity of multiple reaction monitoring in positive ion mode, the present method showed good performance including specificity, linearity (r(2) ≥ 0.996 within 1-200 ng/mL), sensitivity (the lower limit of quantitation at 1 ng/mL), intra- and inter-day accuracy (88.7-104.5 %) and precision (≤10.3 %), and recovery (94.7-102.6 %). Also, the stability of TAC and ascomycin, the internal standard, in rat whole blood was confirmed before and after the sample preparation. The validated method was satisfactorily applied to a pharmacokinetic study to determine TAC in rat whole blood following oral administration of the marketed product (Prograf(®), Astellas Pharma). In the present study, LLE with mild temperature ultrasonication was successfully expanded to the determination of a drug from whole blood or plasma for the first time. Therefore, the present method can contribute to the rapid in vivo evaluation of novel TAC formulations, and will be able to contribute to the development of TAC formulations with a higher dissolution rate and a higher BA. PMID:26589688

  5. Modified Ionic Liquid Cold-Induced Aggregation Dispersive Liquid-Liquid Microextraction Combined with Spectrofluorimetry for Trace Determination of Ofloxacin in Pharmaceutical and Biological Samples

    Directory of Open Access Journals (Sweden)

    P. Norouzi

    2011-12-01

    Full Text Available Background and the purpose of the study: Ofloxacin is a quinolone synthetic antibiotic, which acts against resistant mutants of bacteria by inhibiting DNA gyrase. This antibacterial agent is widely used in the treatment of respiratory tract, urinary tract and tissue-based infections, which are caused by Gram-positive and Gram-negative bacteria. In this work, an efficient modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction (M-IL-CIA-DLLME was combined with spectrofluorimetry for trace determination of ofloxacin in real samples.Methods: In this microextraction method, hydrophobic 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim] [PF6] ionic liquid (IL as a microextraction solvent was dispersed into a heated sample solution containing sodium hexafluorophosphate (NaPF6 (as a common ion and the analyte of interest. Afterwards, the resultant solution was cooled in an ice-water bath and a cloudy condition was formed due to a considerable decrease of IL solubility. After centrifuging, the enriched phase was introduced to the spectrofluorimeter for the determination of ofloxacin.Results and major conclusion: In this technique, the performance of the microextraction method was not influenced by variations in the ionic strength of the sample solution (up to 30% w/v. Furthermore, [Hmim][PF6] IL was chosen as a green microextraction phase and an alternative to traditional toxic organic solvents. Different parameters affecting the analytical performance were studied and optimized. At optimum conditions, a relatively broad linear dynamic range of 0.15-125 μg l-1 and a limit of detection (LOD of 0.029 μg l-1 were obtained. The relative standard deviation (R.S.D. obtained for the determination of five replicates of the 10 ml solution containing 50 μg l-1 ofloxacin was 2.7%. Finally, the combined methodology was successfully applied to ofloxacin determination in actual pharmaceutical formulations and biological samples.

  6. Determination of some B Vitamins in Sour Cherry Juice Using Dispersive Liquid-liquid Microextraction Followed by High-performance Liquid Chromatography.

    Science.gov (United States)

    Parsaei, Parvin; Bahmaei, Manouchehr; Ghannadi, AliReza

    2014-01-01

    Dispersive liquid-liquid microextraction method (DLLME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine thiamine (B1), nicotinamide (B3) and pyridoxine (B6) in sour cherry juice. This method was rapid, simple and sensitive. Separation was accomplished using a C18 column. The optimum chromatographic conditions were found to be: mobile phase consisted of 8% methanol and 92% aqueous phase (1% (V/V) acetic acid water solution); flow rate, 0.7 mL/min; detection wavelength, 260 nm and pH, 3.3. The extraction efficiency of thiamine, nicotinamide and pyridoxine was influenced by factors such as: additional salt effect, the kind and volume of disperser and extraction solvents. In this research, the limit of detection (LOD) and quantification (LOQ) were 0.9 and 3 ng/mL for thiamine, 1.5 and 5 ng/mL for nicotinamide, 0.9 and 3 ng/mL for pyridoxine. The relative standard deviations (RSDs) were less than 2.87% (n=3). An appropriate linear behavior over the observed concentration range was obtained with the value of R²>0.996 for the target vitamins. This method was successfully applied to the sour cherry juice samples. Sour cherry var. Gise (Prunus cerasus var. Gise), which was used in this research, was a local variety of the sour cherry with large stone, double flowers, double fruits, dark red skin and dark red juice. This variety was identified in high altitude areas of Isfahan province after five years of study, since 2005, by Agricultural and Natural Resources Research Center of Isfahan. PMID:25587335

  7. 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. PMID:26761783

  8. A multiclass method for the analysis of endocrine disrupting chemicals in human urine samples. Sample treatment by dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Vela-Soria, F; Ballesteros, O; Zafra-Gómez, A; Ballesteros, L; Navalón, A

    2014-11-01

    The population is continuously exposed to endocrine disrupting chemicals (EDCs). This has influenced an increase in diseases and syndromes that are more frequent nowadays. Therefore, it is necessary to develop new analytical procedures to evaluate the exposure with the ultimate objective of establishing, in an accurate way, relationships between EDCs and harmful health effects. In the present work, a new method based on a sample treatment by dispersive liquid-liquid microextraction (DLLME) for the extraction of six parabens (methyl-, ethyl-, isopropyl-, propyl-, isobutyl and butylparaben), six benzophenones (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-6, benzophenone-8 and 4-hydroxybenzophenone) and two bisphenols (bisphenol A and bisphenol S) in human urine samples, followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis is proposed. An enzymatic treatment allows determining the total content of the target EDCs. The extraction parameters were accurately optimized using multivariate optimization strategies. Ethylparaben ring-(13)C6 and bisphenol A-d16 were used as surrogates. Found limits of quantification ranging from 0.2 to 0.5 ng mL(-1) and inter-day variability (evaluated as relative standard deviation) ranging from 2.0% to 14.9%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery rates ranged from 94% to 105%. A good linearity, for concentrations up to 300 ng mL(-1) for parabens and 40 ng mL(-1) for benzophenones and bisphenols, respectively, was obtained. The method was satisfactorily applied for the determination of target compounds in human urine samples from 20 randomly selected individuals.

  9. Screen-printed electrode based electrochemical detector coupled with ionic liquid dispersive liquid-liquid microextraction and microvolume back-extraction for determination of mercury in water samples.

    Science.gov (United States)

    Fernández, Elena; Vidal, Lorena; Martín-Yerga, Daniel; Blanco, María del Carmen; Canals, Antonio; Costa-García, Agustín

    2015-04-01

    A novel approach is presented, whereby gold nanostructured screen-printed carbon electrodes (SPCnAuEs) are combined with in-situ ionic liquid formation dispersive liquid-liquid microextraction (in-situ IL-DLLME) and microvolume back-extraction for the determination of mercury in water samples. In-situ IL-DLLME is based on a simple metathesis reaction between a water-miscible IL and a salt to form a water-immiscible IL into sample solution. Mercury complex with ammonium pyrrolidinedithiocarbamate is extracted from sample solution into the water-immiscible IL formed in-situ. Then, an ultrasound-assisted procedure is employed to back-extract the mercury into 10 µL of a 4 M HCl aqueous solution, which is finally analyzed using SPCnAuEs. Sample preparation methodology was optimized using a multivariate optimization strategy. Under optimized conditions, a linear range between 0.5 and 10 µg L(-1) was obtained with a correlation coefficient of 0.997 for six calibration points. The limit of detection obtained was 0.2 µg L(-1), which is lower than the threshold value established by the Environmental Protection Agency and European Union (i.e., 2 µg L(-1) and 1 µg L(-1), respectively). The repeatability of the proposed method was evaluated at two different spiking levels (3 and 10 µg L(-1)) and a coefficient of variation of 13% was obtained in both cases. The performance of the proposed methodology was evaluated in real-world water samples including tap water, bottled water, river water and industrial wastewater. Relative recoveries between 95% and 108% were obtained. PMID:25640123

  10. Application of dispersive liquid-liquid microextraction for the determination of aflatoxins B1, B2, G1 and G2 in cereal products.

    Science.gov (United States)

    Campone, Luca; Piccinelli, Anna Lisa; Celano, Rita; Rastrelli, Luca

    2011-10-21

    The application of dispersive liquid-liquid microextraction (DLLME) technique for the rapid analysis of aflatoxins B(1), B(2), G(1) and G(2) in maize, rice and wheat products has been evaluated. After extraction of aflatoxins from cereal matrices with a mixture of methanol/water 8:2 (v/v), the analytes were rapidly transferred from the extract to another small volume of organic solvent, chloroform, by DLLME. Aflatoxins were determined using high performance liquid chromatography with florescence detection and photochemical post-column derivatization. Parameters affecting both extraction and DLLME procedures, such as extraction solvent, type and volume of DLLME extractant, volume of water and salt effect, were systematically investigated and optimized to achieve the best extraction efficiency. Under the optimal experimental conditions, the whole analytical method provides enrichment factors around 2.5 times and detection limits (0.01-0.17 μg kg(-1)) below the maximum levels imposed by current regulation for aflatoxins in cereals and cereal products intended for direct human consumption. Recoveries (67-92%) and repeatability (RSD<10, n=3), tested in three different cereal matrices, meet the performance criteria required by EC Regulation No. 401/2006 for the determination of the levels of mycotoxins in foodstuffs. The proposed method was successfully applied to the analysis of retail cereal products with quantitative results comparable to the immunoaffinity chromatography (IAC). The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost. PMID:21636088

  11. 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 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. PMID:27372718

  12. Fluorescent derivatization combined with aqueous solvent-based dispersive liquid-liquid microextraction for determination of butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma.

    Science.gov (United States)

    Chen, Yi-Ching; Tsai, Chia-Ju; Feng, Chia-Hsien

    2016-09-16

    A novel aqueous solvent-based dispersive liquid-liquid microextraction (AS-DLLME) method was combined with narrow-bore liquid chromatography and fluorescence detection for the determination of hydrophilic compounds. A remover (non-polar solvent) and extractant (aqueous solution) were introduced into the derivatization system (acetonitrile) to obtain a water-in-oil emulsion state that increased the mass transfer of analytes. As a proof of concept, three quaternary ammonium substances, including butyrobetaine, l-carnitine and acetyl-l-carnitine, were also used as analytes and determined in pharmaceuticals, personal care products, food and human plasma. The analytes were derivatized with 4-bromomethylbiphenyl for fluorescence detection and improved retention in the column. The linear response was 10-2000nM for l-carnitine and acetyl-l-carnitine with a good determination coefficient (r(2)>0.998) in the standard solution. The detection limit for l-carnitine and acetyl-l-carnitine was 4.5 fmol. The method was also successfully applied to a 1μL sample of human plasma. In the linearity calculations for determining butyrobetaine, l-carnitine and acetyl-l-carnitine in human plasma, the determination coefficients ranged from 0.996 to 0.999. Linear regression exhibited good reproducibility and a relative standard deviation better than 7.50% for the slope and 9.06% for the intercept. To characterize highly hydrophilic compounds in various samples, the proposed method provides good sensitivity for a small sample volume with a low consumption of toxic solvents. PMID:27562416

  13. Selective extraction of zinc(II) over iron(II) from spent hydrochloric acid pickling effluents by liquid-liquid extraction.

    Science.gov (United States)

    Mansur, Marcelo Borges; Rocha, Sônia Denise Ferreira; Magalhães, Fernando Silva; Benedetto, Jeaneth dos Santos

    2008-02-11

    The selective removal of zinc(II) over iron(II) by liquid-liquid extraction from spent hydrochloric acid pickling effluents produced by the zinc hot-dip galvanizing industry was studied at room temperature. Two distinct effluents were investigated: effluent 1 containing 70.2g/L of Zn, 92.2g/L of Fe and pH 0.6, and effluent 2 containing 33.9 g/L of Zn, 203.9g/L of Fe and 2M HCl. The following extractants were compared: TBP (tri-n-butyl phosphate), Cyanex 272 [bis(2,4,4-trimethylpentyl)phosphinic acid], Cyanex 301 [bis(2,4,4-trimethylpentyl) dithiophosphinic acid] and Cyanex 302 [bis(2,4,4-trimethylpentyl) monothiophosphinic acid]. The best separation results were obtained for extractants TBP and Cyanex 301. Around 92.5% of zinc and 11.2% of iron were extracted from effluent 1 in one single contact using 100% (v/v) of TBP. With Cyanex 301, around 80-95% of zinc and less than 10% of iron were extracted from effluent 2 at pH 0.3-1.0. For Cyanex 272, the highest extraction yield for zinc (70% of zinc with 20% of iron extraction) was found at pH 2.4. Cyanex 302 presented low metal extraction levels (below 10%) and slow phase disengagement characteristics. Reactions for the extraction of zinc with TBP and Cyanex 301 from hydrochloric acid solution were proposed. PMID:17570579

  14. Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

    Science.gov (United States)

    Peng, Guilong; He, Qiang; Al-Hamadani, Sulala M Z F; Zhou, Guangming; Liu, Mengzi; Zhu, Hui; Chen, Junhua

    2015-05-01

    Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution. After 5min, 0.6g of NaCl was added and the sample vial was shaken. After 5min, the sample was centrifuged at 3500rpm for 3min, and then placed in an ice bath. When the extraction solvent floating on the aqueous solution had solidified, it was transferred into another conical vial where it was melted quickly at room temperature, and was diluted with methanol to 1mL, and analyzed by HPLC-UV detection. Parameters influencing the extraction efficiency were thoroughly examined and optimized. The extraction recoveries (ER) and the enrichment factors (EF) ranged from 67% to 72% and 223 to 241, respectively. The limits of detection (LODs) (S/N=3) were 0.33 and 0.56µgL(-1) for TAP and FF, respectively. Linear dynamic range (LDR) was in the range of 1.0-550µgL(-1) for TAP and 1.5-700µgL(-1) for FF, the relative standard deviations (RSDs) were in the range of 2.6-3.5% and the recoveries of spiked samples ranged from 94% to 106%. PMID:25723132

  15. Separation of curcuminoids using ionic liquid based aqueous two-phase system coupled with in situ dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Shu, Yang; Gao, Mingcen; Wang, Xueying; Song, Rusheng; Lu, Jun; Chen, Xuwei

    2016-01-01

    An aqueous two-phase extraction system (ATPS) combined with an in situ dispersive liquid-liquid microextraction (DLLME) method using imidazolium ionic liquids (ILs) for the separation of curcuminoids is developed. The influence of structure of IL, the type of metathesis reagents, and the back extraction agents on the extraction efficiency is investigated. 2.0mg of curcuminoids are extracted by an IL ATPS composed of 0.4g 1,3-diethylimidazolium iodine (EeimI), 0.6g potassium hydrogen phosphate, 1.0g water. Then the bis[(trifluoromethyl)sulfonyl]imide lithium (LiNTf2) aqueous solution is added to the EeimI-rich phase of the ATPS. The water-immiscible ionic liquids, 1,3-diethylimidazole bis[(trifluoromethyl)sulfonyl]imide (EeimNTf2), forms by the metathesis reaction. The in situ DLLME is triggered simultaneously and further purifies the curcuminoids. 92% of EeimI transforms into EeimNTf2 and thus the Eeim(+) cation is used for twice in this method. Finally, 0.1mol/L NaOH aqueous solution is used as the back extraction reagent. The curcuminoids precipitate is achieved with 93% of recovery when the aqueous solution is adjusted to pH 3.0. This ATPS-DLLME method is successfully applied to the separation of curcuminoids from Curcuma Longa (0.96±0.02% of extraction yield, a purity of >51% with respect to the total dry mass of the product).

  16. Exploiting the Phenomenon of Liquid-Liquid Phase Separation for Enhanced and Sustained Membrane Transport of a Poorly Water-Soluble Drug.

    Science.gov (United States)

    Indulkar, Anura S; Gao, Yi; Raina, Shweta A; Zhang, Geoff G Z; Taylor, Lynne S

    2016-06-01

    Recent studies on aqueous supersaturated lipophilic drug solutions prepared by methods including antisolvent addition, pH swing, or dissolution of amorphous solid dispersions (ASDs) have demonstrated that when crystallization is slow, these systems undergo liquid-liquid phase separation (LLPS) when the concentration of the drug in the medium exceeds its amorphous solubility. Following LLPS, a metastable equilibrium is formed where the concentration of drug in the continuous phase corresponds to the amorphous solubility while the dispersed phase is composed of a nanosized drug-rich phase. It has been reasoned that the drug-rich phase may act as a reservoir, enabling the rate of passive transport of the drug across a membrane to be maintained at the maximum value for an extended period of time. Herein, using clotrimazole as a model drug, and a flow-through diffusion cell, the reservoir effect is demonstrated. Supersaturated clotrimazole solutions at concentrations below the amorphous solubility show a linear relationship between the maximum flux and the initial concentration. Once the concentration exceeds the amorphous solubility, the maximum flux achieved reaches a plateau. However, the duration for which the high flux persists was found to be highly dependent on the number of drug-rich nanodroplets present in the donor compartment. Macroscopic amorphous particles of clotrimazole did not lead to the same reservoir effect observed with the nanodroplets formed through the process of LLPS. A first-principles mathematical model was developed which was able to fit the experimental receiver concentration-time profiles for concentration regimes both below and above amorphous solubility, providing support for the contention that the nanodroplet phase does not directly diffuse across the membrane but, instead, rapidly replenishes the drug in the aqueous phase that has been removed by transport across the membrane. This study provides important insight into the properties of

  17. Optical Kerr-effect study of trans- and cis-1,2-dichloroethene: liquid-liquid transition or super-Arrhenius relaxation.

    Science.gov (United States)

    Turton, David A; Martin, David F; Wynne, Klaas

    2010-04-28

    The evidence that a molecular liquid in its thermodynamically-stable state can undergo a liquid-liquid transition (LLT) is still uncertain. Therefore, trans-1,2-dichloroethene is of interest due to reports of a LLT above the melting point [S. Kawanishi, T. Sasuga and M. Takehisa, J. Phys. Soc. Jpn., 1982, 51, 1579-1583; S. Rzoska, J. Ziolo, A. Drozd-Rzoska, J. L. Tamarit and N. Veglio, J. Phys.: Condens. Matter, 2008, 20, 244124; K. Merkel, A. Kocot, R. Wrzalik and J. Ziolo, J. Chem. Phys., 2008, 129, 074503-074508]. Ultrafast optical Kerr-effect (OKE) spectroscopy enables accurate measurement of the low-frequency modes arising from interactions in liquids and therefore should be sensitive to the change in liquid structure inherent in such a transition. In the OKE data presented here, no sharp transitions are discernible, nor are there any in calorimetry data. However, the same data do reveal that neither trans- nor cis-1,2-dichloroethene is a simple liquid: in each case, a non-Arrhenius temperature dependence (with a Debye lineshape) is observed for the alpha relaxation. This dependence can be fitted by the Vogel-Fulcher-Tammann (VFT) law over the measurable temperature range suggesting that at low temperature, cooperative relaxation, due to the formation of clusters or structure, is present. Accurate analysis of the OKE spectrum in the terahertz region is generally limited by approximations inherent in the models. Here the diffusional modes are convoluted with librational modes to give a more physically meaningful approximation to the inertial response.

  18. Emulsification liquid-liquid microextraction based on deep eutectic solvent: An extraction method for the determination of benzene, toluene, ethylbenzene and seven polycyclic aromatic hydrocarbons from water samples.

    Science.gov (United States)

    Khezeli, Tahere; Daneshfar, Ali; Sahraei, Reza

    2015-12-18

    In this study, for the first time, a simple, inexpensive and sensitive method named emulsification liquid-liquid microextraction based on deep eutectic solvent (ELLME-DES) was used for the extraction of benzene, toluene, ethylbenzene (BTE) and seven polycyclic aromatic hydrocarbons (PAHs) from water samples. In a typical experiment, 100μL of DES (as water-miscible extraction solvent) was added to 1.5mL of sample solution containing target analytes. A homogeneous solution was formed immediately. Injection of 100μL of THF (as emulsifier agent) into homogeneous solution provided a turbid state. After extraction, phase separation (aqueous phase/DES rich phase) was performed by centrifugation. DES rich phase was withdrawn by a micro-syringe and submitted to isocratic reverse-phase HPLC with UV detection. Under optimum conditions obtained by response surface methodology (RSM) and desirability function (DF), the calibration graphs were linear in the concentration range from 10 to 200μg/L for benzene, 10-400μg/L for toluene, 1-400μg/L for ethylbenzene, biphenyl, chrysene and fluorene, and 0.1-400μg/L for anthracene, benzo[a]pyrene, phenanthrene and pyrene. The coefficients of determination (r(2)) and limits of detection were 0.9924-0.9997 and 0.02-6.8μg/L, respectively. This procedure was successfully applied to the determination of target analytes in spiked water samples. The relative mean recoveries ranged from 93.1 to 103.3%. PMID:26614169

  19. Homogeneous liquid-liquid extraction combined with gas chromatography-electron capture detector for the determination of three pesticide residues in soils

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xuedong [School of Environmental Science and Public Health, Wenzhou Medical College, Wenzhou 325035 (China)], E-mail: zjuwxd@yahoo.com.cn; Zhao Xinna; Liu Xiujuan; Li Yanyan; Fu Lingyan; Hu Jia [Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Central China Normal University, Wuhan 430079 (China); Huang Changjiang [School of Environmental Science and Public Health, Wenzhou Medical College, Wenzhou 325035 (China)

    2008-07-14

    In this study, a new method was developed for analyzing malathion, cypermethrin and lambda-cyhalothrin from soil samples by using homogeneous liquid-liquid extraction (HLLE) and gas chromatography with electron capture detector (GC-ECD). Acetone was used as extraction solvent for the extraction of target pesticides from soil samples. When the extraction process was finished, the target analytes in the extraction solvent were rapidly transferred from the acetone extract to carbon tetrachloride, using HLLE. Under the optimum conditions, linearity was obtained in the range of 0.05-40 {mu}g kg{sup -1} for malathion, 0.04-10 {mu}g kg{sup -1} for lambda-cyhalothrin and 0.05-50 {mu}g kg{sup -1} for cypermethrin, respectively. Coefficients of correlation (r{sup 2}) ranged from 0.9993 to 0.9998. The repeatability was carried out by spiking soil samples at concentration levels of 2.5 {mu}g kg{sup -1} for lambda-cyhalothrin, and 10 {mu}g kg{sup -1} for malathion and cypermethrin, respectively. The relative standard deviations (RSDs) varied between 2.3 and 9.6% (n = 3). The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, varied between 0.01 and 0.04 {mu}g kg{sup -1}. The relative recoveries of three pesticides from soil A1, A2 and A3 at spiking levels of 2.5, 5 and 10 {mu}g kg{sup -1} were in the range of 82.20-91.60%, 88.90-110.5% and 77.10-98.50%, respectively. In conclusion, the proposed method can be successfully applied for the determination of target pesticide residues in real soil samples.

  20. Simultaneous derivatization and ultrasound-assisted dispersive liquid-liquid microextraction of chloropropanols in soy milk and other aqueous matrices combined with gas-chromatography-mass spectrometry.

    Science.gov (United States)

    Carro, A M; González, P; Lorenzo, R A

    2013-12-01

    A novel approach involving ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and derivatization combined with gas chromatography-mass spectrometry was developed for the determination of chloropropanols in water and beverages. UA-DLLME was optimized as less solvent-consuming and cost-effective extraction method for water, fruit juice, milk and soy milk samples. The effect of parameters such as the type and volume of extraction solvent, the type and volume of dispersive solvent, amount of derivatization agent, temperature, pH of sample and ionic strength was investigated and optimized for each specimen, using experimental designs. By adding acetonitrile as dispersive solvent, N-heptafluorobutyrylimizadole (HFBI) as derivatization agent and chloroform as extraction solvent, the extraction-derivatization and preconcentration were simultaneously performed. The analytical concentration range was investigated in detail for each analyte in the different samples, obtaining linearity with R(2) ranging between 0.9990 and 0.9999. The method detection limits were in the range of 0.2-1.8μgL(-1) (water), 0.5-15μgL(-1) (fruit juices) and 0.9-3.6μgkg(-1) (milk) and 0.1-1.0μgkg(-1) (soy milk). The method was applied to the analysis of a variety of specimens, with recoveries of 98-101% from water, 97-102% from juices, 99-103% from milk and 97-105% from soy beverage. The relative standard deviation (precision, n=6) varied between 1.3 and 4.9%RSD in water, 2.3 and 5.8%RSD in juices, 1.0 and 5.7%RSD in milk and 3.9 and 9.3%RSD in soy milk. The proposed method was applied to analysis of twenty-eight samples. 1,3-Dichloro-2-propanol was found in an influent water sample from urban wastewater treatment plant (WWTP) (2.1±0.04mgL(-1)) but no chloropropanols were found in the corresponding effluent water sample. This result suggests that the purification system used in the WWTP has been effective for this compound. Moreover, the results revealed the presence of 3