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Sample records for capillary liquid chromatography

  1. Monoliths in capillary electrochromatography and capillary liquid chromatography in conjunction with mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Rantamäki, A. H.; Duša, Filip; Wiedmer, S. K.

    2016-01-01

    Roč. 37, 7-8 (2016), s. 880-912 ISSN 0173-0835 Institutional support: RVO:68081715 Keywords : capillary electrochromatography * capillary liquid chromatography * mass spec- trometry * monolithic columns Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.744, year: 2016

  2. VIII All-Russian symposium on molecular liquid chromatography and capillary electrophoresis. Program. Summary of reports

    International Nuclear Information System (INIS)

    2001-01-01

    Program and summary of reports of the VIII All-Russian symposium on molecular liquid chromatography and capillary electrophoresis are performed. The meeting took place 15-19 October, 2001 in Moscow. Many problems of liquid and ion exchange chromatography, capillary electrophoresis, thin-layer chromatography have been discussed extensively. Reports covering properties of sorbents and devices for chromatography are incorporated in the collection [ru

  3. Growth of metal-organic framework HKUST-1 in capillary using liquid-phase epitaxy for open-tubular capillary electrochromatography and capillary liquid chromatography.

    Science.gov (United States)

    Bao, Tao; Zhang, Juan; Zhang, Wenpeng; Chen, Zilin

    2015-02-13

    Much attention is being paid to applying metal-organic frameworks (MOFs) as stationary phases in chromatography because of their fascinating properties, such as large surface-to-volume ratios, high levels of porosity, and selective adsorption. HKUST-1 is one of the best-studied face-centered-cubic MOF containing nano-sized channels and side pockets for film growth. However, growth of HKUST-1 framework inside capillary column as stationary phase for capillary electrochromatography is a challenge work. In this work, we carry out the growth of HKUST-1 on the inner wall of capillary by using liquid-phase epitaxy process at room temperature. The fabricated HKUST-1@capillary can be successfully used for the separation of substituted benzene including methylbenzene, ethylbenzene, styrene, chlorobenzene, bromobenzene, o-dichlorobenzene, benzene series, phenolic acids, and benzoic acids derivates. High column efficiency of 1.5×10(5) N/m for methylbenzene was achieved. The formation of HKUST-1 grown in the capillary was confirmed and characterized by scanning electron microscopy images, Fourier transform infrared spectra and X-ray diffraction. The column showed long lifetime and excellent stability. The relative standard deviations for intra-day and inter-day repeatability of the HKUST-1@capillary were lower than 7%. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Separation and quantification of ropinirole and some impurities using capillary liquid chromatography

    NARCIS (Netherlands)

    Coufal, P.; Stulik, K.; Claessens, H.A.; Hardy, M.J.; Webb, M.

    1999-01-01

    Ropinirole, 4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one, is a potent anti-Parkinson’s disease drug developed by SmithKline Beecham Pharmaceuticals. Capillary liquid chromatography (CLC) was used for the separation and quantification of ropinirole and its five related impurities,

  5. 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 neu...... neutralisation. The extracts were analysed by capillary gas chromatography. Dual detection by flame Ionisation and electron capture was used to reduce analysis time....

  6. Controlled crosslinking of trimethylolpropane trimethacrylate for preparation of organic monolithic columns for capillary liquid chromatography.

    Science.gov (United States)

    Gama, Mariana R; Aggarwal, Pankaj; Lee, Milton L; Bottoli, Carla B G

    2017-11-01

    Organic monolithic columns based on single crosslinking of trimethylolpropane trimethacrylate (TRIM) monomer were prepared in a single step by living/controlled free-radical polymerization. Full optimization of the preparation, such as using different percentages of TRIM and different amounts of radical promoter as well as various porogen solvents were explored. The resulting monolithic columns were characterized by scanning electronic microscopy and nitrogen sorption for structure morphology studies and surface area measurements, respectively. Using capillary liquid chromatography, 150 μm i.d. columns were applied to separate a mixture of small hydrophobic molecules. The results indicated that column performance is highly sensitive to the type and the amount of porogen solvents used in the polymerization mixture composition. Good resolution factors and methylene selectivity were obtained, indicating the promising potential of this material for capillary liquid chromatography separations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Enantioselective analysis of drugs: contributions of high-performance liquid chromatography and capillary electrophoresis

    OpenAIRE

    Bonato, Pierina Sueli; Jabor, Valquíria Aparecida Polisel; Gaitani, Cristiane Masetto de

    2005-01-01

    The demand for analytical methods suitable for accurate and reproducible determination of drug enantiomers has increased significantly in the last years. High-performance liquid chromatography (HPLC) using chiral stationary phases and capillary electrophoresis (CE) are the most important techniques used for this purpose. In this paper, the fundamental aspects of chiral separations using both techniques are presented. Some important aspects for the development of enantioselective methods, part...

  8. Characterization of free and bound fatty acids in human gallstones by capillary gas liquid chromatography

    International Nuclear Information System (INIS)

    Channa, N.A.; Khand, F.D.; Noorani, M.A.; Bhanger, M.I.

    2002-01-01

    Forty-four human gallstone samples either of pure cholesterol or cholesterol and bilirubin were randomly selected and analyzed by capillary gas liquid chromatography for the relative percentage composition of free and total fatty acids. The results showed that bound fatty acids were present in higher amounts than the free fatty acids. Amongst the bound fatty acids the percentage occurrence for palmitic acid was highest followed by stearic, oleic, linoleic and myristic acids. Fatty acids myristic, palmitic and linoleic were present in higher amounts in cholesterol gallstones, whereas stearic acid in cholesterol and bilirubin gallstones. When compared, no significant difference (p < 0.05) in the levels of free and bound fatty acids were seen in gallstones of males and females. The results suggest that bound fatty acids have a role to play in the structure of gallstones. (author)

  9. Monolithic columns based on a poly(styrene-divinylbenzene-methacrylic acid) copolymer for capillary liquid chromatography of small organic molecules

    Czech Academy of Sciences Publication Activity Database

    Svobodová, A.; Křížek, T.; Širc, Jakub; Šálek, Petr; Tesařová, E.; Coufal, P.; Štulík, K.

    2011-01-01

    Roč. 1218, č. 11 (2011), s. 1544-1547 ISSN 0021-9673 R&D Projects: GA AV ČR KAN200520804 Institutional research plan: CEZ:AV0Z40500505 Keywords : capillary liquid chromatography * methacrylic acid * polystyrene-based monolithic stationary phase Subject RIV: EI - Biotechnology ; Bionics Impact factor: 4.531, year: 2011

  10. Flow rate dependent extra-column variance from injection in capillary liquid chromatography.

    Science.gov (United States)

    Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L

    2015-02-06

    Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23 nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ∼130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2018-02-15

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

  12. Analytical potential of mid-infrared detection in capillary electrophoresis and liquid chromatography: A review

    International Nuclear Information System (INIS)

    Kuligowski, Julia; Quintas, Guillermo; Guardia, Miguel de la; Lendl, Bernhard

    2010-01-01

    Literature published in the last decade concerning the use of mid-infrared spectrometry as a detection system in separation techniques employing a liquid mobile phase is reviewed. In addition to the continued use of isocratic liquid chromatographic (LC) techniques, advances in chemometric data evaluation techniques now allow the use of gradient techniques on a routine basis, thus significantly broadening the range of possible applications of LC-IR. The general trend towards miniaturized separation systems was also followed for mid-IR detection where two key developments are of special importance. Firstly, concerning on-line detection the advent of micro-fabricated flow-cells with inner volumes of only a few nL for transmission as well as attenuated total reflection measurements enabled on-line mid-IR detection in capillary LC and opened the path for the first successful realization of on-line mid-IR detection in capillary zone electrophoresis as well as micellar electrokinetic chromatography. Secondly, concerning off-line detection the use of micro-flow through dispensers now enables to concentrate eluting analytes on dried spots sized a few tens of micrometers, thus matching the dimensions for sensitive detection by mid-IR microscopy. Finally in an attempt to increase detection sensitivity of on-line mid-IR detection, mid-IR quantum cascade lasers have been used. Applications cover the field of food analysis, environmental analysis and the characterization of explosives among others. Best detection sensitivities for on-line and off-line detection have been achieved in miniaturized systems and are in the order of 50 ng and 2 ng on column, respectively.

  13. Highly crosslinked polymeric monoliths for reversed-phase capillary liquid chromatography of small molecules.

    Science.gov (United States)

    Liu, Kun; Tolley, H Dennis; Lee, Milton L

    2012-03-02

    Seven crosslinking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic capillary columns for reversed-phase liquid chromatography (RPLC) of small molecules. Dodecanol and methanol were chosen as "good" and "poor" porogenic solvents, respectively, for these monoliths, and were investigated in detail to provide insight into the selection of porogen concentration using 1,12-DoDDMA. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Optimized monoliths synthesized from all seven crosslinking monomers showed high permeability. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. Column preparation was highly reproducible; the relative standard deviation (RSD) values (n=3) for run-to-run and column-to-column were less than 0.25% and 1.20%, respectively, based on retention times of alkylbenzenes. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Green sample preparation for liquid chromatography and capillary electrophoresis of anionic and cationic analytes.

    Science.gov (United States)

    Wuethrich, Alain; Haddad, Paul R; Quirino, Joselito P

    2015-04-21

    A sample preparation device for the simultaneous enrichment and separation of cationic and anionic analytes was designed and implemented in an eight-channel configuration. The device is based on the use of an electric field to transfer the analytes from a large volume of sample into small volumes of electrolyte that was suspended into two glass micropipettes using a conductive hydrogel. This simple, economical, fast, and green (no organic solvent required) sample preparation scheme was evaluated using cationic and anionic herbicides as test analytes in water. The analytical figures of merit and ecological aspects were evaluated against the state-of-the-art sample preparation, solid-phase extraction. A drastic reduction in both sample preparation time (94% faster) and resources (99% less consumables used) was observed. Finally, the technique in combination with high-performance liquid chromatography and capillary electrophoresis was applied to analysis of quaternary ammonium and phenoxypropionic acid herbicides in fortified river water as well as drinking water (at levels relevant to Australian guidelines). The presented sustainable sample preparation approach could easily be applied to other charged analytes or adopted by other laboratories.

  15. Analysis of microdialysate monoamines, including noradrenaline, dopamine and serotonin, using capillary ultra-high performance liquid chromatography and electrochemical detection.

    Science.gov (United States)

    Ferry, Barbara; Gifu, Elena-Patricia; Sandu, Ioana; Denoroy, Luc; Parrot, Sandrine

    2014-03-01

    Electrochemical methods are very often used to detect catecholamine and indolamine neurotransmitters separated by conventional reverse-phase high performance liquid chromatography (HPLC). The present paper presents the development of a chromatographic method to detect monoamines present in low-volume brain dialysis samples using a capillary column filled with sub-2μm particles. Several parameters (repeatability, linearity, accuracy, limit of detection) for this new ultrahigh performance liquid chromatography (UHPLC) method with electrochemical detection were examined after optimization of the analytical conditions. Noradrenaline, adrenaline, serotonin, dopamine and its metabolite 3-methoxytyramine were separated in 1μL of injected sample volume; they were detected above concentrations of 0.5-1nmol/L, with 2.1-9.5% accuracy and intra-assay repeatability equal to or less than 6%. The final method was applied to very low volume dialysates from rat brain containing monoamine traces. The study demonstrates that capillary UHPLC with electrochemical detection is suitable for monitoring dialysate monoamines collected at high sampling rate. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Restricted-access media development for direct analysis of drugs in biofluids using capillary liquid chromatography.

    Science.gov (United States)

    Jarmalaviciene, Reda; Kornysova, Olga; Bendokas, Vidmantas; Westerlund, Douglas; Buszewski, Boguslaw; Maruska, Audrius

    2008-07-01

    In analytical sciences the design of novel materials and stationary phases for the sample preparation and separation of analytes from biological fluids is needed. In this work we present different strategies for modification of stationary phases to produce tailored solutions for the analytical problem. In this context a novel shielded polymeric reversed-phase monolithic material was prepared in the presence of different numbers of reactive groups and concentrations of the coating polymer. Chromatographic experiments were performed using benzoic acid propyl ester in order to characterize the hydrophobicity and efficiency of the different restricted-access continuous beds prepared. Inverse size-exclusion chromatography was used for investigation of the pore structure properties of the beds. Capillary columns were applied for nanochromatography of biological fluids containing a mixture of nitrazepamum and medazepamum.

  17. Using contemporary liquid chromatography theory and technology to improve capillary gradient ion-exchange separations.

    Science.gov (United States)

    Wouters, Bert; Broeckhoven, Ken; Wouters, Sam; Bruggink, Cees; Agroskin, Yury; Pohl, Christopher A; Eeltink, Sebastiaan

    2014-11-28

    The gradient-performance limits of capillary ion chromatography have been assessed at maximum system pressure (34.5 MPa) using capillary columns packed with 4.1 μm macroporous anion-exchange particles coated with 65 nm positively-charged nanobeads. In analogy to the van-Deemter curve, the gradient performance was assessed applying different flow rates, while decreasing the gradient time inversely proportional to the increase in flow rate in order to maintain the same retention properties. The gradient kinetic-performance limits were determined at maximum system pressure, applying tG/t0=5, 10, and 20. In addition, the effect of retention on peak width was assessed in gradient mode for mono-, di-, and trivalent inorganic anions. The peak width of late-eluting ions can be significantly reduced by using concave gradient, resulting in better detection sensitivity. A signal enhancement factor of 8 was measured for a late-eluting ion when applying a concave instead of a linear gradient. For the analysis of a complex anion mixture, a coupled column with a total length of 1.05 m was operated at the kinetic-performance limit applying a linear 250 min gradient (tG/t0=10). The peak capacity varied between 200 and 380 depending on analyte retention, and hence on charge and size of the ion. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography.

    Science.gov (United States)

    Tran, MinhPhuong; Turner, Erica B; Segro, Scott S; Fang, Li; Seyyal, Emre; Malik, Abdul

    2017-11-03

    A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0-pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. An Automated High Performance Capillary Liquid Chromatography Fourier Transform Ion Cyclotron Resonance Mass Spectrometer for High-Throughput Proteomics

    International Nuclear Information System (INIS)

    Belov, Mikhail E.; Anderson, Gordon A.; Wingerd, Mark A.; Udseth, Harold R.; Tang, Keqi; Prior, David C.; Swanson, Kenneth R.; Buschbach, Michael A.; Strittmatter, Eric F.; Moore, Ronald J.; Smith, Richard D.

    2004-01-01

    We report on a fully automated 9.4 tesla Fourier transform ion resonance cyclotron (FTICR) mass spectrometer coupled to reverse-phase chromatography for high-throughput proteomic studies. Modifications made to the front-end of a commercial FTICR instrument--a dual-ESI-emitter ion source; dual-channel electrodynamic ion funnel; and collisional-cooling, selection and accumulation quadrupoles--significantly improved the sensitivity, dynamic range and mass measurement accuracy of the mass spectrometer. A high-pressure capillary liquid chromatography (LC) system was incorporated with an autosampler that enabled 24 h/day operation. A novel method for accumulating ions in the ICR cell was also developed. Unattended operation of the instrument revealed the exceptional reproducibility (1-5% deviation in elution times for peptides from a bacterial proteome), repeatability (10-20% deviation in detected abundances for peptides from the same aliquot analyzed a few weeks apart) and robustness (high-throughput operation for 5 months without downtime) of the LC/FTICR system. When combined with modulated-ion-energy gated trapping, the internal calibration of FTICR mass spectra decreased dispersion of mass measurement errors for peptide identifications in conjunction with high resolution capillary LC separations to < 5 ppm over a dynamic range for each spectrum of 10 3

  20. Capillary gas-solid chromatography

    International Nuclear Information System (INIS)

    Berezkin, V.G.

    1996-01-01

    Modern state of gas adsorption chromatography in open capillary columns has been analyzed. The history of the method development and its role in gas chromatography, ways to construct open adsorptional capillary columns, foundations of the theory of retention and washing of chromatographic regions in gas adsorption capillary columns have been considered. The fields is extensively and for analyzing volatile compounds of different isotopic composition, inorganic and organic gases, volatile organic polar compounds, aqueous solutions of organic compounds. Separation of nuclear-spin isomers and isotopes of hydrogen is the first illustrative example of practical application of the adsorption capillary chromatography. It is shown that duration of protium and deuterium nuclear isomers may be reduced if the column temperature is brought to 47 K

  1. Green and simple analytical method to determine benzimidazoles in milk samples by using salting-out assisted liquid-liquid extraction and capillary liquid chromatography.

    Science.gov (United States)

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

    2018-08-01

    A green and simple multiresidue method using capillary liquid chromatography (CLC) with UV-diode array detection (DAD) has been developed for the determination of sixteen benzimidazoles (BZs) and its metabolites in milk samples. The separation was achieved in  0.9985 for all BZs) with limits of detection (LOD) between 1.0 and 2.8 μg kg -1 . Relative standard deviations of repeatability and intermediate precision were below 1.6 and 14.2%, respectively. Satisfactory recoveries between 79.1 and 99.6% were also obtained for three types of milk samples (cow, sheep and goat). The advantages of a miniaturized technique such as CLC in terms of better efficiencies and reduced solvent consumption, combined with the simplicity of the SALLE procedure, make this method a useful alternative for the monitoring of these residues at trace level. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Silica-based monolithic capillary columns modified by liposomes for characterization of analyte–liposome interactions by capillary liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Planeta, Josef; Wiedmer, S. K.

    2013-01-01

    Roč. 1317, SI (2013), s. 159-166 ISSN 0021-9673 R&D Projects: GA MV VG20112015021; GA ČR(CZ) GAP206/11/0138 Institutional support: RVO:68081715 Keywords : monolithic silica capillary column * immobilized liposomes * biomimicking stationary phase Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.258, year: 2013

  3. Reversed-phase liquid chromatography coupled on-line with capillary gas chromatography use of an anion-exchange membrane to remove an ion-pair reagent from the eluent.

    NARCIS (Netherlands)

    Brinkman, U.A.T.; Goosens, E.C.; de Jong, D.; de Jong, G.J.; Beerthuizen, I.M.

    1995-01-01

    In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant

  4. High-Throughput Proteomics Using High Efficiency Multiple-Capillary Liquid Chromatography With On-Line High-Performance ESI FTICR Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yufeng (BATTELLE (PACIFIC NW LAB)); Tolic, Nikola (BATTELLE (PACIFIC NW LAB)); Zhao, Rui (ASSOC WESTERN UNIVERSITY); Pasa Tolic, Ljiljana (BATTELLE (PACIFIC NW LAB)); Li, Lingjun (Illinois Univ Of-Urbana/Champa); Berger, Scott J.(ASSOC WESTERN UNIVERSITY); Harkewicz, Richard (BATTELLE (PACIFIC NW LAB)); Anderson, Gordon A.(BATTELLE (PACIFIC NW LAB)); Belov, Mikhail E.(BATTELLE (PACIFIC NW LAB)); Smith, Richard D.(BATTELLE (PACIFIC NW LAB))

    2000-12-01

    We report on the design and application of a high-efficiency multiple-capillary liquid chromatography (LC) system for high-throughput proteome analysis. The multiple-capillary LC system was operated at the pressure of 10,000 psi using commercial LC pumps to deliver the mobile phase and newly developed passive feedback valves to switch the mobile phase flow and introduce samples. The multiple-capillary LC system was composed of several serially connected dual-capillary column devices. The dual-capillary column approach was designed to eliminate the time delay for regeneration (or equilibrium) of the capillary column after its use under the mobile phase gradient condition (i.e. one capillary column was used in separation and the other was washed using mobile phase A). The serially connected dual-capillary columns and ESI sources were operated independently, and could be used for either''backup'' operation or with other mass spectrometer(s). This high-efficiency multiple-capillary LC system uses switching valves for all operations and is highly amenable to automation. The separations efficiency of dual-capillary column device, optimal capillary dimensions (column length and packed particle size), suitable mobile phases for electrospray, and the capillary re-generation were investigated. A high magnetic field (11.5 tesla) Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was coupled on-line with this high-efficiency multiple-capillary LC system through an electrospray ionization source. The capillary LC provided a peak capacity of {approx}600, and the 2-D capillary LC-FTICR provided a combined resolving power of > 6 x 10 7 polypeptide isotopic distributions. For yeast cellular tryptic digests, > 100,000 polypeptides were typically detected, and {approx}1,000 proteins can be characterized in a single run.

  5. Indirect Determination of Vapor Pressures by Capillary Gas-Liquid Chromatography: Analysis of the Reference Vapor-Pressure Data and Their Treatment

    Czech Academy of Sciences Publication Activity Database

    Růžička, K.; Koutek, Bohumír; Fulem, M.; Hoskovec, Michal

    2012-01-01

    Roč. 57, č. 5 (2012), s. 1349-1368 ISSN 0021-9568 R&D Projects: GA ČR GA203/09/1327 Institutional research plan: CEZ:AV0Z40550506 Keywords : vapor pressures * capillary gas–liquid chromatography * reference data * relative retention time Subject RIV: CC - Organic Chemistry Impact factor: 2.004, year: 2012

  6. Periodic imidazolium-bridged hybrid monolith for high-efficiency capillary liquid chromatography with enhanced selectivity.

    Science.gov (United States)

    Qiao, Xiaoqiang; Zhang, Niu; Han, Manman; Li, Xueyun; Qin, Xinying; Shen, Shigang

    2017-03-01

    A novel periodic imidazolium-bridged hybrid monolithic column was developed. With diene imidazolium ionic liquid 1-allyl-3-vinylimidazolium bromide as both cross-linker and organic functionalized reagent, a new periodic imidazolium-bridged hybrid monolithic column was facilely prepared in capillary with homogeneously distributed cationic imidazolium by a one-step free-radical polymerization with polyhedral oligomeric silsesquioxane methacryl substituted. The successful preparation of the new column was verified by Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, and surface area analysis. Most interestingly, the bonded amount of 1-allyl-3-vinylimidazolium bromide of the new column is three times higher than that of the conventional imidazolium-embedded hybrid monolithic column and the specific surface area of the column reached 478 m 2 /g. The new column exhibited high stability, excellent separation efficiency, and enhanced separation selectivity. The column efficiency reached 151 000 plates/m for alkylbenzenes. Furthermore, the new column was successfully used for separation of highly polar nucleosides and nucleic acid bases with pure water as mobile phase and even bovine serum albumin tryptic digest. All these results demonstrate the periodic imidazolium-bridged hybrid monolithic column is a good separation media and can be used for chromatographic separation of small molecules and complex biological samples with high efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Characterisation of capillary ionic liquid columns for gas chromatography-mass spectrometry analysis of fatty acid methyl esters.

    Science.gov (United States)

    Zeng, Annie Xu; Chin, Sung-Tong; Nolvachai, Yada; Kulsing, Chadin; Sidisky, Leonard M; Marriott, Philip J

    2013-11-25

    Due to their distinct chemical properties, the application of ionic liquid (IL) compounds as gas chromatography (GC) stationary phases offer unique GC separation especially in the analysis of geometric and positional fatty acid methyl ester (FAME) isomers. Elution behaviour of FAME on several commercialised IL capillary columns including phosphonium based SLB-IL59, SLB-IL60, SLB-IL61 and SLB-IL76 and imidazolium based SLB-IL82, SLB-IL100, and SLB-IL111 as well as a general purpose column SLB-5ms, were evaluated in gas chromatography-mass spectrometry (GC-MS) analysis. The phases were further characterised by using a linear solvation energy relationship (LSER) approach according to the equivalent chain length (ECL) index of FAME. Among all tested IL columns, elution temperatures of saturated FAME increased as their McReynolds' polarity value decreased, except for IL60. ECL values increased markedly as the stationary phase polarity increased, particularly for the polyunsaturated FAME. The LSER study indicated a lowest l/e value at 0.864 for IL111, displaying phase selectivity towards unsaturated FAME, with higher peak capacity within a carbon number isomer group. s and e descriptors calculated from LSER were validated by excellent correlation with dipole moments and lowest unoccupied molecular orbital (LUMO) energies, with R(2) values of 0.99 and 0.92 respectively, calculated using GAUSSIAN. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Urea functionalized surface-bonded sol-gel coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

    Science.gov (United States)

    Jillani, Shehzada Muhammad Sajid; Alhooshani, Khalid

    2018-03-30

    Sol-gel urea functionalized-[bis(hydroxyethyl)amine] terminated polydimethylsiloxane coating was developed for capillary microextraction-high performance liquid chromatographic analysis from aqueous samples. A fused silica capillary is coated from the inside with surface bonded coating material and is created through in-situ sol-gel reaction. The urea-functionalized coating was immobilized to the inner surface of the capillary by the condensation reaction of silanol groups of capillary and sol-solution. The characterization of the coating material was successfully done by using X-ray photoelectron spectroscopy, thermogravimetric analysis, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. To make a setup of online capillary microextraction-high performance liquid chromatography, the urea functionalized capillary was installed in the HPLC manual injection port. The analytes of interest were pre-concentrated in the coated sampling loop, desorbed by the mobile phase, chromatographically separated on C-18 column, and analyzed by UV detector. Sol-gel coated capillaries were used for online extraction and high-performance liquid chromatographic analysis of phenols, ketones, aldehydes, and polyaromatic hydrocarbons. This newly developed coating showed excellent extraction for a variety of analytes ranging from highly polar to non-polar in nature. The analysis using sol-gel coating showed excellent overall sensitivity in terms of lower detection limits (S/N = 3) for the analytes (0.10 ng mL -1 -14.29 ng mL -1 ) with acceptable reproducibility that is less than 12.0%RSD (n = 3). Moreover, the capillary to capillary reproducibility of the analysis was also tested by changing the capillary of the same size. This provided excellent%RSD of less than 10.0% (n = 3). Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Simultaneous determination of caffeine, paracetamol, and ibuprofen in pharmaceutical formulations by high-performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection.

    Science.gov (United States)

    Cunha, Rafael R; Chaves, Sandro C; Ribeiro, Michelle M A C; Torres, Lívia M F C; Muñoz, Rodrigo A A; Dos Santos, Wallans T P; Richter, Eduardo M

    2015-05-01

    Paracetamol, caffeine and ibuprofen are found in over-the-counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high-performance liquid chromatography with diode-array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high-performance liquid chromatography with diode-array detection was achieved on a C18 column (250×4.6 mm(2), 5 μm) with a gradient mobile phase comprising 20-100% acetonitrile in 40 mmol L(-1) phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused-silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L(-1) 3,4-dimethoxycinnamate and 10 mmol L(-1) β-alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L(-1) by liquid chromatography and 39, 32, and 49 μmol L(-1) by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92-107% for both proposed methods. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. On-line combination of liquid chromatography and capillary gas chromatography : preconcentration and analysis of organic compounds in aqueous samples

    NARCIS (Netherlands)

    Noij, T.H.M.; Weiss, E.; Herps, T.; Cruchten, van H.; Rijks, J.A.

    1988-01-01

    This paper describes the design of a new, versatile, and low-cost on-line LC-GC interface that allows the fast and reliable introduction of large sample volumes onto a capillary GC column. The sample introduction procedure consists successively of: evaporation of the entire sample (LC fraction),

  11. A microanalytical method for ammonium and short-chain primary aliphatic amines using precolumn derivatization and capillary liquid chromatography.

    Science.gov (United States)

    Moliner-Martínez, Y; Herráez-Hernández, R; Campíns-Falcó, P

    2007-09-14

    A new microscale method is presented for the determination of ammonium and primary short-chain aliphatic amines (methylamine, ethylamine, propylamine, n-butylamine and n-pentylamine) in water. The assay uses precolumn derivatization with the reagent o-phthaldialdehyde (OPA) in combination with the thiol N-acetyl-L-cysteine (NAC), and capillary liquid chromatography with UV detection at 330 nm. The described method is very simple and rapid as no preconcentration of the analytes is necessary, and the volume of sample required is only 0.1 mL. Under the proposed conditions good linearity has been obtained up to a concentration of the analytes of 10.0 mgL(-1), the limits of detection being of 8-50 microgL(-1). No matrix effect was found, and recoveries between 97 and 110% were obtained. The precision of the method was good, and the achieved variation coefficients were below 12%. The reliability of the proposed approach has been tested by analyzing a microsample of fogwater collected from leaf surfaces.

  12. Eco-friendly ionic liquid assisted capillary electrophoresis and α-acid glycoprotein-assisted liquid chromatography for simultaneous determination of anticancer drugs in human fluids.

    Science.gov (United States)

    Abd El-Hady, Deia; Albishri, Hassan M; Rengarajan, Rajesh

    2015-06-01

    In the current work, two eco-friendly analytical methods based on capillary electrophoresis (CE) and reversed phase liquid chromatography (RPLC) were developed for simultaneous determination of the most commonly used anticancer drugs for Hodgkin's disease: methotrexate (MTX), vinblastine, chlorambucil and dacarbazine. A background electrolyte (BGE) of 12.5 mmol/L phosphate buffer at pH 7.4 and 0.1 µmol/L 1-butyl-3-methyl imidazolium bromide (BMImBr) ionic liquid (IL) was used for CE measurements at 250 nm detection wavelength, 20 kV applied voltage and 25 °C. The rinsing protocol was significantly improved to reduce the adsorption of IL on the interior surface of capillary. Moreover, RPLC method was developed on α-1-acid glycoprotein (AGP) column. Mobile phase was 10 mmol/L phosphate buffer at pH 6.0 (100% v/v) and flow rate at 0.1 mL/min. As AGP is a chiral column, it was successfully separated l-MTX from its enantiomer impurity d-MTX. Good linearity of quantitative analysis was achieved with coefficients of determinations (r(2) ) >0.995. The stability of drugs measurements was investigated with adequate recoveries up to 24 h storage time under ambient temperature. The limits of detection were <50 and 90 ng/mL by CE and RPLC, respectively. The using of short-chain IL as an additive in BGE achieved 600-fold sensitivity enhancement compared with conventional Capillary Zone Electrophoresis (CZE). Therefore, for the first time, the proposed methods were successfully applied to determine simultaneously the analytes in human plasma and urine samples at clinically relevant concentrations with fast and simple pretreatments. Developed IL-assisted CE and RPLC methods were also applied to measure MTX levels in patients' samples over time. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Fast preparation of hybrid monolithic columns via photo-initiated thiol-yne polymerization for capillary liquid chromatography.

    Science.gov (United States)

    Ma, Shujuan; Zhang, Haiyang; Li, Ya; Li, Yanan; Zhang, Na; Ou, Junjie; Ye, Mingliang; Wei, Yinmao

    2018-02-23

    Although several approaches have been developed to fabricate hybrid monoliths, it would still take a few hours to finish the formation of monoliths. Herein, photo-initiated thiol-yne polymerization was first adopted to in situ fabricate hybrid monoliths within the confines of UV-transparent fused-silica capillary. A silicon-containing diyne (1,3-diethynyltetramethyl-disiloxane, DYDS) was copolymerized with three multithiols, 1,6-hexanedithiol, trimethylolpropane tris(3-mercaptopropionate) and pentaerythriol tetrakis(3-mercaptopropionate), by using a binary porogenic system of diethylene glycol diethyl ether (DEGDE)/poly(ethylene glycol) (PEG200) within 10 min. Several characterizations of three hybrid monoliths (assigned as I, II and III, respectively) were performed. The results showed that these hybrid monoliths possessed bicontinuous porous structure, which was remarkably different from that via typical free-radical polymerization. The highest column efficiency of 76,000 plates per meter for butylbenzene was obtained on the column I in reversed-phase liquid chromatography (RPLC). It was observed that the efficiencies for strong-retained butylbenzene were almost close to those of weak-retained benzene, indicating a retention-independent efficient performance of small molecules on hybrid column I. The surface area of this hybrid monolith was very small in the dry state (less than 10.0 m 2 /g), and the chromatographic behavior of hybrid monolithic columns would be possibly explained by radical-mediated step-growth process of thiol-yne polymerization. Finally, the column I was applied for separation of BSA tryptic digest by cLC-MS/MS, indicating satisfactory separation ability for complicated samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Facile preparation of organic-silica hybrid monolith for capillary hydrophilic liquid chromatography based on "thiol-ene" click chemistry.

    Science.gov (United States)

    Chen, Ming-Luan; Zhang, Jun; Zhang, Zheng; Yuan, Bi-Feng; Yu, Qiong-Wei; Feng, Yu-Qi

    2013-04-05

    In this work, a one-step approach to facile preparation of organic-inorganic hybrid monoliths was successfully developed. After vinyl-end organic monomers and azobisisobutyronitrile (AIBN) were mixed with hydrolyzed tetramethoxysilane (TMOS) and 3-mercaptopropyltrimethoxysilane (MPTMS), the homogeneous mixture was introduced into a fused-silica capillary for simultaneous polycondensation and "thiol-ene" click reaction to form the organic-silica hybrid monoliths. By employing this strategy, two types of organic-silica hybrid monoliths with positively charged quaternary ammonium and amide groups were prepared, respectively. The functional groups were successfully introduced onto the monoliths during the sol-gel process with "thiol-ene" click reaction, which was demonstrated by ζ-potential assessment, energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FT-IR) spectroscopy. The porous structure of the prepared monolithic columns was examined by scanning electron microscopy (SEM), nitrogen adsorption-desorption measurement, and mercury intrusion porosimetry. These results indicate the prepared organic-silica hybrid monoliths possess homogeneous column bed, large specific surface area, good mechanical stability, and excellent permeability. The prepared monolithic columns were then applied for anion-exchange/hydrophilic interaction liquid chromatography. Different types of analytes, including benzoic acids, inorganic ions, nucleosides, and nucleotides, were well separated with high column efficiency around 80,000-130,000 plates/m. Taken together, we present a facile and universal strategy to prepare organic-silica hybrid monoliths with a variety of organic monomers using one-step approach. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Determination of dasatinib in the tablet dosage form by ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis.

    Science.gov (United States)

    Gonzalez, Aroa Garcia; Taraba, Lukáš; Hraníček, Jakub; Kozlík, Petr; Coufal, Pavel

    2017-01-01

    Dasatinib is a novel oral prescription drug proposed for treating adult patients with chronic myeloid leukemia. Three analytical methods, namely ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis, were developed, validated, and compared for determination of the drug in the tablet dosage form. The total analysis time of optimized ultra high performance liquid chromatography and capillary zone electrophoresis methods was 2.0 and 2.2 min, respectively. Direct ultraviolet detection with detection wavelength of 322 nm was employed in both cases. The optimized sequential injection analysis method was based on spectrophotometric detection of dasatinib after a simple colorimetric reaction with folin ciocalteau reagent forming a blue-colored complex with an absorbance maximum at 745 nm. The total analysis time was 2.5 min. The ultra high performance liquid chromatography method provided the lowest detection and quantitation limits and the most precise and accurate results. All three newly developed methods were demonstrated to be specific, linear, sensitive, precise, and accurate, providing results satisfactorily meeting the requirements of the pharmaceutical industry, and can be employed for the routine determination of the active pharmaceutical ingredient in the tablet dosage form. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. ICSH recommendations for assessing automated high-performance liquid chromatography and capillary electrophoresis equipment for the quantitation of HbA2.

    Science.gov (United States)

    Stephens, A D; Colah, R; Fucharoen, S; Hoyer, J; Keren, D; McFarlane, A; Perrett, D; Wild, B J

    2015-10-01

    Automated high performance liquid chromatography and Capillary electrophoresis are used to quantitate the proportion of Hemoglobin A2 (HbA2 ) in blood samples order to enable screening and diagnosis of carriers of β-thalassemia. Since there is only a very small difference in HbA2 levels between people who are carriers and people who are not carriers such analyses need to be both precise and accurate. This paper examines the different parameters of such equipment and discusses how they should be assessed. © 2015 John Wiley & Sons Ltd.

  17. Plasma L-ergothioneine measurement by high-performance liquid chromatography and capillary electrophoresis after a pre-column derivatization with 5-iodoacetamidofluorescein (5-IAF) and fluorescence detection.

    Science.gov (United States)

    Sotgia, Salvatore; Pisanu, Elisabetta; Pintus, Gianfranco; Erre, Gian Luca; Pinna, Gerard Aime; Deiana, Luca; Carru, Ciriaco; Zinellu, Angelo

    2013-01-01

    Two sensitive and reproducible capillary electrophoresis and high-performance liquid chromatography-fluorescence procedures were established for quantitative determination of L-egothioneine in plasma. After derivatization of L-ergothioneine with 5-iodoacetamidofluorescein, the separation was carried out by HPLC on an ODS-2 C-18 sperisorb column by using a linear gradient elution and by HPCE on an uncoated fused silica capillary, 50 µm id, and 60 cm length. The methods were validated and found to be linear in the range of 0.3 to 10 µmol/l. The limit of quantification was 0.27 µmol/l for HPCE and 0.15 µmol/l for HPLC. The variations for intra- and inter-assay precision were around 6 RSD%, and the mean recovery accuracy close to 100% (96.11%).

  18. Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography.

    Science.gov (United States)

    Hau Fung Cheung, Rodney; Morrison, Paul D; Small, Darryl M; Marriott, Philip J

    2008-12-05

    A single enzyme treatment with alpha-amylase, prior to the quantification of added folic acid (FA) in fortified instant fried Asian noodles with analysis performed by capillary zone electrophoresis (CZE) and reversed-phase high performance liquid chromatography (RP-HPLC) with UV detection, is described. The method was validated and optimized for capillary electrophoresis (CE) with separation achieved using a 8 mM phosphate-12 mM borate run buffer with 5% MeOH at pH 9.5. FA was well separated from matrix components with nicotinic acid (NA) employed as an internal standard. In a comparative study, separation of FA was performed using HPLC with a mobile phase consisting of 27% MeOH (v/v) in aqueous potassium phosphate buffer (3.5 mM KH(2)PO(4) and 3.2 mM K(2)HPO(4)), pH 8.5, and containing 5 mM tetrabutylammonium dihydrogen phosphate as an ion-pairing agent. For both methods, excellent results were obtained for various analytical parameters including linearity, accuracy and precision. The limit of detection was calculated to be 2.2 mg/L for CE without sample stacking and 0.10 mg/L with high performance liquid chromatography (HPLC). Sample extraction involved homogenization and enzymatic extraction with alpha-amylase. Results indicated that FA was stable during four main stages of instant fried noodle manufacturing (dough crumbs, cut sheets, steaming and frying).

  19. Research Article. The Influence of Some Parameters on Chiral Separation of Ibuprofen by High-Performance Liquid Chromatography and Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Balint Alina

    2017-03-01

    Full Text Available Objective: The aim of the study was to compare the influence of mobile phase composition and temperature on chiral separation of racemic ibuprofen by capillary electrophoresis and high performance liquid chromatography with UV detection. Materials and methods: Racemic ibuprofen was analysed on a chiral OVM column with an HPLC system 1100 Agilent Technologies, under isocratic elution, by using potassium dihydrogen phosphate 20 mM and ethanol in mobile phase. The flow rate was set at 1 mL/min, UV detector at 220 nm and different column temperatures were tested. For electrophoresis separation an Agilent CE G1600AX Capillary Electrophoresis System system, with UV detection, was used. The electrophoresis analysis was performed at different pH values and temperatures, with phosphate buffer 25 mM and methyl-β-cyclodextrin as chiral selector. Results: The chromatograhic analysis reveals a high influence of mobile phase pH on ibuprofen enantiomers separation. An elution with a mixture of potassium dihydrogen phosphate 20 mM pH=3 and ethanol, at 25°C, allowed enantiomers separation with good resolution in less than 8 min. Conclusions: The proposed HPLC method proved suitable for the separation of ibuprofen enantiomers with a good resolution, but the capillary electrophoresis tested parameters did not allow chiral discrimination.

  20. Rapid analysis of ethanol and water in commercial products using ionic liquid capillary gas chromatography with thermal conductivity detection and/or barrier discharge ionization detection.

    Science.gov (United States)

    Weatherly, Choyce A; Woods, Ross M; Armstrong, Daniel W

    2014-02-26

    Analysis of ethanol and water in consumer products is important in a variety of processes and often is mandated by regulating agencies. A method for the simultaneous quantitation of ethanol and water that is simple, accurate, precise, rapid, and cost-effective is demonstrated. This approach requires no internal standard for the quantitation of both ethanol and water at any/all levels in commercial products. Ionic liquid based gas chromatography (GC) capillary columns are used to obtain a fast analysis with high selectivity and resolution of water and ethanol. Typical run times are just over 3 min. Examination of the response range of water and ethanol with GC, thermal conductivity detection (TCD), and barrier ionization detection (BID) is performed. Quantitation of both ethanol and water in consumer products is accomplished with both TCD and BID GC detectors using a nonlinear calibration. Validation of method accuracy is accomplished by using standard reference materials.

  1. Capillary column switching restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry system for simultaneous and direct analysis of drugs in biofluids.

    Science.gov (United States)

    Santos-Neto, Alvaro J; Markides, Karin E; Sjöberg, Per J R; Bergquist, Jonas; Lancas, Fernando M

    2007-08-15

    Capillary online restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry (RAM-LC-ESI-MS/MS) for direct analysis of drugs and metabolites spiked in biological fluids was developed. Using a column switching setup it was possible to perform effective sample preparation and analysis of raw biological fluids (plasma and urine) without matrix effects in the electrospray mass spectrometric detection step. The peak focusing efficiency of the extraction column was more effective in backflush compared to foreflush mode. The system was able to concentrate diminished samples of polar drugs and their metabolites reaching quantifiable results as low as 1 ng/mL utilizing a sample volume of only 333 nL of biofluids. New column hardware was developed to circumvent clogging problems experienced with plasma injections. The glass fiber filter frit, which is commonly used, was replaced with a short piece of 20 microm i.d. fused silica capillary. The extraction columns were able to handle up to 60 injections and showed a high loading capacity, making the saturation of the MS detector the limiting factor on the linear dynamic range. The simultaneous separation and detection of 10 drugs and metabolites was obtained in 8 min of analysis, including the online sample preparation and enrichment step.

  2. Evaluation of Carbon Nanotubes Functionalized Polydimethylsiloxane Based Coatings for In-Tube Solid Phase Microextraction Coupled to Capillary Liquid Chromatography

    OpenAIRE

    Neus Jornet-Martínez; Pascual Serra-Mora; Yolanda Moliner-Martínez; Rosa Herráez-Hernández; Pilar Campíns-Falcó

    2015-01-01

    In the present work, the performance of carbon nanotubes (c-CNTs) functionalized polydimethylsiloxane (PDMS) based coatings as extractive phases for in-tube solid phase microextraction (IT-SPME) coupled to Capillary LC (CapLC) has been evaluated. Carboxylic-single walled carbon nanotubes (c-SWNTs) and carboxylic-multi walled carbon nanotubes (c-MWNTs) have been immobilized on the activated surface of PDMS capillary columns. The effect of different percentages of diphenyl groups in the PDMS ex...

  3. Evaluation of Carbon Nanotubes Functionalized Polydimethylsiloxane Based Coatings for In-Tube Solid Phase Microextraction Coupled to Capillary Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Neus Jornet-Martínez

    2015-08-01

    Full Text Available In the present work, the performance of carbon nanotubes (c-CNTs functionalized polydimethylsiloxane (PDMS based coatings as extractive phases for in-tube solid phase microextraction (IT-SPME coupled to Capillary LC (CapLC has been evaluated. Carboxylic-single walled carbon nanotubes (c-SWNTs and carboxylic-multi walled carbon nanotubes (c-MWNTs have been immobilized on the activated surface of PDMS capillary columns. The effect of different percentages of diphenyl groups in the PDMS extractive phase has also been evaluated. The extraction capability of the capillary columns has been tested for different organic pollutants, nitrogen heterocyclic compounds and polycyclic aromatic compounds (PAHs. The results indicated that the use of the c-CNTs-PDMS capillary columns improve pyriproxyfen and mainly PAH extraction. Triazines were better extracted by unmodified TRB-35 and modified c-CNTs-PDMSTRB-5. The results showed that the extraction capability of the c-CNT capillary columns depends not only on the polarity of the analytes (as it occurs with PDMS columns but also on the interactions that the analytes can establish with the immobilized c-CNTs on the PDMS columns. The extraction efficiency has been evaluated on the basis of the preconcentration rate that can be achieved, and, in this sense, the best c-CNTs-PDMS capillary column for each group of compounds can be proposed.

  4. Bioanalytical Applications of Fluorescence Line-Narrowing and Non-Line-Narrowing Spectroscopy Interfaced with Capillary Electrophoresis and High-Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Kenneth Paul [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) are widely used analytical separation techniques with many applications in chemical, biochemical, and biomedical sciences. Conventional analyte identification in these techniques is based on retention/migration times of standards; requiring a high degree of reproducibility, availability of reliable standards, and absence of coelution. From this, several new information-rich detection methods (also known as hyphenated techniques) are being explored that would be capable of providing unambiguous on-line identification of separating analytes in CE and HPLC. As further discussed, a number of such on-line detection methods have shown considerable success, including Raman, nuclear magnetic resonance (NMR), mass spectrometry (MS), and fluorescence line-narrowing spectroscopy (FLNS). In this thesis, the feasibility and potential of combining the highly sensitive and selective laser-based detection method of FLNS with analytical separation techniques are discussed and presented. A summary of previously demonstrated FLNS detection interfaced with chromatography and electrophoresis is given, and recent results from on-line FLNS detection in CE (CE-FLNS), and the new combination of HPLC-FLNS, are shown.

  5. Analytical biotechnology: Capillary electrophoresis and chromatography

    International Nuclear Information System (INIS)

    Horvath, C.; Nikelly, J.G.

    1990-01-01

    The papers describe the separation, characterization, and equipment required for the electrophoresis or chromatography of cyclic nucleotides, pharmaceuticals, therapeutic proteins, recombinant DNA products, pheromones, peptides, and other biological materials. One paper, On-column radioisotope detection for capillary electrophoresis, has been indexed separately for inclusion on the data base

  6. Liquid Chromatography in 1982.

    Science.gov (United States)

    Freeman, David H.

    1982-01-01

    Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

  7. Column Liquid Chromatography.

    Science.gov (United States)

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  8. A chiral capillary electrophoresis method for ropivacaine hydrochloride in pharmaceutical formulations : Validation and comparison with chiral liquid chromatography

    NARCIS (Netherlands)

    Sänger-Van De Griend, C. E.; Wahlström, H.; Gröningsson, K.; Widahl-Näsman, Monica E.

    A capillary electrophoresis method for the determination of the enantiomeric purity of the local anaesthetic ropivacaine hydrochloride in injection solutions has been validated. The method showed the required limit of quantitation of 0.1% enantiomeric impurity. Good performances were shown for

  9. Determination of simple carbohydrates in citrus juices by using capillary electrophoresis with indirect detection and high performance liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Cabálková, J.; Chmelík, Josef

    96(S), - (2002), s. S150-S152 ISSN 0009-2770. [Meeting of Chemistry & Life /2./. Brno, 10.09.2002-11.09.2002] Institutional research plan: CEZ:AV0Z4031919 Keywords : carbohydrates * citrus juice * capillary electrophoresis Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.336, year: 2002

  10. Phosphatidylcholine covalently linked to a methacrylate-based monolith as a biomimetic stationary phase for capillary liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Carrasco-Correa, E. J.; Planeta, Josef; Lämmerhofer, M.; Wiedmer, S. K.

    2015-01-01

    Roč. 1402, JUL (2015), s. 27-35 ISSN 0021-9673 R&D Projects: GA MV VG20112015021 Institutional support: RVO:68081715 Keywords : Capillary LC * analyte–membrane interaction * monolithic column * phospholipids Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.926, year: 2015 http://hdl.handle.net/11104/0247268

  11. Detection of compound heterozygous of hb constant spring and hb q-Thailand by capillary electrophoresis and high performance liquid chromatography.

    Science.gov (United States)

    Pornprasert, Sakorn; Punyamung, Manoo

    2015-06-01

    A capillary electrophoresis (CE) has proven to be superior to a high performance liquid chromatography (HPLC) in the detection of hemoglobin Constant Spring (Hb CS). Thus the aim of this study was to analyze the efficacy of CE and HPLC for the detection of Hb CS in samples with compound heterozygous of Hb CS and Hb Q-Thailand. Hemoglobin analysis was performed in blood samples of 2 patients with compound heterozygous of Hb CS and Hb Q-Thailand by using HPLC and CE. The HPLC chromatogram and CE electrophoregram of the two techniques were compared. Hb CS was not found on HPLC chromatogram while Hb QA2 (α2 (QT)δ2), a derivative of Hb Q-Thailand, was presented at the retention time of 4.70-4.80 min and it was close to the retention time of Hb CS. On CE electrophoregram, Hb CS was presented at zone 2 (Z2) and it was distinctly separated from Hb QA2 which was presented at Z1. Therefore, CE was more efficient to the HPLC for diagnosis of compound heterozygous of Hb CS and Hb Q-Thailand.

  12. Trace determination of 10 beta-lactam antibiotics in environmental and food samples by capillary liquid chromatography.

    Science.gov (United States)

    Bailón-Pérez, M I; García-Campaña, A M; del Olmo-Iruela, M; Gámiz-Gracia, L; Cruces-Blanco, C

    2009-11-20

    A sensitive and reliable method using capillary HPLC with UV-diode array detection (DAD) has been developed and validated for the trace determination of residues of 10 beta-lactam antibiotics of human and veterinary use, in milk, chicken meat and environmental water samples. The analytes included ampicillin, amoxicillin, penicillin V, penicillin G, cloxacillin, oxacillin, dicloxacillin, nafcillin, piperacillin and clavulanic acid. Legal levels are regulated by the EU Council regulation 2377/90 in animal edible tissues for these compounds. For food analysis, a solid-phase extraction (SPE) procedure consisting in a tandem of Oasis HLB and Alumina N cartridges was applied for off-line preconcentration and cleanup. For water analysis, the first step was only necessary. The limits of detection for the studied compounds were between 0.04-0.06 microg l(-1) for water samples and 0.80-1.40 microg l(-1) (or microg kg(-1)) in the case of foods derived from animals. Average recoveries for fortified samples at different concentration levels ranged between 82.9% and 98.2%, with relative standard deviations (RSDs) lower than 9%. The method showed the advantages of capillary HPLC for the detection of these widely applied antibiotics in different samples at very low concentration levels.

  13. Enantiomeric separation of some demethylated analogues of clofibric acid by capillary zone electrophoresis and nano-liquid chromatography.

    Science.gov (United States)

    Fantacuzzi, Marialuigia; Bettoni, Giancarlo; D'Orazio, Giovanni; Fanali, Salvatore

    2006-03-01

    The enantiomeric separation of some demethylated analogues of clofibric acid, namely 2-(6-chloro-benzothiazol-2-ylsulfanyl)-, 2-(6-methoxy-benzothiazol-2-ylsulfanyl)-, 2-(quinolin-2-yloxy)-, 2-(6-chloro-quinolin-2-yloxy)-, 2-(7-chloro-quinolin-4-yloxy)-propionic acid (compounds A-E, respectively), has been studied by CZE and nano-LC using for the first technique two beta-CD derivatives and vancomycin added to the BGE and vancomycin-modified silica particles for the second one, with the aim to find the optimum experimental conditions for the baseline resolution. The type and the concentration of the chiral selector added to the BGE, the buffer pH, the type of organic modifier and its concentration, the capillary temperature and the applied voltage played a very important role in the enantioresolution of the analysed compounds. The use of 6-monodeoxy-6-monoamino-beta-CD allowed to achieve baseline resolution of four of five clofibric acid derivatives in less than 10 min while heptakis-(2,3,6-tri-O-methyl)-beta-CD partially resolved the same compounds in their enantiomers. Employing vancomycin as the chiral selector in CZE, the counter-current partial filling method was chosen achieving baseline resolution of four analytes. All the studied compounds were enantioresolved employing a capillary column packed with vancomycin stationary phase by nano-LC, and the resolution was strongly influenced by the concentration of the organic modifier and by the pH of the mobile phase. The best results were achieved at pH 4.5 in presence of 60% of methanol (MeOH). However, longer analysis times were observed in the experiments carried out by nano-LC.

  14. Preparation of polymer monolithic column functionalized by arsonic acid groups for mixed-mode capillary liquid chromatography.

    Science.gov (United States)

    Qin, Zhang-Na; Yu, Qiong-Wei; Wang, Ren-Qi; Feng, Yu-Qi

    2018-04-27

    A mixed-mode polymer monolithic column functionalized by arsonic acid groups was prepared by single-step in situ copolymerization of monomers p-methacryloylaminophenylarsonic acid (p-MAPHA) and pentaerythritol triacrylate (PETA). The prepared poly(p-MAPHA-co-PETA) monolithic column has a homogeneous monolithic structure with good permeability and mechanical stability. Zeta potential measurements reveal that the monolithic stationary phase holds a negative surface charge when the mobile phase resides in the pH range of 3.0-8.0. The retention mechanisms of prepared monolithic column are explored by the separation of selected polycyclic aromatic hydrocarbons (PAHs), nucleosides, and three basic compounds. The results indicate that the column functions in three different separation modes associated with reversed-phase chromatography based on hydrophobic interaction, hydrophilic interaction chromatography, and cation-exchange chromatography. The column efficiency of prepared monolithic column is estimated to be 70,000 and 76,000 theoretical plates/m for thiourea and naphthalene, respectively, at a linear flow velocity of 0.85 mm/s using acetonitrile/H 2 O (85/15, v/v) as the mobile phase. Furthermore, an analysis of the retention factors obtained for the PAHs indicates that the prepared monolithic column exhibits good reproducibility with relative standard deviations of 2.9%, 4.0%, and 4.7% based on run-to-run injections, column-to-column preparation, and batch-to-batch preparation, respectively. Finally, we investigate the separation performance of the proposed monolithic column for select phenols, sulfonamides, nucleobases and nucleosides. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Polar and nonpolar organic polymer-based monolithic columns for capillary electrochromatography and high-performance liquid chromatography.

    Science.gov (United States)

    Rathnasekara, Renuka; Khadka, Shantipriya; Jonnada, Murthy; El Rassi, Ziad

    2017-01-01

    This review article is a continuation of the previous reviews on the area of monolithic columns covering the progress made in the field over the last couple of years from the beginning of the second half of 2014 until the end of the first half of 2016. It summarizes and evaluates the evolvement of both polar and nonpolar organic monolithic columns and their use in hydrophilic interaction LC and CEC and reversed-phase chromatography and RP-CEC. The review article discusses the results reported in a total of 62 references. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Chiral separations of cathinone and amphetamine-derivatives: Comparative study between capillary electrochromatography, supercritical fluid chromatography and three liquid chromatographic modes.

    Science.gov (United States)

    Albals, Dima; Heyden, Yvan Vander; Schmid, Martin G; Chankvetadze, Bezhan; Mangelings, Debby

    2016-03-20

    The screening part of an earlier defined chiral separation strategy in capillary electrochromatography (CEC) was used for the separation of ten cathinone- and amphetamine derivatives. They were analyzed using 4 polysaccharide-based chiral stationary phases (CSPs), containing cellulose tris(3,5-dimethylphenylcarbamate) (ODRH), amylose tris(3,5-dimethylphenylcarbamate) (ADH), amylose tris(5-chloro-2-methylphenylcarbamate) (LA2), and cellulose tris(4-chloro-3-methylphenylcarbamate) (LC4) as chiral selectors. After applying the screening to each compound, ADH and LC4 showed the highest success rate. In a second part of the study, a comparison between CEC and other analytical techniques used for chiral separations i.e., supercritical fluid chromatography (SFC), polar organic solvent chromatography (POSC), reversed-phase (RPLC) and normal-phase liquid chromatography (NPLC), was made. For this purpose, earlier defined screening approaches for each technique were applied to separate the 10 test substances. This allowed an overall comparison of the success rates of the screening steps of the 5 techniques for these compounds. The results showed that CEC had a similar enantioselectivity rate as NPLC and RPLC, producing the highest number of separations (9 out of 10 racemates). SFC resolved 7 compounds, while POSC gave only 2 separations. On the other hand, the baseline separation success rates for NPLC and RPLC was better than for CEC. For a second comparison, the same chiral stationary phases as in the CEC screening were also tested with all techniques at their specific screening conditions, which allowed a direct comparison of the performance of CEC versus the same CSPs in the other techniques. This comparison revealed that RPLC was able to separate all tested compounds, and also produced the highest number of baseline separations on the CSP that were used in the CEC screening step. CEC and NPLC showed the same success rate: nine out of ten substances were separated. When

  17. Determination of thromboxanes, leukotrienes and lipoxins using high-temperature capillary liquid chromatography-tandem mass spectrometry and on-line sample preparation

    DEFF Research Database (Denmark)

    Dahl, Sandra Rinne; Kleiveland, Charlotte Ramstad; Kassem, Moustapha

    2009-01-01

    An on-line strong cation-exchange (SCX)-reversed-phase (RP) capillary liquid chromatographic (cLC) method with ion-trap tandem mass spectrometric (IT-MS/MS) detection for the simultaneous determination of thromboxane (TX) B(2), TXB(3), leukotriene (LT) B(4), LTD(4) and lipoxin (LX) A(4) in cell...

  18. High-throughput determination of urinary hexosamines for diagnosis of mucopolysaccharidoses by capillary electrophoresis and high-performance liquid chromatography.

    Science.gov (United States)

    Coppa, Giovanni V; Galeotti, Fabio; Zampini, Lucia; Maccari, Francesca; Galeazzi, Tiziana; Padelia, Lucia; Santoro, Lucia; Gabrielli, Orazio; Volpi, Nicola

    2011-04-01

    Mucopolysaccharidoses (MPS) diagnosis is often delayed and irreversible organ damage can occur, making possible therapies less effective. This highlights the importance of early and accurate diagnosis. A high-throughput procedure for the simultaneous determination of glucosamine and galactosamine produced from urinary galactosaminoglycans and glucosaminoglycans by capillary electrophoresis (CE) and HPLC has been performed and validated in subjects affected by various MPS including their mild and severe forms, Hurler and Hurler-Scheie, Hunter, Sanfilippo, Morquio, and Maroteaux-Lamy. Contrary to other analytical approaches, the present single analytical procedure, which is able to measure total abnormal amounts of urinary GAGs, high molecular mass, and related fragments, as well as specific hexosamines belonging to a group of GAGs, would be useful for possible application in their early diagnosis. After a rapid urine pretreatment, free hexosamines are generated by acidic hydrolysis, derivatized with 2-aminobenzoic acid and separated by CE/UV in ∼10min and reverse-phase (RP)-HPLC in fluorescence in ∼21min. The total content of hexosamines was found to be indicative of abnormal urinary excretion of GAGs in patients compared to the controls, and the galactosamine/glucosamine ratio was observed to be related to specific MPS syndromes in regard to both their mild and severe forms. As a consequence, important correlations between analytical response and clinical diagnosis and the severity of the disorders were observed. Furthermore, we can assume that the severity of the syndrome may be ascribed to the quantity of total GAGs, as high-molecular-mass polymers and fragments, accumulated in cells and directly excreted in the urine. Finally, due to the high-throughput nature of this approach and to the equipment commonly available in laboratories, this method is suitable for newborn screening in preventive public health programs for early detection of MPS disorders

  19. In situ synthesis of metal-organic frameworks in a porous polymer monolith as the stationary phase for capillary liquid chromatography.

    Science.gov (United States)

    Yang, Shengchao; Ye, Fanggui; Zhang, Cong; Shen, Shufen; Zhao, Shulin

    2015-04-21

    In this study, HKUST-1 was synthesized in situ on the porous polymer monolith as the stationary phase for capillary liquid chromatography (cLC). The unique carboxyl functionalized poly(methacrylic acid-co-ethylene dimethacrylate) (poly(MAA-co-EDMA)) monolith was used as a support to directly grow HKUST-1 by a controlled layer-by-layer self-assembly strategy. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy of the resulting HKUST-1-poly(MAA-co-EDMA) monoliths indicated that HKUST-1 was successfully grafted onto the pore surface of the poly(MAA-co-EDMA) monolith. The column performance of HKUST-1-poly(MAA-co-EDMA) monoliths for the separation of various small molecules, such as benzenediols, xylenes, ethylbenzenes, and styrenes, was evaluated. The chromatographic performance was found to improve with increasing HKUST-1 density, and the column efficiencies and resolutions of HKUST-1-poly(MAA-co-EDMA) monoliths were 18 320-19 890 plates m(-1) and 1.62-6.42, respectively, for benzenediols. The HKUST-1-poly(MAA-co-EDMA) monolith displayed enhanced resolution for the separation of positional isomers when compared to the traditional C18 and HKUST-1 incorporated polymer monoliths. Hydrophobic, π-π, and hydrogen bonding interactions within the HKUST-1-poly(MAA-co-EDMA) monolith were observed in the separation of small molecules. The results showed that the HKUST-1-poly(MAA-co-EDMA) monoliths are promising stationary phases for cLC.

  20. Temperature-assisted On-column Solute Focusing: A General Method to Reduce Pre-column Dispersion in Capillary High Performance Liquid Chromatography

    Science.gov (United States)

    Groskreutz, Stephen R.; Weber, Stephen G.

    2014-01-01

    Solvent-based on-column focusing is a powerful and well known approach for reducingthe impact of pre-column dispersion in liquid chromatography. Here we describe an orthogonal temperature-based approach to focusing called temperature-assisted on-column solute focusing (TASF). TASF is founded on the same principles as the more commonly used solvent-based method wherein transient conditions are created thatlead to high solute retention at the column inlet. Combining the low thermal mass of capillary columns and the temperature dependence of solute retentionTASF is used effectivelyto compress injection bands at the head of the column through the transient reduction in column temperature to 5 °C for a defined 7 mm segment of a 6 cm long 150 μm I.D. column. Following the 30 second focusing time, the column temperature is increased rapidly to the separation temperature of 60 °C releasing the focused band of analytes. We developed a model tosimulate TASF separations based on solute retention enthalpies, focusing temperature, focusing time, and column parameters. This model guides the systematic study of the influence of sample injection volume on column performance.All samples have solvent compositions matching the mobile phase. Over the 45 to 1050 nL injection volume range evaluated, TASF reducesthe peak width for all soluteswith k’ greater than or equal to 2.5, relative to controls. Peak widths resulting from injection volumes up to 1.3 times the column fluid volume with TASF are less than 5% larger than peak widths from a 45 nL injection without TASF (0.07 times the column liquid volume). The TASF approach reduced concentration detection limits by a factor of 12.5 relative to a small volume injection for low concentration samples. TASF is orthogonal to the solvent focusing method. Thus, it canbe used where on-column focusing is required, but where implementation of solvent-based focusing is difficult. PMID:24973805

  1. performance liquid chromatography

    African Journals Online (AJOL)

    user

    2010-11-22

    Nov 22, 2010 ... ISSN 1684–5315 © 2010 Academic Journals. Full Length Research Paper. Determination ... Key words: Processed food, high-performance liquid chromatography, acrylamide, health hazard. INTRODUCTION. In the year 2002, the ... potatoes, breakfast cereals etc. It was thus confirmed that acrylamide has ...

  2. Micellar liquid chromatography

    International Nuclear Information System (INIS)

    Basova, Elena M; Ivanov, Vadim M; Shpigun, Oleg A

    1999-01-01

    Background and possibilities of practical applications of micellar liquid chromatography (MLC) are considered. Various retention models in MLC, the effects of the nature and concentration of surfactants and organic modifiers, pH, temperature and ionic strength on the MLC efficiency and selectivity are discussed. The advantages and limitations of MLC are demonstrated. The performance of MLC is critically evaluated in relationship to the reversed-phase HPLC and ion-pair chromatography. The potential of application of MLC for the analysis of pharmaceuticals including that in biological fluids and separation of inorganic anions, transition metal cations, metal chelates and heteropoly compounds is described. The bibliography includes 146 references.

  3. Determination of the distribution constants of aromatic compounds and steroids in biphasic micellar phosphonium ionic liquid/aqueous buffer systems by capillary electrokinetic chromatography

    Czech Academy of Sciences Publication Activity Database

    Lokajová, Jana; Railila, A.; King, A. W. T.; Wiedmer, S. K.

    2013-01-01

    Roč. 1308, Sep 20 (2013), s. 144-151 ISSN 0021-9673 Institutional support: RVO:61388963 Keywords : critical micelle concentration * electrokinetic chromatography * distribution constant * PeakMaster * phosphonium ionic liquid Subject RIV: CC - Organic Chemistry Impact factor: 4.258, year: 2013

  4. Integrated Solid-Phase Extraction-Capillary Liquid Chromatography (speLC) Interfaced to ESI-MS/MS for Fast Characterization and Quantification of Protein and Proteomes

    DEFF Research Database (Denmark)

    Falkenby, Lasse Gaarde; Such-Sanmartín, Gerard; Larsen, Martin Røssel

    2014-01-01

    min speLC-MS/MS experiment. Analysis by selected reaction monitoring by speLC-SRM-MS/MS of distinct peptides derived from the blood proteins IGF1, IGF2, IBP2, and IBP3 demonstrated protein quantification with CV values below 10% across 96 replicates. The speLC-MS/MS system is ideally suited for fast......The high peptide sequencing speed provided by modern hybrid tandem mass spectrometers enables the utilization of fast liquid chromatographic (LC) separation techniques. We present a robust solid-phase extraction/capillary LC system (speLC) for 5-10 min separation of semicomplex peptide mixtures...

  5. Preparation and evaluation of open-tubular capillary column combining a metal-organic framework and a brush-shaped polymer for liquid chromatography.

    Science.gov (United States)

    Chen, Kai; Zhang, Lingyi; Zhang, Weibing

    2018-03-30

    In this work, an open-tubular capillary liquid-phase column was prepared by modifying chain polymer on the inner surface of capillary and chemical bonding of metal organic frameworks, NH 2 -UiO-66, to the brushes of chain polymer (poly(glycidyl methacrylate)). Besides advantages of facial preparation and good permeability, the chain polymer effectively increases the modification amount of NH 2 -UiO-66 nanoparticles to increase the phase ratio of open-tubular capillary column and enhance the interactions with analytes. The results of scanning electron microscope energy-dispersive X-ray spectra indicated that NH 2 -UiO-66 nanoparticles were successfully bonded to the chain polymer. Because of the hydrophobic interaction and hydrogen bonding interaction between the analytes and the ligand of NH 2 -UiO-66, different analytes were well separated on the NH 2 -UiO-66-modified poly(glycidyl methacrylate) capillary (1.12 m × 25 μm id × 365 μm od) with the high absolute column efficiency reaching 121 477 plates, benefiting from an open-tubular column and low mass transfer resistance provided by polymer brush and metal-organic framework crystal. The relative standard deviations of the retention time for run-to-run, day-to-day, and column-to-column (n = 3) runs are below 4.28%, exhibiting good repeatability. Finally, the column was successfully applied to separation of flavonoids in licorice. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Instrument platforms for nano liquid chromatography.

    Science.gov (United States)

    Šesták, Jozef; Moravcová, Dana; Kahle, Vladislav

    2015-11-20

    The history of liquid chromatography started more than a century ago and miniaturization and automation are two leading trends in this field. Nanocolumn liquid chromatography (nano LC) and largely synonymous capillary liquid chromatography (capillary LC) are the most recent results of this process where miniaturization of column dimensions and sorbent particle size play crucial role. Very interesting results achieved in the research of extremely miniaturized LC columns at the end of the last century lacked distinctive raison d'être and only advances in mass spectrometry brought a real breakthrough. Configuration of nano LC-electrospray ionization mass spectrometry (LC-ESI-MS) has become a basic tool in bioanalytical chemistry, especially in proteomics. This review discusses and summarizes past and current trends in the realization of nano liquid chromatography (nano LC) platforms. Special attention is given to the mobile phase delivery under nanoflow rates (isocratic, gradient) and sample injection to the nanocolumn. Available detection techniques applied in nano LC separations are also briefly discussed. We followed up the key themes from the original scientific reports over gradual improvements up to the contemporary commercial solutions. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Ion-pair in-tube solid-phase microextraction and capillary liquid chromatography using a titania-based column: application to the specific lauralkonium chloride determination in water.

    Science.gov (United States)

    Prieto-Blanco, M C; Moliner-Martínez, Y; López-Mahía, P; Campíns-Falcó, P

    2012-07-27

    A quick, miniaturized and on-line method has been developed for the determination in water of the predominant homologue of benzalkonium chloride, dodecyl dimethyl benzyl ammonium chloride or lauralkonium chloride (C(12)-BAK). The method is based on the formation of an ion-pair in both in-tube solid-phase microextraction (IT-SPME) and capillary liquid chromatography. The IT-SPME optimization required the study of the length and nature of the stationary phase of capillary and the processed sample volume. Because to the surfactant character of the analyte both, the extracting and replacing solvents, have played a decisive role in the IT-SPME optimized procedure. Conditioning the capillary with the mobile phase which contains the counter ion (acetate), using an organic additive (tetrabutylammonium chloride) added to the sample and a mixture water/methanol as replacing solvent (processed just before the valve is switched to the inject position), allowed to obtain good precision of the retention time and a narrow peak for C(12)-BAK. A reversed-phase capillary based TiO(2) column and a mobile phase containing ammonium acetate at pH 5.0 for controlling the interactions of cationic surfactant with titania surface were proposed. The optimized procedure provided adequate linearity, accuracy and precision at the concentrations interval of 1.5-300 μg L(-1) .The limit of detection (LOD) was 0.5 μg L(-1) using diode array detection (DAD). The applicability of proposed IT-SPME-capillary LC method has been assessed in several water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Ionic liquid stationary phases for gas chromatography.

    Science.gov (United States)

    Poole, Colin F; Poole, Salwa K

    2011-04-01

    This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The Determination of Pesticidal and Non-Pesticidal Organotin Compounds by in situ Ethylation and Capillary Gas Chromatography with Pulsed Flame Photometric Detection

    Science.gov (United States)

    The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

  10. Simultaneous quantification of eight organic acid components in Artemisia capillaris Thunb (Yinchen extract using high-performance liquid chromatography coupled with diode array detection and high-resolution mass spectrometry

    Directory of Open Access Journals (Sweden)

    Fangjun Yu

    2018-04-01

    Full Text Available We aim to determine the chemical constituents of Yinchen extract and Yinchen herbs using high-performance liquid chromatography coupled with diode array detection and high-resolution mass spectrometry. The method was developed to analyze of eight organic acid components of Yinchen extract (including neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, caffeic acid, 1,3-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid. The separation was conducted using an Agilent TC-C18 column with acetonitrile – 0.2% formic acid solution as the mobile phases under gradient elution. The analytical method was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery, and subsequently the method was performed for the quantitative assessment of Yinchen extracts and Yinchen herbs. In addition, the changes of selected markers were studied when Yinchen herbs decocting in water and isomerization occurred between the chlorogenic acids. The proposed method enables both qualitative and quantitative analyses and could be developed as a new tool for the quality evaluation of Yinchen extract and Yinchen herbs. The changes of selected markers in water decoction process could give us some novel idea when studying the link between substances and drug efficacy. Keywords: Artemisia capillaris Thunb (Yinchen extract, Quality control, Organic acid, Transformation pathways, High-performance liquid chromatography

  11. Preparation and evaluation of open-tubular capillary columns modified with metal-organic framework incorporated polymeric porous layer for liquid chromatography.

    Science.gov (United States)

    Zhu, Manman; Zhang, Lingyi; Chu, Zhanying; Wang, Shulei; Chen, Kai; Zhang, Weibing; Liu, Fan

    2018-07-01

    An open tubular capillary liquid phase chromatographic column (1 m × 25 µm i.d.× 375 µm o.d.) was prepared by incorporating metal organic framework particles modified with vancomycin directly into zwitterionic polymer coating synthesized by the copolymerization of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide and N,N'-methylenebisacrylamide. The incorporation of IRMOF-3 (isoreticular metal organic framework-3) particles improved selectivity of zwitterionic polymer coating with absolute column efficiency reaching 79900 plates for p-xylene. Besides strong hydrophilic interaction, the separation of neutral, basic, and acidic compounds demonstrates that π-π stacking interaction and the coordination effect of unsaturated Zn 2+ of MOF also contribute to separation of various analytes. The RSD values (run-to-run, day-to-day, column-to-column, n = 3) of retention time of neutral compounds were less than 0.71%, 0.69% and 3.08% respectively, suggesting good repeatability. In addition, the column was applied to the analysis of the trypsin digest of bovine serum albumin, revealing the potential in separating biological samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Capillaries modified by noncovalent anionic polymer adsorption for capillary zone electrophoresis, micellar electrokinetic capillary chromatography and capillary electrophoresis mass spectrometry

    DEFF Research Database (Denmark)

    Bendahl, L; Hansen, S H; Gammelgaard, Bente

    2001-01-01

    A simple coating procedure for generation of a high and pH-independent electroosmotic flow in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) is described. The bilayer coating was formed by noncovalent adsorption of the ionic polymers Polybrene...... capillaries was (4.9+/-0.1) x 10(-4) cm2V(-1)s(-1) in a pH-range of 2-10 (ionic strength = 30 mM). When alkaline compounds were used as test substances intracapillary and intercapillary migration time variations (n = 6) were less than 1% relative standard deviation (RSD) and 2% RSD, respectively in the entire...... pH range. The coating was fairly stable in the presence of sodium dodecyl sulfate, and this made it possible to perform fast MEKC separations at low pH. When neutral compounds were used as test substances, the intracapillary migration time variations (n = 6) were less than 2% RSD in a pH range of 2...

  13. Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis

    Directory of Open Access Journals (Sweden)

    Árpád Gyéresi

    2013-02-01

    Full Text Available Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis.

  14. Introduction to modern liquid chromatography

    National Research Council Canada - National Science Library

    Snyder, Lloyd R; Kirkland, J. J; Dolan, John W

    2010-01-01

    "High-performance liquid chromatography (HPLC) is today the leading technique for chemical analysis and related applications, with an ability to separate, analyze, and/or purify virtually any sample...

  15. Identification of Sarin and Related Compounds in Snow by Packed Capillary Liquid Chromatography-Electrospray Mass Spectrometry (LC-ESI-MS)

    National Research Council Canada - National Science Library

    D'Agostino, Paul

    2001-01-01

    Packed capillary LC-ESl-MS was used for the analysis of a snow sample that was accidentally contaminated with an organophosphorus chemical warfare agent during the destruction of a chemical munition...

  16. Application of ionic liquids in liquid chromatography and electrodriven separation.

    Science.gov (United States)

    Huang, Yi; Yao, Shun; Song, Hang

    2013-08-01

    Ionic liquids (ILs) are salts in the liquid state at ambient temperature, which are nonvolatile, nonflammable with high thermal stability and dissolve easily for a wide range of inorganic and organic materials. As a kind of potential green solvent, they show high efficiency and selectivity in the field of separation research, especially in instrumental analysis. Thus far, ILs have been successfully applied by many related researchers in high-performance liquid chromatography and capillary electrophoresis as chromatographic stationary phases, mobile phase additives or electroosmotic flow modifiers. This paper provides a detailed review of these applications in the study of natural products, foods, drugs and other fine chemicals. Furthermore, the prospects of ILs in liquid chromatographic and electrodriven techniques are discussed.

  17. Analysis of bovine milk caseins on organic monolithic columns: an integrated capillary liquid chromatography-high resolution mass spectrometry approach for the study of time-dependent casein degradation.

    Science.gov (United States)

    Pierri, Giuseppe; Kotoni, Dorina; Simone, Patrizia; Villani, Claudio; Pepe, Giacomo; Campiglia, Pietro; Dugo, Paola; Gasparrini, Francesco

    2013-10-25

    Casein proteins constitute approximately 80% of the proteins present in bovine milk and account for many of its nutritional and technological properties. The analysis of the casein fraction in commercially available pasteurized milk and the study of its time-dependent degradation is of considerable interest in the agro-food industry. Here we present new analytical methods for the study of caseins in fresh and expired bovine milk, based on the use of lab-made capillary organic monolithic columns. An integrated capillary high performance liquid chromatography and high-resolution mass spectrometry (Cap-LC-HRMS) approach was developed, exploiting the excellent resolution, permeability and biocompatibility of organic monoliths, which is easily adaptable to the analysis of intact proteins. The resolution obtained on the lab-made Protein-Cap-RP-Lauryl-γ-Monolithic column (270 mm × 0.250 mm length × internal diameter, L × I.D.) in the analysis of commercial standard caseins (αS-CN, β-CN and κ-CN) through Cap-HPLC-UV was compared to the one observe using two packed capillary C4 columns, the ACE C4 (3 μm, 150 mm × 0.300 mm, L × I.D.) and the Jupiter C4 column (5 μm, 150 mm × 0.300 mm, L × I.D.). Thanks to the higher resolution observed, the monolithic capillary column was chosen for the successive degradation studies of casein fractions extracted from bovine milk 1-4 weeks after expiry date. The comparison of the UV chromatographic profiles of skim, semi-skim and whole milk showed a major stability of whole milk towards time-dependent degradation of caseins, which was further sustained by high-resolution analysis on a 50-cm long monolithic column using a 120-min time gradient. Contemporarily, the exact monoisotopic and average molecular masses of intact αS-CN and β-CN protein standards were obtained through high resolution mass spectrometry and used for casein identification in Cap-LC-HRMS analysis. Finally, the proteolytic degradation of β-CN in skim milk

  18. Determination of carbohydrates in juices by capillary electrophoresis, high-performance liquid chromatography, and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Cabálková, Jana; Žídková, Jitka; Přibyla, Lubomír; Chmelík, Josef

    2004-01-01

    Roč. 25, č. 3 (2004), s. 487-493 ISSN 0173-0835 R&D Projects: GA ČR GA526/03/1182 Institutional research plan: CEZ:AV0Z4031919 Keywords : capillary electrophoresis with indirect detection * juices * major carbohydrate profile Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.743, year: 2004

  19. Potential of capillary-column-switching liquid chromatography-tandem mass spectrometry for the quantitative trace analysis of small molecules. Application to the on-line screening of drugs in water.

    Science.gov (United States)

    Pitarch, Elena; Hernandez, Felix; ten Hove, Jan; Meiring, Hugo; Niesing, Willem; Dijkman, Ellen; Stolker, Linda; Hogendoorn, Elbert

    2004-03-26

    We have investigated the potential of capillary-column-switching liquid chromatography coupled to tandem mass spectrometry (cLC-MS-MS) for the quantitative on-line trace analysis of target compounds in aqueous solutions. The technical design of the nano-scale cLC system developed at our Institute for peptide and protein identification has been tested and evaluated for the direct trace analysis of drugs in water samples. Sulphametoxazole, bezafibrate, metoprolol, carbamazepine and bisoprolol occurring frequently in Dutch waters, were selected as test compounds. Adequate conditions for trapping, elution and MS-MS detection were investigated by employing laboratory made 200 microm i.d. capillary columns packed with 5 microm aqua C18 material. In the final cLC-MS-MS conditions, a 1 cm length trapping column and a 4 cm length analytical column were selected. Under these conditions, the target compounds could be directly determined in water down to a level of around 50 ng/l employing only 25 microl of water sample. Validation was done by recovery experiments in ground-, surface- and drinking-water matrices as well as by the analysis of water samples with incurred residues and previously analyzed with a conventional procedure involving off-line solid-phase extraction and narrow-bore LC with MS-MS detection. The new methodology provided recoveries (50-500 ng/l level) between 50 and 114% with RSDs (n = 3, each level) below 20% for most of the compounds. Despite the somewhat less analytical performance in comparison to the conventional procedure, the on-line approach of the new methodology is very suitable for screening of drugs in aqueous samples.

  20. [Determination of acetochlor and oxyfluorfen by capillary gas chromatography].

    Science.gov (United States)

    Xiang, Wen-Sheng; Wang, Xiang-Jing; Wang, Jing; Wang, Qing

    2002-09-01

    A method is described for the determination of acetochlor and oxyfluorfen by capillary gas chromatography with FID and an SE-30 capillary column (60 m x 0.53 mm i. d., 1.5 microm), using dibutyl phthalate as the internal standard. The standard deviations for acetochlor and oxyfluorfen concentration(mass fraction) were 0.44% and 0.47% respectively. The relative standard deviations for acetochlor and oxyfluorfen were 0.79% and 0.88% and the average recoveries for acetochlor and oxyfluorfen were 99.3% and 101.1% respectively. The method is simple, rapid and accurate.

  1. Development and characterization of a novel plug and play liquid chromatography-mass spectrometry (LC-MS) source that automates connections between the capillary trap, column, and emitter.

    Science.gov (United States)

    Bereman, Michael S; Hsieh, Edward J; Corso, Thomas N; Van Pelt, Colleen K; Maccoss, Michael J

    2013-06-01

    We report the development and characterization of a novel, vendor-neutral ultra-high pressure-compatible (~10,000 p.s.i.) LC-MS source. This device is the first to make automated connections with user-packed capillary traps, columns, and capillary emitters. The source uses plastic rectangular inserts (referred to here as cartridges) where individual components (i.e. trap, column, or emitter) can be exchanged independent of one another in a plug and play manner. Automated robotic connections are made between the three cartridges using linear translation powered by stepper motors to axially compress each cartridge by applying a well controlled constant compression force to each commercial LC fitting. The user has the versatility to tailor the separation (e.g. the length of the column, type of stationary phase, and mode of separation) to the experimental design of interest in a cost-effective manner. The source is described in detail, and several experiments are performed to evaluate the robustness of both the system and the exchange of the individual trap and emitter cartridges. The standard deviation in the retention time of four targeted peptides from a standard digest interlaced with a soluble Caenorhabditis elegans lysate ranged between 3.1 and 5.3 s over 3 days of analyses. Exchange of the emitter cartridge was found to have an insignificant effect on the abundance of various peptides. In addition, the trap cartridge can be replaced with minimal effects on retention time (<20 s).

  2. Liquid chromatography in migration studies

    International Nuclear Information System (INIS)

    Carlsen, L.; Batsberg, W.

    1982-01-01

    Liquid chromatography ahs been suggested as a facile experimental technique to determine important physico-chemical properties, as permeability, porosity, dispersion-, diffusion-, and sorption charcteristics for geological material as chalk samples. The feasibility of the trechnique as a rapid method to evaluate the possible influence of changes in ground water composition on the migration behavior of radionuclides has been demonstrated

  3. Liquid phase chromatography on microchips

    DEFF Research Database (Denmark)

    Kutter, Jörg Peter

    2012-01-01

    explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important...

  4. Chromatographic selectivity of poly(alkyl methacrylate-co-divinylbenzene) monolithic columns for polar aromatic compounds by pressure-driven capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wang, Chih-Chieh; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2016-10-05

    In this study, divinylbenzene (DVB) was used as the cross-linker to prepare alkyl methacrylate (AlMA) monoliths for incorporating π-π interactions between the aromatic analytes and AlMA-DVB monolithic stationary phases in capillary LC analysis. Various AlMA/DVB ratios were investigated to prepare a series of 30% AlMA-DVB monolithic stationary phases in fused-silica capillaries (250-μm i.d.). The physical properties (such as porosity, permeability, and column efficiency) of the synthesized AlMA-DVB monolithic columns were investigated for characterization. Isocratic elution of phenol derivatives was first employed to evaluate the suitability of the prepared AlMA-DVB columns for small molecule separation. The run-to-run (0.16–1.20%, RSD; n = 3) and column-to-column (0.26–2.95%, RSD; n = 3) repeatabilities on retention times were also examined using the selected AlMA-DVB monolithic columns. The π-π interactions between the aromatic ring and the DVB-based stationary phase offered better recognition on polar analytes with aromatic moieties, which resulted in better separation resolution of aromatic analytes on the AlMA-DVB monolithic columns. In order to demonstrate the capability of potential environmental and/or food safety applications, eight phenylurea herbicides with single benzene ring and seven sulfonamide antibiotics with polyaromatic moieties were analyzed using the selected AlMA-DVB monolithic columns. - Highlights: • First investigation on chromatographic selectivity of AlMA-DVB monolithic columns. • Good run-to-run/column-to-column repeatability (<3%) on AlMA-DVB monolithic columns. • Efficient separation of phenylurea herbicides and sulfonamides on AlMA-DVB columns.

  5. Preparation and evaluation of poly(alkyl methacrylate-co-methacrylic acid-co-ethylene dimethacrylate) monolithic columns for separating polar small molecules by capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wu, Yu-Ru; Lin, Tzuen-Yeuan; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2015-04-29

    Highlights: • Methacrylic acid (MAA) was used to increase hydrophilicity of polymeric monoliths. • Fast separation of phenol derivatives was achieved in 5 min using MAA-incorporated column. • Separations of aflatoxins and phenicol antibiotics were achieved using MAA-incorporated column. - Abstract: In this study, methacrylic acid (MAA) was incorporated with alkyl methacrylates to increase the hydrophilicity of the synthesized ethylene dimethacrylate-based (EDMA-based) monoliths for separating polar small molecules by capillary LC analysis. Different alkyl methacrylate–MAA ratios were investigated to prepare a series of 30% alkyl methacrylate–MAA–EDMA monoliths in fused-silica capillaries (250-μm i.d.). The porosity, permeability, and column efficiency of the synthesized MAA-incorporated monolithic columns were characterized. A mixture of phenol derivatives is employed to evaluate the applicability of using the prepared monolithic columns for separating small molecules. Fast separation of six phenol derivatives was achieved in 5 min with gradient elution using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. In addition, the effect of acetonitrile content in mobile phase on retention factor and plate height as well as the plate height-flow velocity curves were also investigated to further examine the performance of the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. Moreover, the applicability of prepared polymer-based monolithic column for potential food safety applications was also demonstrated by analyzing five aflatoxins and three phenicol antibiotics using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column.

  6. Changes in the basic experimental parameters of capillary gas chromatography in the 20th century.

    Science.gov (United States)

    Berezkin, V G; Viktorova, E N

    2003-01-24

    Studies of qualitative changes in capillary gas chromatography are of significant practical and scientific interest. This paper analyzes the evolution of the most important experimental chromatographic parameters over the last three decades and is based on the use of a new approach to scientometrical research that is referred to as applied scientometry. One essential feature of this approach is that it looks at the entire contents of each paper rather than only taking account its title, abstract. and references (as is typical for conventional scientometry). In this paper, we monitor how the most important chromatographic parameters, such as column length and diameter, layer thickness, stationary liquid phases, separation temperature mode. etc., have been evolving over the period 1970-2000. We used data from the following journals: Chromatographia, Journal of Chromatography, and Journal of High Resolution Chromatography and Chromatography Communications.

  7. Solute partitioning between the ionic liquid 1-n-butyl-3-methylimidazolium tetrafluoroborate and supercritical CO.sub.2./sub. from capillary-column chromatography

    Czech Academy of Sciences Publication Activity Database

    Planeta, Josef; Roth, Michal

    2005-01-01

    Roč. 109, č. 31 (2005), s. 15165-15171 ISSN 1520-6106 R&D Projects: GA AV ČR(CZ) KJB400310504 Institutional research plan: CEZ:AV0Z40310501 Keywords : ionic liquid - supercritical CO2 system * solute partition coefficient * linear solvation energy relationship Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.033, year: 2005

  8. Automated Gain Control and Internal Calibration With External Ion Accumulation Capillary liquid chromatography-electrospray ionization-fourier transform ion cyclotron resonance.

    Energy Technology Data Exchange (ETDEWEB)

    Belov, Mikhail E.(VISITORS); Zhang, Rui (BATTELLE (PACIFIC NW LAB)); Strittmatter, Eric F.(BATTELLE (PACIFIC NW LAB)); Prior, David C.(BATTELLE (PACIFIC NW LAB)); Tang, Keqi (BATTELLE (PACIFIC NW LAB)); Smith, Richard D.(BATTELLE (PACIFIC NW LAB))

    2003-08-15

    When combined with capillary LC separations, Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FTICR MS) has increasingly been applied for advanced characterization of proteolytic digests. Incorporation of external (to the ICR cell) ion accumulation multipoles with FTICR for ion pre selection and accumulation has enhanced the dynamic range, sensitivity and duty cycle of measurements. However, the highly variable ion production rate from an LC separation can result in overfilling of the external trap, resulting in m/z discrimination and fragmentation of peptide ions. An excessive space charge trapped in the ICR cell causes significant shifts in the detected ion cyclotron frequencies, reducing the achievable mass measurement accuracy (MMA) for protein identification. To eliminate m/z discrimination in the external ion trap, further increase the duty cycle and improve MMA, we developed a capability for data-dependent adjustment of ion accumulation times in the course of an LC separation, referred to as Automated Gain Control (AGC), in combination with low kinetic energy gated ion trapping and internal calibration using a dual-channel electrodynamic ion funnel. The system was initially evaluated in the analysis of a 0.5 mg/mL tryptic digest of bovine serum albumin. The implementation of LC/ESI/AGC/FTICR with internal calibration gave rise to a {approx} 10-fold increase in the number of identified tryptic peptides within mass measurement accuracy of 2 ppm as compared to that detected during the conventional LC/FTICR run with a fixed ion accumulation time and external calibration.

  9. Capillary Flow of Liquid Metals in Brazing

    Science.gov (United States)

    Dehsara, Mohammad

    Capillary flow is driven or controlled by capillary forces, exerted at the triple line where the fluid phases meet the solid boundary. Phase field (PF) models naturally accommodate diffusive triple line motion with variable contact angle, thus allowing for the no-slip boundary condition without the stress singularities. Moreover, they are uniquely suited for modeling of topological discontinuities which often arise during capillary flows. In this study, we consider diffusive triple line motion within two PF models: the compositionally compressible (CC) and the incompressible (IC) models. We derive the IC model as a systematic approximation to the CC model, based on a suitable choice of continuum velocity field. The CC model, applied to the fluids of dissimilar mass densities, exhibits a computational instability at the triple line. The IC model perfectly represents the analytic equilibria. We develop the parameter identification procedure and show that the triple line kinetics can be well represented by the IC model's diffusive boundary condition. The IC model is first tested by benchmarking the phase-field and experimental kinetics of water, and silicone oil spreading over the glass plates in which two systems do not interact with the substrate. Then, two high-temperature physical settings involving spreading of the molten Al-Si alloy: one over a rough wetting substrate, the other over a non-wetting substrate are modeled in a T-joint structure which is a typical geometric configuration for many brazing and soldering applications. Surface roughness directly influences the spreading of the molten metal by causing break-ups of the liquid film and trapping the liquid away from the joint. In the early stages of capillary flow over non-wetting surface, the melting and flow are concurrent, so that the kinetics of wetting is strongly affected by the variations in effective viscosity of the partially molten metal. We define adequate time-dependent functions for the

  10. Liquid chromatography - mass spectrometry analysis of pharmaceuticals

    International Nuclear Information System (INIS)

    Macasek, F.

    2003-01-01

    The drugs represent mostly non-volatile and thermally labile solutes, often available only in small amounts like it is in case of radiopharmaceuticals. Therefor, the favourable separation techniques for such compounds are HPLC, capillary electrophoresis and also TLC 1. Liquid chromatography with mass spectrometric detector (LC/MS) is especially powerful for their microanalysis. Mass spectrometry separating the ions in high vacuum was presumably used as detector for gas chromatography effluent but the on-line coupling with liquid eluant flow 0.1-1 mL/min is far more challenging. New types of ion sources were constructed for simultaneous removal of solvent and ionisation of solutes at atmospheric pressure (API). At present, a relatively wide choice of successfully designed commercial equipment is available either for small organic molecules and larger biomolecules (Perkin-Elmer, Agilent, Jeol, Bruker Daltonics, ThermoQuest, Shimadzu). The features of the LC/MS systems are presented. LC/MS as a new quality control tool for [F-18]fluorodeoxyglucose (FDG) radiopharmaceutical, which has became the most spread radiopharmaceutical for positron emission tomography (PET), was proposed. Other applications of the LC/MS are reviewed. (author)

  11. New rapid methods for determination of total LAS in sewage sludge by high performance liquid chromatography (HPLC) and capillary electrophoresis (CE)

    International Nuclear Information System (INIS)

    Villar, M.; Callejon, M.; Jimenez, J.C.; Alonso, E.; Guiraum, A.

    2009-01-01

    Linear alkylbenzene sulfonates (LAS) are the most common synthetic anionic surfactant used in domestic and industrial detergents, with a global production of 2.4 x 10 6 t year -1 . After use and disposal, LAS may enter the environment by one of the several routes, including by direct discharge to surface water or discharge to water from sewage treatment plants. Sewage treatment plants break down LAS only partly: some of them remain in effluent and other fraction is adsorbed in sewage solid. New and rapid methods for determination of total LAS from sewage sludge based on microwave assisted extraction and HPLC-FL and CE-DAD determination are proposed. The extraction of total LAS is carried out by using microwaves energy, an extraction time of 10 min and 5 mL of methanol. For HPLC-FL determination, mobile phase acetonitrile-water was used, comprising 60% (v/v) from 0 to 1 min and a flow rate of 1 mL min -1 programmed to 100% acetonitrile between 1 and 2 min and a flow rate of 2 mL min -1 . The final composition was maintained for a further 5 min. The determination of total LAS by CE-DAD was performed in a phosphate buffer (10 mM, pH 9). The separation voltage was 25 kV and the temperature of the capillary was 30 deg. C. Injections were performed in the pressure mode and the injection time was set at 12 s. The determination of total LAS is carried out in less than 5 min. The methods did not require clean-up or preconcentration steps. Detection limit for total LAS in the sludge was 3.03 mg kg -1 using HPLC-FL and 21.0 mg kg -1 using CE-DAD, and recoveries were >85% using both determination methods. Concentrations of total LAS obtained using both methods were compared with the sum of concentrations of homologues LAS C-10, LAS C-11, LAS C-12 and LAS C-13 obtained using microwaves assisted extraction and HPLC-FL and CE-DAD determination

  12. New rapid methods for determination of total LAS in sewage sludge by high performance liquid chromatography (HPLC) and capillary electrophoresis (CE).

    Science.gov (United States)

    Villar, M; Callejón, M; Jiménez, J C; Alonso, E; Guiraúm, A

    2009-02-23

    Linear alkylbenzene sulfonates (LAS) are the most common synthetic anionic surfactant used in domestic and industrial detergents, with a global production of 2.4x10(6) t year(-1). After use and disposal, LAS may enter the environment by one of the several routes, including by direct discharge to surface water or discharge to water from sewage treatment plants. Sewage treatment plants break down LAS only partly: some of them remain in effluent and other fraction is adsorbed in sewage solid. New and rapid methods for determination of total LAS from sewage sludge based on microwave assisted extraction and HPLC-FL and CE-DAD determination are proposed. The extraction of total LAS is carried out by using microwaves energy, an extraction time of 10 min and 5 mL of methanol. For HPLC-FL determination, mobile phase acetonitrile-water was used, comprising 60% (v/v) from 0 to 1 min and a flow rate of 1 mL min(-1) programmed to 100% acetonitrile between 1 and 2 min and a flow rate of 2 mL min(-1). The final composition was maintained for a further 5 min. The determination of total LAS by CE-DAD was performed in a phosphate buffer (10 mM, pH 9). The separation voltage was 25 kV and the temperature of the capillary was 30 degrees C. Injections were performed in the pressure mode and the injection time was set at 12 s. The determination of total LAS is carried out in less than 5 min. The methods did not require clean-up or preconcentration steps. Detection limit for total LAS in the sludge was 3.03 mg kg(-1) using HPLC-FL and 21.0 mg kg(-1) using CE-DAD, and recoveries were >85% using both determination methods. Concentrations of total LAS obtained using both methods were compared with the sum of concentrations of homologues LAS C-10, LAS C-11, LAS C-12 and LAS C-13 obtained using microwaves assisted extraction and HPLC-FL and CE-DAD determination.

  13. Comparative evaluation of capillary electrophoresis and high-performance liquid chromatography for the separation of cis-cis, cis-trans, and trans-trans isomers of atracurium besylate.

    Science.gov (United States)

    de Moraes, M de L; Polakiewicz, B; Mattua, M F; Tavares, M F

    1998-01-01

    Atracurium besylate is a highly selective nondepolarizing neuromuscular blocking agent routinely used during anesthetic procedures. The commercial presentation of this drug is a mixture of positional isomers, cis-cis, cis-trans, and trans-trans. Reversed-phase high-performance liquid chromatography has been the technique of choice for the analysis of atracurium besylate formulations at the quality control laboratory of Núcleo de Desenvolvimento Cristália (São Paulo, Brazil), a local pharmaceutical company. HPLC analysis is usually conducted under gradient elution using acetonitrile/0.1 M phosphate buffer eluent mixture as mobile phase and an octadecyl silica (ODS)-packed column. The complete elution of the three isomers takes about 1 hr. In this work, an alternative capillary electrophoresis methodology was developed. The complete resolution of all three isomers was accomplished in about 13 min (+20 kV/72 cm, 211 nm direct detection) using a 60-mM phosphate buffer solution (pH 4) containing 20 mM beta-cyclodextrin and 4 M urea. The isomer ratio was found to be 59.1% cis-cis, 35.9% cis-trans, and 5.02% trans-trans (expected ratio: 59:35:6). Laudanosine, a major metabolite of atracurium besylate, was identified in two commercially available formulations, Tracur (Núcleo de Desenvolvimento Cristália) and Tracrium (Glaxo Wellcome, S.A., Rio de Janeiro, Brazil). Its concentration increases considerably during storage of the product, even if the product is stored at low temperatures.

  14. Quantitative analysis of N-glycans from human alfa-acid-glycoprotein using stable isotope labeling and zwitterionic hydrophilic interaction capillary liquid chromatography electrospray mass spectrometry as tool for pancreatic disease diagnosis

    International Nuclear Information System (INIS)

    Giménez, Estela; Balmaña, Meritxell; Figueras, Joan; Fort, Esther; Bolós, Carme de; Sanz-Nebot, Victòria; Peracaula, Rosa; Rizzi, Andreas

    2015-01-01

    Highlights: • The method enables relative quantitation of hAGP glycans from pathological samples • Pancreatic cancer samples clearly showed an increase of hAGP fucosylated glycans. • Fucosylated glycans could be potential biomarkers for diagnosing pancreatic cancer. • The established method could be extremely useful to find novel glycoprotein biomarkers - Abstract: In this work we demonstrate the potential of glycan reductive isotope labeling (GRIL) using [ 12 C]- and [ 13 C]-coded aniline and zwitterionic hydrophilic interaction capillary liquid chromatography electrospray mass spectrometry (μZIC-HILIC-ESI-MS) for relative quantitation of glycosylation variants in selected glycoproteins present in samples from cancer patients. Human α 1 -acid-glycoprotein (hAGP) is an acute phase serum glycoprotein whose glycosylation has been described to be altered in cancer and chronic inflammation. However, it is not clear yet whether some particular glycans in hAGP can be used as biomarker for differentiating between these two pathologies. In this work, hAGP was isolated by immunoaffinity chromatography (IAC) from serum samples of healthy individuals and from those suffering chronic pancreatitis and different stages of pancreatic cancer, respectively. After de-N-glycosylation, relative quantitation of the hAGP glycans was carried out using stable isotope labeling and μZIC-HILIC-ESI-MS analysis. First, protein denaturing conditions prior to PNGase F digestion were optimized to achieve quantitative digestion yields, and the reproducibility of the established methodology was evaluated with standard hAGP. Then, the proposed method was applied to the analysis of the clinical samples (control vs. pathological). Pancreatic cancer samples clearly showed an increase in the abundance of fucosylated glycans as the stage of the disease increases and this was unlike to samples from chronic pancreatitis. The results gained here indicate the mentioned glycan in hAGP as a

  15. Quantitative analysis of N-glycans from human alfa-acid-glycoprotein using stable isotope labeling and zwitterionic hydrophilic interaction capillary liquid chromatography electrospray mass spectrometry as tool for pancreatic disease diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Giménez, Estela, E-mail: estelagimenez@ub.edu [Department of Analytical Chemistry, University of Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Balmaña, Meritxell [Biochemistry and Molecular Biology Unit, Department of Biology, University of Girona, Campus Montilivi s/n, 17071 Girona (Spain); Figueras, Joan [Department of Surgery, Dr. Josep Trueta University Hospital, IdlBGi, 17007 Girona (Spain); Fort, Esther [Digestive Unit, Dr. Josep Trueta University Hospital, 17007 Girona (Spain); Bolós, Carme de [Gastroesophagic Cancer Research Group, Research Programme in Cancer, Hospital del Mar Medical Research Institute (IMIM), Dr. Aiguader, 88, 08003 Barcelona (Spain); Sanz-Nebot, Victòria [Department of Analytical Chemistry, University of Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Peracaula, Rosa [Biochemistry and Molecular Biology Unit, Department of Biology, University of Girona, Campus Montilivi s/n, 17071 Girona (Spain); Rizzi, Andreas [Institute of Analytical Chemistry, University of Vienna, Währinger Straße 38, A-1090 Vienna (Austria)

    2015-03-25

    Highlights: • The method enables relative quantitation of hAGP glycans from pathological samples • Pancreatic cancer samples clearly showed an increase of hAGP fucosylated glycans. • Fucosylated glycans could be potential biomarkers for diagnosing pancreatic cancer. • The established method could be extremely useful to find novel glycoprotein biomarkers - Abstract: In this work we demonstrate the potential of glycan reductive isotope labeling (GRIL) using [{sup 12}C]- and [{sup 13}C]-coded aniline and zwitterionic hydrophilic interaction capillary liquid chromatography electrospray mass spectrometry (μZIC-HILIC-ESI-MS) for relative quantitation of glycosylation variants in selected glycoproteins present in samples from cancer patients. Human α{sub 1}-acid-glycoprotein (hAGP) is an acute phase serum glycoprotein whose glycosylation has been described to be altered in cancer and chronic inflammation. However, it is not clear yet whether some particular glycans in hAGP can be used as biomarker for differentiating between these two pathologies. In this work, hAGP was isolated by immunoaffinity chromatography (IAC) from serum samples of healthy individuals and from those suffering chronic pancreatitis and different stages of pancreatic cancer, respectively. After de-N-glycosylation, relative quantitation of the hAGP glycans was carried out using stable isotope labeling and μZIC-HILIC-ESI-MS analysis. First, protein denaturing conditions prior to PNGase F digestion were optimized to achieve quantitative digestion yields, and the reproducibility of the established methodology was evaluated with standard hAGP. Then, the proposed method was applied to the analysis of the clinical samples (control vs. pathological). Pancreatic cancer samples clearly showed an increase in the abundance of fucosylated glycans as the stage of the disease increases and this was unlike to samples from chronic pancreatitis. The results gained here indicate the mentioned glycan in h

  16. Capillary supercritical fluid chromatography - Fourier transform infrared spectrometry

    International Nuclear Information System (INIS)

    Olesik, S.V.; French, S.B.; Movotny, M.

    1984-01-01

    One of the most demanding tasks asked of an analytical chemist today is to separate and identify the components of a nonvolatile complex mixture. An efficient separation technique combined with a universal detector that provides structural information, therefore, would be a great asset to analytical chemists. Capillary supercritical fluid chromatography (SFC) - Fourier transform infrared spectrometry (FTIR) shows great potential for being such a technique. SFC-FTIR shows great potential as a very powerful technique for separation and identification of thermally labile and nonvolatile compounds. Research is continuing in these labs to further optimize the technique. 2 refs

  17. 用于高效液相色谱和开管毛细管电色谱的氢化硅胶分离材料%Hydride-Based Separation Materials for High Performance Liquid Chromatography and Open Tubular Capillary Electrochromatography

    Institute of Scientific and Technical Information of China (English)

    PESEK Joseph J; MATYSKA Maria T

    2005-01-01

    Silica hydride is a recent development in chromatographic support materials for high performance liquid chromatography (HPLC) where hydride groups replace 95% of the silanols on the surface. This conversion changes many of the fundamental properties of the material as well as the bonded stationary phases that are the result of further chemical modification of the hydride surface. Some unique chromatographic properties of hydride-based phases are described as well as some general application areas where these bonded materials may be used in preference to or have advantages not available from typical stationary phases. The fabrication, properties and applications of etched chemically modified capillaries for electrophoretic analysis are also reviewed. It is shown that the etching process creates a surface that is fundamentally different than a bare fused silica capillary. The new surface matrix produces unique electroosmotic flow properties and is more compatible with basic and biological compounds. After chemical modification of the surface, the bonded organic moiety (stationary phase) contributes to the control of migration of solutes in the capillary. Both electrophoretic and chromatographic processes take place in the etched chemically modified capillaries leading to a variety of experimental variables that can be used to optimize separations. A number of examples of separations on these capillaries are described.

  18. Free silanols and ionic liquids as their suppressors in liquid chromatography.

    Science.gov (United States)

    Buszewska-Forajta, Magdalena; Markuszewski, Michał J; Kaliszan, Roman

    2018-07-20

    In this review, we will firstly discuss the types and the general properties of silica, focusing on the silica support used in chromatography and capillary electrophoresis. Additionally, the characterization of functional groups (silanols and siloxanes) will be considered in terms of activity of the stationary phases. We will then discuss physical chemistry of the stationary phases applied in liquid chromatography and capillary electrophoresis. The use of ionic liquids as a silanols' suppressors will be presented in the next parts of the study, along with the examples of specific applications. The review is completed with conclusions and an outlook for the future developments in the area of analytical applications of ionic liquids. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. The profile of a capillary liquid bridge between solid surfaces

    NARCIS (Netherlands)

    van Honschoten, J.W.; Tas, Niels Roelof; Elwenspoek, Michael Curt

    2010-01-01

    Scanning force microscopy, such as atomic force microscopy (AFM) is complicated by the capillary force of a water meniscus formed in air between the probe tip and the sample. This small liquid bridge between the hydrophilic sample and the sharp AFM tip can be formed by capillary condensation from

  20. Capillary sieving electrophoresis and micellar electrokinetic capillary chromatography produce highly correlated separation of tryptic digests

    Science.gov (United States)

    Dickerson, Jane A.; Dovichi, Norman J.

    2011-01-01

    We perform two-dimensional capillary electrophoresis on fluorescently labeled proteins and peptides. Capillary sieving electrophoresis was performed in the first dimension and micellar electrokinetic capillary chromatography was performed in the second. A cellular homogenate was labeled with the fluorogenic reagent FQ and separated using the system. This homogenate generated a pair of ridges; the first had essentially constant migration time in the CSE dimension, while the second had essentially constant migration time in the MEKC dimension. In addition a few spots were scattered through the electropherogram. The same homogenate was digested using trypsin, and then labeled and subjected to the two dimensional separation. In this case, the two ridges observed from the original two-dimensional separation disappeared, and were replaced by a set of spots that fell along the diagonal. Those spots were identified using a local-maximum algorithm and each was fit using a two-dimensional Gaussian surface by an unsupervised nonlinear least squares regression algorithm. The migration times of the tryptic digest components were highly correlated (r = 0.862). When the slowest migrating components were eliminated from the analysis, the correlation coefficient improved to r = 0.956. PMID:20564272

  1. Análise enantiosseletiva de fármacos: contribuições da cromatografia líquida de alta eficiência e eletroforese capilar Enantioselective analysis of drugs: contributions of high-performance liquid chromatography and capillary electrophoresis

    Directory of Open Access Journals (Sweden)

    Pierina Sueli Bonato

    2005-08-01

    Full Text Available The demand for analytical methods suitable for accurate and reproducible determination of drug enantiomers has increased significantly in the last years. High-performance liquid chromatography (HPLC using chiral stationary phases and capillary electrophoresis (CE are the most important techniques used for this purpose. In this paper, the fundamental aspects of chiral separations using both techniques are presented. Some important aspects for the development of enantioselective methods, particularly for the analysis of drugs and metabolites in biological samples, are also discussed.

  2. Rotor for processing liquids using movable capillary tubes

    Science.gov (United States)

    Johnson, W.F.; Burtis, C.A.; Walker, W.A.

    1987-07-17

    A rotor assembly for processing liquids, especially whole blood samples, is disclosed. The assembly includes apparatus for separating non-liquid components of whole blood samples from liquid components, apparatus for diluting the separated liquid component with a diluent and apparatus for transferring the diluted sample to an external apparatus for analysis. The rotor assembly employs several movable capillary tubes to handle the sample and diluents. A method for using the rotor assembly to process liquids is also described. 5 figs.

  3. [High-performance liquid-liquid chromatography in beverage analysis].

    Science.gov (United States)

    Bricout, J; Koziet, Y; de Carpentrie, B

    1978-01-01

    Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase.

  4. Temperature-based on-column solute focusing in capillary liquid chromatography reduces peak broadening from pre-column dispersion and volume overload when used alone or with solvent-based focusing.

    Science.gov (United States)

    Groskreutz, Stephen R; Horner, Anthony R; Weber, Stephen G

    2015-07-31

    On-column focusing is essential for satisfactory performance using capillary scale columns. On-column focusing results from generating transient conditions at the head of the column that lead to high solute retention. Solvent-based on-column focusing is a well-known approach to achieve this. Temperature-assisted on-column focusing (TASF) can also be effective. TASF improves focusing by cooling a short segment of the column inlet to a temperature that is lower than the column temperature during the injection and then rapidly heating the focusing segment to the match the column temperature. A troublesome feature of an earlier implementation of TASF was the need to leave the capillary column unpacked in that portion of the column inside the fitting connecting it to the injection valve. We have overcome that problem in this work by packing the head of the column with solid silica spheres. In addition, technical improvements to the TASF instrumentation include: selection of a more powerful thermo-electric cooler to create faster temperature changes and electronic control for easy incorporation into conventional capillary instruments. Used in conjunction with solvent-based focusing and with isocratic elution, volumes of paraben samples (esters of p-hydroxybenzoic acid) up to 4.5-times the column liquid volume can be injected without significant bandspreading due to volume overload. Interestingly, the shapes of the peaks from the lowest volume injections that we can make, 30nL, are improved when using TASF. TASF is very effective at reducing the detrimental effects of pre-column dispersion using isocratic elution. Finally, we show that TASF can be used to focus the neuropeptide galanin in a sample solvent with elution strength stronger than the mobile phase. Here, the stronger solvent is necessitated by the need to prevent peptide adsorption prior to and during analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Temperature-based on-column solute focusing in capillary liquid chromatography reduces peak broadening from precolumn dispersion and volume overload when used alone or with solvent-based focusing

    Science.gov (United States)

    Groskreutz, Stephen R.; Horner, Anthony R.; Weber, Stephen G.

    2015-01-01

    On-column focusing is essential for satisfactory performance using capillary scale columns. On-column focusing results from generating transient conditions at the head of the column that lead to high solute retention. Solvent-based on-column focusing is a well-known approach to achieve this. Temperature-assisted on-column focusing (TASF) can also be effective. TASF improves focusing by cooling a short segment of the column inlet to a temperature that is lower than the column temperature during the injection and then rapidly heating the focusing segment to the match the column temperature. A troublesome feature of an earlier implementation of TASF was the need to leave the capillary column unpacked in that portion of the column inside the fitting connecting it to the injection valve. We have overcome that problem in this work by packing the head of the column with solid silica spheres. In addition, technical improvements to the TASF instrumentation include: selection of a more powerful thermo-electric cooler to create faster temperature changes and electronic control for easy incorporation into conventional capillary instruments. Used in conjunction with solvent-based focusing and with isocratic elution, volumes of paraben samples (esters of p-hydroxybenzoic acid) up to 4.5-times the column liquid volume can be injected without significant bandspreading due to volume overload. Interestingly, the shapes of the peaks from the lowest volume injections that we can make, 30 nL, are improved when using TASF. TASF is very effective at reducing the detrimental effects of precolumn dispersion using isocratic elution. Finally, we show that TASF can be used to focus the neuropeptide galanin in a sample solvent with elution strength stronger than the mobile phase. Here, the stronger solvent is necessitated by the need to prevent peptide adsorption prior to and during analysis. PMID:26091787

  6. Gradient High Performance Liquid Chromatography Method ...

    African Journals Online (AJOL)

    Purpose: To develop a gradient high performance liquid chromatography (HPLC) method for the simultaneous determination of phenylephrine (PHE) and ibuprofen (IBU) in solid ..... nimesulide, phenylephrine. Hydrochloride, chlorpheniramine maleate and caffeine anhydrous in pharmaceutical dosage form. Acta Pol.

  7. UHPLC: The Greening Face of Liquid Chromatography

    OpenAIRE

    Cielecka-Piontek, Judyta; Zalewski, Przemys?aw; Jeli?ska, Anna; Garbacki, Piotr

    2013-01-01

    Pharmaceutical analysis based on chromatographic separation is an important part of studies aimed at developing routine quality analysis of drugs. High-performance liquid chromatography (HPLC) is one of the main analytical techniques recommended for drug analysis. Although it meets many criteria vital for analysis, it is time-consuming and uses a relatively high amount of organic solvents compared to other analytical techniques. Recently, Ultra-high-performance liquid chromatography (UHPLC) h...

  8. Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones.

    Science.gov (United States)

    Carnes, Stephanie; O'Brien, Stacey; Szewczak, Angelica; Tremeau-Cayel, Lauriane; Rowe, Walter F; McCord, Bruce; Lurie, Ira S

    2017-09-01

    A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite-5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. High-performance liquid chromatography determination of dapsone, monoacetyldapsone, and pyrimethamine in filter paper blood spots

    DEFF Research Database (Denmark)

    Rønn, A M; Lemnge, M M; Angelo, H R

    1995-01-01

    A high-performance liquid chromatography method for the simultaneous analysis of dapsone (DDS), the major metabolite of DDS, monoacetyldapsone (MADDS), and pyrimethamine (PYR) was modified for capillary blood samples obtained by finger prick and dried on filter paper. Limit of quantitation using...

  10. Steroids in porcine follicular fluid: analysis by HPLC, capillary CG and capillary CG/MS after purification on SEP-PAK C18 and ion exchange chromatography.

    Science.gov (United States)

    Khalil, M W; Lawson, V

    1983-04-01

    Steroids in porcine follicular fluid have been concentrated by reverse phase chromatography in SEP-PAK C18 and purified further on the cation exchanger SP-Sephadex C-25. Fractionation into unconjugated neutral and phenolic steroids, glucuronides and sulfates was carried out on triethylaminohydroxypropyl Sephadex LH-20 (TEAP-LH-20). The unconjugated neutral fraction was analysed by high pressure liquid chromatography (HPLC) on a C18 radial cartridge 5 mm I.D.; 10 mu, or on a C18 5 mu RESOLVE column, and by capillary gas chromatography (GC) on a 12 M OV-1 cross linked fused silica column. Testosterone, progesterone and androstenedione were the major steroids detected by HPLC monitored at 254 nm, although 17- hydroxy-, 20 alpha-dihydro- and 20 beta-dihydroprogesterone were also present. Pregnenolone, pregnanediol, dehydroepiandrosterone, 17-hydroxypregnenolone and androsterone were detected by capillary CG as their 0-methyloxime trimethylsilyether derivatives. Further confirmation of structure was provided by complete mass spectral data or by selective ion monitoring (SIM).

  11. Liquid chromatography detection unit, system, and method

    Science.gov (United States)

    Derenzo, Stephen E.; Moses, William W.

    2015-10-27

    An embodiment of a liquid chromatography detection unit includes a fluid channel and a radiation detector. The radiation detector is operable to image a distribution of a radiolabeled compound as the distribution travels along the fluid channel. An embodiment of a liquid chromatography system includes an injector, a separation column, and a radiation detector. The injector is operable to inject a sample that includes a radiolabeled compound into a solvent stream. The position sensitive radiation detector is operable to image a distribution of the radiolabeled compound as the distribution travels along a fluid channel. An embodiment of a method of liquid chromatography includes injecting a sample that comprises radiolabeled compounds into a solvent. The radiolabeled compounds are then separated. A position sensitive radiation detector is employed to image distributions of the radiolabeled compounds as the radiolabeled compounds travel along a fluid channel.

  12. Continuous determination of volatile products in anaerobic fermenters by on-line capillary gas chromatography

    International Nuclear Information System (INIS)

    Diamantis, V.; Melidis, P.; Aivasidis, A.

    2006-01-01

    Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer

  13. Wall modified photonic crystal fibre capillaries as porous layer open tubular columns for in-capillary micro-extraction and capillary chromatography

    International Nuclear Information System (INIS)

    Kazarian, Artaches A.; Sanz Rodriguez, Estrella; Deverell, Jeremy A.; McCord, James; Muddiman, David C.; Paull, Brett

    2016-01-01

    Wall modified photonic crystal fibre capillary columns for in-capillary micro-extraction and liquid chromatographic separations is presented. Columns contained 126 internal parallel 4 μm channels, each containing a wall bonded porous monolithic type polystyrene-divinylbenzene layer in open tubular column format (PLOT). Modification longitudinal homogeneity was monitored using scanning contactless conductivity detection and scanning electron microscopy. The multichannel open tubular capillary column showed channel diameter and polymer layer consistency of 4.2 ± 0.1 μm and 0.26 ± 0.02 μm respectively, and modification of 100% of the parallel channels with the monolithic polymer. The modified multi-channel capillaries were applied to the in-capillary micro-extraction of water samples. 500 μL of water samples containing single μg L"−"1 levels of polyaromatic hydrocarbons were extracted at a flow rate of 10 μL min"−"1, and eluted in 50 μL of acetonitrile for analysis using HPLC with fluorescence detection. HPLC LODs were 0.08, 0.02 and 0.05 μg L"−"1 for acenaphthene, anthracene and pyrene, respectively, with extraction recoveries of between 77 and 103%. The modified capillaries were also investigated briefly for direct application to liquid chromatographic separations, with the retention and elution of a standard protein (cytochrome c) under isocratic conditions demonstrated, proving chromatographic potential of the new column format, with run-to-run retention time reproducibility of below 1%. - Highlights: • Novel PS-DVB modified photonic crystal fibres for in-capillary micro-extraction. • New method for micro-extraction of PAHs and HPLC-FL detection at sub-ppb levels. • Demonstration of PS-DVB modified photonic crystal fibres for capillary bioseparations.

  14. Wall modified photonic crystal fibre capillaries as porous layer open tubular columns for in-capillary micro-extraction and capillary chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Kazarian, Artaches A. [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); W.M. Keck FT-ICR-MS Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Sanz Rodriguez, Estrella; Deverell, Jeremy A. [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); McCord, James; Muddiman, David C. [W.M. Keck FT-ICR-MS Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Paull, Brett, E-mail: Brett.Paull@utas.edu.au [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); ARC Centre of Excellence for Electromaterials Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia)

    2016-01-28

    Wall modified photonic crystal fibre capillary columns for in-capillary micro-extraction and liquid chromatographic separations is presented. Columns contained 126 internal parallel 4 μm channels, each containing a wall bonded porous monolithic type polystyrene-divinylbenzene layer in open tubular column format (PLOT). Modification longitudinal homogeneity was monitored using scanning contactless conductivity detection and scanning electron microscopy. The multichannel open tubular capillary column showed channel diameter and polymer layer consistency of 4.2 ± 0.1 μm and 0.26 ± 0.02 μm respectively, and modification of 100% of the parallel channels with the monolithic polymer. The modified multi-channel capillaries were applied to the in-capillary micro-extraction of water samples. 500 μL of water samples containing single μg L{sup −1} levels of polyaromatic hydrocarbons were extracted at a flow rate of 10 μL min{sup −1}, and eluted in 50 μL of acetonitrile for analysis using HPLC with fluorescence detection. HPLC LODs were 0.08, 0.02 and 0.05 μg L{sup −1} for acenaphthene, anthracene and pyrene, respectively, with extraction recoveries of between 77 and 103%. The modified capillaries were also investigated briefly for direct application to liquid chromatographic separations, with the retention and elution of a standard protein (cytochrome c) under isocratic conditions demonstrated, proving chromatographic potential of the new column format, with run-to-run retention time reproducibility of below 1%. - Highlights: • Novel PS-DVB modified photonic crystal fibres for in-capillary micro-extraction. • New method for micro-extraction of PAHs and HPLC-FL detection at sub-ppb levels. • Demonstration of PS-DVB modified photonic crystal fibres for capillary bioseparations.

  15. A Partial Equilibrium Theory for Drops and Capillary Liquids

    International Nuclear Information System (INIS)

    Searcy, Alan W.; Beruto, Dario T.; Barberis, Fabrizio

    2006-01-01

    The two-century old theory of Young and Laplace retains a powerful influence on surface and interface studies because it quantitatively predicts the height of rise of capillary liquids from the contact angles of drops. But the classical theory does not acknowledge that equilibrium requires separate minimization of partial free energies of one-component liquids bonded to immiscible solids. We generalize a theorem of Gibbs and Curie to obtain a partial equilibrium (PE) theory that does so and that also predicts the height of capillary rise from contact angles of drops. Published observations and our own measurements of contact angles of water bonded to glass and Teflon surfaces support the conclusion of PE theory that contact angles of meniscuses and of drops are different dependent variables. PE theory provides thermodynamic and kinetic guidance to nanoscale processes that the classical theory obscures, as illustrated by examples in our concluding section

  16. Validated High Performance Liquid Chromatography Method for ...

    African Journals Online (AJOL)

    Purpose: To develop a simple, rapid and sensitive high performance liquid chromatography (HPLC) method for the determination of cefadroxil monohydrate in human plasma. Methods: Schimadzu HPLC with LC solution software was used with Waters Spherisorb, C18 (5 μm, 150mm × 4.5mm) column. The mobile phase ...

  17. Electronic spectral detection in liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Biggs, Wilton R. [ChevronTexaco Chemical Co., P. O. Box 1627, Richmond, CA 94802 (United States); Fetzer, John C. [Fetzpahs Consulting, 1283 Santa Fe St., Hercules, CA 94547 (United States)

    2002-07-01

    The use of absorbance and fluorescence spectrometers as liquid chromatography detectors is described. These detectors offer sensitive detection that can also identify the peaks in a chromatogram. Many examples, mainly from the separation of polycyclic aromatic hydrocarbons, are given that show the selectivity and usefulness of these detectors. (orig.)

  18. Instrument platforms for nano liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Šesták, Jozef; Moravcová, Dana; Kahle, Vladislav

    2015-01-01

    Roč. 1421, NOV (2015), s. 2-17 ISSN 0021-9673 R&D Projects: GA MV VG20112015021 Institutional support: RVO:68081715 Keywords : nano liquid chromatography * splitless gradient generation * nano LC platforms Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.926, year: 2015 http://hdl.handle.net/11104/0250900

  19. Ultra Performance Liquid Chromatography Tandem Mass ...

    African Journals Online (AJOL)

    NICOLAAS

    drugs alone.16. After a single oral dose of 120–800 mg of NTB in healthy sub- jects in a fasting state the peak plasma NTB concentration (tmax) was found to be 4–7 h, with a half-life of approximately 9–17 h.17 ... performance liquid chromatography mass spectrometry/mass .... to the likely biological plasma constituents.

  20. Application of micellar electrokinetic capillary chromatography for routine analysis of different materials

    Directory of Open Access Journals (Sweden)

    Injac Rade

    2008-01-01

    Full Text Available Micellar electrokinetic capillary chromatography (MEKC has become a popular mode among the several capillary electro-migration techniques. Most drug analysis can be performed by using MEKC because of its wide applicability. Separation of very complex mixtures, determination of drugs in the biological materials, etc., can be successfully achieved by MEKC. This review surveys typical applications of MEKC analysis. Recent advances in MEKC, especially with solid-phase extraction and large-volume sample stacking, are described. Modes of electrokinetic chromatography including MEKC, a separation theory of MEKC, environmental friendly analysis, and selectivity manipulation in MEKC are also briefly mentioned.

  1. High Performance Liquid Chromatography Experiments to Undergraduate Laboratories

    Science.gov (United States)

    Kissinger, Peter T.; And Others

    1977-01-01

    Reviews the principles of liquid chromatography with electrochemical detection (LCEC), an analytical technique that incorporates the advantages of both liquids chromatography and electrochemistry. Also suggests laboratory experiments using this technique. (MLH)

  2. Development of a high performance liquid chromatography method ...

    African Journals Online (AJOL)

    Development of a high performance liquid chromatography method for simultaneous ... Purpose: To develop and validate a new low-cost high performance liquid chromatography (HPLC) method for ..... Several papers have reported the use of ...

  3. Gas chromatography-mass spectrometry and high-performance liquid chromatographic analyses of thermal degradation products of common plastics

    OpenAIRE

    Pacakova, V.; Leclercq, P.A.

    1991-01-01

    The thermo-oxidation of five commonly used materials, namely low-density polyethylene, retarded polyethylene, paper with a polyethylene foil, a milk package and filled polypropylene, was studied. Capillary gas chromatography and gas chromatography-mass spectrometry were used to analyze the volatile degradation products, while high-performance liquid chromatography was employed to measure polycyclic aromatic hydrocarbons. The results are discussed from the point of view of toxicity of the prod...

  4. Optimizing separations in online comprehensive two‐dimensional liquid chromatography

    OpenAIRE

    Pirok, Bob W.J.; Gargano, Andrea F.G.; Schoenmakers, Peter J.

    2017-01-01

    Abstract Online comprehensive two‐dimensional liquid chromatography has become an attractive option for the analysis of complex nonvolatile samples found in various fields (e.g. environmental studies, food, life, and polymer sciences). Two‐dimensional liquid chromatography complements the highly popular hyphenated systems that combine liquid chromatography with mass spectrometry. Two‐dimensional liquid chromatography is also applied to the analysis of samples that are not compatible with mass...

  5. Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay

    International Nuclear Information System (INIS)

    Castro, A.; Ibanez, J.; DiCesare, J.L.; Adams, R.F.; Malkus, H.

    1978-01-01

    Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoasay, enzyme immunoassay, and liquid chromatography. The assay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods

  6. Nanomaterials as stationary phases and supports in liquid chromatography.

    Science.gov (United States)

    Beeram, Sandya R; Rodriguez, Elliott; Doddavenkatanna, Suresh; Li, Zhao; Pekarek, Allegra; Peev, Darin; Goerl, Kathryn; Trovato, Gianfranco; Hofmann, Tino; Hage, David S

    2017-10-01

    The development of various nanomaterials over the last few decades has led to many applications for these materials in liquid chromatography (LC). This review will look at the types of nanomaterials that have been incorporated into LC systems and the applications that have been explored for such systems. A number of carbon-based nanomaterials and inorganic nanomaterials have been considered for use in LC, ranging from carbon nanotubes, fullerenes and nanodiamonds to metal nanoparticles and nanostructures based on silica, alumina, zirconia and titanium dioxide. Many ways have been described for incorporating these nanomaterials into LC systems. These methods have included covalent immobilization, adsorption, entrapment, and the synthesis or direct development of nanomaterials as part of a chromatographic support. Nanomaterials have been used in many types of LC. These applications have included the reversed-phase, normal-phase, ion-exchange, and affinity modes of LC, as well as related methods such as chiral separations, ion-pair chromatography and hydrophilic interaction liquid chromatography. Both small and large analytes (e.g., dyes, drugs, amino acids, peptides and proteins) have been used to evaluate possible applications for these nanomaterial-based methods. The use of nanomaterials in columns, capillaries and planar chromatography has been considered as part of these efforts. Potential advantages of nanomaterials in these applications have included their good chemical and physical stabilities, the variety of interactions many nanomaterials can have with analytes, and their unique retention properties in some separation formats. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. High perfomance liquid chromatography in pharmaceutical analyses.

    Science.gov (United States)

    Nikolin, Branko; Imamović, Belma; Medanhodzić-Vuk, Saira; Sober, Miroslav

    2004-05-01

    In testing the pre-sale procedure the marketing of drugs and their control in the last ten years, high performance liquid chromatography replaced numerous spectroscopic methods and gas chromatography in the quantitative and qualitative analysis. In the first period of HPLC application it was thought that it would become a complementary method of gas chromatography, however, today it has nearly completely replaced gas chromatography in pharmaceutical analysis. The application of the liquid mobile phase with the possibility of transformation of mobilized polarity during chromatography and all other modifications of mobile phase depending upon the characteristics of substance which are being tested, is a great advantage in the process of separation in comparison to other methods. The greater choice of stationary phase is the next factor which enables realization of good separation. The separation line is connected to specific and sensitive detector systems, spectrafluorimeter, diode detector, electrochemical detector as other hyphernated systems HPLC-MS and HPLC-NMR, are the basic elements on which is based such wide and effective application of the HPLC method. The purpose high performance liquid chromatography (HPLC) analysis of any drugs is to confirm the identity of a drug and provide quantitative results and also to monitor the progress of the therapy of a disease.1) Measuring presented on the Fig. 1. is chromatogram obtained for the plasma of depressed patients 12 h before oral administration of dexamethasone. It may also be used to further our understanding of the normal and disease process in the human body trough biomedical and therapeutically research during investigation before of the drugs registration. The analyses of drugs and metabolites in biological fluids, particularly plasma, serum or urine is one of the most demanding but one of the most common uses of high performance of liquid chromatography. Blood, plasma or serum contains numerous endogenous

  8. Recent development of ionic liquid stationary phases for liquid chromatography.

    Science.gov (United States)

    Shi, Xianzhe; Qiao, Lizhen; Xu, Guowang

    2015-11-13

    Based on their particular physicochemical characteristics, ionic liquids have been widely applied in many fields of analytical chemistry. Many types of ionic liquids were immobilized on a support like silica or monolith as stationary phases for liquid chromatography. Moreover, different approaches were developed to bond covalently ionic liquids onto the supporting materials. The obtained ionic liquid stationary phases show multi-mode mechanism including hydrophobic, hydrophilic, hydrogen bond, anion exchange, π-π, and dipole-dipole interactions. Therefore, they could be used in different chromatographic modes including ion-exchange, RPLC, NPLC and HILIC to separate various classes of compounds. This review mainly summarizes the immobilized patterns and types of ionic liquid stationary phases, their retention mechanisms and applications in the recent five years. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Monitoring the behaviour of 4-ketocyclophosphamide versus cyclophosphamide during capillary gas chromatography by mass spectrometry

    NARCIS (Netherlands)

    Bruijn, de E.A.; Oosterom, van A.T.; Leclercq, P.A.; Haan, de J.W.; Ven, van de L.J.M.; Tjaden, U.R.

    1987-01-01

    Capillary Gas Chromatography (CGC) is capable of determining underivatized cyclophosphamide (CPA) using SCOT OV 275 columns. Then CPA is subjected to in situ degradation resulting in formation of a cyclization product which can be determined selectively in biological fluids. In routine bioanalysis

  10. Flow rate control in pressure-programmed capillary supercritical fluid chromatography

    NARCIS (Netherlands)

    Janssen, J.G.M.; Rijks, J.A.; Cramers, C.A.M.G.

    1990-01-01

    A versatile and simple system is described that allows variation of the column flow rate in open-tubular capillary supercritical fluid chromatography using both on-column and postcolumn detection. The system is based on column-effluent splitting in a low-dead-volume T piece at the column exit just

  11. Investigation of parameters affecting the online combination of supercritical fluid extraction with capillary gas chromatography

    NARCIS (Netherlands)

    Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.M.G.

    1996-01-01

    Two different injectors, a split/splitless injector and a programmed temperature vaporizer (PTV) injector were investigated as the interface in on-line supercritical fluid extraction (SFE)-capillary gas chromatography (cGC). The parameters affecting the chromatographic peak shapes as well as the

  12. Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

    Directory of Open Access Journals (Sweden)

    Glen McHale

    2011-03-01

    Full Text Available In the wetting of a solid by a liquid it is often assumed that the substrate is rigid. However, for an elastic substrate the rigidity depends on the cube of its thickness and so reduces rapidly as the substrate becomes thinner as it approaches becoming a thin sheet. In such circumstances, it has been shown that the capillary forces caused by a contacting droplet of a liquid can shape the solid rather than the solid shaping the liquid. A substrate can be bent and folded as a (pinned droplet evaporates or even instantaneously and spontaneously wrapped on contact with a droplet. When this effect is used to create three dimensional shapes from initially flat sheets, the effect is called capillary origami or droplet wrapping.In this work, we consider how the conditions for the spontaneous, capillary induced, folding of a thin ribbon substrate might be altered by a rigid surface structure that, for a rigid substrate, would be expected to create Cassie–Baxter and Wenzel effects. For smooth thin substrates, droplet wrapping can occur for all liquids, including those for which the Young’s law contact angle (defined by the interfacial tensions is greater than 90° and which would therefore normally be considered relatively hydrophobic. However, consideration of the balance between bending and interfacial energies suggests that the tendency for droplet wrapping can be suppressed for some liquids by providing the flexible solid surface with a rigid topographic structure. In general, it is known that when a liquid interacts with such a structure it can either fully penetrate the structure (the Wenzel case or it can bridge between the asperities of the structure (the Cassie–Baxter case.In this report, we show theoretically that droplet wrapping should occur with both types of solid–liquid contact. We also derive a condition for the transition between the Cassie–Baxter and Wenzel type droplet wrapping and relate it to the same transition condition

  13. UHPLC: The Greening Face of Liquid Chromatography.

    Science.gov (United States)

    Cielecka-Piontek, Judyta; Zalewski, Przemysław; Jelińska, Anna; Garbacki, Piotr

    2013-01-01

    Pharmaceutical analysis based on chromatographic separation is an important part of studies aimed at developing routine quality analysis of drugs. High-performance liquid chromatography (HPLC) is one of the main analytical techniques recommended for drug analysis. Although it meets many criteria vital for analysis, it is time-consuming and uses a relatively high amount of organic solvents compared to other analytical techniques. Recently, Ultra-high-performance liquid chromatography (UHPLC) has been frequently proposed as an alternative to HPLC, which means introducing an environment-friendly approach to drug analysis achieved by reducing the consumption of solvents. It also offers greater chromatographic resolution and higher sensitivity as well as requiring less time due to faster analysis. This review focuses on the basics of UHPLC, compares that technique with HPLC and discusses the possibilities of applying UHPLC for the analysis of different pharmaceuticals and biopharmaceuticals.

  14. High performance liquid chromatography in pharmaceutical analyses

    Directory of Open Access Journals (Sweden)

    Branko Nikolin

    2004-05-01

    Full Text Available In testing the pre-sale procedure the marketing of drugs and their control in the last ten years, high performance liquid chromatographyreplaced numerous spectroscopic methods and gas chromatography in the quantitative and qualitative analysis. In the first period of HPLC application it was thought that it would become a complementary method of gas chromatography, however, today it has nearly completely replaced gas chromatography in pharmaceutical analysis. The application of the liquid mobile phase with the possibility of transformation of mobilized polarity during chromatography and all other modifications of mobile phase depending upon the characteristics of substance which are being tested, is a great advantage in the process of separation in comparison to other methods. The greater choice of stationary phase is the next factor which enables realization of good separation. The separation line is connected to specific and sensitive detector systems, spectrafluorimeter, diode detector, electrochemical detector as other hyphernated systems HPLC-MS and HPLC-NMR, are the basic elements on which is based such wide and effective application of the HPLC method. The purpose high performance liquid chromatography(HPLC analysis of any drugs is to confirm the identity of a drug and provide quantitative results and also to monitor the progress of the therapy of a disease.1 Measuring presented on the Fig. 1. is chromatogram obtained for the plasma of depressed patients 12 h before oral administration of dexamethasone. It may also be used to further our understanding of the normal and disease process in the human body trough biomedical and therapeutically research during investigation before of the drugs registration. The analyses of drugs and metabolites in biological fluids, particularly plasma, serum or urine is one of the most demanding but one of the most common uses of high performance of liquid chromatography. Blood, plasma or

  15. Ion exchange and liquid column chromatography

    International Nuclear Information System (INIS)

    Walton, H.F.

    1980-01-01

    Major accomplishments in liquid chromatography for the past two years and reported in journals available to December 31, 1979 are reviewed. Emphasis has been placed on principles and methodology with some representative examples of application included. Applications are illustrated in two rather lenghtly tables, one covering inorganic ions and the other covering organic compounds. 544 references, 8 books, and 15 reviews are listed in the bibliography

  16. Comparison of capillary electrophoresis and high performance liquid chromatography methods for caffeine determination in decaffeinated coffee Comparação de métodos por eletroforese capilar e cromatografia líquida de alta eficiência para a determinação de cafeína em café descafeinado

    Directory of Open Access Journals (Sweden)

    Carolina Schaper Bizzotto

    2013-03-01

    Full Text Available Decaffeinated coffee accounts for 10 percent of coffee sales in the world; it is preferred by consumers that do not wish or are sensitive to caffeine effects. This article presents an analytical comparison of capillary electrophoresis (CE and high performance liquid chromatography (HPLC methods for residual caffeine quantification in decaffeinated coffee in terms of validation parameters, costs, analysis time, composition and treatment of the residues generated, and caffeine quantification in 20 commercial samples. Both methods showed suitable validation parameters. Caffeine content did not differ statistically in the two different methods of analysis. The main advantage of the high performance liquid chromatography (HPLC method was the 42-fold lower detection limit. Nevertheless, the capillary electrophoresis (CE detection limit was 115-fold lower than the allowable limit by the Brazilian law. The capillary electrophoresis (CE analyses were 30% faster, the reagent costs were 76.5-fold, and the volume of the residues generated was 33-fold lower. Therefore, the capillary electrophoresis (CE method proved to be a valuable analytical tool for this type of analysis.O comércio de café descafeinado constitui 10% das vendas mundiais de café, sendo preferido pelos consumidores que não desejam ou são sensíveis aos efeitos da cafeína. Este artigo apresenta uma comparação analítica de métodos por eletroforese capilar (CE e cromatografia líquida de alta eficiência (HPLC para a quantificação de cafeína residual em café descafeinado, quanto aos parâmetros de validação, custos, tempo de análise, composição e tratamento dos resíduos gerados, bem como quantificação de cafeína em 20 amostras comerciais. Ambos os métodos apresentaram parâmetros de validação adequados. O teor de cafeína não diferiu estatisticamente pelos dois métodos. A vantagem do método por HPLC foi o limite de detecção 42 vezes mais baixo. Não obstante, o

  17. Flow Rates in Liquid Chromatography, Gas Chromatography and Supercritical Fluid Chromatography: A Tool for Optimization

    Directory of Open Access Journals (Sweden)

    Joris Meurs

    2016-08-01

    Full Text Available This paper aimed to develop a standalone application for optimizing flow rates in liquid chromatography (LC, gas chromatography (GC and supercritical fluid chromatography (SFC. To do so, Van Deemter’s equation, Knox’ equation and Golay’s equation were implemented in a MATLAB script and subsequently a graphical user interface (GUI was created. The application will show the optimal flow rate or linear velocity and the corresponding plate height for the set input parameters. Furthermore, a plot will be shown in which the plate height is plotted against the linear flow velocity. Hence, this application will give optimized flow rates for any set conditions with minimal effort.

  18. Chromatography, solid-phase extraction, and capillary electrochromatography with MIPs.

    Science.gov (United States)

    Tóth, Blanka; Horvai, George

    2012-01-01

    Most analytical applications of molecularly imprinted polymers are based on their selective adsorption properties towards the template or its analogs. In chromatography, solid phase extraction and electrochromatography this adsorption is a dynamic process. The dynamic process combined with the nonlinear adsorption isotherm of the polymers and other factors results in complications which have limited the success of imprinted polymers. This chapter explains these problems and shows many examples of successful applications overcoming or avoiding the problems.

  19. The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Steven [Iowa State Univ., Ames, IA (United States)

    1999-02-12

    The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

  20. Interfacial layering and capillary roughness in immiscible liquids.

    Science.gov (United States)

    Geysermans, P; Pontikis, V

    2010-08-21

    The capillary roughness and the atomic density profiles of extended interfaces between immiscible liquids are determined as a function of the interface area by using molecular dynamics and Lennard-Jones (12-6) potentials. We found that with increasing area, the interface roughness diverges logarithmically, thus fitting the theoretical mean-field prediction. In systems small enough for the interfacial roughness not to blur the structural details, atomic density profiles across the fluid interface are layered with correlation length in the range of molecular correlations in liquids. On increasing the system size, the amplitude of the thermally excited position fluctuations of the interface increases, thus causing layering to rapidly vanish, if density profiles are computed without special care. In this work, we present and validate a simple method, operating in the direct space, for extracting from molecular dynamics trajectories the "intrinsic" structure of a fluid interface that is the local density profile of the interface cleaned from capillary wave effects. Estimated values of interfacial properties such as the tension, the intrinsic width, and the lower wavelength limit of position fluctuations are in agreement with results collected from the literature.

  1. Coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry for arsenic speciation.

    Science.gov (United States)

    Cheng, Heyong; Shen, Lihuan; Liu, Jinhua; Xu, Zigang; Wang, Yuanchao

    2018-04-01

    Nanoliter high-performance liquid chromatography shows low consumption of solvents and samples, offering one of the best choices for arsenic speciation in precious samples in combination with inuctively coupled plasma mass spectrometry. A systematic investigation on coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry from instrument design to injected sample volume and mobile phase was performed in this study. Nanoflow mobile phase was delivered by flow splitting using a conventional high-pressure pump with reuse of mobile phase waste. Dead volume was minimized to 60 nL for the sheathless interface based on the previously developed nanonebulizer. Capillary columns for nanoliter high-performance liquid chromatography were found to be sensitive to sample loading volume. An apparent difference was also found between the mobile phases for nanoliter and conventional high-performance liquid chromatography. Baseline separation of arsenite, arsenate, monomethylarsenic, and dimethylarsenic was achieved within 11 min on a 15 cm C 18 capillary column and within 12 min on a 25 cm strong anion exchange column. Detection limits of 0.9-1.8 μg/L were obtained with precisions variable in the range of 1.6-4.2%. A good agreement between determined and certified values of a certified reference material of human urine (GBW 09115) validated its accuracy along with good recoveries (87-102%). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Spillage detector for liquid chromatography systems

    Science.gov (United States)

    Jarvis, M. J.; Fulton, D. S. (Inventor)

    1986-01-01

    A spillage detector device for use in conjunction with fractionation of liquid chromatography systems which includes a spillage recieving enclosure beneath the fractionation area is described. A sensing device having a plurality of electrodes of alternating polarity is mounted within the spillage recieving enclosure. Detection circuitry, responsive to conductivity between electrodes, is operatively connected to the sensing device. The detection circuitry feeds into the output circuitry. The output circuit has relaying and switching circuitry directed to a solenoid, an alarm system and a pump. The solenoid is connected to the pliable conduit of the chromatography system. The alarm system comprises an audio alarm and a visual signal. A 115-volt power system interconnected with the pump, the solenoid, the sensing device, and the detection and output circuitry.

  3. Determination of surface tension coefficient of liquids by diffraction of light on capillary waves

    International Nuclear Information System (INIS)

    Nikolić, D; Nešić, Lj

    2012-01-01

    This paper describes a simple technique for determining the coefficient of the surface tension of liquids, based on laser light diffraction on capillary waves. Capillary waves of given frequency are created by an exciter needle acting on the surface of liquid and represent a reflective diffraction grating, the constant of which (the wavelength of capillary waves) can be determined based on a known incidence angle of light (grazing angle). We obtain the coefficient of the surface tension of liquids by applying the dispersion relation for capillary waves and analyze the difficulties that arise when setting up and conducting the experiment in detail. (paper)

  4. Characterisation of uremic "Middle molecular"fractions by gas chromatography mass spectrometry, isotachophoresis, and liquid chromatography

    NARCIS (Netherlands)

    Schoots, A.C.; Mikkers, F.E.P.; Claessens, H.A.; Smet, de R.; Landschoot, van N.; Ringoir, S.M.G.

    1982-01-01

    Uremic ultrafiltrates (and normal serum, for comparison) were fractionated by means of gel filtration. The collected fractions were further investigated by combined analytical techniques: "high- performance" liquid chromatography, gas chromatography, mass spectrometry, and isotachophoresis.

  5. Optimizing separations in online comprehensive two‐dimensional liquid chromatography

    Science.gov (United States)

    Gargano, Andrea F.G.; Schoenmakers, Peter J.

    2017-01-01

    Abstract Online comprehensive two‐dimensional liquid chromatography has become an attractive option for the analysis of complex nonvolatile samples found in various fields (e.g. environmental studies, food, life, and polymer sciences). Two‐dimensional liquid chromatography complements the highly popular hyphenated systems that combine liquid chromatography with mass spectrometry. Two‐dimensional liquid chromatography is also applied to the analysis of samples that are not compatible with mass spectrometry (e.g. high‐molecular‐weight polymers), providing important information on the distribution of the sample components along chemical dimensions (molecular weight, charge, lipophilicity, stereochemistry, etc.). Also, in comparison with conventional one‐dimensional liquid chromatography, two‐dimensional liquid chromatography provides a greater separation power (peak capacity). Because of the additional selectivity and higher peak capacity, the combination of two‐dimensional liquid chromatography with mass spectrometry allows for simpler mixtures of compounds to be introduced in the ion source at any given time, improving quantitative analysis by reducing matrix effects. In this review, we summarize the rationale and principles of two‐dimensional liquid chromatography experiments, describe advantages and disadvantages of combining different selectivities and discuss strategies to improve the quality of two‐dimensional liquid chromatography separations. PMID:29027363

  6. Optimizing separations in online comprehensive two-dimensional liquid chromatography.

    Science.gov (United States)

    Pirok, Bob W J; Gargano, Andrea F G; Schoenmakers, Peter J

    2018-01-01

    Online comprehensive two-dimensional liquid chromatography has become an attractive option for the analysis of complex nonvolatile samples found in various fields (e.g. environmental studies, food, life, and polymer sciences). Two-dimensional liquid chromatography complements the highly popular hyphenated systems that combine liquid chromatography with mass spectrometry. Two-dimensional liquid chromatography is also applied to the analysis of samples that are not compatible with mass spectrometry (e.g. high-molecular-weight polymers), providing important information on the distribution of the sample components along chemical dimensions (molecular weight, charge, lipophilicity, stereochemistry, etc.). Also, in comparison with conventional one-dimensional liquid chromatography, two-dimensional liquid chromatography provides a greater separation power (peak capacity). Because of the additional selectivity and higher peak capacity, the combination of two-dimensional liquid chromatography with mass spectrometry allows for simpler mixtures of compounds to be introduced in the ion source at any given time, improving quantitative analysis by reducing matrix effects. In this review, we summarize the rationale and principles of two-dimensional liquid chromatography experiments, describe advantages and disadvantages of combining different selectivities and discuss strategies to improve the quality of two-dimensional liquid chromatography separations. © 2017 The Authors. Journal of Separation Science published by WILEY-VCH Verlag GmbH & Co. KGaA.

  7. Harvesting liquid from unsaturated vapor - nanoflows induced by capillary condensation

    Science.gov (United States)

    Vincent, Olivier; Marguet, Bastien; Stroock, Abraham

    2016-11-01

    A vapor, even subsaturated, can spontaneously form liquid in nanoscale spaces. This process, known as capillary condensation, plays a fundamental role in various contexts, such as the formation of clouds or the dynamics of hydrocarbons in the geological subsurface. However, large uncertainties remain on the thermodynamics and fluid mechanics of the phenomenon, due to experimental challenges as well as outstanding questions about the validity of macroscale physics at the nanometer scale. We studied experimentally the spatio-temporal dynamics of water condensation in a model nanoporous medium (pore radius 2 nm), taking advantage of the color change of the material upon hydration. We found that at low relative humidities ( 60 % RH, driven by a balance between the pore capillary pressure and the condensation stress given by Kelvin equation. Further analyzing the imbibition dynamics as a function of saturation allowed us to extract detailed information about the physics of nano-confined fluids. Our results suggest excellent extension of macroscale fluid dynamics and thermodynamics even in pores 10 molecules in diameter.

  8. Electrically modulated capillary filling imbibition of nematic liquid crystals

    Science.gov (United States)

    Dhar, Jayabrata; Chakraborty, Suman

    2018-04-01

    The flow of nematic liquid crystals (NLCs) in the presence of an electric field is typically characterized by the variation in its rheological properties due to transition in its molecular arrangements. Here, we bring out a nontrivial interplay of a consequent alteration in the resistive viscous effects and driving electrocapillary interactions, toward maneuvering the capillary filling dynamics over miniaturized scales. Considering a dynamic interplay of the relevant bulk and interfacial forces acting in tandem, our results converge nicely to previously reported experimental data. Finally, we attempt a scaling analysis to bring forth further insight to the reported observations. Our analysis paves the way for the development of microfluidic strategies with previously unexplored paradigms of interaction between electrical and fluidic phenomenon, providing with an augmented controllability on capillary filling as compared to tthose reported to be achievable by the existing strategies. This, in turn, holds utilitarian scopes in improved designs of functional capillarities in electro-optical systems, electrorheological utilities, electrokinetic flow control, as well as in interfacing and imaging systems for biomedical microdevices.

  9. Liquid Chromatography Applied to Space System

    Science.gov (United States)

    Poinot, Pauline; Chazalnoel, Pascale; Geffroy, Claude; Sternberg, Robert; Carbonnier, Benjamin

    Searching for signs of past or present life in our Solar System is a real challenge that stirs up the curiosity of scientists. Until now, in situ instrumentation was designed to detect and determine concentrations of a wide number of organic biomarkers. The relevant method which was and still is employed in missions dedicated to the quest of life (from Viking to ExoMars) corresponds to the pyrolysis-GC-MS. Along the missions, this approach has been significantly improved in terms of extraction efficiency and detection with the use of chemical derivative agents (e.g. MTBSTFA, DMF-DMA, TMAH…), and in terms of analysis sensitivity and resolution with the development of in situ high-resolution mass spectrometer (e.g. TOF-MS). Thanks to such an approach, organic compounds such as amino acids, sugars, tholins or polycyclic aromatic hydrocarbons (PAHs) were expected to be found. However, while there’s a consensus that the GC-MS of Viking, Huygens, MSL and MOMA space missions worked the way they had been designed to, pyrolysis is much more in debate (Glavin et al. 2001; Navarro-González et al. 2006). Indeed, (1) it is thought to remove low levels of organics, (2) water and CO2 could interfere with the detection of likely organic pyrolysis products, and (3) only low to mid-molecular weight organic molecules can be detected by this technique. As a result, researchers are now focusing on other in situ techniques which are no longer based on the volatility of the organic matter, but on the liquid phase extraction and analysis. In this line, micro-fluidic systems involving sandwich and/or competitive immunoassays (e.g. LMC, SOLID; Parro et al. 2005; Sims et al. 2012), micro-chip capillary electrophoreses (e.g. MOA; Bada et al. 2008), or nanopore-based analysis (e.g. BOLD; Schulze-Makuch et al. 2012) have been conceived for in situ analysis. Thanks to such approaches, molecular biological polymers (polysaccharides, polypeptides, polynucleotides, phospholipids, glycolipids

  10. Thermally excited capillary waves at vapor/liquid interfaces of water-alcohol mixtures

    International Nuclear Information System (INIS)

    Vaknin, David; Bu Wei; Sung, Jaeho; Jeon, Yoonnam; Kim, Doseok

    2009-01-01

    The density profiles of liquid/vapor interfaces of water-alcohol (methanol, ethanol and propanol) mixtures were studied by surface-sensitive synchrotron x-ray scattering techniques. X-ray reflectivity and diffuse scattering measurements, from the pure and mixed liquids, were analyzed in the framework of capillary wave theory to address the characteristic length scales of the intrinsic roughness and the shortest capillary wavelength (alternatively, the upper wavevector cutoff in capillary wave theory). Our results establish that the intrinsic roughness is dominated by average interatomic distances. The extracted effective upper wavevector cutoff indicates capillary wave theory breaks down at distances of the order of bulk correlation lengths.

  11. Comprehensive two-dimensional liquid chromatography: Ion chromatography × reversed-phase liquid chromatography for separation of low-molar-mass organic acids

    NARCIS (Netherlands)

    Brudin, S.S.; Shellie, R.A.; Haddad, P.R.; Schoenmakers, P.J.

    2010-01-01

    In the work presented here a novel approach to comprehensive two-dimensional liquid chromatography is evaluated. Ion chromatography is chosen for the first-dimension separation and reversed-phase liquid chromatography is chosen for the second-dimension separation mode. The coupling of these modes is

  12. Oscillation of an isolated liquid plug inside a dry capillary

    Science.gov (United States)

    Srinivasan, Vyas; Kumar, Siddhartha; Asfer, Mohammed; Khandekar, Sameer

    2017-11-01

    The present work reports an experimental study on the dynamics of partially wetting isolated liquid plug (DI water), which is made to oscillate inside a square, glass capillary tube (1 mm × 1 mm; 60 mm length). The liquid plug is made to oscillate pneumatically at two different frequencies (0.25 and 0.35 Hz), using a cam-follower mechanism. Bright field imaging is used to visualize the three-phase contact line behavior, while, micro-Particle Imaging Velocimetry (PIV) apparatus is used to discern the nature of flow inside the oscillating liquid plug. During a cycle, due to the partial wetting nature of DI water, the three-phase contact line at the menisci gets pinned at the extreme end of each stroke, where the dynamic apparent contact angle gets drastically altered before the initiation of the next stroke. The difference between the apparent contact angle of the front and rear meniscus are seen to be a function of the oscillating frequency; the difference increasing with increasing frequency. The flow inside the liquid plug reveals unique non-Poiseuille flow features near the meniscus, due to free-slip boundary condition, which leads to formation of distinct vortex pairs behind it. The vortices too change their direction during each stroke of the oscillation, eventually leading to an alternating recirculation pattern inside the plug. The results clearly indicate that improved mathematical models are required for predicting transport parameters in such flows, which are important in engineering systems such as pulsating heat pipes, lab-on-chip devices and PEM fuel cells.

  13. Optimization of the combination micro-high-performance liquid-chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    Haider, K.

    1997-03-01

    The coupling of liquid chromatography and mass spectrometry is still growing in significance. In this thesis, a particle beam interface has been investigated for combining ion chromatography with mass spectrometric detection. To introduce the eluent directly (without membrane suppressor) into the spectrometer, only methods with low flow rates like microcolumn chromatography can be used. For the preparation of the columns, reversed-phase and silica-based anion exchange materials were packed into PEEK, steel and fused-silica capillaries with i.d. from 130 to 1000 μm using different methods. The performance of the particle beam interface (modified with a new miniaturized aerosol generator) and the mass spectrometric detection has been studied for a series of inorganic anions as well as aminopolycarboxylic acids and the metal-EDTA complexes. Detection limits between 10 and 100 ng injected could be achieved in the multiple ion detection mode of the mass spectrometer for the investigated solutes. A second type of interface, the direct liquid introduction (DLI) has been used to analyze the priority pollutant phenols. This interface is based on a modified GC-interface into the MS. Separation columns used so far include packed fused-silica capillaries with inner diameter of 75 μm and polystyrene-divinylbenzene (functionalized with tert. butyl groups) as stationary phase. Aspects of instrumentation and effects of chemical ionization in the direct liquid introduction mode are discussed. (author)

  14. Determination of carbofuran on hydrophilic interaction liquid chromatography using TSK gel amide 80 as stationary phase

    International Nuclear Information System (INIS)

    A Kurnia; LW Lim; T Takeuchi

    2016-01-01

    The hydrophilic interaction liquid chromatography (HILIC) coupled to environmental friendly capillary liquid chromatography was employed to investigate retention behavior of carbofuran. Aim of this research is to investigate retention behavior of carbofuran using TSK gel amide 80 as stationary phase. Several condition was conducted to investigate retention behavior of carbofuran such as comparison study of TSK gel amide 80 with other polar column, comparison study retention behavior of carbofuran on various system wavelength, water content effect in HILIC mode, effect of buffer concentration on HILIC mode, and analytical performance. Results showed that TSK gel imidazole was superior compare to other polar stationary phase on determine carbofuran, wavelength 251 and 254 nm was resulting higher absorbance for carbofuran than others, increase of water content on mobile phase was decrease the retention time, also increase buffer salt concentration was decrease the retention time and according to analysis performance that is the accuracy was 101±10,1, the LOD 0.66 ppm while LOQ 2.22 ppm. As conclusions that TSK gel amide 80 was offering good determine on carbofuran even using capillary liquid chromatography with 10 cm length of column. (author)

  15. On the capillary restriction in start-up regimes of liquid metal evaporation from capillary-porous surfaces

    International Nuclear Information System (INIS)

    Prosvetov, V.V.

    1979-01-01

    Evaporation of liquid metals from capillary-porous structures is one of the most effective methods of surface cooling, to which essential heat quantity is delivered at high temperatures. The paper deals with heat flux limitation, caused by incapability of core capillary forces to overcome pressure differential in heat carrier circulation shape in such evaporation regimes, when average length of free path of vapour molecule exceeds core cell size. Suggested are theoretical correlations for determination of critical heat flux density and temperature of liquid surface in starting regimes of liquid metal evaporation from rectangular slots and compound cores with screens made of foil with round perforations. The catculative and experimental values of critical heat flux density in starting regimes of sodium evaporation from rectangular slots satisfactorily agree with each other

  16. Capillary Structured Suspensions from in Situ Hydrophobized Calcium Carbonate Particles Suspended in a Polar Liquid Media

    NARCIS (Netherlands)

    Dunstan, Timothy S.; Das, Anupam A.K.; Starck, Pierre; Stoyanov, Simeon D.; Paunov, Vesselin N.

    2018-01-01

    We demonstrate that capillary suspensions can be formed from hydrophilic calcium carbonate particles suspended in a polar continuous media and connected by capillary bridges formed of minute amounts of an immiscible secondary liquid phase. This was achieved in two different polar continuous phases,

  17. Determination of cocaine in brazilian paper currency by capillary gas chromatography/mass spectrometry

    Directory of Open Access Journals (Sweden)

    Enrico Di Donato

    2007-01-01

    Full Text Available The presence of illicit drugs such as cocaine and marijuana in US paper currency is very well demonstrated. However, there is no published study describing the presence of cocaine and/or other illicit drugs in Brazilian paper currency. In this study, Brazilian banknotes were collected from nine cities, extracted and analyzed by capillary gas chromatography/mass spectrometry, in order to investigate the presence of cocaine. Bills were extracted with deionized water followed by ethyl acetate. Results showed that 93% of the bills presented cocaine in a concentration range of 2.38-275.10 µg/bill.

  18. Liquid distribution and cohesion in wet granular assemblies beyond the capillary bridge regime

    International Nuclear Information System (INIS)

    Scheel, M; Seemann, R; Brinkmann, M; Herminghaus, S; Di Michiel, M; Sheppard, A

    2008-01-01

    Dry sand turns into a stiff and moldable material as soon as it is mixed with some liquid. This is a direct consequence of the internal liquid-air interfaces spanning between the grains which causes capillary cohesion by virtue of the surface tension of the liquid. As a model for wet granulates we investigated random packings of submillimeter spherical beads mixed with water. Measurements of the tensile strength and the fluidization threshold demonstrate that the mechanical stiffness is rather insensitive to the liquid content over a wide range. Only for a high liquid content, when more than half of the available pore space is filled with liquid, does the capillary cohesion weaken. In order to understand the interplay between the mechanical properties and the liquid content, we investigated the liquid distribution in random packings of glass spheres by means of x-ray microtomography. The three-dimensional images reveal that the liquid forms a network of capillary bridges fused at local triangular bead configurations. The spontaneous organization of the liquid into these ramified structures, which exhibit a large liquid-air interface, is responsible for the constancy of the cohesive forces in a wide range of liquid contents beyond the onset of capillary bridge coalescence.

  19. Mass-controlled capillary viscometer for a Newtonian liquid: Viscosity of water at different temperatures

    Science.gov (United States)

    Digilov, Rafael M.; Reiner, M.

    2007-03-01

    The operation principle of the mass-controlled capillary viscometer is presented for a Newtonian liquid. The derived equation for the temporal changes of the mass in a liquid column draining under gravity through a discharge capillary tube accounts self-consistently for the inertial convective term associated with the acceleration effect. The viscosity of water measured at different temperatures using the new approach is in good agreement with literature data.

  20. Susceptibility cancellation of a microcoil wound with a paramagnetic-liquid-filled copper capillary

    Science.gov (United States)

    Takeda, Kazuyuki; Takasaki, Tomoya; Takegoshi, K.

    2015-09-01

    Even though microcoils improve the sensitivity of NMR measurement of tiny samples, magnetic-field inhomogeneity due to the bulk susceptibility effect of the coil material can cause serious resonance-line broadening. Here, we propose to fabricate the microcoil using a thin, hollow copper capillary instead of a wire and fill paramagnetic liquid inside the capillary, so as to cancel the diamagnetic contribution of the copper. Susceptibility cancellation is demonstrated using aqueous solution of NiSO4. In addition, the paramagnetic liquid serves as coolant when it is circulated through the copper capillary, effectively transferring the heat generated by radiofrequency pulses.

  1. Liquid Film Capillary Mechanism for Densification of Ceramic Powders during Flash Sintering

    Directory of Open Access Journals (Sweden)

    Rachman Chaim

    2016-04-01

    Full Text Available Recently, local melting of the particle surfaces confirmed the formation of spark and plasma during spark plasma sintering, which explains the rapid densification mechanism via liquid. A model for rapid densification of flash sintered ceramics by liquid film capillary was presented, where liquid film forms by local melting at the particle contacts, due to Joule heating followed by thermal runaway. Local densification is by particle rearrangement led by spreading of the liquid, due to local attractive capillary forces. Electrowetting may assist this process. The asymmetric nature of the powder compact represents an invasive percolating system.

  2. Microchip-based monolithic column for high performance liquid chromatography

    Data.gov (United States)

    National Aeronautics and Space Administration — We have developed microchip based monolithic columns that can be used for liquid chromatography of small organic molecules, as well as, macromolecules such as...

  3. High Performance Liquid Chromatography of Vitamin A: A Quantitative Determination.

    Science.gov (United States)

    Bohman, Ove; And Others

    1982-01-01

    Experimental procedures are provided for the quantitative determination of Vitamin A (retinol) in food products by analytical liquid chromatography. Standard addition and calibration curve extraction methods are outlined. (SK)

  4. A generalized theory of chromatography and multistep liquid extraction

    Science.gov (United States)

    Chizhkov, V. P.; Boitsov, V. N.

    2017-03-01

    A generalized theory of chromatography and multistep liquid extraction is developed. The principles of highly efficient processes for fine preparative separation of binary mixture components on a fixed sorbent layer are discussed.

  5. Proof of concept for continuous enantioselective liquid-liquid extraction in capillary microreactors using 1-octanol as a sustainable solvent

    NARCIS (Netherlands)

    Susanti, S.; Meinds, Tim G.; Pinxterhuis, Erik B.; Schuur, Boelo; De Vries, Johannes G.; Feringa, Ben L.; Winkelman, Jozef G.M.; Yue, Jun; Heeres, Hero J.

    2017-01-01

    The use of capillary microreactors for enantioselective liquid-liquid extraction (ELLE) was successfully demonstrated using a model system consisting of a buffered aqueous amino acid derivative (3,5-dinitrobenzoyl-(R,S)-leucine) solution (phosphate buffer, pH 6.58) and a chiral cinchona alkaloid

  6. Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic...

  7. Radioactivity monitor for high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Reeve, D.R.; Crozier, A.

    1977-01-01

    The coupling of a homogeneous radioactivity monitor to a liquid chromatograph involves compromises between the sensitivity of the monitor and the resolution and speed of analysis of the chromatograph. The theoretical relationships between these parameters are considered and expressions derived which make it possible to calculate suitable monitor operating conditions for most types of high-performance liquid chromatography

  8. Estimation of Fatty Acids in Corn Oil by Gas Capillary Chromatography

    International Nuclear Information System (INIS)

    Kamal, Mohammad A; Klein Peter

    2007-01-01

    Fatty acids provide energy as well as play important role in some cellular structures like cell membrane and certain hormones. Saturated fatty acids are usually found in animal products and in some vegetable oils as well. These saturated fatty acids may be a factor in weight gain and obesity but eating them in moderate amounts may not be damaging to health of every person. Monounsaturated fatty acids can lower blood levels of low density lipoprotein cholesterol and have potential to increase blood levels of high density lipoprotein cholesterol and by this way plays protective role against heart disease. The omega 3 and 6 fatty acids have vital roles in many biological systems such as nervous, immune, cardiovascular, dermal and vision systems. Therefore, it is essential to optimize the instrumental conditions and column specification for the estimation of various fatty acids in the oil, which was considered in the current study using Gas Capillary Chromatography. (author)

  9. Rapid determination of cholesterol in milk and milk products by direct saponification and capillary gas chromatography.

    Science.gov (United States)

    Fletouris, D J; Botsoglou, N A; Psomas, I E; Mantis, A I

    1998-11-01

    A simple method is described for the determination of cholesterol in milk and milk products. Samples (0.2 g) are saponified in capped tubes with 0.5 M methanolic KOH solution by heating for 15 min at 80 degrees C. Water is added to the mixtures, and the unsaponifiable fractions are extracted with hexane to be further analyzed by capillary gas chromatography. Because of the rapid sample preparation and gas chromatographic procedures, a single sample can be analyzed in 30 min. Overall recovery was 98.6%, and the linearity was excellent for the fortification range examined. Precision data that were based on the variation within and between days suggested an overall relative standard deviation value of 1.4%. The method has been successfully applied to quantitate cholesterol in a variety of milk products.

  10. Determination of clebopride in plasma by capillary gas chromatography-negative-ion chemical ionization mass spectrometry.

    Science.gov (United States)

    Robinson, P R; Jones, M D; Maddock, J

    1988-11-18

    A procedure for the analysis of clebopride in plasma using capillary gas chromatography-negative-ion chemical ionization mass spectrometry has been developed. Employing an ethoxy analogue as internal standard, the two compounds were extracted from basified plasma using dichloromethane. Subsequent reaction with heptafluorobutyryl imidazole produced volatile monoheptafluorobutyryl derivatives whose ammonia negative-ion mass spectra proved ideal for selected-ion monitoring. The recovery of clebopride from plasma at 0.536 nmol/l was found to be 85.5 +/- 0.9% (n = 3) whilst measurement down to 0.268 nmol/l was possible with a coefficient of variation of 7.9%. Plasma levels of the compound are reported in two volunteers following ingestion of 1 mg of clebopride as the malate salt.

  11. Analysis of polycyclic aromatic hydrocarbons I. Determination by gas chromatography with glass and fused silica capillary columns

    International Nuclear Information System (INIS)

    Perez, M. M.; Gonzalez, D.

    1987-01-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (Author) 17 refs

  12. Analysis of polycyclic aromatic hydrocarbons. I. Determination by gas chromatography with glass and fused solica capillary columns

    International Nuclear Information System (INIS)

    Perez Garcia, M.; Gonzalez, D.

    1987-01-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silice capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (author). 3 figs., 17 refs

  13. Determination of DDTs and PCBs by capillary gas chromatography and electron capture detection

    International Nuclear Information System (INIS)

    1988-01-01

    This reference method deals with the determination of DDTs and PCBs in marine environmental samples using high resolution gas chromatography. Several other halogenated pesticides and other electron capturing organic compounds may be present in samples and many of these may also be determined by this method. Not all electron capturing residues will be resistant to all of the clean up procedures described here for the analysis of DTTs and PCBs. Therefore, additional information on the stability of some common pesticides using this methodology is also provided. The high separation power of open tubular (''capillary'') columns allows the identification and quantification of many compounds in the complex mixtures occurring in environmental samples. This manual provides information on the theoretical and practical aspects of the use of these high resolution columns for the analysis of DDTs and PCBs in environmental samples. The qualitative and quantitative method can be applied to any sample type (aerosol/vapour, water, particulates, biota, etc.) provided that suitable cleaned-up extracts dissolved in n-hexane are available for injection into the GC system. For example, methods for obtaining these cleaned-up sample extracts from marine organisms are described in detail in UNEP Reference Method no. 14 and for sediments in No. 17. The change in the field of application by analysing by capillary rather than packed columns may be less dramatic for DDTs. However, with the increased separation, the possibilities of inaccurate analysis resulting from overlap with interfering compounds is reduced. 7 refs, 1 fig., 3 tabs

  14. X-ray reflectivity study of thermal capillary waves on liquid surfaces

    International Nuclear Information System (INIS)

    Ocko, B.M.; Wu, X.Z.; Sirota, E.B.; Sinha, S.K.; Deutsch, M.

    1994-01-01

    X-ray reflectivity measurements have been carried out at the liquid/vapor interface of normal alkanes. The reflectivities over a large temperature range of different chain lengths (C20 and C36) provide a critical test of the various capillary wave models. Our data are most consistent with the hybrid model which allows for a molecular size dependent cutoff q max for the capillary waves and an intrinsic interface width σ 0

  15. New Liquid Phases for the Gas Chromatographic Separation of Strong Bases on Capillary Columns

    OpenAIRE

    Grob, K.

    2017-01-01

    The current practice of pretreating the solid support with free alkali to increase separation efficiency for basic compounds proved to be unsuitable for capillary columns. Instead of this, homogenous organic materials of high base strength are required. We found polyethylene imine (PEI) and polypropylene imine (PPI) to be very efficient as liquid phases of capillary columns for the separation of bases. The preparation of polymers is mentioned. Silanization or acetylation of the free hydroxyl ...

  16. A liquid chromatographic method for determination of theophylline in serum and capillary blood--a comparison.

    Science.gov (United States)

    Gartzke, J; Jäger, H; Vins, I

    1991-01-01

    A simple, fast and reliable liquid chromatographic method for the determination of theophylline in serum and capillary blood after a solid phase extraction is described for therapeutic drug monitoring. The employment of capillary blood permits the determination of an individual drug profile and other pharmacokinetic studies in neonates and infants. There were no differences in venous- and capillary-blood levels but these values compared poorly with those in serum. An adjustment of the results by correction of the different volumes of serum and blood by haematocrit was unsuccessful. Differences in the binding of theophylline to erythrocytes could be an explanation for the differences in serum at blood levels of theophylline.

  17. Ultra-high Performance Liquid Chromatography in Steroid Analysis

    OpenAIRE

    Salonen, Fanny

    2017-01-01

    The latest version of liquid chromatography is ultra-high performance (or pressure) chromatography (UHPLC). In the technique, short and narrow-bore columns with particle sizes below 3 µm are used. The extremely high pressure used results in very short analysis times, excellent separation, and good resolution. This makes UHPLC a good choice for steroidal analysis. Steroids are a highly interesting area of study; they can be recognized as biomarkers for several diseases and are a relevant topic...

  18. Pump effect of a capillary discharge in electrically conductive liquids

    Czech Academy of Sciences Publication Activity Database

    De Baerdemaeker, F.; Šimek, Milan; Leys, C.; Verstraete, W.

    2007-01-01

    Roč. 27, č. 4 (2007), s. 473-485 ISSN 0272-4324 R&D Projects: GA AV ČR IAA1043403 Institutional research plan: CEZ:AV0Z20430508 Keywords : water * conductive * capillary * AC discharge * pump Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.747, year: 2007 http://www.springerlink.com/content/w802073563282272/fulltext.pdf

  19. Capillary Condensation of Liquid 4He in Aerogel on Cooling Through λ Point

    International Nuclear Information System (INIS)

    Miyashita, W.; Yoneyama, K.; Kato, H.; Nomura, R.; Okuda, Y.

    2006-01-01

    Capillary condensation of liquid 4He in silica aerogel with a 90% porosity was investigated visually. The initial condition of the experiment was such that liquid 4He was present in the sample cell but not in the aerogel. This situation was realized by introducing the liquid into the cell at a fast rate to avoid liquefaction in the aerogel. The free surface of the liquid rose up in the cell with filling and eventually reached the bottom of the aerogel. Then, the aerogel absorbed the liquid by capillary condensation. The height of the liquid in the aerogel rose with time t roughly as t1/2 in the normal fluid phase. This behavior was consistent with the Washburn model. When the system was cooled through the λ point during the condensation, the liquid height started to rise faster in the superfluid phase with a constant velocity of about 0.3 mm/sec. The dynamics of capillary condensation was strongly dependent on whether the liquid 4He was in the normal or the superfluid phase

  20. Fractionation of fecal neutral steroids by high performance liquid chromatography

    International Nuclear Information System (INIS)

    Jackson, E.M.; Kloss, C.A.; Weintraub, S.T.; Mott, G.E.

    1985-01-01

    Fecal neutral steroids were fractionated by high performance liquid chromatography (HPLC) into three major fractions: 5 beta-H, 3-keto steroids; 5 beta-H, 3 beta-hydroxy steroids; and 5 alpha-H and delta 5-3 beta-hydroxy steroids. This separation was achieved in about 10 minutes, with greater than 97% recovery of standards in each fraction. Gas-liquid chromatographic quantitation of fecal steroids fractionated by either HPLC or thin-layer chromatography gave nearly identical results. A method using both C18 reverse phase and silica HPLC to purify radiolabeled sterols is also described

  1. Development and Validation of Liquid Chromatography- Mass ...

    African Journals Online (AJOL)

    HP

    Method: A novel liquid chromatography–tandem mass spectrometry method for the quantitative determination of naproxen in human K2-EDTA plasma in negative ion mode was employed ..... Practice and Applications of Bio-analytical Method.

  2. Liquid chromatography and liquid chromatography-mass spectrometry analysis of donepezil degradation products

    Directory of Open Access Journals (Sweden)

    Mladenović Aleksandar R.

    2015-01-01

    Full Text Available This study describes the investigation of degradation products of donepezil (DP using stability indicating RP-HPLC method for determination of donepezil, which is a centrally acting reversible acetylcholinesterase inhibitor. In order to investigate the stability of drug and formed degradation products, a forced degradation study of drug sample and finished product under different forced degradation conditions has been conducted. Donepezil hydrochloride and donepezil tablets were subjected to stress degradation conditions recommended by International Conference on Harmonization (ICH. Donepezil hydrochloride solutions were subjected to acid and alkali hydrolysis, chemical oxidation and thermal degradation. Significant degradation was observed under alkali hydrolysis and oxidative degradation conditions. Additional degradation products were observed under the conditions of oxidative degradation. The degradation products observed during forced degradation studies were monitored using the high performance liquid chromatography (HPLC method developed. The parent method was modified in order to obtain LC-MS compatible method which was used to identify the degradation products from forced degradation samples using high resolution mass spectrometry. The mass spectrum provided the precise mass from which derived molecular formula of drug substance and degradation products formed and proved the specificity of the method unambiguously. [Projekat Ministarstva nauke Republike Srbije, br. 172013

  3. Instrumental liquid chromatography: a practical manual on high-performance liquid chromatographic methods

    National Research Council Canada - National Science Library

    Parris, N. A

    1976-01-01

    Available texts on liquid chromatography have tended to emphasize the developments in the theoretical understanding of the technique and methodology or to list numerous applications, complete with experimental details...

  4. Liquid-adsorption chromatography of metal 8-hydroxyquinolinates

    International Nuclear Information System (INIS)

    Basova, E.M.; Bol'shova, T.A.; Shirshova, T.S.

    1988-01-01

    Using the method of liquid-adsorption chromatography separation of 8-hydroxyquinolinates of Cu, Fe, Ga, In, Al, Ni is realized. Thin-layer chromatography (TLC) is used to define the optimum conditions of separation and highly efficient liquid column chromatography (HELC) - for chelate separation. Applicaton of the same sorbent is a very important condition of transition from TLC to HELC. Solica gel Partisil, mobile phase: benzene - isopropanol mixture, containing 1 x 10 -3 M of 8-hydroxyquinoline, are the optimal conditions for the studied chelates separation. But In and Ga in TLC move together, and in HELC they are partially separated, therefore, for their separation the column selectivity should be improved by selection of mobile phase

  5. Validated High Performance Liquid Chromatography Method for ...

    African Journals Online (AJOL)

    Purpose: To develop a simple, rapid and sensitive high performance liquid ... response, tailing factor and resolution of six replicate injections was < 3 %. ... Cefadroxil monohydrate, Human plasma, Pharmacokinetics Bioequivalence ... Drug-free plasma was obtained from the local .... Influence of probenicid on the renal.

  6. Determination of Caffeine in Beverages by High Performance Liquid Chromatography.

    Science.gov (United States)

    DiNunzio, James E.

    1985-01-01

    Describes the equipment, procedures, and results for the determination of caffeine in beverages by high performance liquid chromatography. The method is simple, fast, accurate, and, because sample preparation is minimal, it is well suited for use in a teaching laboratory. (JN)

  7. Beta-induced fluorescence detection in liquid chromatography

    International Nuclear Information System (INIS)

    Malcolme-Lawes, D.J.; Massey, S.; Warwick, P.

    1981-01-01

    A theoretical analysis of beta-induced fluorescence is used to determine the factors which influence the sensitivity of the technique as applied to liquid chromatography. Equations are presented for detector response and for signal-to-noise ratios and the theoretical response for a typical detector is compared with experimentally determined values. (author)

  8. Mallow carotenoids determined by high-performance liquid chromatography

    Science.gov (United States)

    Mallow (corchorus olitorius) is a green vegetable, which is widely consumed either fresh or dry by Middle East population. This study was carried out to determine the contents of major carotenoids quantitatively in mallow, by using a High Performance Liquid Chromatography (HPLC) equipped with a Bis...

  9. High-Performance Liquid Chromatography-Mass Spectrometry.

    Science.gov (United States)

    Vestal, Marvin L.

    1984-01-01

    Reviews techniques for online coupling of high-performance liquid chromatography with mass spectrometry, emphasizing those suitable for application to nonvolatile samples. Also summarizes the present status, strengths, and weaknesses of various techniques and discusses potential applications of recently developed techniques for combined liquid…

  10. Monitoring aged reversed-phase high performance liquid chromatography columns

    NARCIS (Netherlands)

    Bolck, A; Smilde, AK; Bruins, CHP

    1999-01-01

    In this paper, a new approach for the quality assessment of routinely used reversed-phase high performance liquid chromatography columns is presented. A used column is not directly considered deteriorated when changes in retention occur. If attention is paid to the type and magnitude of the changes,

  11. Ultra high performance liquid chromatography of seized drugs

    NARCIS (Netherlands)

    Lurie, I.S.

    2010-01-01

    The primary goal of this thesis is to investigate the use of ultra high performance liquid chromatography (UHPLC) for the analysis of seized drugs. This goal was largely achieved and significant progress was made in achieving improved separation and detection of drugs of forensic interest.

  12. Quantification of Tea Flavonoids by High Performance Liquid Chromatography

    Science.gov (United States)

    Freeman, Jessica D.; Niemeyer, Emily D.

    2008-01-01

    We have developed a laboratory experiment that uses high performance liquid chromatography (HPLC) to quantify flavonoid levels in a variety of commercial teas. Specifically, this experiment analyzes a group of flavonoids known as catechins, plant-derived polyphenolic compounds commonly found in many foods and beverages, including green and black…

  13. Characterization of porous silicon integrated in liquid chromatography chips

    NARCIS (Netherlands)

    Tiggelaar, Roald M.; Verdoold, Vincent; Eghbali, H.; Desmet, G.; Gardeniers, Johannes G.E.

    2009-01-01

    Properties of porous silicon which are relevant for use of the material as a stationary phase in liquid chromatography chips, like porosity, pore size and specific surface area, were determined with high-resolution SEM and N2 adsorption–desorption isotherms. For the anodization conditions

  14. Towards early detection of the hydrolytic degradation of poly(bisphenol A)carbonate by hyphenated liquid chromatography and comprehensive two-dimensional liquid chromatography

    NARCIS (Netherlands)

    Coulier, L.; Kaal, E.R.; Hankemeier, Th.

    2006-01-01

    The hydrolytic degradation of poly(bisphenol A)carbonate (PC) has been characterized by various liquid chromatography techniques. Size exclusion chromatography (SEC) showed a significant decrease in molecular mass as a result of hydrolytic degradation, while 'liquid chromatography at critical

  15. Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology

    OpenAIRE

    Brown, Leslie; Earle, Martyn J; Gilea, Manuela; Plechkova, Natalia V; Seddon, Kenneth R

    2017-01-01

    Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous char...

  16. Isotopic fractionation of fentanyl and its deuterated analogues by capillary gas chromatography

    International Nuclear Information System (INIS)

    Sera, Shoji; Goromaru, Tsuyoshi

    1997-01-01

    Isotopic fractionation of fentanyl (FT) and its deuterated analogues by gas chromatography using capillary columns (CBP1 and CBP5) has been investigated. Seven kinds of analogues were labeled with 5 to 19 deuterium atoms at the anilino, propionyl and/or phenylethyl group of FT. The retention times of deuterated FT in CBP1 and CBP5 columns are inversely proportional to the number of labeled deuterium atoms in the molecule. The difference in free enegy changes (ΔΔG) had a linear relationship with the number of labeled deuterium atoms, except for labeling at anilino and phenylethyl group. The contribution of a deuterium atom to the ΔΔG value was estimated to be 1.13 cal/mol in CBP1 and 1.40 cal/mol in CBP5, respectively. While, its contribution in the propiony group was 2.84 cal/mol in CBP1 and 2.48 cal/mol in CBP5, respectively. An important factor in separation by GC may differences in interactions between the stationary phase of the column with the three dimensional protrusive moiety in the molecule. (author)

  17. Isotopic fractionation of fentanyl and its deuterated analogues by capillary gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Sera, Shoji; Goromaru, Tsuyoshi [Fukuyama Univ., Hiroshima (Japan)

    1997-12-01

    Isotopic fractionation of fentanyl (FT) and its deuterated analogues by gas chromatography using capillary columns (CBP1 and CBP5) has been investigated. Seven kinds of analogues were labeled with 5 to 19 deuterium atoms at the anilino, propionyl and/or phenylethyl group of FT. The retention times of deuterated FT in CBP1 and CBP5 columns are inversely proportional to the number of labeled deuterium atoms in the molecule. The difference in free enegy changes ({Delta}{Delta}G) had a linear relationship with the number of labeled deuterium atoms, except for labeling at anilino and phenylethyl group. The contribution of a deuterium atom to the {Delta}{Delta}G value was estimated to be 1.13 cal/mol in CBP1 and 1.40 cal/mol in CBP5, respectively. While, its contribution in the propiony group was 2.84 cal/mol in CBP1 and 2.48 cal/mol in CBP5, respectively. An important factor in separation by GC may differences in interactions between the stationary phase of the column with the three dimensional protrusive moiety in the molecule. (author)

  18. Determination of strobilurin fungicide residues in fruits and vegetables by micellar electrokinetic capillary chromatography with sweeping.

    Science.gov (United States)

    Wang, Kun; Chen, Guan-hua; Wu, Xian; Shi, Jie; Guo, Dong-shan

    2014-02-01

    A new assay of micellar electrokinetic capillary chromatography with sweeping was developed to determine azoxystrobin, kresoxim-methyl and pyraclostrobin in fruits and vegetables. The key factors affecting resolution and peak height were studied and the optimum conditions were obtained for separation and enrichment. The running buffer consisted of 40 mM borate, 25 mM sodium dodecyl sulfate and 15% acetonitrile, and its pH was adjusted to 8.4. The sample was injected for 677 nL and the separation voltage was 25 kV. Under the optimum conditions, the enrichment factors of azoxystrobin, kresoxim-methyl and pyraclostrobin were 861, 550 and 403; the linear dynamic ranges were all 0.01-5.0 mg/L; the limits of detection were 0.002, 0.001 and 0.002 mg/kg; the recoveries of spiked samples were 85.1-98.5%, 87.5-97.0% and 89.1-99.1%, respectively. The assay can meet the requirement of maximum residue limits for these three strobilurin fungicides, and has been applied for determining their residues in fruits and vegetables.

  19. Invariance of the solid-liquid interfacial energy in electrowetting probed via capillary condensation.

    Science.gov (United States)

    Gupta, Rohini; Olivier, Gloria K; Frechette, Joelle

    2010-07-20

    Capillary condensation is employed to probe the solid-liquid interfacial energy in electrowetting on dielectric. The height of an annular water meniscus formed via capillary condensation inside the surface force apparatus is measured as a function of the potential applied across the meniscus and the dielectric stack where the meniscus is formed. According to the Kelvin equation, a decrease in the solid-liquid interfacial energy at constant temperature and relative humidity should lead to an increase in the meniscus height. Our experimental results on nanometer-sized meniscus are in agreement with the work of Mugele [J. Phys.: Condens. Matter 2007, 19, 375112] and unequivocally demonstrate that the real contact angle (or the solid-liquid interfacial energy) remains unaltered in electrowetting on dielectric.

  20. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    Science.gov (United States)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  1. Thickness of Residual Wetting Film in Liquid-Liquid Displacement in Capillary Channels

    Science.gov (United States)

    Beresnev, I. A.; Gaul, W.; Vigil, D.

    2010-12-01

    Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a non-wetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of this wetting film? Understanding this question may determine the ultimate oil recovery. A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. We develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of about 20 % the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

  2. Hyphenation of capillary high-performance ion-exchange chromatography with mass spectrometry using sheath-flow electrospray ionization.

    Science.gov (United States)

    Kochmann, Sven; Matysik, Frank-Michael

    2014-12-15

    Mass spectrometry (MS) is an attractive method for extending capillary-size ion chromatography (cHPIC) to create a valuable technique for speciation analysis. For hyphenation, the aqueous effluent of cHPIC has to be transformed into a volatile mixture for MS while preserving analytical concentrations as well as peak shapes during transfer from cHPIC to MS. Finally, the approach should technically be flexible and easy-to-use. A combination of cHPIC and sheath-flow electrospray ionization (ESI)-MS offers to solve all these challenges. cHPIC/sheath-flow-ESI-TOFMS was used in this study for the speciation analysis of various arsenic model compounds. These model compounds were analyzed with different hyphenation setups and configurations of cHPIC/MS and their respective assets and drawbacks were examined and discussed. The parameters (flow rate and composition of sheath liquid) of sheath-flow ESI and their influence on the performance of the spray and the sensitivity of the detector were investigated and compared with those of sheathless ESI. Using an injection valve to couple cHPIC and MS was found to be the best method for hyphenation, since it constitutes a flexible and dead-volume-free approach. The investigation of sheath-flow ESI revealed that the flow rate of the sheath liquid has to resemble the flow rate of the IC effluent to ensure a stable spray and that a composition of 2-propanol/water/ammonia at 50:50:0.2 (v/v/v) suits most applications without unilaterally promoting the sensitivity for either organic or inorganic compounds. The optimized setup and conditions were successfully applied to the analysis of a mixture of important arsenic species and used to determine limits of detection of organic and inorganic arsenic species (3.7 µg L(-1) elemental arsenic). A method for cHPIC/sheath-flow-ESI-MS was developed. The method was shown to be a valuable tool for speciation and trace analysis. It features no dead volume, fast transfer from IC to MS, only minimal

  3. Theories to support method development in comprehensive two-dimensional liquid chromatography - A review

    NARCIS (Netherlands)

    Bedani, F.; Schoenmakers, P.J.; Janssen, H.-G.

    2012-01-01

    On-line comprehensive two-dimensional liquid chromatography techniques promise to resolve samples that current one-dimensional liquid chromatography methods cannot adequately deal with. To make full use of the potential of two-dimensional liquid chromatography, optimization is required. Optimization

  4. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from a...

  5. 21 CFR 862.2260 - High pressure liquid chromatography system for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false High pressure liquid chromatography system for... Clinical Laboratory Instruments § 862.2260 High pressure liquid chromatography system for clinical use. (a) Identification. A high pressure liquid chromatography system for clinical use is a device intended to separate...

  6. Application of genetic algorithms for parameter estimation in liquid chromatography

    International Nuclear Information System (INIS)

    Hernandez Torres, Reynier; Irizar Mesa, Mirtha; Tavares Camara, Leoncio Diogenes

    2012-01-01

    In chromatography, complex inverse problems related to the parameters estimation and process optimization are presented. Metaheuristics methods are known as general purpose approximated algorithms which seek and hopefully find good solutions at a reasonable computational cost. These methods are iterative process to perform a robust search of a solution space. Genetic algorithms are optimization techniques based on the principles of genetics and natural selection. They have demonstrated very good performance as global optimizers in many types of applications, including inverse problems. In this work, the effectiveness of genetic algorithms is investigated to estimate parameters in liquid chromatography

  7. Thin-layer chromatography - liquid chromatography, an ideal supplement demonstrated by the separation of lanthanoids

    International Nuclear Information System (INIS)

    Specker, H.; Hufnagel, A.

    1984-01-01

    All lanthanoids have been separated by thin-layer chromatography (TLC) with short retention times by using a mixture of ether/tetrahydrofurane (THF)/bis-(2-ethylhexyl)-phosphate (HDEHP)/nitric acid. The eluent was empirically tested by synergistic effects. The results have been transferred to high-performance liquid chromatography /HPLC). It was possible to use the same eluent in TLC and HPLC both for the analytical separation of all lanthanoids and for the separation of fission products. The experimental experience gained in HPLC could be applied to the pre-concentration of isotopes in TLC. Both methods excellently supplemented each other in the separation of lanthanoids. (orig.) [de

  8. Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology.

    Science.gov (United States)

    Brown, Leslie; Earle, Martyn J; Gîlea, Manuela A; Plechkova, Natalia V; Seddon, Kenneth R

    2017-08-10

    Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

  9. Nano-liquid chromatography applied to enantiomers separation.

    Science.gov (United States)

    Fanali, Salvatore

    2017-02-24

    This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers' separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc. This is reported in the first part of the paper illustrating the features of the nano-LC. In addition, chiral resolution methods are briefly illustrated. Some chiral selectors, used in high-performance liquid chromatography have also been applied in nano-LC including cyclodextrins, glycopeptide antibiotics, modified polysaccharides etc. This is discussed in the second part of the review. Finally some examples of the applications available in literature are reported. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Combined high-performance liquid chromatography-radioimmunoassay for cytokinins

    International Nuclear Information System (INIS)

    MacDonald, E.M.S.; Akiyoshi, D.E.; Morris, R.O.

    1981-01-01

    The cytokinins isopentenyladenosine and ribosylzeatin were conjugated to bovine serum albumin and the conjugates used to raise antisera in rabbits. The resulting antisera had high specificity towards the cytokinin haptens and low cross-reactivity towards other purines. They were used as the basis for a radioimmunoassay for cytokinins, which, when applied in conjunction with high-performance liquid chromatography, allowed rapid and sensitive (to the picogram range) estimation and identification of multiple cytokinins from natural plant and bacterial sources. (orig.)

  11. High performance liquid chromatography in studies of radiolabeled antibodies

    International Nuclear Information System (INIS)

    Hnatowich, D.J.

    1986-01-01

    High performance liquid chromatography (HPLC) as applied to the separation of antibodies displays the same advantages as in its other applications, namely good resolution accompanied by fast analysis. It is therefore not surprising that many HPLC columns designed for use with antibodies and other proteins are now available commercially. The properties of proteins which provide the separation are size, hydrophobicity, charge and affinity. The features of each are discussed. (author)

  12. Evolution and Current Trends in Liquid and Supercritical Fluid Chromatography

    OpenAIRE

    Fekete, Szabolcs; Grand-Guillaume-Perrenoud, Alexandre; Guillarme, Davy

    2014-01-01

    The current trend in high performance liquid chromatography (HPLC) tends toward the achievement of higher separation efficiency and shorter analysis time. Indeed, better performance in LC has become increasingly important in recent years mainly driven by the challenges of either analyzing more complex samples or increasing the numbers of samples per time unit. In the recent development of particle technology, the use of fully porous sub-2 m particles and sub-3 m shell particles have received ...

  13. Liquid Chromatography for Analysis of Metformin in Myrmeleon sp.

    OpenAIRE

    Afidatul Muadifah; Hermin Sulistyarti; Sasangka Prasetyawan

    2017-01-01

    Myrmeleon sp is a typical of insect larva which has been used in Indonesia for diabetes treatment. However, there is no sufficient scientific report explaining the bioactive compounds in this insect. Based on our preliminary research, this insect contained metformin, i.e. one of bioactive compounds for the treatment of type-2 diabetes. Therefore, this study is focused on the development of separation technique using high performance liquid chromatography (HPLC) on a reverse phase C-18 column ...

  14. Capillary evaporation of the ionic liquid [EMIM][BF4] in nanoscale solvophobic confinement

    Science.gov (United States)

    Shrivastav, Gourav; Remsing, Richard C.; Kashyap, Hemant K.

    2018-05-01

    Solvent density fluctuations play a crucial role in liquid-vapor transitions in solvophobic confinement and can also be important for understanding solvation of polar and apolar solutes. In the case of ionic liquids (ILs), density fluctuations can be used to understand important processes in the context of nanoscale aggregation and colloidal self-assemblies. In this article, we explore the nature of density fluctuations associated with capillary evaporation of the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) in the confined region of model solvophobic nanoscale sheets by using molecular dynamics simulations combined with non-Boltzmann sampling techniques. We demonstrate that density fluctuations of the confined IL play an important role in capillary evaporation, suggesting analogies to dewetting transitions involving water. Significant changes in the interfacial structure of the IL are also detailed and suggested to underlie a non-classical (non-parabolic) dependence of the free energy barrier to evaporation on the degree of confinement.

  15. Simultaneous determination of oxalic, citric, nitrilotriacetic and ethylenediamenetetraacetic acids by gas liquid chromatography of their methyl esters

    International Nuclear Information System (INIS)

    Eskell, C.J.; Pick, M.E.

    1980-04-01

    A procedure for simultaneous determination of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid and oxalic acid by gas liquid chromatography is described. The involatile acids are first concerted to their volatile methyl ester derivatives by reaction with boron trifluoride in methanol. Transition metal ions (Fe 3+ , Cr 3+ and Ni 2+ ) which will be present in decontamination liquors from nuclear reactors, and form strong chelates with the acids, have been shown to cause no interference to the esterification reaction. The esters were separated by temperature programming on a 3.5 metre capillary column packed with 3% OV1 on Diatomite CQ and were detected by flame ionisation. (author)

  16. High-resolution tracking using large capillary bundles filled with liquid scintillator

    CERN Document Server

    Annis, P; Benussi, L; Bruski, N; Buontempo, S; Currat, C; D'Ambrosio, N; Van Dantzig, R; Dupraz, J P; Ereditato, A; Fabre, Jean-Paul; Fanti, V; Feyt, J; Frekers, D; Frenkel, A; Galeazzi, F; Garufi, F; Goldberg, J; Golovkin, S V; Gorin, A M; Grégoire, G; Harrison, K; Höpfner, K; Holtz, K; Konijn, J; Kozarenko, E N; Kreslo, I E; Kushnirenko, A E; Liberti, B; Martellotti, G; Medvedkov, A M; Michel, L; Migliozzi, P; Mommaert, C; Mondardini, M R; Panman, J; Penso, G; Petukhov, Yu P; Rondeshagen, D; Siegmund, W P; Tyukov, V E; Van Beek, G; Vasilchenko, V G; Vilain, P; Visschers, J L; Wilquet, G; Winter, Klaus; Wolff, T; Wörtche, H J; Wong, H; Zimyn, K V

    2000-01-01

    We have developed large high-resolution tracking detectors based on glass capillaries filled with organic liquid scintillator of high refractive index. These liquid-core scintillating optical fibres act simultaneously as detectors of charged particles and as image guides. Track images projected onto the readout end of a capillary bundle are visualized by an optoelectronic chain consisting of a set of image-intensifier tubes followed by a photosensitive CCD or by an EBCCD camera. Two prototype detectors, each composed of \\hbox{$\\approx 10^6$} capillaries with \\hbox{20$-$25 $\\mu$m} diameter and \\hbox{0.9$-$1.8 m} length, have been tested, and a spatial resolution of the order of \\hbox{20$-$40 $\\mu$m} has been attained. A high scintillation efficiency and a large light-attenuation length, in excess of 3 m, was achieved through special purification of the liquid scintillator. Along the tracks of minimum-ionizing particles, the hit densities obtained were $\\sim$ 8 hits/mm at the readout window, and \\hbox{$\\sim$ 3 ...

  17. Motion of liquid plugs between vapor bubbles in capillary tubes: a comparison between fluids

    Science.gov (United States)

    Bertossi, Rémi; Ayel, Vincent; Mehta, Balkrishna; Romestant, Cyril; Bertin, Yves; Khandekar, Sameer

    2017-11-01

    Pulsating heat pipes (PHP) are now well-known devices in which liquid/vapor slug flow oscillates in a capillary tube wound between hot and cold sources. In this context, this paper focuses on the motion of the liquid plug, trapped between vapor bubbles, moving in capillary tubes, to try to better understand the thermo-physical phenomena involved in such devices. This study is divided into three parts. In the first part, an experimental study presents the evolution of the vapor pressure during the evaporation process of a liquid thin film deposited from a liquid plug flowing in a heated capillary tube: it is found that the behavior of the generated and removed vapor can be very different, according to the thermophysical properties of the fluids. In the second part, a transient model allows to compare, in terms of pressure and duration, the motion of a constant-length liquid plug trapped between two bubbles subjected to a constant difference of vapor pressure: the results highlight that the performances of the four fluids are also very different. Finally, a third model that can be considered as an improvement of the second one, is also presented: here, the liquid slug is surrounded by two vapor bubbles, one subjected to evaporation, the pressure in both bubbles is now a result of the calculation. This model still allows comparing the behaviors of the fluid. Even if our models are quite far from a complete model of a real PHP, results do indicate towards the applicability of different fluids as suitable working fluids for PHPs, particularly in terms of the flow instabilities which they generate.

  18. Liquid to liquid extraction and liquid chromatography-tandem mass spectrometry determination of hainanmycin in feed.

    Science.gov (United States)

    Wang, Ze Ping; Shen, Jian Zhong; Linhardt, Robert J; Jiang, Hui; Cheng, Lin Li

    2017-03-01

    Hainanmycin is a new veterinary polyether antibiotic and has few sensitive analytical method in present days. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) relying on multiple reaction monitoring (MRM) detection was developed for analysis of hainanmycin in animal feed. Feed samples were extracted with ethyl acetate and purified by two steps of liquid-liquid extraction (LLE) to get rid of water solvable matrix and lipids one by one. The final simple was analyzed by LC-MS/MS. The LC mobile phase was composed of 0.1% aqueous formic acid and 0.1% formic acidified acetonitrile by gradient elution. Average recoveries ranged from 74.22% to 87.85%, as determined by spiking with 2.0 (LOQ) ∼2500μgkg -1 of hainanmycin. The inter-day and intra-day coefficient of variation was 9.21% to 11.77% and 7.67% to 13.49%, respectively. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.36μgkg -1 and 2.0μgkg -1 , respectively. Copyright © 2016. Published by Elsevier B.V.

  19. Comprehensive two-dimensional liquid chromatography and hyphenated liquid chromatography to study the degradation of poly(bisphenol A)carbonate

    NARCIS (Netherlands)

    Coulier, L.; Kaal, E.R.; Hankemeier, T.

    2005-01-01

    Size exclusion chromatography (SEC), gradient polymer elution chromatography (GPEC) and liquid chromatography at critical conditions (LC-CC) have been developed and applied to observe chemical changes in poly(bisphenol A)carbonate (PC) due to hydrolytic degradation. Especially LC-CC appeared to be

  20. Protein separations using enhanced-fluidity liquid chromatography.

    Science.gov (United States)

    Bennett, Raffeal; Olesik, Susan V

    2017-11-10

    Enhanced-fluidity liquid chromatography (EFLC) methods using methanol/H 2 O/CO 2 and hydrophilic interaction liquid chromatography (HILIC) were explored for the separation of proteins and peptides. EFLC is a separation mode that uses a mobile phase made of conventional solvents combined with liquid carbon dioxide (CO 2 ) in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis. TFA additive and elevated temperature were leveraged as key factors in the separation of a 13-analyte intact protein mixture in under 5min. Under these conditions EFLC showed modest improvement in terms of peak asymmetry and analysis time over the competing ACN/H 2 O separation. Protein analytes detected by electrospray ionization - quadrupole time of flight, were shown to be unaffected by the addition of CO 2 in the mobile phase. Herein, the feasibility of separating hydrophilic proteins up to 80kDa (with transferrin) is demonstrated for CO 2 -containing mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Capillary isotachophoresis for the analysis of ionic liquid entities.

    Science.gov (United States)

    Markowska, Aleksandra; Stepnowski, Piotr

    2010-07-01

    Simple, selective and sensitive isotachophoretic methods for the analysis of ionic liquid (IL) compartments were developed in this study. A leading electrolyte containing 10 mM L-histidine + 10 mM histidine hydrochloride and a terminating electrolyte containing 5 mM glutamic acid + 5 mM L-histidine were selected to separate nitrate(V), chlorate(V), hexafluorophosphate, dicyanimide, trifluoromethanesulfonate, phosphate(V) and bis(trifluoromethanesulfonyl)imide in anionic mode. In contrast, seven short-chain alkylimidazolium, alkylpyrrolidinium, alkylpyridinium and non-chromophoric tetraalkylammonium and tetraalkylphosphonium IL cations were separated with 10 mM potassium hydroxide + 10 mM acetic acid as leading electrolyte, and 10 mM beta-alanine + 10 mM acetate as terminating electrolyte. Both methods were optimized and validated with good analytical performance parameters. LOD was about 3-5 microM, and the repeatability lay in the range of 1.06-5.59%. These methods were evaluated for their applicability to the analysis of soil samples and freshwater contaminated with ILs. In light of hitherto the absence of reports on the determination of non-chromophoric IL cations, this study delivers for the first time a universal method enabling analysis of these species. Moreover, as there is still significant lack of methodologies of IL anion analysis, the obtained results offer an interesting alternative in that matter.

  2. Study on stair-step liquid triggered capillary valve for microfluidic systems

    Science.gov (United States)

    Zhang, Lei; Jones, Ben; Majeed, Bivragh; Nishiyama, Yukari; Okumura, Yasuaki; Stakenborg, Tim

    2018-06-01

    In lab-on-a-chip systems, various microfluidic technologies are being developed to handle fluids at very small quantities, e.g. in the scale of nano- or pico-liter. To achieve autonomous fluid handling at a low cost, passive fluidic control, based on the capillary force between the liquid and microchannel surface, is of the utmost interest in the microsystem. Valves are an essential component for flow control in many microfluidic systems, which enables a sequence of fluidic operations to be performed. In this paper, we present a new passive valve structure for a capillary driven microfluidic device. It is a variation of a capillary trigger valve that is amenable to silicon microfabrication; it will be referred to as a stair-step liquid triggered valve. In this paper, the valve functionality and its dependencies on channel geometry, surface contact angle, and surface roughness are studied both experimentally and with numerical modeling. The effect of the contact angle was explored in experiments on the silicon microfabricated valve structure; a maximal working contact angle, above which the valve fails to be triggered, was demonstrated. The fluidic behavior in the stair-step channel structure was further explored computationally using the finite volume method with the volume-of-fluid approach. Surface roughness due to scalloping of the sidewall during the Bosch etch process was hypothesized to reduce the sidewall contact angle. The reduced contact angle has considerable impacts on the capillary pressure as the liquid vapor interface traverses the stair-step structure of the valve. An improved match in the maximal working contact angle between the experiments and model was obtained when considering this surface roughness effect.

  3. Determination of C6-C10 aromatic hydrocarbons in water by purge-and-trap capillary gas chromatography

    Science.gov (United States)

    Eganhouse, R.P.; Dorsey, T.F.; Phinney, C.S.; Westcott, A.M.

    1993-01-01

    A method is described for the determination of the C6-C10 aromatic hydrocarbons in water based on purge-and-trap capillary gas chromatography with flame ionization and mass spectrometric detection. Retention time data and 70 eV mass spectra were obtained for benzene and all 35 C7-C10 aromatic hydrocarbons. With optimized chromatographic conditions and mass spectrometric detection, benzene and 33 of the 35 alkylbenzenes can be identified and measured in a 45-min run. Use of a flame ionization detector permits the simultaneous determination of benzene and 26 alkylbenzenes.

  4. Csaba Horváth and preparative liquid chromatography.

    Science.gov (United States)

    Guiochon, Georges

    2005-06-24

    Few chromatographers have been interested in furthering preparative liquid chromatography. The pioneers, Tswett, Kuhn and Lederer, A.J.P. Martin, Tiselius, isolated fractions but as an intermediate step in the analysis of their samples. The progress in electronics and sensors, and in their miniaturization has lead to the paradoxical situation that the analysts never see the transient pure fractions that their detector quantitates. Yet, over the last 25 years, preparative liquid chromatography has become an important industrial process for the separation, the extraction, and/or the purification of many pharmaceuticals or pharmaceutical intermediates, including pure enantiomers, purified peptides and proteins, compounds that are manufactured at the relatively large industrial scale of a few kilograms to several hundred tons per year. This development that has strongly affected the modem pharmaceutical industry is mainly due to the pioneering work of Csaba Horváth. His work in preparative HPLC was critical at both the practical and the theoretical levels. He was the first scientist in modem times to pay serious attention to the relationships between the curvature of the equilibrium isotherms, the competitive nature of nonlinear isotherms, and the chromatographic band profiles of complex mixtures. The thermodynamics of multi-component phase equilibria and mass transfer kinetics in chromatography attracted his interest and were the focus of ground-breaking contributions. He investigated displacement chromatography, an old method invented by Tiselius that Csaba was first to implement in HPLC. This choice was explained by the essential characteristic of displacement chromatography, in that it delivers fractions that can be far more concentrated than the feed. Remarkably, once the basics of nonlinear chromatography had been mastered in his group, most of the applications that were studied by his coworkers dealt with peptides of various sizes and with proteins. Thus, all

  5. Comparison of plastic scintillating fibres and capillaries filled with liquid scintillator

    International Nuclear Information System (INIS)

    Cardini, A.; Cavasinni, V.; Girolamo, B. di; Flaminio, V.; Golovkin, S.V.; Gorin, A.M.; Kulichenko, A.V.; Kushnirenko, A.E.; Pyshev, A.I.; Manuilov, I.; Vasilchenko, V.G.

    1994-01-01

    A comparison is made between the light yield, attenuation length, time response and light propagation speed in plastic scintillating fibres (SCSF-38 and Kuraray-3HF) and quartz capillaries filled with liquid scintillator (LS) 1-methilnaphthalene (1MN) doped with new dyes R45 and R39. The inner diameter of capillaries and diameter of plastic fibres is 0.5 mm. The number of photoelectrons detected at the far end (2 m) was 2.9 for capillaries filled with 1MN+3 g/l R45 while it was 1.8 times smaller in the case of SCSF-38 and 3 times smaller in the case of Kuraray 3HF plastic fibres. Taking into account the quantum efficiency of the photodetector used these reduction factors became 3.0 and 2.0, respectively. Good attenuation length, high light output and also excellent radiation resistance of capillaries filled with LS (>60 Mrad, measured elsewhere) show that they are a very promising alternative to plastic scintillating fibres for future applications in tracking detectors and calorimeters. ((orig.))

  6. On-line radiometry in high-performance liquid chromatography using a storage loop

    International Nuclear Information System (INIS)

    Nieuwkerk, H.J. van.

    1987-01-01

    Difficulty with radiometric chromatography is that large measured volumes are required for accurate detections, but large volumes cause band widening and thus poor separation capacity. The solution proposed here is based on the use of a capillary storage loop for temporary residence of the column eluate. To avoid back mixing, the liquid is interspaced with a second, immiscible, phase ('spacer') so as to form a sequence of small 10-50 μl separate segments. This train passes the on-line radiometric detector to obtain a first scan of the chromatogram, called the 'direct' measurement. It then reaches the storage loop. The usual on-line UV measurement is done in the same run. The eluate cum spacer is, at a later stage, pumped through the detector at a greatly reduced flow rate to obtain the 'reversed' or 'delayed' measurement. Beta-detection is based on liquid scintillation. Accordingly, the (organic) liquid scintillant is used as the 'spacer'. In most cases it is possible to extract the analyte from the aqueous eluate into the organic phase during transport to and storage in the loop. This ensures a high counting efficiency. If the analyte is non-extractable, the counting efficiency is considerably less but the number of counts collected is still sufficient for quantitative assay, due to the extended counting time. The report is divided into 5 chapters, each dealing with a radiometric HPCL separation making use of this method. 36 figs.; 124 refs.; 16 tables

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

    Science.gov (United States)

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Greyce Kelly Steinhorst Alcantara

    2016-01-01

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

  9. Analysis of radioactive mixed hazardous waste using derivatization gas chromatography/mass spectrometry, liquid chromatography, and liquid chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    Campbell, J.A.; Lerner, B.D.; Bean, R.M.; Grant, K.E.; Lucke, R.B.; Mong, G.M.; Clauss, S.A.

    1994-08-01

    Six samples of core segments from Tank 101-SY were analyzed for chelators, chelator fragments, and several carboxylic acids by derivatization gas chromatography/mass spectrometry. The major components detected were ethylenediaminetetraacetic acid, nitroso-iminodiacetic acid, nitrilotriacetic acid, citric acid, succinic acid, and ethylenediaminetriacetic acid. The chelator of highest concentration was ethylenediaminetetraacetic acid in all six samples analyzed. Liquid chromatography was used to quantitate low molecular weight acids including oxalic, formic, glycolic, and acetic acids, which are present in the waste as acid salts. From 23 to 61% of the total organic carbon in the samples analyzed was accounted for by these acids

  10. Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

    Directory of Open Access Journals (Sweden)

    Sławomir Boncel

    2011-06-01

    Full Text Available The physical compatibility of a highly aligned carbon nanotube (HACNT film with liquids was established using a fast and convenient experimental protocol. Two parameters were found to be decisive for the infiltration process. For a given density of nanotube packing, the thermodynamics of the infiltration process (wettability were described by the contact angle between the nanotube wall and a liquid meniscus (θ. Once the wettability criterion (θ < 90° was met, the HACNT film (of free volume equal to 91% was penetrated gradually by the liquid in a rate that can be linearly correlated to dynamic viscosity of the liquid (η. The experimental results follow the classical theory of capillarity for a steady process (Lucas–Washburn law, where the nanoscale capillary force, here supported by gravity, is compensated by viscous drag. This most general theory of capillarity can be applied in a prediction of both wettability of HACNT films and the dynamics of capillary rise in the intertube space in various technological applications.

  11. Dynamics of the liquid film around elongated bubbles rising in vertical capillaries

    Science.gov (United States)

    Magnini, Mirco; Khodaparast, Sepideh; Matar, Omar K.; Stone, Howard A.; Thome, John R.

    2017-11-01

    We performed a theoretical, numerical and experimental study on elongated bubbles rising in vertical tubes in co-current liquid flows. The flow conditions were characterized by capillary, Reynolds and Bond numbers within the range of Ca = 0.005 - 0.1 , Re = 1 - 2000 and Bo = 0 - 20 . Direct numerical simulations of the two-phase flows are run with a self-improved version of OpenFOAM, implementing a coupled Level Set and Volume of Fluid method. A theoretical model based on an extension of the traditional Bretherton theory, accounting for inertia and the gravity force, is developed to obtain predictions of the profiles of the front and rear menisci of the bubble, liquid film thickness and bubble velocity. Different from the traditional theory for bubbles rising in a stagnant liquid, the gravity force impacts the flow already when Bo < 4 . Gravity effects speed up the bubble compared to the Bo = 0 case, making the liquid film thicker and reducing the amplitude of the undulation on the surface of the bubble near its tail. Gravity effects are more apparent in the visco-capillary regime, i.e. when the Reynolds number is below 1.

  12. Determination of trimethyllead reference material using high performance liquid chromatography-inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Lu Hai; Wei Chao; Wang Jun; Chao Jingbo; Zhou Tao; Chen Dazhou

    2005-01-01

    A high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) was combined, and the chromatography conditions were optimized. The stability and homogeneity of a trimethyllead reference material were determined using this method. (authors)

  13. The high pressure electronic control system in liquid chromatography

    International Nuclear Information System (INIS)

    Popescu, Stefan; Popeneciu, Gabriel; Toadere, Florin

    2002-01-01

    The Liquid Chromatography system can perform a wide variety of measurements and separations especially for the organic liquids, with maximum applications flexibility for less than half price of Gas Chromatography. The repeatability and accuracy of results in quantitative high pressure liquid chromatography are highly dependent on the reproducibility and accuracy of both integrated flow rate and mobile phase composition. Flow rate fluctuation leads to poor reproducibility in both integrated peak areas and retention times. Similarly, poor control of mobile phase composition will cause poor repeatability of retention time and peak heights. The our Solvent Delivery System SDS 200 is a single pump system which provides precise compensated flow rates from 0.01 to 10 mL/min, selectable upper pressure limits of 0 to 100 bar or 10 to 450 bar, and solvent compressibility correction. Ternary solvent system on-line mixing capability saves time, reduces solvent waste and provides more flexibility for difficult separations. The pump itself has two different displacement pistons which are used alternately on both suction and discharge, so that intake of the solvent are synchronous. The evacuated solvent from the two pump's chambers is mixed in the reference unit and then is supplied to the damping unit for flow ripple reduction. The SDS Electronic Module ensures the functions: controls the programmed flow rate, detects and shows the solvent pressure in solvent, supplies the step motor, measures and limits the solvent pressure. The control panel of SDS 200, contains a two-stages flow decimal programmer, a eight-positions knob for upper pressure limits, an alarm LED and a parallel port for connection to a PC system. (authors)

  14. Experimental results from a large volume active target made of glass capillaries and liquid scintillator

    International Nuclear Information System (INIS)

    Annis, P.; Buontempo, S.; Brunner, J.; De Jong, M.; Fabre, J.P.; Frenkel, A.; Galeazzi, F.; Golovkin, S.; Gregoire, G.; Hoepfner, K.; Konijn, J.; Kozarenko, E.; Kreslo, I.; Kushnirenko, A.; Martellotti, G.; Mazzoni, M.A.; Medvedkov, A.; Michel, L.; Mondardini, M.R.; Panman, J.; Penso, G.; Petukhov, Y.; Riccardi, F.; Siegmund, W.P.; Strack, R.; Tyukov, V.; Vasilchenko, V.; Vilain, P.; Wilquet, G.; Winter, K.; Wong, H.; Zymin, K.

    1995-01-01

    We are investigating the feasibility of high-resolution tracking with an active target made of glass capillaries filled with organic liquid scintillator. This technique allows real time detection of short-lived particle decays. In this paper, we report on experimental results obtained from an active target having 2 x 2 cm 2 cross section and 180 cm length, installed in front of the CHORUS detector and exposed to the CERN Wide Band Neutrino Beam. The detector consists of 5.1 x 10 5 capillaries with 20 μm inner diameter, read out by a single optoelectronic chain and a Megapixel CCD. Details on tests in the neutrino beam will be reported. First neutrino interactions have been detected. (orig.)

  15. Simultaneous analysis of fourteen tertiary amine stimulants in human urine for doping control purposes by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry

    International Nuclear Information System (INIS)

    Lu Jianghai; Wang San; Dong Ying; Wang Xiaobing; Yang Shuming; Zhang Jianli; Deng Jing; Qin Yang; Xu Youxuan; Wu Moutian; Ouyang Gangfeng

    2010-01-01

    A method for the simultaneous screening and confirmation of the presence of fourteen tertiary amine stimulants in human urine by gas chromatography-mass spectrometry (GC-MS) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. Solid phase extraction (SPE) and liquid-liquid extraction (LLE) approaches were utilized for the pre-treatment of the urine samples. The study indicated that the capillary temperature played a significant role in the signal abundances of the protonated molecules of cropropamide and crotethamide under positive ion electrospray ionization (ESI) conditions. In addition, comparison studies of two different pre-treatment approaches as well as the two ionization modes were conducted. The LODs of the developed method for all the analytes were lower than the minimum required performance limit (MRPL) as set forth in the World Anti-Doping Agency (WADA) technical document for laboratories. The human urine sample obtained after oral administration of prolintane.HCl was successfully analyzed by the developed method, which demonstrated the applicability and reliability of the method for routine doping control analysis.

  16. Hydrazine Determination in Sludge Samples by High Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    G. Elias; G. A. Park

    2006-02-01

    A high-performance liquid chromatographic method using ultraviolet (UV) detection was developed to detect and quantify hydrazine in a variety of environmental matrices. The method was developed primarily for sludge samples, but it is also applicable to soil and water samples. The hydrazine in the matrices was derivatized to their hydrazones with benzaldehyde. The derivatized hydrazones were separated using high performance liquid chromatography (HPLC) with a reversed-phase C-18 column in an isocratic mode with methanol-water (95:5, v/v), and detected with UV detection at 313 nm. The detection limit (25 ml) for the new analytical method is 0.0067 mg ml-1of hydrazine. Hydrazine showed low recovery in soil samples because components in soil oxidized hydrazine. Sludge samples that contained relatively high soil content also showed lower recovery. The technique is relatively simple and cost-effective, and is applicable for hydrazine analysis in different environmental matrices.

  17. Analysis of penicillin G in milk by liquid chromatography.

    Science.gov (United States)

    Boison, J O; Keng, L J; MacNeil, J D

    1994-01-01

    A liquid chromatographic (LC) method that was previously developed for penicillin G residues in animal tissues has been adapted to milk and milk products. After protein precipitation with sodium tungstate, samples are applied to a C18 solid-phase extraction cartridge, from which penicillin is eluted, derivatized with 1,2,4-triazole-mercuric chloride solution, and analyzed by isocratic liquid chromatography (LC) on a C18 column with UV detection at 325 nm. Quantitation is done with reference to penicillin V as an internal standard. Penicillin G recoveries were determined to be > 70% on standards fortified at 3-60 ppb. Accuracy approached 100% using the penicillin V internal standard. The detection limit for penicillin G residues was 3 ppb in fluid milk. Samples may be confirmed by thermospray/LC at concentrations approaching the detection limit of the UV method.

  18. Fiber-based monolithic columns for liquid chromatography.

    Science.gov (United States)

    Ladisch, Michael; Zhang, Leyu

    2016-10-01

    Fiber-based monoliths for use in liquid chromatographic separations are defined by columns packed with aligned fibers, woven matrices, or contiguous fiber structures capable of achieving rapid separations of proteins, macromolecules, and low molecular weight components. A common denominator and motivating driver for this approach, first initiated 25 years ago, was reducing the cost of bioseparations in a manner that also reduced residence time of retained components while achieving a high ratio of mass to momentum transfer. This type of medium, when packed into a liquid chromatography column, minimized the fraction of stagnant liquid and resulted in a constant plate height for non-adsorbing species. The uncoupling of dispersion from eluent flow rate enabled the surface chemistry of the stationary phase to be considered separately from fluid transport phenomena and pointed to new ways to apply chemistry for the engineering of rapid bioseparations. This paper addresses developments and current research on fiber-based monoliths and explains how the various forms of this type of chromatographic stationary phase have potential to provide new tools for analytical and preparative scale separations. The different stationary phases are discussed, and a model that captures the observed constant plate height as a function of mobile phase velocity is reviewed. Methods that enable hydrodynamically stable fiber columns to be packed and operated over a range of mobile phase flow rates, together with the development of new fiber chemistries, are shown to provide columns that extend the versatility of liquid chromatography using monoliths, particularly at the preparative scale. Graphical Abstract Schematic representation of a sample mixture being separated by a rolled-stationary phase column, resulting separated peaks shown in the chromatogram.

  19. From catastrophic acceleration to deceleration of liquid plugs in prewetted capillary tubes

    Science.gov (United States)

    Magniez, Juan; Baudoin, Michael; Zoueshtiagh, Farzam; Lemac/Lics Team

    2016-11-01

    Liquid/gas flows in capillaries are involved in a multitude of systems including flow in porous media, petroleum extraction, imbibition of paper or flows in pulmonary airways in pathological conditions. Liquid plugs, witch compose the biphasic flows, can have a dramatic impact on patients with pulmonary obstructive diseases, since they considerably alter the circulation of air in the airways and thus can lead to severe breathing difficulties. Here, the dynamics of liquid plugs in prewetted capillary tube is investigated experimentally and theoretically, with a particular emphasis on the role of the prewetting films and of the driving condition (constant flow rate, constant pressure). For both driving conditions, the plugs can either experience a continuous increase or decrease of their size. While this phenomenon is regular in the case of imposed flow rate, a constant pressure head can lead to a catastrophic acceleration of the plug and eventually its rupture or a dramatic increase of the plug size. A theoretical model is proposed to explain the transition between theses two regimes. These results give a new insight on the critical pressure required for airways obstruction and reopening. IEMN, International Laboratory LEMAC/LICS, UMR CNRS 8520, University of Lille.

  20. Microsphere Wetting, Meniscus Structure, and Capillary Interactions on a Curved Liquid Interface

    Science.gov (United States)

    Kim, Paul; Dinsmore, Anthony; Hoagland, David; Russell, Thomas

    A small spherical microparticle on a cylindrically curved liquid interface locally induces a quadrupolar interface deformation to maintain a constant contact angle about its wetted periphery. Measured by optical profilometry, this deformation was compared to a recent theoretical expression, and good agreement was noted for contact line shape, particle vertical position, and deformation vs. (distance, angle, particle size, interfacial curvature). Interface quadrupoles lead to particle capillary interactions in analogy to 2D electrostatic quadrupoles, and as one consequence, spheres on a cylindrical interface assemble tetragonally, i.e., into a square lattice. This assembly was monitored in the optical microscope, with particles interacting as predicted, into a square lattice aligned with the underlying cylindrical axis. These particles and assemblies were driven to the middle of the curved interface by capillary interaction with pinned liquid contact lines on each side of the liquid cylindrical section used in the experiments. These phenomena can inform the directed interfacial assembly of micro-sized spherical objects, with potential application in fabrication of functional devices and materials, encapsulation, and emulsification.

  1. Performance of a liquid-junction interface for capillary electrophoresis mass spectrometry using continuous-flow fast-atom bombardment

    NARCIS (Netherlands)

    Reinhoud, N.J.; Niessen, W.M.A.; Tjaden, U.R.; Gramberg, L.G.; Verheij, E.R.; Greef, J. van der

    1989-01-01

    The on-line coupling of capillary electrophoresis and mass spectrometry using a continuous-flow fast-atom bombardment system in combination with a liquid-junction interface is described. The influence of the liquid-junction coupling on the efficiency and the resolution is investigated. Qualitative

  2. Determination of pertechnetate by liquid chromatography with reductive electrochemical detection

    International Nuclear Information System (INIS)

    Lewis, J.Y.; Zodda, J.P.; Deutsch, E.; Heineman, W.R.

    1983-01-01

    A method utilizing liquid chromatography with electrochemical detection has been developed for the determination of total TcO 4 - (/sup 99m/TcO 4 - and /sup 99m/TcO 4 - ) in 99 Mo//sup 99m/Tc generator eluents. Pertechnetate, which is the starting material for the preparation of many diagnostic radiopharmaceuticals, is generally present in these eluents in the concentration range of 5 X 10 -8 M to 5 X 10 -6 M. No sample pretreatment is necessary since impurities and other components are separated by the high-pressure liquid chromatography (HPLC) NH 2 -bonded column. By use of both static mercury drop (SMDE) and solid electrode detectors, in conjuction with rigorous deoxygenation procedures, total TcO 4 - in generator eluents is readily determined. A severe electrode fouling phenomenon limits the use of solid electrode detectors to TcO 4 - concentrations less than 10 -7 M, the working range for a carbon electrode being 8.5 X 10 -9 to 1.0 X 10 -7 M. The working range for the SMDE is 2.1 X 10 -8 to 1.0 X 10 -4 M TcO 4 -

  3. Description of Adsorption in Liquid Chromatography under Nonideal Conditions.

    Science.gov (United States)

    Ortner, Franziska; Ruppli, Chantal; Mazzotti, Marco

    2018-05-15

    A thermodynamically consistent description of binary adsorption in reversed-phase chromatography is presented, accounting for thermodynamic nonidealities in the liquid and adsorbed phases. The investigated system involves the adsorbent Zorbax 300SB-C18, as well as phenetole and 4- tert-butylphenol as solutes and methanol and water as inert components forming the eluent. The description is based on adsorption isotherms, which are a function of the liquid-phase activities, to account for nonidealities in the liquid phase. Liquid-phase activities are calculated with a UNIQUAC model established in this work, based on experimental phase equilibrium data. The binary interaction in the adsorbed phase is described by the adsorbed solution theory, assuming an ideal (ideal adsorbed solution theory) or real (real adsorbed solution theory) adsorbed phase. Implementation of the established adsorption model in a chromatographic code achieves a quantitative description of experimental elution profiles, with feed compositions exploiting the entire miscible region, and involving a broad range of different eluent compositions (methanol/water). The quantitative agreement of the model and experimental data serves as a confirmation of the underlying physical (thermodynamic) concepts and of their applicability to a broad range of operating conditions.

  4. New separation and detection methods in capillary electrophoresis and ion chromatography for the analysis of ionic compounds

    International Nuclear Information System (INIS)

    Mayrhofer, K.

    1999-10-01

    The first part of the thesis deals with the simultaneous analysis of inorganic anions and organic acids in electrodeposition coatings with the co-electroosmotic capillary electrophoresis. The coating of workpieces, e.g. car bodies, by means of an electrodeposition process is an important methodology especially in the automotiv industries. It is usually performed by introducing the object into a basin filled with a water-based electro-dipcoat, applying a voltage of 200-400 Volts (direct current) and using the bodywork as cathode. Because the workpiece has to pass a number of preliminary treatments before the coating procedure, ionic compound may be carried into the basin. If the concentrations of these ionic impurities is too high, the electro-deposition of the binding agent fails or the thickness of the coating is not reproducible. The organic acids are used as neutralization agents in order to control and to keep the pH of the basin constant. The common method of analysing ionic impurities is ion chromatography. The organic acids have to be separated in an ion exclusion chromatography column because organic acids may coelute with the inorganic anions or elute with the dead volume. Therefore a separation method for capillary electrophoresis was developed which enables the simultaneouse analysis of inorganic anions and organic acids in less then 5 minutes. Chloride, nitrate, sulfate, fuoride, phosphate, carbonate, formic acid, acetic acid, lactic acid and butyric acid were detected with indirect UV-detection at 254 nm. For removal of the the binding agent and the pigments the lacquer was mixed with a 0.01 M sodium hydroxide solution and then filtered through a 0.45 μm filter cartridge. 5 mM trimellitic acid, titrated with sodium hydroxid to pH 10, 0.001 % hexadimethrinbromide and 20 % acetonitrile served as buffer. The analytes were separated with a satisfactory resolution. Between every analysis the fused silica capillary was purged for two minutes with buffer. So

  5. Trends in the analysis of natural gas by capillary gas chromatography

    NARCIS (Netherlands)

    Cramers, C.A.M.G.; Rossum, van G.J.

    1986-01-01

    The importance of correct determination of physical and chemical properties of natural gas is evident. The calculation of calorific value or hydrocarbon dew point requires detailed analysis as can be provided by gas chromatography. Analysis by gas chromatography is a necessary complement to direct

  6. Determination of alcohols, ethers and organic acids in irradiated sweet potato wine by capillary gas chromatography

    International Nuclear Information System (INIS)

    Zhou Yingcai; Yuan Bihuai; Xu Peishu; Wang Xiuying

    1986-01-01

    Alcohols, ethers and organic acids in irradiated sweet potato wine have been determined with capillary GC. The results show that the contents of some components have changed after irradiation, but no new species are formed. The G values of the changed components have been calculated

  7. On-line Automated Sample Preparation-Capillary Gas Chromatography for the Analysis of Plasma Samples.

    NARCIS (Netherlands)

    Louter, A.J.H.; van der Wagt, R.A.C.A.; Brinkman, U.A.T.

    1995-01-01

    An automated sample preparation module, (the automated sample preparation with extraction columns, ASPEC), was interfaced with a capillary gas chromatograph (GC) by means of an on-column interface. The system was optimised for the determination of the antidepressant trazodone in plasma. The clean-up

  8. Identification of thermal degradation products of polymers by capillary gas chromatography

    NARCIS (Netherlands)

    Pacakova, V.; Borecka, M.; Leclercq, P.A.; Kaiser, R.E.

    1981-01-01

    Samples of polyethylene, polypropylene, polystyrene and five styrene copolymers were thermally degraded in a quartz tubular reactor at 5100e in an inert atmosphere. The degradation products were separated on-line on capillary coltmlS coated with squalane, OV-17 and SE-30 as stationary phases. The

  9. A fully automated fast analysis system for capillary gas chromatography. Part 1. Automation of system control

    NARCIS (Netherlands)

    Snijders, H.M.J.; Rijks, J.P.E.M.; Bombeeck, A.J.; Rijks, J.A.; Sandra, P.; Lee, M.L.

    1992-01-01

    This paper is dealing with the design, the automation and evaluation of a high speed capillary gas chromatographic system. A combination of software and hardware was developed for a new cold trap/reinjection device that allows selective solvent eliminating and on column sample enrichment and an

  10. Supercritical fluid extraction-capillary gas chromatography: on-line coupling with a programmed temperature vaporizer

    NARCIS (Netherlands)

    Houben, R.J.; Janssen, J.G.M.; Leclercq, P.A.; Rijks, J.A.; Cramers, C.A.M.G.

    1990-01-01

    A simple and versatile system is described for the on-line coupling of SFE to capillary GC. The interfacing consists of a programmed temperature vaporizer (PTV) injector. With this injector it is possible to combine solute trapping, elimination of a high flow of extraction fluid, and quantitative

  11. Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.

    Science.gov (United States)

    Fan, Yunpeng; Fu, Yanhui; Fu, Qing; Cai, Jianfeng; Xin, Huaxia; Dai, Mei; Jin, Yu

    2016-07-01

    An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Evaluation between ultrahigh pressure liquid chromatography and high-performance liquid chromatography analytical methods for characterizing natural dyestuffs.

    Science.gov (United States)

    Serrano, Ana; van Bommel, Maarten; Hallett, Jessica

    2013-11-29

    An evaluation was undertaken of ultrahigh pressure liquid chromatography (UHPLC) in comparison to high-performance liquid chromatography (HPLC) for characterizing natural dyes in cultural heritage objects. A new UHPLC method was optimized by testing several analytical parameters adapted from prior UHPLC studies developed in diverse fields of research. Different gradient elution programs were tested on seven UHPLC columns with different dimensions and stationary phase compositions by applying several mobile phases, flow rates, temperatures, and runtimes. The UHPLC method successfully provided more improved data than that achieved by the HPLC method. Indeed, even though carminic acid has shown circa 146% higher resolution with HPLC, UHPLC resulted in an increase of 41-61% resolution and a decrease of 91-422% limit of detection, depending on the dye compound. The optimized method was subsequently assigned to analyse 59 natural reference materials, in which 85 different components were ascribed with different physicochemical properties, in order to create a spectral database for future characterization of dyes in cultural heritage objects. The majority of these reference samples could be successfully distinguished with one single method through the examination of these compounds' retention times and their spectra acquired with a photodiode array detector. These results demonstrate that UHPLC analyses are extremely valuable for the acquisition of more precise chromatographic information concerning natural dyes with complex mixtures of different and/or closely related physicochemical properties, essential for distinguishing similar species of plants and animals used to colour cultural heritage objects. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

    Science.gov (United States)

    Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

    2015-07-03

    The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. (Vapour + liquid) equilibria of ternary systems with ionic liquids using headspace gas chromatography

    International Nuclear Information System (INIS)

    Mokhtarani, Babak; Gmehling, Juergen

    2010-01-01

    (Vapour + liquid) equilibrium (VLE) data for the ternary systems (hexane + benzene), (hexane + cyclohexane), (benzene + cyclohexane), and (ethanol + water) with an ionic liquid as entrainer for extractive distillation were measured by headspace gas chromatography. As ionic liquids, 1-hexyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [HMIM][BTI], 1-octyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [OMIM][BTI], 1-octyl-3-methyl-imidazolium trifluoro-methanesulfonate [OMIM][OTF], and 1-butyl-3-methyl-imidazolium trifluoro-methanesulfonate [BMIM][OTF] were used. The experimental data show that the ionic liquids investigated have a great influence on the separation factors of the systems (hexane + benzene), (hexane + cyclohexane), and (benzene + cyclohexane). The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data.

  15. (Vapour + liquid) equilibria of ternary systems with ionic liquids using headspace gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtarani, Babak [Chemistry and Chemical Engineering Research Center of Iran, P.O. Box 14335-186, Tehran (Iran, Islamic Republic of); Gmehling, Juergen, E-mail: gmehling@tech.chem.uni-oldenburg.d [Carl von Ossietzky Universitaet Oldenburg, Technische Chemie, D-26111 Oldenburg (Germany)

    2010-08-15

    (Vapour + liquid) equilibrium (VLE) data for the ternary systems (hexane + benzene), (hexane + cyclohexane), (benzene + cyclohexane), and (ethanol + water) with an ionic liquid as entrainer for extractive distillation were measured by headspace gas chromatography. As ionic liquids, 1-hexyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [HMIM][BTI], 1-octyl-3-methyl-imidazolium bis (trifluoromethyl-sulfonyl) imide [OMIM][BTI], 1-octyl-3-methyl-imidazolium trifluoro-methanesulfonate [OMIM][OTF], and 1-butyl-3-methyl-imidazolium trifluoro-methanesulfonate [BMIM][OTF] were used. The experimental data show that the ionic liquids investigated have a great influence on the separation factors of the systems (hexane + benzene), (hexane + cyclohexane), and (benzene + cyclohexane). The experimental data were compared with the predicted results using mod. UNIFAC (Do). The predicted results are in good agreement with the experimental data.

  16. Thermogravimetric and Pyrolysis-Capillary Gas Chromatography-Mass Spectrometric Analysis of Pinus Halepensis Mill. Wood

    International Nuclear Information System (INIS)

    Hafsi, S.; Benbouzid, M.; Zimny, T.

    2005-01-01

    The analytical methods TG and Py-capillary-GC-MS were used to study the thermal degradation of Pinus Halepensis Mill. wood. The TG analysis in air and in nitrogen showed that the percentage content of char and ash were, 23.1% and 7.7% respectively. TG and DTG analysis proved that the evolution of organic degradation products occurs mainly between 215C and 380C and has its maximum evolution rate at 360C in nitrogen and 347C in air. Py-capillary-GC-MS analysis of the pyrolysis at 400C identified the presence of valuable chemicals such aliphatic and aromatic hydrocarbons, phenols, aldehydes, esters and saturated and unsaturated long chain fatty acids. (author)

  17. Reduction of silanophilic interactions in liquid chromatography with the use of ionic liquids

    International Nuclear Information System (INIS)

    MarszaII, MichaI Piotr; Baczek, Tomasz; Kaliszan, Roman

    2005-01-01

    A suppression of silanophilic interactions by the selected ionic liquids added to the mobile phase in thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) is reported. Acetonitrile was used as the eluent, alone or with various concentrations of water and phosphoric buffer pH 3. Selectivity of the normal (NP) and the reversed (RP) stationary phase material was examined using a series of proton-acceptor basic drugs analytes. The ionic liquids studied appeared to significantly affect analyte retention in NP-TLC, RP-TLC and RP-HPLC systems tested. Consequently, the increased separation selectivity was attained. Due to ionic liquid additives to eluent even analytes could be chromatographed, which were not eluted from the silica-based stationary phase materials with 100% of acetonitrile in the mobile phase. Addition of ionic liquid already in very small concentration (0.5%, v/v) could reduce the amount of acetonitrile used during the optimization of basic analytes separations in TLC and HPLC systems. Moreover, the influence of temperature on the separation of basic analytes was demonstrated and considered in practical HPLC method development

  18. Reduction of silanophilic interactions in liquid chromatography with the use of ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    MarszaII, MichaI Piotr [Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gen. J. Hallera 107, 80-416 Gdansk (Poland); Baczek, Tomasz [Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gen. J. Hallera 107, 80-416 Gdansk (Poland); Kaliszan, Roman [Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gen. J. Hallera 107, 80-416 Gdansk (Poland)]. E-mail: roman.kaliszan@amg.gda.pl

    2005-08-22

    A suppression of silanophilic interactions by the selected ionic liquids added to the mobile phase in thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) is reported. Acetonitrile was used as the eluent, alone or with various concentrations of water and phosphoric buffer pH 3. Selectivity of the normal (NP) and the reversed (RP) stationary phase material was examined using a series of proton-acceptor basic drugs analytes. The ionic liquids studied appeared to significantly affect analyte retention in NP-TLC, RP-TLC and RP-HPLC systems tested. Consequently, the increased separation selectivity was attained. Due to ionic liquid additives to eluent even analytes could be chromatographed, which were not eluted from the silica-based stationary phase materials with 100% of acetonitrile in the mobile phase. Addition of ionic liquid already in very small concentration (0.5%, v/v) could reduce the amount of acetonitrile used during the optimization of basic analytes separations in TLC and HPLC systems. Moreover, the influence of temperature on the separation of basic analytes was demonstrated and considered in practical HPLC method development.

  19. Chiral separation on sulfonated cellulose tris(3,5-dimethylphenyl carbamate)-coated zirconia monolith by capillary electro chromatography

    International Nuclear Information System (INIS)

    Lee, Jeongmi; Park, Jung Hag; Jang, Myung Duk

    2012-01-01

    Sulfonated cellulose tris(3,5-dimethylphenyl carbamate) (SCDMPC)-coated zirconia monolith (ZM) was used as the chiral stationary phase in capillary electro chromatography for separation of enantiomers of ten chiral compounds in acetonitrile (ACN)-phosphate buffer mixtures as the eluent. Influences of the ACN content, buffer concentration and pH on chiral separation have been investigated. Separation data on SCDMPC-ZM have been compared with those on CDMPC-ZM. Resolution factors were better on SCDMPC-ZM than CDMPC-ZM while retention factors were in general shorter on the former than the latter. Best chiral resolutions on SCDMPC-ZM were obtained with the eluent of 50% ACN containing 50 mM phosphate at pH around 4

  20. Simultaneous determination of metoprolol and metabolites in urine by capillary column gas chromatography as oxazolidineone and trimethylsilyl derivatives.

    Science.gov (United States)

    Gyllenhaal, O; Hoffmann, K J

    1984-08-10

    A method for the determination of metoprolol and its main metabolites in urine is presented. The method comprises derivatization of the aminopropanol side-chain with phosgene at alkaline pH and isolation in an organic phase at acidic pH. After trimethylsilylation, separation and quantification are performed by capillary column gas chromatography with flame ionization detection. The reaction is performed at pH 12 with 60 microliters of 2 M phosgene in toluene added in three portions. Diethyl ether--dichloromethane is used as extraction medium and bis(trimethylsilyl) acetamide as silylating agent. With spiked samples linear standard curves were obtained for metoprolol and three of its main metabolites with a detection limit varying between 4 and 20 mumol/l of urine. The method was applied to urine samples from a normal individual who had taken 292 mumol of metoprolol as tartrate.

  1. Hydrophilic interaction liquid chromatography in the speciation analysis of selenium.

    Science.gov (United States)

    Sentkowska, Aleksandra; Pyrzynska, Krystyna

    2018-02-01

    The hydrophilic interaction liquid chromatography (HILIC) coupled to mass spectrometry was employed to study retention behavior of selected selenium compounds using two different HILIC stationary phases: silica and zwitterionic. Two organic solvents - acetonitrile and methanol - were compared as a component of mobile phase. Separation parameters such as a content of organic modifier, the eluent pH and inorganic buffer concentration were investigated. Based on all observations, methanol seems to be beneficial for the separation of studied compounds. The optimal HILIC separation method involved silica column and eluent composed of 85% MeOH and CH 3 COONH 4 (8 mM, pH 7) was compared to RP method in terms of time of the single run, the separation efficiency and limit of detection. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Cortisol production rates measured by liquid chromatography/mass spectrometry

    International Nuclear Information System (INIS)

    Esteban, N.V.; Yergey, A.L.

    1990-01-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references

  3. Modern Aspects Of Fluorometric Detection In Liquid-Phase Chromatography

    Science.gov (United States)

    Bousquet, Bernard; Garnier, Jean P.; Dreux, Claude

    1983-10-01

    Recent advances are described in the combined use of fluorometric derivatization and high performance liquid chromatography (HPLC) for clinical chemistry determinations. Derivatives (especially dansyl derivatives) can be formed prior to chromatography in the case of estrogens, amino acids, and catecholamines. In post-column reactions, we preferred to use air-segmented reactions as they conform better to all the optimized chromatographic and spectrofluorometric parameters. Fluorescent derivatives produced from cate-cholamines, tryptophan and its metabolites, hydroxyindoles, tryptamine, amino acids, sugars, polyamines, and other substances are often sufficiently sensitive to be detected in picogram quantities by HPLC. Their reaction principle and some of their applications to samples are described. Recently, chemical excitation of fluorophore-like dansyl amino acid was proposed as a detection system for HPLC. By a post-column reaction, a fluorophore can be made to emit light by its reaction with trichlorophenyl oxalate (TCPO) and hydrogen peroxide. The detection limit of this system is about 10 fmol for each dansyl amino acid. Application of this new reaction to catecholamines opens up new prospects for fluorometric detection.

  4. Group type analysis of asphalt by column liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.; Yang, J.; Xue, Y.; Li, Y. [Chinese Academy of Science, Taiyuan (China)

    2008-07-01

    An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

  5. Practical capillary electrophoresis

    CERN Document Server

    Weinberger, Robert

    2000-01-01

    In the 1980s, capillary electrophoresis (CE) joined high-performance liquid chromatography (HPLC) as the most powerful separation technique available to analytical chemists and biochemists. Published research using CE grew from 48 papers in the year of commercial introduction (1988) to 1200 in 1997. While only a dozen major pharmaceutical and biotech companies have reduced CE to routine practice, the applications market is showing real or potential growth in key areas, particularly in the DNA marketplace for genomic mapping and forensic identification. For drug development involving small molecules (including chiral separations), one CE instrument can replace 10 liquid chromatographs in terms of speed of analysis. CE also uses aqueous rather than organic solvents and is thus environmentally friendlier than HPLC. The second edition of Practical Capillary Electrophoresis has been extensively reorganized and rewritten to reflect modern usage in the field, with an emphasis on commercially available apparatus and ...

  6. Analytical method for high resolution liquid chromatography for quality control French Macaw

    International Nuclear Information System (INIS)

    Garcia Penna, Caridad M; Torres Amaro, Leonid; Menendez Castillo, Rosa; Sanchez, Esther; Martinez Espinosa, Vivian; Gonzalez, Maria Lidia; Rodriguez, Carlos

    2007-01-01

    Was developed and validated an analytical method for high resolution liquid chromatography applicable to quality control of drugs dry French Macaw (Senna alata L. Roxb.) With ultraviolet detection at 340 nm. The method for high resolution liquid chromatography used to quantify the sennosides A and B, main components, was validated and proved to be specific, linear, precise and accurate. (Author)

  7. Recent advances in ultra-high performance liquid chromatography for the analysis of traditional chinese medicine

    Science.gov (United States)

    Traditional Chinese medicines (TCMs) have been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra Performance Liquid Chromatography (UHPLC) is a relatively new technique offering new possibilities in liquid chromatography. This paper reviews recen...

  8. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges

    Science.gov (United States)

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep

    2009-01-01

    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  9. Towards Chip Scale Liquid Chromatography and High Throughput Immunosensing

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Jing [Iowa State Univ., Ames, IA (United States)

    2000-09-21

    This work describes several research projects aimed towards developing new instruments and novel methods for high throughput chemical and biological analysis. Approaches are taken in two directions. The first direction takes advantage of well-established semiconductor fabrication techniques and applies them to miniaturize instruments that are workhorses in analytical laboratories. Specifically, the first part of this work focused on the development of micropumps and microvalves for controlled fluid delivery. The mechanism of these micropumps and microvalves relies on the electrochemically-induced surface tension change at a mercury/electrolyte interface. A miniaturized flow injection analysis device was integrated and flow injection analyses were demonstrated. In the second part of this work, microfluidic chips were also designed, fabricated, and tested. Separations of two fluorescent dyes were demonstrated in microfabricated channels, based on an open-tubular liquid chromatography (OT LC) or an electrochemically-modulated liquid chromatography (EMLC) format. A reduction in instrument size can potentially increase analysis speed, and allow exceedingly small amounts of sample to be analyzed under diverse separation conditions. The second direction explores the surface enhanced Raman spectroscopy (SERS) as a signal transduction method for immunoassay analysis. It takes advantage of the improved detection sensitivity as a result of surface enhancement on colloidal gold, the narrow width of Raman band, and the stability of Raman scattering signals to distinguish several different species simultaneously without exploiting spatially-separated addresses on a biochip. By labeling gold nanoparticles with different Raman reporters in conjunction with different detection antibodies, a simultaneous detection of a dual-analyte immunoassay was demonstrated. Using this scheme for quantitative analysis was also studied and preliminary dose-response curves from an immunoassay of a

  10. Capillary detectors

    International Nuclear Information System (INIS)

    Konijn, J.; Winter, K.; Vilain, P.; Wilquet, G.; Fabre, J.P.; Kozarenko, E.; Kreslo, I.; Goldberg, J.; Hoepfner, K.; Bay, A.; Currat, C.; Koppenburg, P.; Frekers, D.; Wolff, T.; Buontempo, S.; Ereditato, A.; Frenkel, A.; Liberti, B.; Martellotti, G.; Penso, G.; Ekimov, A.; Golovkin, S.; Govorun, V.; Medvedkov, A.; Vasil'chenko, V.

    1998-01-01

    The option for a microvertex detector using glass capillary arrays filled with liquid scintillator is presented. The status of capillary layers development and possible read-out techniques for high rate environment are reported. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

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

    Science.gov (United States)

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

    2015-01-01

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

  12. Analysis of short-chain acids from anaerobic bacteria by high-performance liquid chromatography.

    OpenAIRE

    Guerrant, G O; Lambert, M A; Moss, C W

    1982-01-01

    A standard mixture of 25 short-chain fatty acids was resolved by high-performance liquid chromatography, using an Aminex HPX-87 column. The acids produced in culture media by anaerobic bacteria were analyzed by high-performance liquid chromatography after extraction with ether and reextraction into a small volume of 0.1 N NaOH. The presence of fumaric acid in culture extracts of Peptostreptococcus anaerobius was confirmed by gas chromatography-mass spectrometry analysis of the trapped eluent ...

  13. Silica particles encapsulated poly(styrene-divinylbenzene) monolithic stationary phases for micro-high performance liquid chromatography.

    Science.gov (United States)

    Bakry, R; Stöggl, W M; Hochleitner, E O; Stecher, G; Huck, C W; Bonn, G K

    2006-11-03

    In the paper we demonstrate a new approach for the preparation and application of continuous silica bed columns that involve encapsulation (entrapment) of functionalized silica microparticles, which can be used as packing material in micro high performance liquid chromatography (micro-HPLC) and capillary electrochromatography (CEC). Like traditional packed columns, these capillaries possess characterized silica particles that offer high phase ratio and narrow pore size distribution leading to high retention and separation efficiency, respectively. More importantly, immobilization of the microparticles stabilizes the separation bed and eliminates the need for retaining frits. The developed capillary columns were fabricated in exactly the same way as a packed capillary column (slurry packing) but with an additional entrapment step. This immobilization of the packed bed was achieved by in situ polymerization of styrene and divinylbenzene in presence of decanol as a porogen and azobisisobutyronitrile as thermal initiator. Silica particles with different particle sizes and pore sizes ranging from 60 to 4000 A were studied. In addition different modified silica was used, including C-18 reversed phase, anion exchange and chiral stationary phases. Efficient separation of polyphenolic compounds, peptides, proteins and even DNA mutation were achieved using the developed technique depending on the properties of the silica particles used (particles pore size). For example, using 3 microm ProntoSIL C-18 particles with 300 A pore size, separation efficiencies in the range of 120,000-200,000 plates/m were obtained for protein separation, in a 6 cm x 200 microm i.d. capillary column. Using encapsulated silica C-18 with 1000 A pore size, separation of DNA homo and hetero duplexes were achieved under denaturing HPLC conditions for mutation detection. In addition, nucleotides were separated using anion exchange material encapsulated with poly(styrene-divinylbenzene) (PS/DVB), which

  14. Exploitation of a microporous organic polymer as a stationary phase for capillary gas chromatography

    International Nuclear Information System (INIS)

    Lu, Cuiming; Liu, Shuqin; Xu, Jianqiao; Ding, Yajuan; Ouyang, Gangfeng

    2016-01-01

    Microporous organic polymers (MOPs) have emerged as a new class of functional porous materials with unique characteristics and potential uses in diverse areas. However, the field of MOPs for gas chromatographic (GC) separations has not been well explored. Herein, a MOP namely KAPs-1 was dynamic coated onto a capillary column for the first time. The fabricated column exhibited a nonpolar nature and the column efficiency for n-dodecane was up to 7769 plates m"−"1. The KAPs-1 coated column showed high GC separation performance for a series of volatile organic compounds (VOCs) including the challenging ethylbenzene and xylene isomers, which could not be resolved at baseline on the commercial 5% phenyl polysiloxane stationary phase. Moreover, the relative standard deviations for five replicate determinations of the studied analytes were 0.0–0.6%, 0.9–3.2%, 1.1–5.9%, 0.8–3.7% for retention time, peak area, peak height and peak width, respectively. To investigate the interaction between some analytes and the stationary phase, thermodynamic and kinetic parameters were also evaluated. The results of this study show it is very promising to utilize MOPs as stationary phases for capillary GC. - Highlights: • A microporous organic polymer was explored as a novel stationary phase for capillary GC. • The column showed high separation performance for VOCs including the challenging ethylbenzene and xylene isomers. • Thermodynamic and kinetic parameters for BTEXs were determined to study the analyte-stationary phase interaction.

  15. Exploitation of a microporous organic polymer as a stationary phase for capillary gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Cuiming; Liu, Shuqin; Xu, Jianqiao; Ding, Yajuan; Ouyang, Gangfeng, E-mail: cesoygf@mail.sysu.edu.cn

    2016-01-01

    Microporous organic polymers (MOPs) have emerged as a new class of functional porous materials with unique characteristics and potential uses in diverse areas. However, the field of MOPs for gas chromatographic (GC) separations has not been well explored. Herein, a MOP namely KAPs-1 was dynamic coated onto a capillary column for the first time. The fabricated column exhibited a nonpolar nature and the column efficiency for n-dodecane was up to 7769 plates m{sup −1}. The KAPs-1 coated column showed high GC separation performance for a series of volatile organic compounds (VOCs) including the challenging ethylbenzene and xylene isomers, which could not be resolved at baseline on the commercial 5% phenyl polysiloxane stationary phase. Moreover, the relative standard deviations for five replicate determinations of the studied analytes were 0.0–0.6%, 0.9–3.2%, 1.1–5.9%, 0.8–3.7% for retention time, peak area, peak height and peak width, respectively. To investigate the interaction between some analytes and the stationary phase, thermodynamic and kinetic parameters were also evaluated. The results of this study show it is very promising to utilize MOPs as stationary phases for capillary GC. - Highlights: • A microporous organic polymer was explored as a novel stationary phase for capillary GC. • The column showed high separation performance for VOCs including the challenging ethylbenzene and xylene isomers. • Thermodynamic and kinetic parameters for BTEXs were determined to study the analyte-stationary phase interaction.

  16. A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography

    International Nuclear Information System (INIS)

    Wang Yu; Deng Qiliang; Fang Guozhen; Pan Mingfei; Yu Yang; Wang Shuo

    2012-01-01

    Highlights: ► ILs as functional monomer for capillary monolithic column. ► Separation of alkylbenzenes, thiourea analogues, and amino acids. ► The column generate a stable reversed EOF from pH 2.0 to 12.0. ► The column efficiency of 147,000 plates m −1 was obtained for thiourea. - Abstract: A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm + Cl − ) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0–12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ∼6.8 μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ∼147,000 plates m −1 for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.

  17. Quantitation of Metformin in Human Plasma and Urine by Hydrophilic Interaction Liquid Chromatography and Application to a Pharmacokinetic Study

    DEFF Research Database (Denmark)

    Nielsen, Flemming; Hougaard Christensen, Mette Marie; Brøsen, Kim

    2014-01-01

    : We describe an analytical method for the quantification of the widely used antihyperglycemic agent, metformin, in human plasma and urine. The separation was performed using isocratic hydrophilic interaction liquid chromatography on a Luna hydrophilic interaction liquid chromatography column (125...

  18. [Determination of 44 organophosphorus pesticides in food by SPE disk extraction-capillary gas chromatography with pulsed flame photometric detection].

    Science.gov (United States)

    Luo, Xiao-Fei; Yang, Yuan; Sun, Cheng-Jun

    2012-01-01

    To develop a method for the simultaneous determination of 44 organophosphorus pesticides in food by SPE disk extraction-capillary gas chromatography with pulsed flame photometric detection. Organophosphorus pesticides in food were extracted ultrasonically with water. Then the extract was cleaned-up with SPE disk and eluted with ethyl acetate. Finally the eluent was condensed to 1mL under N2 at 55 degrees C. Gas chromatography was applied for quantitative detection of the organophosphorus pesticides in the sample. The linear range of the method for all the pesticides were in the range of 0.01-0.5 mg/kg with correlation coefficients of 0.992-1.000. The detection limits of the method were in the range of 0.0005-0.01 mg/kg. The recoveries for most pesticides were 60%-120% with relative standard deviations of less than 15%. The method is simple, sensitive, environmentally friendly and suitable for the determination of organophosphorous pesticides in food.

  19. Liquid chromatography/mass spectrometric determination of patulin in apple juice using atmospheric pressure photoionization.

    Science.gov (United States)

    Takino, Masahiko; Daishima, Shigeki; Nakahara, Taketoshi

    2003-01-01

    This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) technique for the liquid chromatography/mass spectrometric (LC/MS) determination of patulin in clear apple juice. A column switching technique for on-line extraction of clear apple juice was developed. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for both APCI and APPI. The results indicated that APPI provides lower chemical noise and signal suppression in comparison with APCI. The linear range for patulin in apple juice (correlation coefficient >0.999) was 0.2-100 ng mL(-1). Mean recoveries of patulin in three apple juices ranged from 94.5 to 103.2%, and the limit of detection (S/N = 3), repeatability and reproducibility were 1.03-1.50 ng mL(-1), 3.9-5.1% and 7.3-8.2%, respectively. The total analysis time was 10.0 min. Copyright 2003 John Wiley & Sons, Ltd.

  20. Thermodynamic and kinetic characterization of polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.

    Science.gov (United States)

    Howerton, Samuel B; McGuffin, Victoria L

    2003-07-15

    The retention of six polycyclic aromatic hydrocarbons (PAHs) was characterized by reversed-phase liquid chromatography. The PAHs were detected by laser-induced fluorescence at four points along an optically transparent capillary column. The profiles were characterized in space and time using an exponentially modified Gaussian equation. The resulting parameters were used to calculate the retention factors, as well as the concomitant changes in molar enthalpy and molar volume, for each PAH on monomeric (2.7 micromol/m2) and polymeric (5.4 micromol/m2) octadecylsilica. The changes in molar enthalpy become more exothermic as ring number increases and as annelation structure becomes less condensed. The changes in molar volume become more negative as ring number increases for the planar PAHs, but are positive for the nonplanar solutes. In addition, the rate constants, as well as the concomitant activation enthalpy and activation volume, are calculated for the first time. The kinetic data demonstrate that many of the PAHs exhibit very fast transitions between the mobile and stationary phases. The transition state is very high in energy, and the activation enthalpies and volumes become greater as ring number increases and as annelation structure becomes less condensed. The changes in thermodynamic and kinetic behavior are much more pronounced for the polymeric phase than for the monomeric phase.

  1. Trace analysis in the food and beverage industry by capillary gas chromatography: system performance and maintenance.

    Science.gov (United States)

    Hayes, M A

    1988-04-01

    Gas chromatography (GC) is the most widely used analytical technique in the food and beverage industry. This paper addresses the problems of sample preparation and system maintenance to ensure the most sensitive, durable, and efficient results for trace analysis by GC in this industry.

  2. Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

    NARCIS (Netherlands)

    Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

    1991-01-01

    Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

  3. Phytochemical Profile of Erythrina variegata by Using High-Performance Liquid Chromatography and Gas Chromatography-Mass Spectroscopy Analyses

    OpenAIRE

    Suriyavathana Muthukrishnan; Subha Palanisamy; Senthilkumar Subramanian; Sumathi Selvaraj; Kavitha Rani Mari; Ramalingam Kuppulingam

    2016-01-01

    Natural products derived from plant sources have been utilized to treat patients with numerous diseases. The phytochemical constituents present in ethanolic leaf extract of Erythrina variegata (ELEV) were identified by using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectroscopy (GC-MS) analyses. Shade dried leaves were powdered and extracted with ethanol for analyses through HPLC to identify selected flavonoids and through GC-MS to identify other molecules. Th...

  4. A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography.

    Science.gov (United States)

    Wang, Yu; Deng, Qi-Liang; Fang, Guo-Zhen; Pan, Ming-Fei; Yu, Yang; Wang, Shuo

    2012-01-27

    A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm(+)Cl(-)) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0-12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ~6.8 μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ~147,000 plates m(-1) for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. A high-resolution tracking hodoscope based on capillary layers filled with liquid scintillator

    CERN Document Server

    Bay, A; Bruski, N; Buontempo, S; Currat, C; D'Ambrosio, N; Ekimov, A V; Ereditato, A; Fabre, Jean-Paul; Fanti, V; Frekers, D; Frenkel, A; Golovkin, S V; Govorun, V N; Harrison, K; Koppenburg, P; Kozarenko, E N; Kreslo, I E; Liberti, B; Martellotti, G; Medvedkov, A M; Mondardini, M R; Penso, G; Siegmund, W P; Vasilchenko, V G; Vilain, P; Wilquet, G; Winter, Klaus; Wörtche, H J

    2001-01-01

    Results are given on tests of a high-resolution tracking hodoscope based on layers of \\hbox{26-$\\mu$m-bore} glass capillaries filled with organic liquid scintillator (1-methylnaphthalene doped with R39). The detector prototype consisted of three 2-mm-thick parallel layers, with surface areas of $2.1 \\times 21$~cm$^2$. The layers had a centre-to-centre spacing of 6~mm, and were read by an optoelectronic chain comprising two electrostatically focused image intensifiers and an Electron-Bombarded Charge-Coupled Device (EBCCD). Tracks of cosmic-ray particles were recorded and analysed. The observed hit density was 6.6~hits/mm for particles crossing the layers perpendicularly, at a distance of 1~cm from the capillaries' readout end, and 4.2~hits/mm for particles at a distance of 20~cm. A track segment reconstructed in a single layer had an rms residual of $\\sim$~20~$\\mu$m, and allowed determination of the track position in a neighbouring layer with a precision of $\\sim$~170~$\\mu$m. This latter value corresponded to...

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

    Science.gov (United States)

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

    2012-09-12

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

  7. Study of Separation and Identification of the Active Ingredients in Gardenia jasminoides Ellis Based on a Two-Dimensional Liquid Chromatography by Coupling Reversed Phase Liquid Chromatography and Hydrophilic Interaction Liquid Chromatography.

    Science.gov (United States)

    Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

    2017-01-01

    In this paper, by coupling reversed phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC), a two-dimensional liquid chromatography system was developed for separation and identification of the active ingredients in Gardenia jasminoides Ellis (GJE). By applying the semi-preparative C18 column as the first dimension and the core-shell column as the second dimension, a total of 896 peaks of GJE were separated. Among the 896 peaks, 16 active ingredients including geniposide, gardenoside, gardoside, etc. were identified by mass spectrometry analysis. The results indicated that the proposed two-dimensional RPLC/HILIC system was an effective method for the analysis of GJE and might hold a high potential to become a useful tool for analysis of other complex mixtures. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. High Resolution Tracking Devices Based on Capillaries Filled with Liquid Scintillator

    CERN Multimedia

    Bonekamper, D; Vassiltchenko, V; Wolff, T

    2002-01-01

    %RD46 %title\\\\ \\\\The aim of the project is to develop high resolution tracking devices based on thin glass capillary arrays filled with liquid scintillator. This technique provides high hit densities and a position resolution better than 20 $\\mu$m. Further, their radiation hardness makes them superior to other types of tracking devices with comparable performance. Therefore, the technique is attractive for inner tracking in collider experiments, microvertex devices, or active targets for short-lived particle detection. High integration levels in the read-out based on the use of multi-pixel photon detectors and the possibility of optical multiplexing allow to reduce considerably the number of output channels, and, thus, the cost for the detector.\\\\ \\\\New optoelectronic devices have been developed and tested: the megapixel Electron Bombarded CCD (EBCCD), a high resolution image-detector having an outstanding capability of single photo-electron detection; the Vacuum Image Pipeline (VIP), a high-speed gateable pi...

  9. Wetting, meniscus structure, and capillary interactions of microspheres bound to a cylindrical liquid interface.

    Science.gov (United States)

    Kim, Paul Y; Dinsmore, Anthony D; Hoagland, David A; Russell, Thomas P

    2018-03-14

    Wetting, meniscus structure, and capillary interactions for polystyrene microspheres deposited on constant curvature cylindrical liquid interfaces, constructed from nonvolatile ionic or oligomeric liquids, were studied by optical interferometry and optical microscopy. The liquid interface curvature resulted from the preferential wetting of finite width lines patterned onto planar silicon substrates. Key variables included sphere diameter, nominal (or average) contact angle, and deviatoric interfacial curvature. Menisci adopted the quadrupolar symmetry anticipated by theory, with interfacial deformation closely following predicted dependences on sphere diameter and nominal contact angle. Unexpectedly, the contact angle was not constant locally around the contact line, the nominal contact angle varied among seemingly identical spheres, and the maximum interface deviation did not follow the predicted dependence on deviatoric interfacial curvature. Instead, this deviation was up to an order-of-magnitude larger than predicted. Trajectories of neighboring microspheres visually manifested quadrupole-quadrupole interactions, eventually producing square sphere packings that foreshadow interfacial assembly as a potential route to hierarchical 2D particle structures.

  10. The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

    Directory of Open Access Journals (Sweden)

    Daniel Gandyra

    2015-01-01

    Full Text Available We report a novel, practical technique for the concerted, simultaneous determination of both the adhesion force of a small structure or structural unit (e.g., an individual filament, hair, micromechanical component or microsensor to a liquid and its elastic properties. The method involves the creation and development of a liquid meniscus upon touching a liquid surface with the structure, and the subsequent disruption of this liquid meniscus upon removal. The evaluation of the meniscus shape immediately before snap-off of the meniscus allows the quantitative determination of the liquid adhesion force. Concurrently, by measuring and evaluating the deformation of the structure under investigation, its elastic properties can be determined. The sensitivity of the method is remarkably high, practically limited by the resolution of the camera capturing the process. Adhesion forces down to 10 µN and spring constants up to 2 N/m were measured. Three exemplary applications of this method are demonstrated: (1 determination of the water adhesion force and the elasticity of individual hairs (trichomes of the floating fern Salvinia molesta. (2 The investigation of human head hairs both with and without functional surface coatings (a topic of high relevance in the field of hair cosmetics was performed. The method also resulted in the measurement of an elastic modulus (Young’s modulus for individual hairs of 3.0 × 105 N/cm2, which is within the typical range known for human hair. (3 Finally, the accuracy and validity of the capillary adhesion technique was proven by examining calibrated atomic force microscopy cantilevers, reproducing the spring constants calibrated using other methods.

  11. On-line liquid chromatography-gas chromatography: A novel approach for the analysis of phytosterol oxidation products in enriched foods.

    Science.gov (United States)

    Scholz, Birgit; Wocheslander, Stefan; Lander, Vera; Engel, Karl-Heinz

    2015-05-29

    A novel methodology for the automated qualitative and quantitative determination of phytosterol oxidation products in enriched foods via on-line liquid chromatography-gas chromatography (LC-GC) was established. The approach is based on the LC pre-separation of acetylated phytosterols and their corresponding oxides using silica as stationary phase and a mixture of n-hexane/methyl tert-butyl ether/isopropanol as eluent. Two LC-fractions containing (i) 5,6-epoxy- and 7-hydroxyphytosterols, and (ii) 7-ketophytosterols are transferred on-line to the GC for the analysis of their individual compositions on a medium polar trifluoropropylmethyl polysiloxane capillary column. Thus, conventionally employed laborious off-line purification and enrichment steps can be avoided. Validation data, including recovery, repeatability, and reproducibility of the method, were elaborated using an enriched margarine as example. The margarine was subjected to a heating procedure in order to exemplarily monitor the formation of phytosterol oxidation products. Quantification was performed using on-line LC-GC-FID, identification of the analytes was based on on-line LC-GC-MS. The developed approach offers a new possibility for the reliable and fast analysis of phytosterol oxidation products in enriched foods. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Unified pH values of liquid chromatography mobile phases.

    Science.gov (United States)

    Suu, Agnes; Jalukse, Lauri; Liigand, Jaanus; Kruve, Anneli; Himmel, Daniel; Krossing, Ingo; Rosés, Martí; Leito, Ivo

    2015-03-03

    This work introduces a conceptually new approach of measuring pH of mixed-solvent liquid chromatography (LC) mobile phases. Mobile phase pH is very important in LC, but its correct measurement is not straightforward, and all commonly used approaches have deficiencies. The new approach is based on the recently introduced unified pH (pH(abs)) scale, which enables direct comparison of acidities of solutions made in different solvents based on chemical potential of the proton in the solutions. This work represents the first experimental realization of the pH(abs) concept using differential potentiometric measurement for comparison of the chemical potentials of the proton in different solutions (connected by a salt bridge), together with earlier published reference points for obtaining the pH(abs) values (referenced to the gas phase) or pH(abs)(H₂O) values (referenced to the aqueous solution). The liquid junction potentials were estimated in the framework of Izutsu's three-component method. pH(abs) values for a number of common LC and LC-MS mobile phases have been determined. The pH(abs) scale enables for the first time direct comparison of acidities of any LC mobile phases, with different organic additives, different buffer components, etc. A possible experimental protocol of putting this new approach into chromatographic practice has been envisaged and its applicability tested. It has been demonstrated that the ionization behavior of bases (cationic acids) in the mobile phases can be better predicted by using the pH(abs)(H₂O) values and aqueous pKa values than by using the alternative means of expressing mobile phase acidity. Description of the ionization behavior of acids on the basis of pH(abs)(H₂O) values is possible if the change of their pKa values with solvent composition change is taken into account.

  13. Liquid chromatography-mass spectrometry in forensic toxicology.

    Science.gov (United States)

    Van Bocxlaer, J F; Clauwaert, K M; Lambert, W E; Deforce, D L; Van den Eeckhout, E G; De Leenheer, A P

    2000-01-01

    Liquid chromatography-mass spectrometry has evolved from a topic of mainly research interest into a routinely usable tool in various application fields. With the advent of new ionization approaches, especially atmospheric pressure, the technique has established itself firmly in many areas of research. Although many applications prove that LC-MS is a valuable complementary analytical tool to GC-MS and has the potential to largely extend the application field of mass spectrometry to hitherto "MS-phobic" molecules, we must recognize that the use of LC-MS in forensic toxicology remains relatively rare. This rarity is all the more surprising because forensic toxicologists find themselves often confronted with the daunting task of actually searching for evidence materials on a scientific basis without any indication of the direction in which to search. Through the years, mass spectrometry, mainly in the GC-MS form, has gained a leading role in the way such quandaries are tackled. The advent of robust, bioanalytically compatible combinations of liquid chromatographic separation with mass spectrometric detection really opens new perspectives in terms of mass spectrometric identification of difficult molecules (e.g., polar metabolites) or biopolymers with toxicological relevance, high throughput, and versatility. Of course, analytical toxicologists are generally mass spectrometry users rather than mass spectrometrists, and this difference certainly explains the slow start of LC-MS in this field. Nevertheless, some valuable applications have been published, and it seems that the introduction of the more universal atmospheric pressure ionization interfaces really has boosted interests. This review presents an overview of what has been realized in forensic toxicological LC-MS. After a short introduction into LC-MS interfacing operational characteristics (or limitations), it covers applications that range from illicit drugs to often abused prescription medicines and some

  14. Measurement of Muscle Protein Fractional Synthetic Rate by Capillary Gas Chromatography/Combustion Isotope Ratio Mass Spectrometry

    Science.gov (United States)

    Yarasheski, Kevin E.; Smith, Kenneth; Rennie, Michael J.; Bier, Dennis M.

    2014-01-01

    The measurement of skeletal muscle protein fractional synthetic rate using an infusion of (1-13C)leucine and measuring the isotopic abundance of the tracer in skeletal muscle protein by preparative gas chromatography (GC)/ninhydrin isotope ratio mass spectrometry (IRMS) is laborious and subject to errors owing to contamination by 12C. The purpose of this study was to compare muscle (13C)leucine enrichment measured with the conventional preparative GC/ninhydrin IRMS approach to a new, continuous-flow technique using capillary GC/combustion IRMS. Quadriceps muscles were removed from four Sprague–Dawley rats after each was infused at a different rate with (1-13C)leucine for 6–8 h. Muscle leucine enrichment (at.% excess) measured by both methods differed by less than 4%, except at low (13C)leucine enrichments (IRMS was used to assess muscle (13C)leucine enrichment and fractional muscle protein synthesis rate in ten normal young men and women infused with (1,2-13C2)leucine for 12–14 h. This approach reduced the variability of the isotope abundance measure and gave estimates of muscle protein synthesis rate (0.050 ± 0.011% h−1 (mean ± SEM); range = 0.023–0.147% h−1) that agree with published values determined using the standard analytical approach. The measurement of (13C)leucine enrichment from skeletal muscle protein by capillary GC/combustion IRMS provides a simple, acceptable and practical alternative to preparative GC/ninhydrin IRMS. PMID:1420371

  15. Microcystin Detection Characteristics of Fluorescence Immunochromatography and High Performance Liquid Chromatography

    International Nuclear Information System (INIS)

    Pyo, Dong Jin; Park, Geun Young; Choi, Jong Chon; Oh, Chang Suk

    2005-01-01

    Different detection characteristics of fluorescence immunochromatography method and high performance liquid chromatography (HPLC) method for the analysis of cyanobacterial toxins were studied. In particular, low and high limits of detection, detection time and reproducibility and detectable microcystin species were compared when fluorescence immunochromatography method and high performance liquid chromatography method were applied for the detection of microcystin (MC), a cyclic peptide toxin of the freshwater cyanobacterium Microcystis aeruginosa. A Fluorescence immunochromatography assay system has the unique advantages of short detection time and low detection limit, and high performance liquid chromatography detection method has the strong advantage of individual quantifications of several species of microcystins

  16. Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.

    Science.gov (United States)

    Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

    2014-10-03

    Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system. Copyright © 2014. Published by Elsevier B.V.

  17. Determination of basic azaarenes and polynuclear aromatic hydrocarbons in airborne particulate matter by gas chromatography

    DEFF Research Database (Denmark)

    Nielsen, Torben; Clausen, Peraxel; Jensen, Finn Palmgren

    1986-01-01

    phase (adjusted to pH 14 with potassium hydroxide) with dichloromethane, and determined by capillary gas chromatography (g.c.) with a nitrogen-sensitive detector. The PAH in the toluene phase are isolated by means of semipreparative high-performance liquid chromatography and liquid-liquid extraction...

  18. Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

    International Nuclear Information System (INIS)

    Mroczek, Tomasz; Ndjoko-Ioset, Karine; Glowniak, Kazimierz; Mietkiewicz-Capala, Agnieszka; Hostettmann, Kurt

    2006-01-01

    From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C 18 column using a gradient elution. Based on MS n spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2'',3''-epoxyechiumine-N-oxide

  19. Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mroczek, Tomasz [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland)]. E-mail: tmroczek@pharmacognosy.org; Ndjoko-Ioset, Karine [Laboratoire de Pharmacognosie et Phytochimie, Ecole de Pharmacie Geneve-Lausanne, Universite de Geneve, Quai Ernest-Ansermet 30, CH-1211 Geneva 4 (Switzerland); Glowniak, Kazimierz [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland); Mietkiewicz-Capala, Agnieszka [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland); Hostettmann, Kurt [Laboratoire de Pharmacognosie et Phytochimie, Ecole de Pharmacie Geneve-Lausanne, Universite de Geneve, Quai Ernest-Ansermet 30, CH-1211 Geneva 4 (Switzerland)

    2006-05-04

    From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C{sub 18} column using a gradient elution. Based on MS {sup n} spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2'',3''-epoxyechiumine-N-oxide.

  20. Two-dimensional liquid chromatography consisting of twelve second-dimension columns for comprehensive analysis of intact proteins.

    Science.gov (United States)

    Ren, Jiangtao; Beckner, Matthew A; Lynch, Kyle B; Chen, Huang; Zhu, Zaifang; Yang, Yu; Chen, Apeng; Qiao, Zhenzhen; Liu, Shaorong; Lu, Joann J

    2018-05-15

    A comprehensive two-dimensional liquid chromatography (LCxLC) system consisting of twelve columns in the second dimension was developed for comprehensive analysis of intact proteins in complex biological samples. The system consisted of an ion-exchange column in the first dimension and the twelve reverse-phase columns in the second dimension; all thirteen columns were monolithic and prepared inside 250 µm i.d. capillaries. These columns were assembled together through the use of three valves and an innovative configuration. The effluent from the first dimension was continuously fractionated and sequentially transferred into the twelve second-dimension columns, while the second-dimension separations were carried out in a series of batches (six columns per batch). This LCxLC system was tested first using standard proteins followed by real-world samples from E. coli. Baseline separation was observed for eleven standard proteins and hundreds of peaks were observed for the real-world sample analysis. Two-dimensional liquid chromatography, often considered as an effective tool for mapping proteins, is seen as laborious and time-consuming when configured offline. Our online LCxLC system with increased second-dimension columns promises to provide a solution to overcome these hindrances. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Quantification of fentanyl in serum by isotope dilution analysis using capillary gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Sera, Shoji; Goromaru, Tsuyoshi [Fukuyama Univ., Hiroshima (Japan); Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

    1998-06-01

    The quantitative determination of fentanyl (FT) in serum was examined by isotope dilution analysis using a capillary gas chromatograph equipped with a surface ionization detector. The separation of FT and its deuterated analogue, FT-{sup 2}H{sub 19}, was achieved within 15 min a column temperature of 260degC by using a 25 m column. Measurement of the samples prepared by the addition of a known amount of FT in the range of 0.2 to 40 ng/ml with 20 ng/ml of FT-{sup 2}H{sub 19} to human control serum allowed observation of a linear relationship between the peak area ratio and the added amount ratio. The correlation coefficient obtained by regression analysis was 0.999. The advantage of the present isotope dilution method was demonstrated by comparison with other FT analogues which substituted a propionyl group with an acetyl group or a phenethyl group with a benzyl group as the internal standard. The present method was used to determine the serum level of FT in surgical patients after i.v. administration. No endogenous compounds and concomitant drugs interfered with the detection of FT or FT-{sup 2}H{sub 19}. This method was considered to be useful for the pharmacokinetic study of FT in patients. (author)

  2. Quantification of fentanyl in serum by isotope dilution analysis using capillary gas chromatography

    International Nuclear Information System (INIS)

    Sera, Shoji; Goromaru, Tsuyoshi; Sameshima, Teruko; Kawasaki, Koichi; Oda, Toshiyuki

    1998-01-01

    The quantitative determination of fentanyl (FT) in serum was examined by isotope dilution analysis using a capillary gas chromatograph equipped with a surface ionization detector. The separation of FT and its deuterated analogue, FT- 2 H 19 , was achieved within 15 min a column temperature of 260degC by using a 25 m column. Measurement of the samples prepared by the addition of a known amount of FT in the range of 0.2 to 40 ng/ml with 20 ng/ml of FT- 2 H 19 to human control serum allowed observation of a linear relationship between the peak area ratio and the added amount ratio. The correlation coefficient obtained by regression analysis was 0.999. The advantage of the present isotope dilution method was demonstrated by comparison with other FT analogues which substituted a propionyl group with an acetyl group or a phenethyl group with a benzyl group as the internal standard. The present method was used to determine the serum level of FT in surgical patients after i.v. administration. No endogenous compounds and concomitant drugs interfered with the detection of FT or FT- 2 H 19 . This method was considered to be useful for the pharmacokinetic study of FT in patients. (author)

  3. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Keller, David W. [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (Eapp) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of Eapp provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess (Λ) of a solute and changes in interfacial tension (dγ) as a function of both Eapp and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant Eapp is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  4. An apparatus with a horizontal capillary tube intended for measurement of the surface tension of supercooled liquids

    Science.gov (United States)

    Vinš, Václav; Hošek, Jan; Hykl, Jiří; Hrubý, Jan

    2015-05-01

    New experimental apparatus for measurement of the surface tension of liquids under the metastable supercooled state has been designed and assembled in the study. The measuring technique is similar to the method employed by P.T. Hacker [NACA TN 2510] in 1951. A short liquid thread of the liquid sample was sucked inside a horizontal capillary tube partly placed in a temperature-controlled glass chamber. One end of the capillary tube was connected to a setup with inert gas which allowed for precise tuning of the gas overpressure in order of hundreds of Pa. The open end of the capillary tube was precisely grinded and polished before the measurement in order to assure planarity and perpendicularity of the outer surface. The liquid meniscus at the open end was illuminated by a laser beam and observed by a digital camera. Application of an increasing overpressure of the inert gas at the inner meniscus of the liquid thread caused variation of the outer meniscus such that it gradually changed from concave to flat and subsequently convex shape. The surface tension at the temperature of the inner meniscus could be evaluated from the overpressure corresponding to exactly planar outer meniscus. Detailed description of the new setup together with results of the preliminary tests is provided in the study.

  5. Capillary electrochromatography immunoassay for alpha-fetoprotein based on poly(guanidinium ionic liquid) monolithic material.

    Science.gov (United States)

    Liu, Cuicui; Deng, Qiliang; Fang, Guozhen; Dang, Meng; Wang, Shuo

    2017-08-01

    Alpha-fetoprotein (AFP) is widely used as a tumor marker for the serum diagnosis of primary hepatoma. Sensitive detection of AFP level plays an important role in the early diagnosis of disease and highly reliable prediction. In this study, a novel non-competitive immunoassay (IA) based on poly(guanidinium ionic liquid) monolithic material was developed for detecting ultra trace levels of AFP in capillary electrochromatography (CEC) mode. The AFP was mixed with an excess amount of fluorescently labeled antibody. After incubation, the immunocomplex was separated from the free labeled antibody and detected by CEC coupled with laser-induced fluorescence detector. Under the optimized conditions, the developed CEC-IA performed a low detection limit of 0.05 μg L -1  (S/N = 3) and a wide linearity ranging from 0.1 to 1000 μg L -1 for AFP, which can be largely attributed to the high separation and enrichment efficiency of poly(guanidinium ionic liquid) monolithic material for the targets. The application of this method was demonstrated by determining AFP in human serum. Copyright © 2017. Published by Elsevier Inc.

  6. [Methods quantitative for determination of water-soluble vitamins in premixes and fortified food products by micellar electrokinetic chromatography on short end of the capillary].

    Science.gov (United States)

    Bogachuk, M N; Bessonov, V V; Perederiaev, O I

    2011-01-01

    It was purposed new technique by micellar electrokinetic chromatography on short end of the capillary (capillary electrophoresis system Agilent 3D CE, DAD, quartz capillary HPCE stndrd cap 56 cm, 50 microm, 50 mM borate buffer pH=9,3, 100 mM sodium dodecil sulfate) for simultaneous determination of water-soluble vitamins (B1, B2, B6, B12, PP, B5, B9, C, B8) in fortified food products and premixes. It was observed on 6 samples of vitamin premixes and 28 samples of fortified food products using this technique. Our findings are consistent with the results of research on certain vitamins, conducted by other methods. The developed technique can be used in analysis of water-soluble vitamins in premixes and fortified food products.

  7. How to separate ionic liquids: Use of Hydrophilic Interaction Liquid Chromatography and mixed mode phases

    International Nuclear Information System (INIS)

    Lamouroux, C.

    2011-01-01

    This chromatographic study deals with the development of a convenient and versatile method to separate Room Temperature Ionic Liquids. Different modes of chromatography were studied. The study attempts to answer the following question: 'what were the most important interactions for the separation of ionic liquids?'. The results show that the essential interactions to assure a good retention of RTILs are the ionic ones and that hydrophobic interactions play a role in the selectivity of the separation. The separation of five imidazolium salt with a traditional dial columns in Hydrophilic Interaction Chromatography (HILIC) was demonstrated. It shows that neutral diol grafted column allows an important retention that we assume is due to the capability of diol to develop a thick layer of water. Furthermore, stationary phase based on mixed interaction associating ion exchange and hydrophobic properties were studied. Firstly, it will be argued that it is possible to separate RTILs with a convenient retention and resolution according to a reverse phase elution with the Primesep columns made of a brush type long alkyl chain with an embedded negatively charged functional group. Secondly, a successful separation of RTILs in HILIC mode with a mixed phase column containing a cationic exchanger and a hydrophobic octyl chain length will be demonstrated. (author)

  8. Surface-bonded ionic liquid stationary phases in high-performance liquid chromatography--a review.

    Science.gov (United States)

    Pino, Verónica; Afonso, Ana M

    2012-02-10

    Ionic liquids (ILs) are a class of ionic, nonmolecular solvents which remain in liquid state at temperatures below 100°C. ILs possess a variety of properties including low to negligible vapor pressure, high thermal stability, miscibility with water or a variety of organic solvents, and variable viscosity. IL-modified silica as novel high-performance liquid chromatography (HPLC) stationary phases have attracted considerable attention for their differential behavior and low free-silanol activity. Indeed, around 21 surface-confined ionic liquids (SCIL) stationary phases have been developed in the last six years. Their chromatographic behavior has been studied, and, despite the presence of a positive charge on the stationary phase, they showed considerable promise for the separation of neutral solutes (not only basic analytes), when operated in reversed phase mode. This aspect points to the potential for truly multimodal stationary phases. This review attempts to summarize the state-of-the-art about SCIL phases including their preparation, chromatographic behavior, and analytical performance. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Gas chromatography-mass spectrometry and high-performance liquid chromatographic analyses of thermal degradation products of common plastics

    NARCIS (Netherlands)

    Pacakova, V.; Leclercq, P.A.

    1991-01-01

    The thermo-oxidation of five commonly used materials, namely low-density polyethylene, retarded polyethylene, paper with a polyethylene foil, a milk package and filled polypropylene, was studied. Capillary gas chromatography and gas chromatography-mass spectrometry were used to analyze the volatile

  10. Performance Validation and Scaling of a Capillary Membrane Solid-Liquid Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S; Cook, J; Juratovac, J; Goodwillie, J; Burke, T

    2011-10-25

    Algaeventure Systems (AVS) has previously demonstrated an innovative technology for dewatering algae slurries that dramatically reduces energy consumption by utilizing surface physics and capillary action. Funded by a $6M ARPA-E award, transforming the original Harvesting, Dewatering and Drying (HDD) prototype machine into a commercially viable technology has required significant attention to material performance, integration of sensors and control systems, and especially addressing scaling issues that would allow processing extreme volumes of algal cultivation media/slurry. Decoupling the harvesting, dewatering and drying processes, and addressing the rate limiting steps for each of the individual steps has allowed for the development individual technologies that may be tailored to the specific needs of various cultivation systems. The primary performance metric used by AVS to assess the economic viability of its Solid-Liquid Separation (SLS) dewatering technology is algae mass production rate as a function of power consumption (cost), cake solids/moisture content, and solids capture efficiency. An associated secondary performance metric is algae mass loading rate which is dependent on hydraulic loading rate, area-specific hydraulic processing capacity (gpm/in2), filter:capillary belt contact area, and influent algae concentration. The system is capable of dewatering 4 g/L (0.4%) algae streams to solids concentrations up to 30% with capture efficiencies of 80+%, however mass production is highly dependent on average cell size (which determines filter mesh size and percent open area). This paper will present data detailing the scaling efforts to date. Characterization and performance data for novel membranes, as well as optimization of off-the-shelf filter materials will be examined. Third party validation from Ohio University on performance and operating cost, as well as design modification suggestions will be discussed. Extrapolation of current productivities

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

    Science.gov (United States)

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

    2017-03-24

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

  12. Quantification of nucleotides by ICPMS: coupling of ICPMS with capillary electrophoresis or capillary HPLC

    International Nuclear Information System (INIS)

    Inagaki, K.; Fujii, S.; Takatsu, A.; Yarita, T.; Zhu, Y.; Chiba, K.

    2009-01-01

    Full text: Quantification of nucleotides in small volumes of biological samples has eagerly been demanded. A method using ICPMS coupled with capillary electrophoresis or capillary liquid chromatography is reported. A new interface system, which consists of a double tube nebulizer inserted with a fused silica capillary tube and a cylinder mini-chamber with a sheath gas inlet, was designed. Moreover, the surface conditions of the sampling and skimmer cones, and the introduction of H 2 gas into the plasma were found to significantly improve the signal/background ratio for phosphorus determination at m/z 31. (author)

  13. Process of quantity determination of uranium by chromatography in liquid zone

    International Nuclear Information System (INIS)

    Muller, J.P.; Cojean, J.; Daubizit, M.

    1993-01-01

    The invention concerns a process of quantity determination of uranium by chromatography in liquid zone, usable to determine the quantity of uranium traces. Solutions to be treated can be aqueous or organic

  14. Qualitative and quantitative determination of ubiquinones by the method of high-efficiency liquid chromatography

    International Nuclear Information System (INIS)

    Yanotovskii, M.T.; Mogilevskaya, M.P.; Obol'nikova, E.A.; Kogan, L.M.; Samokhvalov, G.I.

    1986-01-01

    A method has been developed for the qualitative and quantitative determination of ubiquinones CoQ 6 -CoQ 10 , using high-efficiency reversed-phase liquid chromatography. Tocopherol acetate was used as the internal standard

  15. Determination of Aspartame, Caffeine, Saccharin, and Benzoic Acid in Beverages by High Performance Liquid Chromatography.

    Science.gov (United States)

    Delaney, Michael F.; And Others

    1985-01-01

    Describes a simple and reliable new quantitative analysis experiment using liquid chromatography for the determinaiton of caffeine, saccharin, and sodium benzoate in beverages. Background information, procedures used, and typical results obtained are provided. (JN)

  16. Experimental hydrophobicity parameters of perfluorinated alkylated substances from reversed-phase high performance liquid chromatography

    NARCIS (Netherlands)

    de Voogt, P.; Zurano, L.; Serné, P.; Haftka, J.J.H.

    2012-01-01

    Capacity factors of perfluorinated alkylated substances were obtained from isocratic reversed-phase high-performance liquid chromatography-mass spectrometry experiments at different organic modifier strengths of the mobile phase. The resulting capacity factor v. modifier strengths plots were

  17. Determination of maduramicin in feedingstuffs and premixtures by liquid chromatography : development, validation and interlaboratory study

    NARCIS (Netherlands)

    Jong, de J.; Stoisser, B.; Wagner, K.; Tomassen, M.J.H.; Driessen, J.J.M.; Hofman, P.; Putzka, H.A.

    2004-01-01

    A reversed-phase liquid chromatography method for determination of maduramicin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol. Maduramicin was detected at 520 nm after postcolumn derivatization with vanillin. Recovery was

  18. Assay for dihydroorotase using high-performance liquid chromatography with radioactivity detection

    International Nuclear Information System (INIS)

    Mehdi, S.; Wiseman, J.S.

    1989-01-01

    An assay for measuring dihydroorotase activity was devised. Radiolabeled substrate and product were separated by high-performance liquid chromatography using a reverse-phase column with ion-pairing, and the radioactivity was quantitated by flow detection

  19. Measurement of rimantadine in plasma by capillary gas chromatography/mass spectrometry with a deuterium-labeled internal standard

    International Nuclear Information System (INIS)

    Herold, D.A.; Anonick, P.K.; Kinter, M.; Hayden, F.G.

    1988-01-01

    Rimantadine is a synthetic antiviral agent used in prophylaxis and in treating the early stages of uncomplicated influenza A illness. We describe a stable isotope-dilution assay involving capillary gas chromatography/mass spectrometry. We used 200 ng of d3-rimantadine, added to 1 mL of plasma, as the internal standard. The rimantadine was extracted from the plasma with a Bond-Elut CN column, the column was washed with water, and the rimantadine was eluted with methanol, dried, and treated to form the t-butyldimethylsilyl derivative. The mass spectrometer was operated in the selected ion monitoring mode. Ions at m/z 236 and m/z 239 were monitored, corresponding to the loss of C4H9 from the rimantadine derivative and d3-rimantadine, respectively. Within-run precision (CVs) ranged from 8.9% at 29 micrograms/L to 3.2% at 1666 micrograms/L. Corresponding data for between-run precision were 5.4% and 1.7%. Treated volunteers (n = 86) provided plasma samples with a concentration range of 153 to 1127 micrograms/L. This simplified method allows rapid, precise assay of rimantadine in plasma

  20. Chromatographic efficiency of polar capillary columns applied for the analysis of fatty acid methyl esters by gas chromatography.

    Science.gov (United States)

    Waktola, Habtewold D; Mjøs, Svein A

    2018-04-01

    The chromatographic efficiency that could be achieved in temperature-programmed gas chromatography was compared for four capillary columns that are typically applied for analysis of fatty acid methyl esters (FAME). Three different carrier gases, hydrogen, helium and nitrogen, were applied. For each experiment, the carrier gas velocities and the temperature rates were varied with a full 9 × 3 design, with nine levels on the carrier gas velocity and temperature rates of 1, 2 or 3°C/min. Response surface methodology was used to create models of chromatographic efficiency as a function of temperature rate and carrier gas velocity. The chromatographic efficiency was defined as the inverse of peak widths measured in retention index units. The final results were standardized so that the efficiencies that could be achieved within a certain time frame, defined by the retention time of the last compound in the chromatogram, could be compared. The results show that there were clear differences in the efficiencies that could be achieved with the different columns and that the efficiency decreased with increasing polarity of the stationary phase. The differences can be explained by higher resistance to mass transfer in the stationary phase in the most polar columns. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The Determination of Pesticidal and Non-Pesticidal Organotin Compounds in Water Matrices by in situ Ethylation and Gas Chromatography with Pulsed Flame Photometric Detection

    Science.gov (United States)

    The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detect...

  2. An efficient hydrophilic interaction liquid chromatography separation of 7 phospholipid classes based on a diol column

    NARCIS (Netherlands)

    Zhu, C.; Dane, A.; Spijksma, G.; Wang, M.; Greef, J. van der; Luo, G.; Hankemeier, T.; Vreeken, R.J.

    2012-01-01

    A hydrophilic interaction liquid chromatography (HILIC) - ion trap mass spectrometry method was developed for separation of a wide range of phospholipids. A diol column which is often used with normal phase chromatography was adapted to separate different phospholipid classes in HILIC mode using a

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

    Science.gov (United States)

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

    2017-07-01

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

  4. Determination of methylphenidate in Calliphorid larvae by liquid-liquid extraction and liquid chromatography mass spectrometry - Forensic entomotoxicology using an in vivo rat brain model

    DEFF Research Database (Denmark)

    Bushby, Sarah K.; Thomas, Nicky; Priemel, Petra A.

    2012-01-01

    and Calliphorid larvae) by liquid-liquid extraction with recovery of >80%, and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LC-MS/MS assay was validated for entomotoxicological use and initially applied to male Sprague-Dawley rats (n=6) that were dosed with MPH (20mg/kg) ante...

  5. Chromatography.

    Science.gov (United States)

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  6. Arsenic speciation by liquid chromatography coupled with ionspray tandem mass spectrometry

    DEFF Research Database (Denmark)

    Corr, J. J.; Larsen, Erik Huusfeldt

    1996-01-01

    Ionspray mass spectrometry, a well established organic analysis technique, has been coupled to high-performance liquid chromatography for speciation of organic arsenic compounds, The ionspray source and differentially pumped interface of the mass spectrometer were operated in dual modes...... fragmentation patterns showing molecular dissociation through an expected common product ion were obtained for the four arsenosugars, Molecular mode detection was utilized for qualitative verification of speciation analysis by high-performance liquid chromatography coupled to inductively coupled plasma mass...

  7. Liquid chromatography-mass spectrometry coupling by the intermediary of a liquid micro chromatography-electro spray interface; Couplage chromatographie liquide-spectrometrie de masse par l`intermediaire d`une interface electrospray-microchromatographie liquide

    Energy Technology Data Exchange (ETDEWEB)

    Gillard Factor, C

    1996-12-06

    The objective of this work is to realize a liquid chromatography- mass spectrometry coupling by the intermediary of an electro spray interface and the evaluation of performances of tis analytical tool to study pollutants in water, and more particularly pesticides whom maximum admissible concentration in a table water is 0.1{mu}g/l. This study has allowed to bring to the fore the interest of the ionization mode by electro spray in a LC/MS coupling to identify and quantify pesticides in the state of traces without treating the sample. Then, it was demonstrated the usefulness of this analytical tool to detect high molecular masses molecules. (N.C.)

  8. Tryptophan and kynurenine determination in human hair by liquid chromatography.

    Science.gov (United States)

    Dario, Michelli F; Freire, Thamires Batello; Pinto, Claudinéia Aparecida Sales de Oliveira; Prado, María Segunda Aurora; Baby, André R; Velasco, Maria Valéria R

    2017-10-15

    Tryptophan, an amino acid found in hair proteinaceous structure is used as a marker of hair photodegradation. Also, protein loss caused by several chemical/physical treatments can be inferred by tryptophan quantification. Kynurenine is a photo-oxidation product of tryptophan, expected to be detected when hair is exposed mainly to UVB (290-320nm) radiation range. Tryptophan from hair is usually quantified directly as a solid or after alkaline hydrolysis, spectrofluorimetrically. However, these types of measure are not sufficiently specific and present several interfering substances. Thus, this work aimed to propose a quantification method for both tryptophan and kynurenine in hair samples, after alkali hydrolysis process, by using high-performance liquid chromatography (HPLC) with fluorimetric and UV detection. The tryptophan and kynurenine quantification method was developed and validated. Black, white, bleached and dyed (blond and auburn) hair tresses were used in this study. Tryptophan and kynurenine were separated within ∼9min by HPLC. Both black and white virgin hair samples presented similar concentrations of tryptophan, while bleaching caused a reduction in the tryptophan content as well as dyeing process. Unexpectedly, UV/vis radiation did not promote significantly the conversion of tryptophan into its photo-oxidation product and consequently, kynurenine was not detected. Thus, this works presented an acceptable method for quantification of tryptophan and its photooxidation metabolite kynurenine in hair samples. Also, the results indicated that bleaching and dyeing processes promoted protein/amino acids loss but tryptophan is not extensively degraded in human hair by solar radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Liquid chromatography method to determine polyamines in thermosetting polymers

    Energy Technology Data Exchange (ETDEWEB)

    Dopico-Garcia, M.S. [Laboratorio de Quimica - Centro de Investigacions Tecnoloxicas, Universidade da Coruna, Campus de Esteiro s/n, 15403 Ferrol (Spain); Centro Galego do Plastico, A Cabana s/n, 15590 Ferrol (Spain); Lopez-Vilarino, J.M. [Laboratorio de Quimica - Centro de Investigacions Tecnoloxicas, Universidade da Coruna, Campus de Esteiro s/n, 15403 Ferrol (Spain); Fernandez-Martinez, G. [Unidad de Tecnicas Cromatograficas, Servizos de Apoio a Investigacion, Edificio Servizos Centrais de Investigacion, Universidade da Coruna, Campus de Elvina s/n, 15071 A Coruna (Spain); Gonzalez-Rodriguez, M.V., E-mail: victoria@udc.es [Dpto. de Quimica Analitica - E.U. Politecnica, Universidade da Coruna, Avda. 19 de Febrero s/n, 15405 Ferrol (Spain)

    2010-05-14

    A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines. The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector ({lambda} excitation 248 nm, {lambda} emision 395 nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H]{sup +} and corresponded to the fully labelled analytes. The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14 mg L{sup -1}). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces.

  10. Liquid chromatography method to determine polyamines in thermosetting polymers.

    Science.gov (United States)

    Dopico-García, M S; López-Vilariño, J M; Fernández-Martínez, G; González-Rodríguez, M V

    2010-05-14

    A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines. The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector (lambda excitation 248nm, lambda emision 395nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H](+) and corresponded to the fully labelled analytes. The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14mgL(-1)). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Liquid chromatography method to determine polyamines in thermosetting polymers

    International Nuclear Information System (INIS)

    Dopico-Garcia, M.S.; Lopez-Vilarino, J.M.; Fernandez-Martinez, G.; Gonzalez-Rodriguez, M.V.

    2010-01-01

    A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines. The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector (λ excitation 248 nm, λ emision 395 nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H] + and corresponded to the fully labelled analytes. The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14 mg L -1 ). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces.

  12. Separation of anionic oligosaccharides by high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Green, E.D.; Baenziger, J.U.

    1986-01-01

    The authors have developed methods for rapid fractionation of anionic oligosaccharides containing sulfate and/or sialic acid moieties by high-performance liquid chromatography (HPLC). Ion-exchange HPLC on amine-bearing columns (Micropak AX-10 and AX-5) at pH 4.0 is utilized to separate anionic oligosaccharides bearing zero, one, two, three, or four charges, independent of the identity of the anionic moieties (sulfate and/or sialic acid). Ion-exchange HPLC at pH 1.7 allows separation of neutral, mono-, di-, and tetrasialylated, monosulfated, and disulfated oligosaccharides. Oligosaccharides containing three sialic acid residues and those bearing one each of sulfate and sialic acid, however, coelute at pH 1.7. Since the latter two oligosaccharide species separate at pH 4.0, analysis at pH 4.0 followed by analysis at pH 1.7 can be utilized to completely fractionate complex mixtures of sulfated and sialylated oligosaccharides. Ion-suppression amine adsorption HPLC has previously been shown to separate anionic oligosaccharides on the basis of net carbohydrate content (size). In this study they demonstrate the utility of ion-suppression amine adsorption HPLC for resolving sialylated oligosaccharide isomers which differ only in the linkages of sialic acid residues (α2,3 vs α2,6) and/or location of α2,3- and α2,6-linked sialic acid moieties on the peripheral branches of oligosaccharides. These two methods can be used in tandem to separate oligosaccharides, both analytically and preparatively, based on their number, types, and linkages of anionic moieties

  13. Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples.

    Science.gov (United States)

    Rodriguez, Estrella Sanz; Poynter, Sam; Curran, Mark; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Paull, Brett

    2015-08-28

    Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core samples is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger sample volumes, with potential for sample contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core samples. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column sample injection and focusing, thus eliminating the requirement for off-column sample preconcentration. This limits the total sample volume needed to 300μL per analysis, allowing for triplicate sample analysis with Application to composite ice-core samples is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Coupling liquid chromatography/mass spectrometry detection with microfluidic droplet array for label-free enzyme inhibition assay.

    Science.gov (United States)

    Wang, Xiu-Li; Zhu, Ying; Fang, Qun

    2014-01-07

    In this work, the combination of droplet-based microfluidics with liquid chromatography/mass spectrometry (LC/MS) was achieved, for providing a fast separation and high-information-content detection method for the analysis of nanoliter-scale droplets with complex compositions. A novel interface method was developed using an oil-covered droplet array chip to couple with an LC/MS system via a capillary sampling probe and a 4 nL injection valve without the need of a droplet extraction device. The present system can perform multistep operations including parallel enzyme inhibition reactions in nanoliter droplets, 4 nL sample injection, fast separation with capillary LC, and label-free detection with ESI-MS, and has significant flexibility in the accurate addressing and sampling of droplets of interest on demand. The system performance was evaluated using angiotensin I and angiotensin II as model samples, and the repeatabilities of peak area for angiotensin I and angiotensin II were 2.7% and 7.5% (RSD, n = 4), respectively. The present system was further applied to the screening for inhibitors of cytochrome P450 (CYP1A2) and measurement of the IC50 value of the inhibitor. The sample consumption for each droplet assay was 100 nL, which is reduced 10-100 times compared with conventional 384-multi-well plate systems usually used in high-throughput drug screening.

  15. Study of high performance liquid chromatography fingerprint for traditional chinese medicine yigongningxue oral liquid

    International Nuclear Information System (INIS)

    Feng, C.; Ruan, J.L.

    2010-01-01

    A simple, reliable and accurate fingerprinting method has been developed for quality control of YiGongNingXue oral liquid. The separation was done by reverse phase chromatography using Zorbax eclipse XDB C/sub 18/ column (250mmx4.6mmi. d. with 5.0 micro m particle size) and detection at 246nm. Methanol (5-95 % in 70 min)-buffer solution (water-phosphorica cid, pH 3.0, 95-0 percent in 70 min) as mobile phase for linear gradient elution. The flow rate was 1.0 mLmin/sup 1/ and the column temperature was at 25 deg. C. The similarity of 20 batches of YGNX oral liquid was more than 90 %. Also 15 common peaks of chromatogram have been detected, ten of them were identified by comparing fingerprint chromatogram with reference substances The HPLC fingerprint can be used to control the quality of YiGongNingXue oral liquid. (author)

  16. Tailored liquid chromatography-mass spectrometry analysis improves the coverage of the intracellular metabolome of HepaRG cells.

    Science.gov (United States)

    Cuykx, Matthias; Negreira, Noelia; Beirnaert, Charlie; Van den Eede, Nele; Rodrigues, Robim; Vanhaecke, Tamara; Laukens, Kris; Covaci, Adrian

    2017-03-03

    Metabolomics protocols are often combined with Liquid Chromatography-Mass Spectrometry (LC-MS) using mostly reversed phase chromatography coupled to accurate mass spectrometry, e.g. quadrupole time-of-flight (QTOF) mass spectrometers to measure as many metabolites as possible. In this study, we optimised the LC-MS separation of cell extracts after fractionation in polar and non-polar fractions. Both phases were analysed separately in a tailored approach in four different runs (two for the non-polar and two for the polar-fraction), each of them specifically adapted to improve the separation of the metabolites present in the extract. This approach improves the coverage of a broad range of the metabolome of the HepaRG cells and the separation of intra-class metabolites. The non-polar fraction was analysed using a C18-column with end-capping, mobile phase compositions were specifically adapted for each ionisation mode using different co-solvents and buffers. The polar extracts were analysed with a mixed mode Hydrophilic Interaction Liquid Chromatography (HILIC) system. Acidic metabolites from glycolysis and the Krebs cycle, together with phosphorylated compounds, were best detected with a method using ion pairing (IP) with tributylamine and separation on a phenyl-hexyl column. Accurate mass detection was performed with the QTOF in MS-mode only using an extended dynamic range to improve the quality of the dataset. Parameters with the greatest impact on the detection were the balance between mass accuracy and linear range, the fragmentor voltage, the capillary voltage, the nozzle voltage, and the nebuliser pressure. By using a tailored approach for the intracellular HepaRG metabolome, consisting of three different LC techniques, over 2200 metabolites can be measured with a high precision and acceptable linear range. The developed method is suited for qualitative untargeted LC-MS metabolomics studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Development of an on-line mixed-mode gel liquid chromatography×reversed phase liquid chromatography method for separation of water extract from Flos Carthami.

    Science.gov (United States)

    Wang, Yu-Qing; Tang, Xu; Li, Jia-Fu; Wu, Yun-Long; Sun, Yu-Ying; Fang, Mei-Juan; Wu, Zhen; Wang, Xiu-Min; Qiu, Ying-Kun

    2017-10-13

    A novel on-line comprehensive two-dimensional liquid chromatography (2D-LC) method by coupling mixed-mode gel liquid chromatography (MMG-LC) with reversed phase liquid chromatography (RPLC) was developed. A mixture of 17 reference compounds was used to study the separation mechanism. A crude water extract of Flos Carthami was applied to evaluate the performance of the novel 2D-LC system. In the first dimension, the extract was eluted with a gradient of water/methanol over a cross-linked dextran gel Sephadex LH-20 column. Meanwhile, the advantages of size exclusion, reversed phase partition and adsorption separation mechanism were exploited before further on-line reversed phase purification on the second dimension. This novel on-line mixed-mode Sephadex LH-20×RPLC method provided higher peak resolution, sample processing ability (2.5mg) and better orthogonality (72.9%) versus RPLC×RPLC and hydrophilic interaction liquid chromatography (HILIC)×RPLC. To the best of our knowledge, this is the first report of a mixed-mode Sephadex LH-20×RPLC separation method with successful applications in on-line mode, which might be beneficial for harvesting targets from complicated medicinal plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Influence of granulometry in the Hurst exponent of air liquid interfaces formed during capillary rising in a granular media

    Directory of Open Access Journals (Sweden)

    Gontijo Guilherme L.

    2017-01-01

    Full Text Available We report results concerning the fractal dimension of a air/fluid interface formed during the capillary rising of a fluid into a dense granular media. The system consists in a modified Hele-Shaw cell filled with grains at different granulometries and confined in a narrow gap between the glass plates. The system is then placed onto a water reservoir, and the liquid penetrates the medium due to capillary forces. We measure the Hurst exponent of the liquid/air interface with help of image processing, and follow the temporal evolution of the profiles. We observe that the Hurst exponent can be related with the granulometry, but the range of values are odd to the predicted values from models or theory.

  19. Purification Efficacy of Synthetic Cannabinoid Conjugates Using High-Pressure Liquid Chromatography

    Science.gov (United States)

    conducted using high-pressure liquid chromatography and gradient screens to determine the most effective means of purifying the SC:dark quencher conjugates...to obtain the highest yields and purity. The purity was verified using liquid chromatographycoupled mass spectroscopy and nuclear magnetic resonance.

  20. Prostate cell membrane chromatography-liquid chromatography-mass spectrometry for screening of active constituents from Uncaria rhynchophylla.

    Science.gov (United States)

    He, Jianyu; Han, Shengli; Yang, Fangfang; Zhou, Nan; Wang, Sicen

    2013-01-01

    Uncaria rhynchophylla is a traditional Chinese medicinal herb used to treat hypertension and convulsive disorders such as epilepsy. Rat prostate cell membrane chromatography combined with liquid chromatography-mass spectrometry (LC-MS) was used to identify active constituents from U. rhynchophylla extracts. Four compounds (corynoxeine, isorhynchophylline, isocorynoxeine and rhynchophylline) were discovered. Competitive binding assay results indicated that the four compounds were in direct competition at a single common binding site and interacted with α1A adrenergic receptors (α1A-AR) in a manner similar to tamsulosin. Affinity constant values of the four compounds binding with α1A-AR were also measured using rat prostate cell membrane chromatography (CMC). Finally, their pharmacodynamic effects were tested on rat caudal arteries. This CMC combined LC-MS system offers a means of drug discovery by screening natural medicinal herbs for new pharmacologically active molecules targeting specific receptors.

  1. Determination of seven pyrethroids and six pyrethrins in water by liquid chromatography/mass spectrometry

    Science.gov (United States)

    ccanccapa, alexander; Masia, Ana; Pico, Yolanda

    2016-04-01

    Pyrethroids are the synthetic analogues of pyrethrins which were developed as pesticides from the extracts of dried and powdered flower heads of Chrysanthemum cinerariaefolium. They are increasingly used in agriculture due to their broad biological activity and slow development of pest resistance. Contamination of fresh-water ecosystems appears either because of the direct discharge of industrial and agricultural effluents or as a result of effluents from sewage treatment works; residues can thus accumulate in the surrounding biosphere [1, 2]. These substances, mostly determined by gas chromatography mass spectrometry (GC-MS) can be difficult to analyse due to their volatility and degradability. The purpose of this study is, as an alternative, to develop a fast and sensitive multi-residue method for the target analysis of 7 pyrethroids and the 6 natural pyrethrins currently used in water samples by liquid chromatography tandem mass spectrometry (LC-MS/MS). The compounds included in the study were acrinathrin, etofenprox, cyfluthrin, esfenvalerate, cyhalothrin, cypermethrin and flumethrin as pyrethroids and a commercial mix of pyrethrins containing Cinerin I, Jasmolin I, pyrethrin I, cinerin II, jasmolin II, pyrethrins II in different percentages. As a preliminary step, the ionization and fragmentation of the compounds were optimized injecting individual solutions of each analyte at 10 ppm in the system, using a gradient elution profile of water-methanol both with 10 mM ammonium formate. The ESI conditions were: capillary voltage 4000 V, nebulizer15 psi, source temperature 300◦C and gas flow 10 L min-1. [M+H]+, [M+Na]+ ,[M+NH3]+ ,[M+NH4+]+ were tested as precursor ions. The most intense signal was for ammonium adduct for all compounds. The optimal fragmentor range for product ions were between 20 to 80 ev and the collision energy ranged between 5 to 86 ev. The efficiency of the method was tested in water samples from Turia River without any known exposure to

  2. Analysis of plant hormones by microemulsion electrokinetic capillary chromatography coupled with on-line large volume sample stacking.

    Science.gov (United States)

    Chen, Zongbao; Lin, Zian; Zhang, Lin; Cai, Yan; Zhang, Lan

    2012-04-07

    A novel method of microemulsion electrokinetic capillary chromatography (MEEKC) coupled with on-line large volume sample stacking was developed for the analysis of six plant hormones including indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, 1-naphthaleneacetic acid, abscisic acid and salicylic acid. Baseline separation of six plant hormones was achieved within 10 min by using the microemulsion background electrolyte containing a 97.2% (w/w) 10 mM borate buffer at pH 9.2, 1.0% (w/w) ethyl acetate as oil droplets, 0.6% (w/w) sodium dodecyl sulphate as surfactant and 1.2% (w/w) 1-butanol as cosurfactant. In addition, an on-line concentration method based on a large volume sample stacking technique and multiple wavelength detection was adopted for improving the detection sensitivity in order to determine trace level hormones in a real sample. The optimal method provided about 50-100 fold increase in detection sensitivity compared with a single MEEKC method, and the detection limits (S/N = 3) were between 0.005 and 0.02 μg mL(-1). The proposed method was simple, rapid and sensitive and could be applied to the determination of six plant hormones in spiked water samples, tobacco leaves and 1-naphthylacetic acid in leaf fertilizer. The recoveries ranged from 76.0% to 119.1%, and good reproducibilities were obtained with relative standard deviations (RSDs) less than 6.6%.

  3. Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring.

    Science.gov (United States)

    Wong, Jon W; Webster, Michael G; Bezabeh, Dawit Z; Hengel, Mathew J; Ngim, Kenley K; Krynitsky, Alexander J; Ebeler, Susan E

    2004-10-20

    A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides. Copyright 2004 American Chemical Society

  4. [Analysis of microalbuminuria with immunonephelometry and high performance liquid chromatography. Evaluation of new criteria].

    Science.gov (United States)

    Markó, Lajos; Molnár, Gergo Attila; Wagner, Zoltán; Koszegi, Tamás; Matus, Zoltán; Mohás, Márton; Kuzma, Mónika; Szijártó, István András; Wittmann, István

    2008-01-13

    Hypertension as well as type 2 diabetes mellitus is a major factor in population mortality. Both diseases damage the endothelium, the early sign of which is microalbuminuria, which can be screened by dipstick and can be diagnosed by using immuno-based and high performance liquid chromatography methods. Using high performance liquid chromatography, the non-immunoreactive albumin can be detected as well. The authors aimed at the examination of albuminuria in the case of immunonephelometrically negative patients with high performance liquid chromatography, in diabetic and hypertensive and non-diabetic hypertensive populations. The authors also wanted to compare the present (albumin-creatinine ratio: male: > or =2.5 mg/mmol, female: > or =3.5 mg/mmol) and a new criteria of the Heart Outcomes Prevention Evaluation study (patients without diabetes: immunological method, > or =0.7 mg/mmol; high performance liquid chromatography, > or =3.1 mg/mmol; individuals with diabetes: immunological method, > or =1.4 mg/mmol; high performance liquid chromatography, > or =5.2 mg/mmol) of microalbuminuria. Examination of fresh urines of 469 microalbuminuria negative patients by dipstick were performed by immunonephelometry. Patients, who were microalbuminuria negative by immunonephelometry as well, were further analyzed by high performance liquid chromatography using the Accumintrade mark Kit, based on size-exclusion chromatography. Three times higher albuminuria were found with high performance liquid chromatography than with immunonephelometry. The intraindividual coefficient of variation did not differ in the two methods (37 +/- 31% vs. 40 +/- 31%, p = 0.869; immunonephelometry vs. high performance liquid chromatography; mean +/- standard deviation). Using the present criteria for microalbuminuria, 43% of immunonephelometrically negative patients proved to be microalbuminuric by high performance liquid chromatography. Using the new criteria of the Heart Outcomes Prevention

  5. Preparation and evaluation of surface-bonded tricationic ionic liquid silica as stationary phases for high-performance liquid chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2015-05-29

    Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Application of Ionic Liquids in High Performance Reversed-Phase Chromatography

    Directory of Open Access Journals (Sweden)

    Wentao Bi

    2009-06-01

    Full Text Available Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC. Ionic liquids demonstrate advantages and potential in chromatographic field.

  7. Characterization of polymer-based monolithic capillary columns by inverse size-exclusion chromatography and mercury-intrusion porosimetry

    NARCIS (Netherlands)

    Urban, J.; Eeltink, S.; Jandera, P.; Schoenmakers, P.J.

    2008-01-01

    Organic-polymer monolithic capillary columns were prepared in fused-silica capillaries by a radical copolymerization reaction of butyl methacrylate and ethylene dimethacrylate monomers in the presence of 1,4-butanediol and 1-propanol as porogen solvents and azobisisobutyronitrile as the initiator.

  8. Quality evaluation of moluodan concentrated pill using high-performance liquid chromatography fingerprinting coupled with chemometrics.

    Science.gov (United States)

    Tao, Lingyan; Zhang, Qing; Wu, Yongjiang; Liu, Xuesong

    2016-12-01

    In this study, a fast and effective high-performance liquid chromatography method was developed to obtain a fingerprint chromatogram and quantitative analysis simultaneously of four indexes including gallic acid, chlorogenic acid, albiflorin and paeoniflorin of the traditional Chinese medicine Moluodan Concentrated Pill. The method was performed by using a Waters X-bridge C 18 reversed phase column on an Agilent 1200S high-performance liquid chromatography system coupled with diode array detection. The mobile phase of the high-performance liquid chromatography method was composed of 20 mmol/L phosphate solution and acetonitrile with a 1 mL/min eluent velocity, under a detection temperature of 30°C and a UV detection wavelength of 254 nm. After the methodology validation, 16 batches of Moluodan Concentrated Pill were analyzed by this high-performance liquid chromatography method and both qualitative and quantitative evaluation results were achieved by similarity analysis, principal component analysis and hierarchical cluster analysis. The results of these three chemometrics were in good agreement and all indicated that batch 10 and batch 16 showed significant differences with the other 14 batches. This suggested that the developed high-performance liquid chromatography method could be applied in the quality evaluation of Moluodan Concentrated Pill. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Isolation and purification of six iridoid glycosides from gardenia jasminoides fruit by medium-pressure liquid chromatography combined with macroporous resin chromatography.

    Science.gov (United States)

    Wang, Yun; Liu, Hui; Shen, Lifeng; Yao, Lan; Ma, Yinlian; Yu, Dingrong; Chen, Jianhong; Li, Puling; Chen, Ying; Zhang, Cun

    2015-12-01

    Gardeniae fructus is one of the most frequently used herbs in traditional Chinese medicine. In the present study, a process for the enrichment of six iridoid glycosides from Gardeniae fructus was developed using medium-pressure liquid chromatography combined with macroporous resin and reversed-phase chromatography. The purities of different fractions from Gardeniae fructus were assessed using quantitative high-performance liquid chromatography. After fractionation using HPD-100 column chromatography, a 30% ethanol fraction was selected based on high-performance liquid chromatography and liquid chromatography with mass spectrometry qualitative analysis to separate and purify. Based on the orientation analysis results, six compounds-deacetyl asperulosidic acid methyl ester, gardenoside, ixoroside, scandoside methyl ester, genipin-1-O-β-d-gentiobioside, and geniposide-were successfully isolated and purified in three to four combined steps from Gardeniae fructus. The purities of these compounds were found by high-performance liquid chromatography analysis to be 97.9, 98.1, 95.5, 96.3, 97.1, and 98.7%, respectively. Moreover, their structures were elucidated by NMR spectroscopy and liquid chromatography with tandem mass spectrometry. The separation process was highly efficient, rapid, and accurate, making it a potential approach for the large-scale production of iridoids in the laboratory and providing several marker compounds for quality control. This procedure may be meaningful for the purification of other natural products used in traditional Chinese medicine. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Mehdi Maham

    2014-09-01

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

  11. Method of determining of polybrominated diphenyl ethers in fish and fish products by the method of liquid chromatography

    Directory of Open Access Journals (Sweden)

    O.N. Timofeeva

    2016-09-01

    Full Text Available The aim of the work was to develop a methodology for determining of polybrominated diphenyl ethers (PBDE in fish and fish products for the control of impurities content in the food and environmental objects in general. The conditions of chromatography (temperature conditions, the impact of the speed and magnitude of dividing of the gas-carrier stream using a HP-1 capillary columns, the DB-5, HP-50 +, DB-1; and lipids destructive and non-destructive cleaning methods of extract during the determination of PBDEs. The method of determination of 2,2,4,4-Tetrabromodiphenyl ether (BDE-47, 2,2,4,4,5-pentabromodiphenyl ether (BDE-99 and decabromodiphenyl ether (BDE-209 in fish and fish products by the liquid chromatography with electron detector was suggested. The method of PBDE is based on the extraction of samples with hexane-acetone (3:1, purification of the extract with concentrated sulfuric acid (phase ratio hexane-sulfuric acid – 5:1. The second purification step is carried out by using solid phase extraction cartridges «SiOH-H2SO4/SA» and hexane as the eluent. Gas chromatographic analysis of the determination of BDE-47 and BDE-99 is carried out on low-polar capillary column DB-5 (30 m x0.25 mm x0.25 mum with the programming of the column temperature. In determining the BDE-209 a DB-1 nonpolar capillary column was used (15 m x 0.25 mm x 0.1 mum with the column temperature programming. Calculation of the content of BDE-47 and BDE-99 is carried out with the internal standard (2,2, 3,4,4-pentabromodiphenyl ether (BDE-85, BDE-209 by absolute calibration. In determining the BDE-209 the calibration matrix was used. The range of concentrations of the calibration solutions for the determination of BDE-47 and BDE-99 is 0.005–0.05 g/cm 3 , for BDE-209 0.05–0.3 g/cm 3 . The technique allows the measurement of BDE-47 and BDE-99 in the range of 0.0002–0.05 mg/kg of the product concerned; BDE-209 – in the range of 0.002–0.3 mg/kg. The metrological

  12. Application of capillary gas chromatography-mass spectrometry to chemical characterization of radiation-induced base damage of DNA: implications for assessing DNA repair processes

    International Nuclear Information System (INIS)

    Dizdaroglu, M.

    1985-01-01

    The application of capillary gas chromatography-mass spectrometry (GC-MS) to the chemical characterization of radiation-induced base products of calf thymus DNA is presented. Samples of calf thymus DNA irradiated in N 2 O-saturated aqueous solution were hydrolyzed with HCOOH, trimethylsilylated, and subjected to GC-MS analysis using a fused-silica capillary column. Hydrolysis conditions suitable for the simultaneous analysis of the radiation-induced products of all four DNA bases in a single run were determined. The trimethylsilyl derivatives of these products had excellent GC properties and easily interpretable mass spectra; an intense molecular ion (M+.) and a characteristic (M-CH 3 )+ ion were observed. The complementary use of t-butyldimethylsilyl derivatives was also demonstrated. These derivatives provided an intense characteristic (M-57)+ ion, which appeared as either the base peak or the second most intense ion in the spectra. All mass spectra obtained are discussed

  13. Comprehensive Two-Dimensional Hydrophilic Interaction Chromatography (HILIC) × Reversed-Phase Liquid Chromatography Coupled to High-Resolution Mass Spectrometry (RP-LC-UV-MS) Analysis of Anthocyanins and Derived Pigments in Red Wine.

    Science.gov (United States)

    Willemse, Chandré M; Stander, Maria A; Vestner, Jochen; Tredoux, Andreas G J; de Villiers, André

    2015-12-15

    Changes in anthocyanin chemistry represent some of the most important transformations involved in red wine aging. However, accurate analysis of the derived pigments, as required to study the evolution of anthocyanins and tannins during aging, is hampered by their extreme structural diversity, low levels, and the fact that many of these compounds have identical mass spectral characteristics. In this context, chromatographic separation is critical. In this contribution, the application of online hydrophilic interaction chromatography (HILIC) × reversed-phase liquid chromatography (RP-LC) separation coupled to high-resolution mass spectrometry (MS) is described for the detailed characterization of anthocyanins and their derived pigments in aged red wine. A systematic approach was followed for the optimization of HILIC × RP-LC separation parameters using a capillary liquid chromatography (LC) system in the first dimension and an ultrahigh-pressure LC system in the second dimension to ensure maximum sensitivity and performance. Ninety four (94) anthocyanin-derived pigments were tentatively identified in one- and six-year-old Pinotage wines using accurate mass and fragmentation information obtained using quadrupole-time-of-flight mass spectrometry (Q-TOF-MS). Online HILIC × RP-LC-MS was found to offer high-resolution separation, because of the combination of two different separation modes, while the structured elution order observed improved the certainty in compound identification. Therefore, this approach shows promise for the detailed elucidation of the chemical alteration of anthocyanins during wine aging.

  14. Liquid-gas and solid-liquid interface: thermodynamics of capillary condensation application to a prosimetry by calorimetric measurements

    International Nuclear Information System (INIS)

    Derrien, Francois; Hartmanshenn, Olivier.

    1978-01-01

    A direct determination of the pore radii distribution is proposed using calorimetric measurements during condensation and evacuation of pores by capillary condensate. This method is independant of any gravimetric or volumetric measurement of adsorption

  15. Recent advances in liquid and gas chromatography methodology for extending coverage of the metabolome.

    Science.gov (United States)

    Haggarty, Jennifer; Burgess, Karl Ev

    2017-02-01

    The metabolome is the complete complement of metabolites (small organic biomolecules). In order to comprehensively understand the effect of stimuli on a biological system, it is important to detect as many of the metabolites within that system as possible. This review briefly describes some new advances in liquid and gas chromatography to improve coverage of the metabolome, including the serial combination of two columns in tandem, column switching and different variations of two-dimensional chromatography. Supercritical fluid chromatography could provide complimentary data to liquid and gas chromatography. Although there have been many recent advancements in the field of metabolomics, it is evident that a combination, rather than a single method, is required to approach full coverage of the metabolome. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Application of liquid column chromatography to preconcentration, separation and determination of platinum metals

    International Nuclear Information System (INIS)

    Alimarin, I.P.; Basova, E.M.; Bol'shova, T.A.; Ivanov, V.M.

    1986-01-01

    Separation and determination of platimum metals using the methods of adsorption, ion-pair, ion-exchange, distributing and sieve chromatography are discussed in the review of literature in 1971-1984. Separation and determination of metals as chelates using the method of adsorption and ion-pair chromatograpy are noted to be most perspective directions of developing highly effective liquid chromatography of inorganic systems

  17. Immunoaffinity chromatography of abscisic acid combined with electrospray liquid chromatography–mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Hradecká, Veronika; Novák, Ondřej; Havlíček, Libor; Strnad, Miroslav

    2007-01-01

    Roč. 847, č. 2 (2007), s. 162-173 ISSN 1570-0232 R&D Projects: GA MŠk(CZ) LC06034; GA AV ČR IBS5038351 Institutional research plan: CEZ:AV0Z50380511 Source of funding: V - iné verejné zdroje ; V - iné verejné zdroje Keywords : abscisic acid * immunoaffinity chromatography * liquid chromatography-mass spectrometry Subject RIV: ED - Physiology Impact factor: 2.935, year: 2007

  18. Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

    Science.gov (United States)

    Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

    2015-11-01

    Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

  19. Improved method for the determination of the cortisol production rate using high-performance liquid chromatography and liquid scintillation counting

    NARCIS (Netherlands)

    van Ingen, H. E.; Endert, E.

    1988-01-01

    Two new methods for the determination of the cortisol production rate using reversed-phase high-performance liquid chromatography are described. One uses ultraviolet detection at 205 nm, the other on-line post-column derivatization with benzamidine, followed by fluorimetric detection. The specific

  20. Characterization of natural organic colorants in historical and art objects by high-performance liquid chromatography.

    Science.gov (United States)

    Pauk, Volodymyr; Barták, Petr; Lemr, Karel

    2014-12-01

    High-performance liquid chromatography plays an important role in analysis of historical organic colorants. A number of papers have been published in this field over the last 30 years. Classification of the most commonly used natural dyes and an overview of high-performance liquid chromatography methods with main focus on recent works (2008 to the beginning of 2014) are provided. The review deals with an entire analytical protocol covering sample preparation, chromatographic separation, and suitable detection (UV/visible and fluorescent spectroscopy and mass spectrometric techniques). High-performance liquid chromatography has been successfully used in the complete characterization of some organic dyestuffs present in historical and art objects. The possibilities and difficulties for identification of natural sources of historical colorants are also discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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...

  2. Fast filtration sampling protocol for mammalian suspension cells tailored for phosphometabolome profiling by capillary ion chromatography - tandem mass spectrometry.

    Science.gov (United States)

    Kvitvang, Hans F N; Bruheim, Per

    2015-08-15

    Capillary ion chromatography (capIC) is the premium separation technology for low molecular phosphometabolites and nucleotides in biological extracts. Removal of excessive amounts of salt during sample preparation stages is a prerequisite to enable high quality capIC separation in combination with reproducible and sensitive MS detection. Existing sampling protocols for mammalian cells used for GC-MS and LC-MS metabolic profiling can therefore not be directly applied to capIC separations. Here, the development of a fast filtration sampling protocol for mammalian suspension cells tailored for quantitative profiling of the phosphometabolome on capIC-MS/MS is presented. The whole procedure from sampling the culture to transfer of filter to quenching and extraction solution takes less than 10s. To prevent leakage it is critical that a low vacuum pressure is applied, and satisfactorily reproducibility was only obtained by usage of a vacuum pressure controlling device. A vacuum of 60mbar was optimal for filtration of multiple myeloma Jjn-3 cell cultures through 5μm polyvinylidene (PVDF) filters. A quick deionized water (DI-water) rinse step prior to extraction was tested, and significantly higher metabolite yields were obtained during capIC-MS/MS analyses in this extract compared to extracts prepared by saline and reduced saline (25%) washing steps only. In addition, chromatographic performance was dramatically improved. Thus, it was verified that a quick DI-water rinse is tolerated by the cells and can be included as the final stage during filtration. Over 30 metabolites were quantitated in JJN-3 cell extracts by using the optimized sampling protocol with subsequent capIC-MS/MS analysis, and up to 2 million cells can be used in a single filtration step for the chosen filter and vacuum pressure. The technical set-up is also highly advantageous for microbial metabolome filtration protocols after optimization of vacuum pressure and washing solutions, and the reduced salt

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

    Science.gov (United States)

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

    2016-03-18

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

  4. High-performance liquid chromatography of oligoguanylates at high pH

    Science.gov (United States)

    Stribling, R.; Deamer, D. (Principal Investigator)

    1991-01-01

    Because of the stable self-structures formed by oligomers of guanosine, standard high-performance liquid chromatography techniques for oligonucleotide fractionation are not applicable. Previously, oligoguanylate separations have been carried out at pH 12 using RPC-5 as the packing material. While RPC-5 provides excellent separations, there are several limitations, including the lack of a commercially available source. This report describes a new anion-exchange high-performance liquid chromatography method using HEMA-IEC BIO Q, which successfully separates different forms of the guanosine monomer as well as longer oligoguanylates. The reproducibility and stability at high pH suggests a versatile role for this material.

  5. Glucose and glycerol concentrations and their tracer enrichment measurements using liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Bornø, Andreas; Foged, Lene; van Hall, Gerrit

    2014-01-01

    The present study describes a new liquid chromatography tandem mass spectrometry method for high-throughput quantification of glucose and glycerol in human plasma using stable isotopically labeled internal standards and is suitable for simultaneous measurements of glucose and glycerol enrichments...... of variation were 2.0% and 9.7%, respectively. After derivatization, plasma samples were stable for at least 14 days. In conclusion, we have developed and validated a novel, accurate, and sensitive high-throughput liquid chromatography tandem mass spectrometry method for simultaneous determination of glucose...

  6. Application of a diode-array detector in capillary electrophoresis

    NARCIS (Netherlands)

    Beck, W.; Hoek, van R.; Engelhardt, H.

    1993-01-01

    In the last decade diode-array detection has proved to be extremely useful in high performance liquid chromatography in recording UV-visible spectra directly and on-line in the column effluent. In capillary electrophoresis (CE) only fast-scanning detectors with long scan times (up to 2 s) are

  7. A simple liquid extraction protocol for overcoming the ion suppression of triacylglycerols by phospholipids in liquid chromatography mass spectrometry studies.

    Science.gov (United States)

    Araujo, Pedro; Tilahun, Ephrem; Breivik, Joar Fjørtoft; Abdulkader, Bashir M; Frøyland, Livar; Zeng, Yingxu

    2016-02-01

    It is well-known that triacylglycerol (TAG) ions are suppressed by phospholipid (PL) ions in regiospecific analysis of TAG by mass spectrometry (MS). Hence, it is essential to remove the PL during sample preparation prior to MS analysis. The present article proposes a cost-effective liquid-liquid extraction (LLE) method to remove PL from TAG in different kinds of biological samples by using methanol, hexane and water. High performance thin layer chromatography confirmed the lack of PL in krill oil and salmon liver samples, submitted to the proposed LLE protocol, and liquid chromatography tandem MS confirmed that the identified TAG ions were highly enhanced after implementing the LLE procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

    International Nuclear Information System (INIS)

    Schmidt, L.; Danigel, H.; Jungclas, H.

    1982-01-01

    A 252 Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures. (orig.)

  9. Bacterial Cell Wall Precursor Phosphatase Assays Using Thin-layer Chromatography (TLC) and High Pressure Liquid Chromatography (HPLC).

    Science.gov (United States)

    Pazos, Manuel; Otten, Christian; Vollmer, Waldemar

    2018-03-20

    Peptidoglycan encases the bacterial cytoplasmic membrane to protect the cell from lysis due to the turgor. The final steps of peptidoglycan synthesis require a membrane-anchored substrate called lipid II, in which the peptidoglycan subunit is linked to the carrier lipid undecaprenol via a pyrophosphate moiety. Lipid II is the target of glycopeptide antibiotics and several antimicrobial peptides, and is degraded by 'attacking' enzymes involved in bacterial competition to induce lysis. Here we describe two protocols using thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC), respectively, to assay the digestion of lipid II by phosphatases such as Colicin M or the LXG toxin protein TelC from Streptococcus intermedius . The TLC method can also monitor the digestion of undecaprenyl (pyro)phosphate, whereas the HPLC method allows to separate the di-, mono- or unphosphorylated disaccharide pentapeptide products of lipid II.

  10. Determination of lysergic acid diethylamide (LSD) in mouse blood by capillary electrophoresis/ fluorescence spectroscopy with sweeping techniques in micellar electrokinetic chromatography.

    Science.gov (United States)

    Fang, Ching; Liu, Ju-Tsung; Chou, Shiu-Huey; Lin, Cheng-Huang

    2003-03-01

    The separation and on-line concentration of lysergic acid diethylamide (LSD) in mouse blood was achieved by means of capillary electrophoresis/fluorescence spectroscopy using sodium dodecyl sulfate (SDS) as the surfactant. Techniques involving on-line sample concentration, including sweeping micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were applied; the optimum on-line concentration and separation conditions were determined. In the analysis of an actual sample, LSD was found in a blood sample from a test mouse (0.1 mg LSD fed to a 20 g mouse; approximately 1/10 to the value of LD(50)). As a result, 120 and 30 ng/mL of LSD was detected at 20 and 60 min, respectively, after ingestion of the doses.

  11. Lipidomic analysis of biological samples: Comparison of liquid chromatography, supercritical fluid chromatography and direct infusion mass spectrometry methods.

    Science.gov (United States)

    Lísa, Miroslav; Cífková, Eva; Khalikova, Maria; Ovčačíková, Magdaléna; Holčapek, Michal

    2017-11-24

    Lipidomic analysis of biological samples in a clinical research represents challenging task for analytical methods given by the large number of samples and their extreme complexity. In this work, we compare direct infusion (DI) and chromatography - mass spectrometry (MS) lipidomic approaches represented by three analytical methods in terms of comprehensiveness, sample throughput, and validation results for the lipidomic analysis of biological samples represented by tumor tissue, surrounding normal tissue, plasma, and erythrocytes of kidney cancer patients. Methods are compared in one laboratory using the identical analytical protocol to ensure comparable conditions. Ultrahigh-performance liquid chromatography/MS (UHPLC/MS) method in hydrophilic interaction liquid chromatography mode and DI-MS method are used for this comparison as the most widely used methods for the lipidomic analysis together with ultrahigh-performance supercritical fluid chromatography/MS (UHPSFC/MS) method showing promising results in metabolomics analyses. The nontargeted analysis of pooled samples is performed using all tested methods and 610 lipid species within 23 lipid classes are identified. DI method provides the most comprehensive results due to identification of some polar lipid classes, which are not identified by UHPLC and UHPSFC methods. On the other hand, UHPSFC method provides an excellent sensitivity for less polar lipid classes and the highest sample throughput within 10min method time. The sample consumption of DI method is 125 times higher than for other methods, while only 40μL of organic solvent is used for one sample analysis compared to 3.5mL and 4.9mL in case of UHPLC and UHPSFC methods, respectively. Methods are validated for the quantitative lipidomic analysis of plasma samples with one internal standard for each lipid class. Results show applicability of all tested methods for the lipidomic analysis of biological samples depending on the analysis requirements

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

    Science.gov (United States)

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

    2013-03-12

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

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

    Science.gov (United States)

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

    2012-09-01

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

  14. Liquid chromatography tandem mass spectrometry determination of total budesonide levels in dog plasma after inhalation exposure.

    Science.gov (United States)

    Berg, Seija; Melamies, Marika; Rajamäki, Minna; Vainio, Outi; Peltonen, Kimmo

    2012-01-01

    A sensitive and selective method to quantify budesonide in dog plasma samples was developed and fully validated. Liquid-liquid extraction was followed by solid-phase extraction and liquid chromatography-tandem mass spectrometry with electrospray ionization. After reconstitution of the analytes in the mobile phase, samples were analysed by reversed-phase liquid chromatography with isocratic elution. d8-Budesonide was used as an internal standard, and characteristic transitions of d8-budesonide and budesonide were used for quantification. The method was validated with respect to selectivity, specificity, linearity, recovery, repeatability, reproducibility and limits of detection and quantification. The validated method was successfully applied to monitor the plasma levels of budesonide in dogs exposed to clinical doses of inhaled and intravenous drug.

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

    Science.gov (United States)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Science.gov (United States)

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

    2017-08-24

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

  18. High-performance liquid chromatography electrospray mass spectrometry as a method in proteomic research

    International Nuclear Information System (INIS)

    Walcher, W.

    2003-06-01

    During the sequencing of the human genome it became clear, that a lot of human diseases and/or malfunctions don't base on genomic information, but on differences at the protein level. Therefore biochemistry, biology and medicine are faced to various novel problems where new and authentic analysis methods are needed. Miniaturized chromatographic separation methods are frequently the methods of choice for the separation of peptides and proteins, when the amount of sample is limited. Monolithic capillary columns were prepared by copolymerization of styrene and divinylbenzene in the presence of a suitable porogen mixture of 1-decanol and tetrahydrofuran. The synthesized columns enabled the highly efficient separation of peptides and proteins by reversed-phase high-performance liquid chromatography (RP-HPLC) with peak capacities of 80 and more in 10 minutes. By the hyphenation of RP-HPLC to electrospray mass spectrometry (ESI-MS) the potential of the analysis method was even extended. The monolithic column technology was further miniaturized from 200 μm to 100 and 50 μm inner diameters to improve detection limits by RP-HPLC-ESI-MS. After the optimization of the RP-HPLC-ESI-MS method, the ion source and the ion transfer optics of an ion trap mass spectrometer (LCQ classic, Thermofinnigan) have been advanced for protein and peptide analysis. The improved RP-HPLC-ESI-MS system was subsequently applied to the detection of posttranslational protein modifications at the example of the nitration of bovine serum albumin (BSA). The results of the RP-HPLC-ESI-MS analysis were found to be highly reproducible, which enabled the determination of nitration degrees for different tyrosine residues in the protein sequence. Y 1 60, Y 4 96 and Y 3 52 or Y369 were found to be the predominant positions of protein nitration in BSA. At last light harvesting proteins from the photosystem II (PSII) of higher plants have been analyzed by RP-HPLC-ESI-MS and RP-HPLC-ESI-MSMS. Beside the

  19. Liquid crystalthermography as compared to X-ray diagnostics, clinical findings and capillary microscopy in sclerodermia progressiva

    International Nuclear Information System (INIS)

    Loreck, D.; Buehler, G.; Brenke, A.; Schmidt, P.; Heerdegen, I.; Huege, H.

    1985-01-01

    The hands of 55 patients suffering from progressive sclerodermia were examined by liquid crystal thermography. The findings were compared with those of X-ray diagnosis and with clinical results. In 20 patients also capillary microscopy was applied. All patients revealed hypothermias in the fingers, independent from X-ray results, duration of the disease and Raynaud's phenomenon. Hypothermia could involve all fingers and was localized proximally or distally. In most of the patients also hyperthermias, not to be cooled, were found. They were diarthrodial and vasal, respectively

  20. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    Science.gov (United States)

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates

    NARCIS (Netherlands)

    Moerdijk-Poortvliet, Tanja C. W.; Schierbeek, Henk; Houtekamer, Marco; van Engeland, Tom; Derrien, Delphine; Stal, Lucas J.; Boschker, Henricus T. S.

    2015-01-01

    We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of δ(13)C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although

  2. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates

    NARCIS (Netherlands)

    Moerdijk-Poortvliet, T.C.W.; Schierbeek, H.; Houtekamer, M.; van Engeland, T.; Derrien, D.; Stal, L.J.; Boschker, H.T.S.

    2015-01-01

    We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of d13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although

  3. Comparison of gas chromatography/isotope ratio mass spectrometry and liquid chromatography/isotope ratio mass spectrometry for carbon stable-isotope analysis of carbohydrates

    NARCIS (Netherlands)

    Moerdijk-Poortvliet, T.C.W.; Schierbeek, H.; Houtekamer, M.; van Engeland, T.; Derrien, D.; Stal, L.J.; Boschker, H.T.S.

    2015-01-01

    Rationale: We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of δ13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence,

  4. High-performance liquid chromatography of human glycoprotein hormones.

    Science.gov (United States)

    Chlenov, M A; Kandyba, E I; Nagornaya, L V; Orlova, I L; Volgin, Y V

    1993-02-12

    The chromatographic behavior of the glycoprotein hormones from human pituitary glands and of placental origin [thyroid-stimulating hormone, luteinizing hormone and chorionic gonadotropin (CG)] was studied. It was shown that hydrophobic interaction chromatography on a microparticulate packing and anion-exchange HPLC can be applied for the purification of these hormones. Reversed-phase HPLC on wide-pore C4-bonded silica at neutral pH can be applied for the determination of the above hormones and for the isolation of pure CG and its subunits.

  5. Separation of hemagglutination-inhibiting immunoglobulin M antibody to rubella virus in human serum by high-performance liquid chromatography.

    OpenAIRE

    Kobayashi, N; Suzuki, M; Nakagawa, T; Matumoto, M

    1986-01-01

    High-performance liquid chromatography was successfully used to separate hemagglutination-inhibiting immunoglobulin M (IgM) rubella virus antibody from IgG rubella virus antibody in human serum. The fractionation by high-performance liquid chromatography was as effective as sucrose density gradient centrifugation in separating IgM antibody from IgG antibody.

  6. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    Science.gov (United States)

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  7. Thermodynamics of the multicomponent vapor-liquid equilibrium under capillary pressure difference

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    2001-01-01

    We discuss the two-phase multicomponent equilibrium, provided that the phase pressures are different due to the action of capillary forces. We prove the two general properties of such an equilibrium, which have previously been known for a single-component case, however, to the best of our knowledge......, not for the multicomponent mixtures. The importance is emphasized on the space of the intensive variables P, T and mu (i), where the laws of capillary equilibrium have a simple geometrical interpretation. We formulate thermodynamic problems specific to such an equilibrium, and outline changes to be introduced to common...... algorithms of flash calculations in order to solve these problems. Sample calculations show large variation of the capillary properties of the mixture in the very neighborhood of the phase envelope and the restrictive role of the spinodal surface as a boundary for possible equilibrium states with different...

  8. AN AFFORDABLE HIGH PERFORMANCE PUMPING SYSTEM FOR GRADIENT CAPILLARY LIQUID CHROMATOGRAPHY. (R825344)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  9. Zwitterionic silica-based monolithic capillary columns for isocratic and gradient hydrophilic interaction liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Planeta, Josef; Kahle, Vladislav; Roth, Michal

    2012-01-01

    Roč. 1270, DEC 28 (2012), s. 178-185 ISSN 0021-9673 R&D Projects: GA MV VG20112015021; GA ČR(CZ) GAP206/11/0138; GA ČR(CZ) GAP106/12/0522 Institutional support: RVO:68081715 Keywords : HILIC * Monolithic silica column * Nucleoside separation * Nucleic acid base Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.612, year: 2012

  10. Recent highlights in electro-driven separations- selected applications of alkylthiol gold nanoparticles in capillary electrophoresis and capillary electro-chromatography.

    Science.gov (United States)

    Guihen, Elizabeth

    2017-09-01

    To date, alkylthiol gold nanoparticles (AuNPs) have been widely used in electro-chromatographic separation techniques as a viable alternative to traditional stationary phases. This is mainly due to their stability, chemical inertness, ease of functionality, increased phase ratio, ability to form self-assembled monolayers. They also yield versatile stationary phases with highly specific targeted functionalities. At the nanoscale region, the chemical and physical properties of a molecule display different attributes to that of the parent molecules or material, hence these features can be harnessed in electro-driven chromatographic separations. Application areas illustrating the use of AuNPs in separation science continue to grow and expand to cover many different kinds of analysis. The last decade has witnessed a successful trend in miniaturisation of chemical separation systems toward the micro and nanoscale ranges. Nanoparticle-based stationary phases fit well with performing chemical separations on microfluidic and capillary platforms. In this review the theory of the use of alkylthiol gold nanoparticles in electro-chromatographic driven separation methods will be discussed. This will be followed by details of recent and selected applications showing alkylthiol gold nanoparticles in capillary electrophoretic and open-tubular electro-chromatographic separations. This review will focus solely on alkylthiol based gold nanoparticles, therefore other kinds of chemical moieties bonded to gold nanoparticles are outside the scope of this review. Finally the future outlook of this exciting technology will be outlined in some detail in the final section. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Resolution of RNA using high-performance liquid chromatography

    NARCIS (Netherlands)

    Mclaughlin, L.W.; Bischoff, Rainer

    1987-01-01

    High-performance liquid chromatographic techniques can be very effective for the resolution and isolation of nucleic acids. The characteristic ionic (phosphodiesters) and hydrophobic (nucleobases) properties of RNAs can be exploited for their separation. In this respect anion-exchange and

  12. Buffer-Free High Performance Liquid Chromatography Method for ...

    African Journals Online (AJOL)

    Purpose: To develop and validate a simple, economical and reproducible high performance liquid chromatographic (HPLC) method for the determination of theophylline in pharmaceutical dosage forms. Method: Caffeine was used as the internal standard and reversed phase C-18 column was used to elute the drug and ...

  13. Determination of ribavirin in human serum using liquid chromatography tandem mass spectrometry

    NARCIS (Netherlands)

    van der Lijke, H.; Alffenaar, J.-W. C.; Kok, W.Th.; Greijdanus, B.; Uges, D.R.A.

    2012-01-01

    A method has been developed for the determination of ribavirin in human serum for therapeutic drug monitoring purposes, using liquid chromatography electrospray ionization mass spectrometry. Separation was obtained with a mobile phase gradient starting and ending in 100% aqueous conditions using a

  14. Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

    Science.gov (United States)

    Fahey, Robert C.; Newton, Gerald L.

    1988-01-01

    Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

  15. Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.

    Science.gov (United States)

    Ondrus, Martin G.; And Others

    1983-01-01

    Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

  16. Determination of Peroxide-Based Explosives Using Liquid Chromatography with On-Line Infrared Detection

    NARCIS (Netherlands)

    Schulte-Ladbeck, Rasmus; Edelmann, Andrea; Quintas, Guillermo; Lendl, Bernhard; Karst, U.

    2006-01-01

    A nondestructive analytical method for peroxide-based explosives determination in solid samples is described. Reversed-phase high-performance liquid chromatography in combination with on-line Fourier transform infrared (FT-IR) detection is used for the analysis of triacetonetriperoxide (TATP) and

  17. Simultaneous quantitative analysis of metabolites using ion-pair liquid chromatography-electrospray ionization mass spectrometry

    NARCIS (Netherlands)

    Coulier, L.; Bas, R.; Jespersen, S.; Verheij, E.; Werf, M.J. van der; Hankemeier, T.

    2006-01-01

    We have developed an analytical method, consisting of ion-pair liquid chromatography coupled to electrospray ionization mass spectrometry (IP-LC-ESI-MS), for the simultaneous quantitative analysis of several key classes of polar metabolites, like nucleotides, coenzyme A esters, sugar nucleotides,

  18. High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory

    Science.gov (United States)

    Frey, Douglas D.; Guo, Hui; Karnik, Nikhila

    2013-01-01

    This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…

  19. Isotope Fractionation in Methane Reactions Studied by Gas Chromatography and Liquid Scintillation

    DEFF Research Database (Denmark)

    Andersen, Bertel Lohmann; Bidoglio, G.; Leip, A.

    1997-01-01

    Determination of C-14-marked methane by gas chromatography and liquid scintillation counting is shown to be useful in studies of isotope effects. Data on the specific activity is used to separate the contributions of (CH4)-C-14, and (CH4)-C-12 to the gas-chromatographic peak area. As an application...

  20. Improvement of recovery and repeatability in liquid chromatography-mass spectrometry analysis of peptides

    NARCIS (Netherlands)

    van Midwoud, Paul M.; Rieux, Laurent; Bischoff, Rainer; Verpoorte, Elisabeth; Niederlander, Harm A. G.

    2007-01-01

    Poor repeatability of peak areas is a problem frequently encountered in peptide analysis with nanoLiquid Chromatography coupled on-line with Mass Spectrometry (nanoLC-MS). As a result, quantitative analysis will be seriously hampered unless the observed variability can be corrected in some way.

  1. Serum Protein Profile Study of Clinical Samples Using High Performance Liquid Chromatography-Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Karemore, Gopal Raghunath; Ukendt, Sujatha; Rai, Lavanya

    2009-01-01

    The serum protein profiles of normal subjects, patients diagnosed with cervical cancer, and oral cancer were recorded using High Performance Liquid Chromatography combined with Laser Induced Fluorescence detection (HPLC-LIF). Serum protein profiles of the above three classes were tested for estab...

  2. Nitrate and nitrite content in bottled beverages by ion-pair high-performance liquid chromatography.

    Science.gov (United States)

    Song, Yang; Deng, Gui-Fang; Xu, Xiang-Rong; Chen, Yong-Hong; Chen, Feng; Li, Hua-Bin

    2013-01-01

    Nitrate and nitrite levels in six types of beverages--total of 292 individual samples from 73 brands (four bottles each)--from Guangzhou city in China were evaluated by ion-pair high-performance liquid chromatography. All samples contained nitrate. Nitrate and nitrite ranges were 0.43-46.08 and safety of Chinese bottled beverages.

  3. DETERMINATION OF CHLOROPHEONIS, NITROPHENOIS AND METHYLPHENOIS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    Science.gov (United States)

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  4. High Performance Liquid Chromatography of Some Analgesic Compounds: An Instrumental Analysis Experiment.

    Science.gov (United States)

    Haddad, Paul; And Others

    1983-01-01

    Background information, procedures, and results are provided for an experiment demonstrating techniques of solvent selection, gradient elution, pH control, and ion-pairing in the analysis of an analgesic mixture using reversed-phase liquid chromatography on an octadecylsilane column. Although developed using sophisticated/expensive equipment, less…

  5. DETERMINATION OF CHLOROPHENOLS, NITROPHENOLS, AND METHYLPHENOLS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

    Science.gov (United States)

    A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

  6. Simultaneous determination of seven flavonoids in Epimedium by liquid chromatography-tandem mass spectrometry method

    Institute of Scientific and Technical Information of China (English)

    Cai Sheng Wu; Bao Lin Guo; Yu Xin Sheng; Jin Lan Zhang

    2008-01-01

    In this paper, a sensitive and specific liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and determination of seven flavonoids, namely epimedin A, epimedin B, epimedin C, icariin, sagittatoside B, 2"-0-rhamnosyl icariside II, and baohuoside I in Epimedium from different sources.

  7. Alternative sample-introduction technique to avoid breakthrough in gradient-elution liquid chromatography of polymers

    NARCIS (Netherlands)

    Reingruber, E.; Bedani, F.; Buchberger, W.; Schoenmakers, P.

    2010-01-01

    Gradient-elution liquid chromatography (GELC) is a powerful tool for the characterization of synthetic polymers. However, gradient-elution chromatograms often suffer from breakthrough phenomena. Breakthrough can be averted by using a sample solvent as weak as the mobile phase. However, this approach

  8. Determination of organophosphorus acids by thermo-spray liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Wils, E.R.J.; Hulst, A.G.

    1988-01-01

    The determination of thirteen organophosphorus acids, hydrolysis products of nerve agents and pesticides, by a combination of ion-pair liquid chromatography on a reversed-phase C18 column and thermospray mass spectrometry was investigated. Ammonium acetate and three tetraalkylammonium salts with

  9. Novel approach to determine ghrelin analogs by liquid chromatography with mass spectrometry using a monolithic column

    Czech Academy of Sciences Publication Activity Database

    Zemenová, Jana; Sýkora, D.; Adámková, H.; Maletínská, Lenka; Elbert, Tomáš; Marek, Aleš; Blechová, Miroslava

    2017-01-01

    Roč. 40, č. 5 (2017), s. 1032-1039 ISSN 1615-9306 Institutional support: RVO:61388963 Keywords : enzyme-linked immunosorbent assay * ghrelin * lipopeptides * liquid chromatography mass spectrometry * monolithic columns Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 2.557, year: 2016

  10. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography

    NARCIS (Netherlands)

    Uliyanchenko, E.; van der Wal, S.; Schoenmakers, P.J.

    2011-01-01

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles

  11. Extraction and Purification of Glucoraphanin by Preparative High-Performance Liquid Chromatography (HPLC)

    Science.gov (United States)

    Lee, Iris; Boyce, Mary C.

    2011-01-01

    A student activity that focuses on the isolation of glucoraphanin from broccoli using preparative high-performance liquid chromatography (HPLC) is presented here. Glucoraphanin is a glucosinolate, whose byproducts are known to possess anticancer properties. It is present naturally at high levels in broccoli and other "Brassica" vegetables. This…

  12. Analysis of Currently Available Analgesic Tablets by Modern Liquid Chromatography: An Undergraduate Laboratory Introduction to HPLC.

    Science.gov (United States)

    Kagel, R. A.; Farwell, S. O.

    1983-01-01

    Background information, procedures, and results, are provided for an undergraduate experiment in which analgesic tablets are analyzed using liquid chromatography. The experiment, an improved, modified version of the Waters Associates Inc. experiment, is simple to prepare, requiring little glassware and minimal sample manipulation by students. (JN)

  13. Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Guo, Xinghua; Bruins, Andries P.; Covey, Thomas R.

    2006-01-01

    The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion

  14. An Advanced, Interactive, High-Performance Liquid Chromatography Simulator and Instructor Resources

    Science.gov (United States)

    Boswell, Paul G.; Stoll, Dwight R.; Carr, Peter W.; Nagel, Megan L.; Vitha, Mark F.; Mabbott, Gary A.

    2013-01-01

    High-performance liquid chromatography (HPLC) simulation software has long been recognized as an effective educational tool, yet many of the existing HPLC simulators are either too expensive, outdated, or lack many important features necessary to make them widely useful for educational purposes. Here, a free, open-source HPLC simulator is…

  15. Simulated Moving Bed Chromatography: Separation and Recovery of Sugars and Ionic Liquid from Biomass Hydrolysates

    Science.gov (United States)

    Caes, Benjamin R.; Van Oosbree, Thomas R.; Lu, Fachuang; Ralph, John; Maravelias, Christos T.

    2015-01-01

    Simulated moving bed chromatography, a continuous separation method, enables the nearly quantitative recovery of sugar products and ionic liquid solvent from chemical hydrolysates of biomass. The ensuing sugars support microbial growth, and the residual lignin from the process is intact. PMID:23939991

  16. Determination of chlormequat in pears by liquid chromatography/mass spectrometry

    NARCIS (Netherlands)

    Mol, H.G.J.; Dam, R.C.J. van; Vreeken, R.J.; Steijger, O.M.

    2000-01-01

    A straightforward and reliable method was developed for the determination of chlormequat in pears by liquid chromatography/mass spectrometry (LC/MS). Water and methanol were compared as extraction solvents. Because no significant differences in extraction efficiency or repeatability were found,

  17. Assay of free urinary cortisol with inverted phase liquid chromatography and radiocompetition

    International Nuclear Information System (INIS)

    Franck, C.; Patricot, M.C.; Mathian, B.; Revol, A.

    1984-01-01

    The authors present an assay method for free urinary cortisol using inverted phase liquid chromatography for purification and radiocompetition for the assay. The usual values for adult men and women were established. The results of 150 routine assays were compared with those of 17 OHCS revealing the value of this assay [fr

  18. Analysis of 2-methylthio-derivatives of isoprenoid cytokinins by liquid chromatography-tandem mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Tarkowski, Petr; Václavíková, Kateřina; Novák, Ondřej; Pertry, I.; Hanuš, Jan; Whenham, R.; Vereecke, D.; Šebela, M.; Strnad, Miroslav

    2010-01-01

    Roč. 680, 1-2 (2010), s. 86-91 ISSN 0003-2670 R&D Projects: GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : Cytokinins * Rhodococcus fascians * High-performance liquid chromatography Subject RIV: CE - Biochemistry Impact factor: 4.310, year: 2010

  19. An on-line high performance liquid chromatography-crocin bleaching assay for detection of antioxidants

    NARCIS (Netherlands)

    Bountagkidou, O.; Klift, van der E.J.C.; Tsimidou, M.Z.; Ordoudi, S.A.; Beek, van T.A.

    2012-01-01

    An on-line HPLC (high performance liquid chromatography) method for the rapid screening of individual antioxidants in mixtures was developed using crocin as a substrate (i.e. oxidation probe) and 2,2'-azobis(2-amidinopropane dihydrochloride (AAPH)) in phosphate buffer (pH 7.5) as a radical

  20. Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

    Science.gov (United States)

    Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

    2012-01-01

    The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

  1. Column liquid chromatography- mass spectrometry: selected techniques in environmental applications for polar pesticides and related compounds.

    NARCIS (Netherlands)

    Slobodnik, J.; van Baar, B.L.M.; Brinkman, U.A.T.

    1995-01-01

    A review covering the field of environmental applications of liquid chromatography-mass spectrometry (LC-MS) is presented. Recent developments and advances are discussed with emphasis on the presently popular thermospray, particle beam and atmospheric pressure ionisation interfaces. Each interface

  2. Magnetic/non-magnetic argan press cake nanocellulose for the selective extraction of sudan dyes in food samples prior to the determination by capillary liquid chromatograpy.

    Science.gov (United States)

    Benmassaoud, Yassine; Villaseñor, María J; Salghi, Rachid; Jodeh, Shehdeh; Algarra, Manuel; Zougagh, Mohammed; Ríos, Ángel

    2017-05-01

    Two methods for the determination of Sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples, by solid phase extraction - capillary liquid chromatography, are proposed. Both methods use nanocellulose (NC) extracted from bleached argan press cake (APC), as a nano-adsorbent recycled from an agricultural waste material. One of the methods involves the dispersion of NC in food sample extracts, along with the waste and eluents being separated by centrifugation. In the other method, NC was modified by magnetic iron nanoparticles before using it in the extraction of Sudan dyes. The use of a magnetic component in the extraction process allows magnetic separation to replace the centrifugation step in a convenient and economical way. The two proposed methods allows the determination of Sudan dye amounts at the 0.25-2.00µgL -1 concentration range. The limit of detections, limit of quantifications and standard deviations achieved were lower than 0.1µgL -1 , 0.20µgL -1 and 3.46% respectively, when using NC as a nano-adsorbent, and lower than 0.07µgL -1 , 0.23µgL -1 and 2.62%, respectively, with the magnetic nanocellulose (MNC) was used. Both methods were applied to the determination of Sudan dyes in barbeque and ketchup sauce samples, obtaining recoveries between 93.4% and 109.6%. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry.

    Science.gov (United States)

    Martín-Ortiz, A; Salcedo, J; Barile, D; Bunyatratchata, A; Moreno, F J; Martin-García, I; Clemente, A; Sanz, M L; Ruiz-Matute, A I

    2016-01-08

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2-0.6min) and good symmetry (As: 0.8-1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40°C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315mgL(-1) for neutral oligosaccharides and from 83 to 251mgL(-1) for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Self-aligning subatmospheric hybrid liquid junction electrospray interface for capillary electrophoresis

    Czech Academy of Sciences Publication Activity Database

    Křenková, Jana; Klepárník, Karel; Grym, Jakub; Luksch, Jaroslav; Foret, František

    2016-01-01

    Roč. 37, č. 3 (2016), s. 414-417 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GBP206/12/G014 Institutional support: RVO:68081715 Keywords : capillary electrophoresis * electrospray interfacing * microfabrication Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 2.744, year: 2016

  5. Separation of carbohydrates using hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Fu, Qing; Liang, Tu; Li, Zhenyu; Xu, Xiaoyong; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

    2013-09-20

    A strategy was developed to rapidly evaluate chromatographic properties of hydrophilic interaction chromatography (HILIC) columns for separating carbohydrates. Seven HILIC columns (Silica, Diol, TSK Amide-80, XAmide, Click Maltose, Click β-CD, and Click TE-Cys columns) were evaluated by using three monosaccharide and seven disaccharides as probes. The influence of column temperature on the peak shape and tautomerization of carbohydrates, as well as column selectivity were investigated. The influence of surface charge property on the retention was also studied by using glucose, glucuronic acid, and glucosamine, which indicated that buffer salt concentration and pH value in mobile phase was necessary to control the ionic interactions between ionic carbohydrates and HILIC columns. According to evaluation results, the XAmide column was selected as an example to establish experimental schemes for separation of complex mixtures of oligosaccharide. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Digital microfluidics platform for interfacing solid-liquid extraction column with portable capillary electropherograph for analysis of soil amino acids.

    Science.gov (United States)

    Gorbatsova, Jelena; Jaanus, Martin; Vaher, Merike; Kaljurand, Mihkel

    2016-02-01

    In this work, the concept of a field-portable analyzer is proposed that operates with milliliter amounts of solvents and samples. The need to develop such an analyzer is not only driven by specific extraterrestrial analysis but also, for example, by forensics applications where the amount of liquid that can be taken to the field is severely limited. The prototype of the proposed analyzer consists of a solid-liquid extractor, the output of which is connected to the micropump, which delivers droplets of extracts to digital microfluidic platform (DMFP). In this way, world-to-chip interfacing is established. Further, the sample droplets are transported to CE capillary inlet port, separated and detected via a contactless conductivity detector. Working buffers and other solvents needed to perform CE analysis are also delivered as droplets to the DMFP and transported through the CE capillary. The performance of the analyzer is demonstrated by analysis of amino acids in sand matrices. The recovery of the spiked amino acids from the inert sand sample was from 34 to 51% with analysis LOD from 0.2 to 0.6 ppm and migration time RSD from 0.2 to 6.0%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development of large-volume, high-resolution tracking detectors based on capillaries filled with liquid scintillator

    International Nuclear Information System (INIS)

    Buontempo, S.; Fabre, J.P.; Frenkel, A.; Gregoire, G.; Hoepfner, K.; Konijn, J.; Kozarenko, E.; Kreslo, I.; Kushnirenko, A.; Martellotti, G.; Michel, L.; Mondardini, M.R.; Penso, G.; Siegmund, W.P.; Strack, R.; Tyukov, V.; Vasilchenko, V.; Vilain, P.; Wilquet, G.; Winter, K.; Wong, H.; Zymin, K.

    1995-01-01

    Searches for the decay of short-lived particles require real time, high-resolution tracking in active targets, which in the case of neutrino physics should be of large volume. The possibility of achieving this by using glass capillaries filled with organic liquid scintillator is being investigated in the framework of the CHORUS experiment at CERN. In this paper, after outlining the application foreseen, advances in the tracking technique are discussed and results from tests are reported. An active target of dimensions 180x2x2 cm 3 has been assembled from capillaries with 20 μm diameter pores. The readout scheme currently in operation allows the reading of similar 5x10 5 channels using a single chain of image intensifiers having a resolution of σ similar 20 μm. Following the development of new liquid scintillators and purification methods an attenuation length of similar 3 m has been obtained. This translates into a hit density of 3.5 per mm for a minimum-ionizing particle that crosses the active target at a distance of 1 m from the readout end. (orig.)

  8. Review of in situ derivatization techniques for enhanced bioanalysis using liquid chromatography with mass spectrometry.

    Science.gov (United States)

    Baghdady, Yehia Z; Schug, Kevin A

    2016-01-01

    Accurate and specific analysis of target molecules in complex biological matrices remains a significant challenge, especially when ultra-trace detection limits are required. Liquid chromatography with mass spectrometry is often the method of choice for bioanalysis. Conventional sample preparation and clean-up methods prior to the analysis of biological fluids such as liquid-liquid extraction, solid-phase extraction, or protein precipitation are time-consuming, tedious, and can negatively affect target recovery and detection sensitivity. An alternative or complementary strategy is the use of an off-line or on-line in situ derivatization technique. In situ derivatization can be incorporated to directly derivatize target analytes in their native biological matrices, without any prior sample clean-up methods, to substitute or even enhance the extraction and preconcentration efficiency of these traditional sample preparation methods. Designed appropriately, it can reduce the number of sample preparation steps necessary prior to analysis. Moreover, in situ derivatization can be used to enhance the performance of the developed liquid chromatography with mass spectrometry-based bioanalysis methods regarding stability, chromatographic separation, selectivity, and ionization efficiency. This review presents an overview of the commonly used in situ derivatization techniques coupled to liquid chromatography with mass spectrometry-based bioanalysis to guide and to stimulate future research. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. High-performance liquid chromatography analysis methods developed for quantifying enzymatic esterification of flavonoids in ionic liquids

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Guo, Zheng; Xu, X.B.

    2008-01-01

    Methods using reversed-phase high-performance liquid chromatography (RP-HPLC) with ELSD were investigated to quantify enzymatic reactions of flavonoids with fatty acids in the presence of diverse room temperature ionic liquids (RTILs). A buffered salt (preferably triethylamine-acetate) was found...... essential for separation of flavonoids from strongly polar RTILs, whereby RTILs were generally visible as two major peaks identified based on an ion-pairing/exchanging hypothesis. C8 and C12 stationary phases were optimal while mobile phase pH (3-7) had only a minor influence on separation. The method...

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

    Science.gov (United States)

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

    2018-01-15

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

  11. Determination of free radical reaction products and metabolites of salicylic acid using capillary electrophoresis and micellar electrokinetic chromatography

    NARCIS (Netherlands)

    Coolen, S.A.J.; Huf, F.A.; Reijenga, J.C.

    1998-01-01

    Hydroxylated radical products of salicylic acid are often used as a relative measurement in free radical research. Several analytical methods exist to determine the amount of 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid. In this study we use capillary zone electrophoresis (CZE) and

  12. Determination of Oxidized Phosphatidylcholines by Hydrophilic Interaction Liquid Chromatography Coupled to Fourier Transform Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Pia Sala

    2015-04-01

    Full Text Available A novel liquid chromatography-mass spectrometry (LC-MS approach for analysis of oxidized phosphatidylcholines by an Orbitrap Fourier Transform mass spectrometer in positive electrospray ionization (ESI coupled to hydrophilic interaction liquid chromatography (HILIC was developed. This method depends on three selectivity criteria for separation and identification: retention time, exact mass at a resolution of 100,000 and collision induced dissociation (CID fragment spectra in a linear ion trap. The process of chromatography development showed the best separation properties with a silica-based Kinetex column. This type of chromatography was able to separate all major lipid classes expected in mammalian samples, yielding increased sensitivity of oxidized phosphatidylcholines over reversed phase chromatography. Identification of molecular species was achieved by exact mass on intact molecular ions and CID tandem mass spectra containing characteristic fragments. Due to a lack of commercially available standards, method development was performed with copper induced oxidation products of palmitoyl-arachidonoyl-phosphatidylcholine, which resulted in a plethora of lipid species oxidized at the arachidonoyl moiety. Validation of the method was done with copper oxidized human low-density lipoprotein (LDL prepared by ultracentrifugation. In these LDL samples we could identify 46 oxidized molecular phosphatidylcholine species out of 99 possible candidates.

  13. Two-Dimensional Liquid Chromatography Analysis of Polystyrene/Polybutadiene Block Copolymers.

    Science.gov (United States)

    Lee, Sanghoon; Choi, Heejae; Chang, Taihyun; Staal, Bastiaan

    2018-05-15

    A detailed characterization of a commercial polystyrene/polybutadiene block copolymer material (Styrolux) was carried out using two-dimensional liquid chromatography (2D-LC). The Styrolux is prepared by statistical linking reaction of two different polystyrene- block-polybutadienyl anion precursors with a multivalent linking agent. Therefore, it is a mixture of a number of branched block copolymers different in molecular weight, composition, and chain architecture. While individual LC analysis, including size exclusion chromatography, interaction chromatography, or liquid chromatography at critical condition, is not good enough to resolve all the polymer species, 2D-LC separations coupling two chromatography methods were able to resolve all polymer species present in the sample; at least 13 block copolymer species and a homopolystyrene blended. Four different 2D-LC analyses combining a different pair of two LC methods provide their characteristic separation results. The separation characteristics of the 2D-LC separations are compared to elucidate the elution characteristics of the block copolymer species.

  14. The determination of antipyrine elimination in saliva by liquid chromatography.

    Science.gov (United States)

    Gartzke, J; Jäger, H

    1991-01-01

    A simple, fast and reliable liquid chromatographic method for the determination of antipyrine in saliva is described. The elimination of antipyrine is a good indicator for general evaluation of the liver function for dispositional purposes for example in occupational and environmental medicine. The described LC method was compared with a more extensive photometric procedure. The results obtained from both methods show very good correlation. Only one measurement is necessary to determine the antipyrine clearance. Furthermore the antipyrine dosage can be minimized, because of the sensitivity of the HPLC-method.

  15. Simultaneous determination of seven anticoagulant rodenticides in agricultural products by gel permeation chromatography and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Saito-Shida, Shizuka; Nemoto, Satoru; Matsuda, Rieko; Akiyama, Hiroshi

    2016-11-01

    A sensitive and reliable method for the simultaneous determination of hydroxycoumarin-type (brodifacoum, bromadiolone, coumatetralyl, and warfarin) and indandione-type (chlorophacinone, diphacinone, and pindone) rodenticides in agricultural products by gel permeation chromatography (GPC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The procedure involved extraction of the rodenticides from samples with acetone, followed by liquid-liquid partitioning with hexane/ethyl acetate (1:1, v/v) and 10% sodium chloride aqueous solution, then cleanup using GPC, and finally, analysis using LC-MS/MS. High recoveries from the GPC column were obtained for all rodenticides tested using a mobile phase of acetone/cyclohexane/triethylamine (400:1600:1, v/v/v). An ODS column, which contains low levels of metal impurities, gave satisfactory peak shapes for both hydroxycoumarin- and indandione-type rodenticides in the LC-MS/MS separation. The average recoveries of rodenticides from eight agricultural foods (apple, eggplant, cabbage, orange, potato, tomato, brown rice, and soybean) fortified at 0.0005-0.001 mg/kg ranged from 76 to 116%, except for bromadiolone in orange (53%) and diphacinone in soybean (54%), and the relative standard deviations ranged from 1 to 16%. The proposed method effectively removed interfering components, such as pigments and lipids, and showed high selectivity. In addition, the matrix effects were negligible for most of the rodenticide/food combinations. The results suggest that the proposed method is reliable and suitable for determining hydroxycoumarin- and indandione-type rodenticides in agricultural products.

  16. Comprehensive lipidomic analysis of human plasma using multidimensional liquid- and gas-phase separations: Two-dimensional liquid chromatography-mass spectrometry vs. liquid chromatography-trapped-ion-mobility-mass spectrometry.

    Science.gov (United States)

    Baglai, Anna; Gargano, Andrea F G; Jordens, Jan; Mengerink, Ynze; Honing, Maarten; van der Wal, Sjoerd; Schoenmakers, Peter J

    2017-12-29

    Recent advancements in separation science have resulted in the commercialization of multidimensional separation systems that provide higher peak capacities and, hence, enable a more-detailed characterization of complex mixtures. In particular, two powerful analytical tools are increasingly used by analytical scientists, namely online comprehensive two-dimensional liquid chromatography (LC×LC, having a second-dimension separation in the liquid phase) and liquid chromatography-ion mobility-spectrometry (LC-IMS, second dimension separation in the gas phase). The goal of the current study was a general assessment of the liquid-chromatography-trapped-ion-mobility-mass spectrometry (LC-TIMS-MS) and comprehensive two-dimensional liquid chromatography-mass spectrometry (LC×LC-MS) platforms for untargeted lipid mapping in human plasma. For the first time trapped-ion-mobility spectrometry (TIMS) was employed for the separation of the major lipid classes and ion-mobility-derived collision-cross-section values were determined for a number of lipid standards. The general effects of a number of influencing parameters have been inspected and possible directions for improvements are discussed. We aimed to provide a general indication and practical guidelines for the analyst to choose an efficient multidimensional separation platform according to the particular requirements of the application. Analysis time, orthogonality, peak capacity, and an indicative measure for the resolving power are discussed as main characteristics for multidimensional separation systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Combined high-performance liquid chromatography/32P-postlabeling assay of N7-methyldeoxyguanosine

    International Nuclear Information System (INIS)

    Shields, P.G.; Povey, A.C.; Wilson, V.L.; Weston, A.; Harris, C.C.

    1990-01-01

    A highly sensitive and specific assay for the detection of N7-methyl-2'-deoxyguanosine (N7methyldG) has been developed by combining high-performance liquid chromatography, 32 P-postlabeling, and nucleotide chromatography. Separation of normal nucleotides and adducts by high-performance liquid chromatography and then combining a portion of 2'-deoxyguanosine to the N7methyldG allows for quantitation using an internal standard. The directly determined molar ratio is not subject to errors in digestion, variable ATP-specific activity, or assumptions in relative adduct-labeling efficiency. The detection limit was one N7methyldG adduct in 10(7) unmodified 2'-deoxyguanosine bases. N7methyldG adducts have been detected in 5 human lung samples in which O6-methyl-2'-deoxyguanosine adducts had been previously determined. The mean ratio of N7methyldG to O6-methyl-2'-deoxyguanosine was determined to be approximately 10. The current assay complements the high-performance liquid chromatography/ 32 P-postlabeling assay for O6-methyl-2'-deoxyguanosine and increases the detection sensitivity of DNA methylated by exogenous alkylating agents

  18. High-Efficiency On-Line Solid-Phase Extraction Coupling to 15-150 um I.D. Column Liquid Chromatography for Proteomic Analysis

    International Nuclear Information System (INIS)

    Shen, Yufeng; Moore, Ronald J.; Zhao, Rui; Blonder, Josip; Auberry, Deanna L.; Masselon, Christophe D.; Pasa Tolic, Ljiljana; Hixson, Kim K.; Auberry, Kenneth J.; Smith, Richard D.

    2003-01-01

    Flexible manipulation of various properties of proteomic samples is important for proteomic analyses, but it has been little explored for newly developed approaches based on liquid chromatography (LC) in combination with mass spectrometry (MS). With miniaturization of the LC column inner diameter dimensions (required for improving the analysis sensitivity), this issue becomes more challenging due to the small flow rates and the increasing effects of extra column volume on the separation quality and its use for resolving complex proteomic mixtures. In this study, we used commercial switching valves (150-mm channels) to implement the on-line coupling of capillary LC columns with relatively large solid phase extraction (SPE) columns operated at 10,000 psi. With optimized column connections, switching modes, and SPE column dimensions, high-efficiency on-line SPE-capillary and nanoscale LC separations were obtained with peak capacities of ∼1000 for capillaries having inner diameters between 15 to 150 mm. The on-line coupled SPE columns increased the sample processing capabilities by ∼400-fold for sample solution volume and ∼10-fold for sample mass. The proteomic applications of this on-line SPE-capillary LC system were evaluated for analysis of both soluble and membrane protein tryptic digests. Used with an ion trap tandem MS we could typically identify 1100-1500 peptides for analyses in a single 5-hour run. Peptides extracted on the SPE column and eluted from the LC column covered a hydrophilicity/hydrophobicity range that include an estimated ∼98% of all the tryptic peptides. The present implementation also facilitates automation and enables use of both disposable SPE columns and electrospray emitters, providing a robust basis for routine proteomic analyses.

  19. Liquid chromatography-tandem mass spectrometric assay for the tyrosine kinase inhibitor afatinib in mouse plasma using salting-out liquid-liquid extraction

    NARCIS (Netherlands)

    Sparidans, Rolf W; van Hoppe, Stephanie; Rood, Johannes J M; Schinkel, Alfred H; Schellens, Jan H M; Beijnen, Jos H

    2016-01-01

    A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for afatinib, an irreversible inhibitor of the ErbB (erythroblastic leukemia viral oncogene homolog) tyrosine kinase family, was developed and validated. Plasma samples were pre-treated using salting-out

  20. Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid-liquid extraction

    Science.gov (United States)

    A method for the highly sensitive determination of 2-, 3- and 4- nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the i...

  1. [Blood levels of homocysteine by high pressure liquid chromatography and comparison with two other techniques].

    Science.gov (United States)

    Ceppa, F; Drouillard, I; Chianea, D; Burnat, P; Perrier, F; Vaillant, C; El Jahiri, Y

    1999-01-01

    Cardio-vascular diseases are the most common cause of death in industrialized countries. A new marker has emerged among offending risk factors in the past few years: homocysteine. This sulphured amino-acid is an important intermediate in transsulphuration and remethylation reactions of methionine's metabolism. We proposed to evaluate a home made method of determination for this parameter by high performance liquid chromatography (HPLC) and to compare it to fluorescence polarization immunoassay technique (FPIA) and to gaz phase chromatography (CG-SM). This method associated with good sensibility and precision remain much less expensive than FPIA technique.

  2. Characterization of Extracellular Vesicles by Size-Exclusion High-Performance Liquid Chromatography (HPLC).

    Science.gov (United States)

    Huang, Tao; He, Jiang

    2017-01-01

    Extracellular vesicles (EVs) have recently attracted substantial attention due to the potential diagnostic and therapeutic relevance. Although a variety of techniques have been used to isolate and analyze EVs, it is still far away from satisfaction. Size-exclusion chromatography (SEC), which separates subjects by size, has been widely applied in protein purification and analysis. The purpose of this chapter is to show the applications of size-exclusion high-performance liquid chromatography (HPLC) as methods for EV characterization of impurities or contaminants of small size, and thus for quality assay for the purity of the samples of EVs.

  3. Nanoparticle Analysis by Online Comprehensive Two-Dimensional Liquid Chromatography combining Hydrodynamic Chromatography and Size-Exclusion Chromatography with Intermediate Sample Transformation

    Science.gov (United States)

    2017-01-01

    Polymeric nanoparticles have become indispensable in modern society with a wide array of applications ranging from waterborne coatings to drug-carrier-delivery systems. While a large range of techniques exist to determine a multitude of properties of these particles, relating physicochemical properties of the particle to the chemical structure of the intrinsic polymers is still challenging. A novel, highly orthogonal separation system based on comprehensive two-dimensional liquid chromatography (LC × LC) has been developed. The system combines hydrodynamic chromatography (HDC) in the first-dimension to separate the particles based on their size, with ultrahigh-performance size-exclusion chromatography (SEC) in the second dimension to separate the constituting polymer molecules according to their hydrodynamic radius for each of 80 to 100 separated fractions. A chip-based mixer is incorporated to transform the sample by dissolving the separated nanoparticles from the first-dimension online in tetrahydrofuran. The polymer bands are then focused using stationary-phase-assisted modulation to enhance sensitivity, and the water from the first-dimension eluent is largely eliminated to allow interaction-free SEC. Using the developed system, the combined two-dimensional distribution of the particle-size and the molecular-size of a mixture of various polystyrene (PS) and polyacrylate (PACR) nanoparticles has been obtained within 60 min. PMID:28745485

  4. Determination of pyrazinamide in human by high performance liquid chromatography.

    Directory of Open Access Journals (Sweden)

    Revankar S

    1994-01-01

    Full Text Available A facile and sensitive high performance liquid chromatographic (HPLC technique has been developed for the determination pyrazinamide (PZA in human plasma. Nicotinamide(NIA is used as internal standard(IS. Plasma is deproteinized with 0.7 M perchloric acid; clear supernatant is neutralized with 1M NaOH and injected onto HPLC. The separation of pyrazinamide and the internal standard is carried out on a Supelco LC-18 (DB column with a basic mobile phase. Pyrazinoic acid, the major metabolite, other anti-tuberculous drugs and endogenous components do not interfere with measurement of pyrazinamide. The limit of detection of pyrazinamide with this method is 0.2 mg/0.2 ml plasma (CV 8.2%.

  5. Coupled thermo-capillary and buoyancy convection in a liquid layer locally heated on its free surface

    International Nuclear Information System (INIS)

    Favre, E.

    1997-01-01

    Coupled buoyancy and thermo-capillary convection lead to a convective motion of the interface liquid/gas, which changes drastically the heat and mass transfer across the liquid layer. Two experiments are considered, depending on the fluid: oil or mercury. The liquid is set in a cooled cylindrical vessel, and heated by a heat flux across the center of the free surface. The basic flow, in the case of oil, is a torus. When the heat parameter increases, a stationary flow looking like petals or rays appears when the aspect ratio length/depth is small, and like concentric rings in the case of large values of the aspect ratio. The lateral confinement selects the azimuthal length wave. In the case of petals-like flow, a sub-critical Hopf bifurcation is underlined. The turbulence is found to be 'weak', even for the largest values of the Marangoni number (Ma ≅ 1.3 * 10 5 ). In the case of mercury, the thermo-capillary effect is reduced to zero, due to impurities at the surface, which have special trajectories we describe and compare to a simpler experiment. The only buoyancy forces induces an un-stationary, weakly turbulent flow as soon as the heating power exceeds 4 W (≅ 4.5 * 10 3 , calculated with h = 1 mm). The last part concerns the analysis of the effect on the flow of the boundary conditions, the geometry, the Prandtl number, the buoyancy force, with the help of the literature. Results concerning heat transfer, especially the exponent of the law Nusselt number vs. heating power, are compared with available data. (author) [fr

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

    Science.gov (United States)

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

    2016-06-05

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

  7. Development and evaluation of a liquid chromatography tandem mass spectrometry method for simultaneous determination of salivary melatonin, cortisol and testosterone

    DEFF Research Database (Denmark)

    Jensen, Marie Aarrebo; Hansen, Åse Marie; Abrahamsson, Peter

    2011-01-01

    saliva. We used liquid-liquid extraction (LLE) followed by liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS) recorded in positive ion mode. Saliva samples were collected by spitting directly into tubes and 250 µL were used for analysis. The limits of detection were 4...

  8. [Separation and purification of the components in Trachelospermum jasminoides by two dimensional hydrophilic interaction liquid chromatography- reversed-phase liquid chromatography].

    Science.gov (United States)

    Jia, Youmei; Cai, Jianfeng; Xin, Huaxia; Feng, Jiatao; Fu, Yanhui; Fu, Qing; Jin, Yu

    2017-06-08

    A preparative two dimensional hydrophilic interaction liquid chromatography/reversed-phase liquid chromatography (Pre-2D-HILIC/RPLC) method was established to separate and purify the components in Trachelospermum jasminoides . The pigments and strongly polar components were removed from the crude extract after the active carbon decolorization and solid phase extraction processes. A Click XIon column (250 mm×20 mm, 10 μm) was selected as stationary phase and water-acetonitrile as mobile phases in the first dimensional HILIC. Finally, 15 fractions were collected under UV-triggered mode. In the second dimensional RPLC, a C18 column (250 mm×20 mm, 5 μm) was selected and water-acetonitrile was used as mobile phases. As a result, 14 compounds with high purity were obtained, which were further identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR). Finally, 11 lignan compounds and three flavonoid compounds were obtained. The method has a good orthogonality, and can improve the resolution and the peak capacity. It is significant for the separation of complex components from Trachelospermum jasminoides .

  9. Chemical fingerprint of Ganmaoling granule by double-wavelength ultra high performance liquid chromatography and ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Lou, Qiong; Ye, Xiaolan; Zhou, Yingyi; Li, Hua; Song, Fenyun

    2015-06-01

    A method incorporating double-wavelength ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was developed for the investigation of the chemical fingerprint of Ganmaoling granule. The chromatographic separations were performed on an ACQUITY UPLC HSS C18 column (2.1 × 50 mm, 1.8 μm) at 30°C using gradient elution with water/formic acid (1%) and acetonitrile at a flow rate of 0.4 mL/min. A total of 11 chemical constituents of Ganmaoling granule were identified from their molecular weight, UV spectra, tandem mass spectrometry data, and retention behavior by comparing the results with those of the reference standards or literature. And 25 peaks were selected as the common peaks for fingerprint analysis to evaluate the similarities among 25 batches of Ganmaoling granule. The results of principal component analysis and orthogonal projection to latent structures discriminant analysis showed that the important chemical markers that could distinguish the different batches were revealed as 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid. This is the first report of the ultra high performance liquid chromatography chemical fingerprint and component identification of Ganmaoling granule, which could lay a foundation for further studies of Ganmaoling granule. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Determination of chloroacetanilide herbicide metabolites in water using high-performance liquid chromatography-diode array detection and high-performance liquid chromatography/mass spectrometry

    Science.gov (United States)

    Hostetler, K.A.; Thurman, E.M.

    2000-01-01

    Analytical methods using high-performance liquid chromatography-diode array detection (HPLC-DAD) and high-performance liquid chromatography/mass spectrometry (HPLC/MS) were developed for the analysis of the following chloroacetanilide herbicide metabolites in water: alachlor ethanesulfonic acid (ESA); alachlor oxanilic acid; acetochlor ESA; acetochlor oxanilic acid; metolachlor ESA; and metolachlor oxanilic acid. Good precision and accuracy were demonstrated for both the HPLC-DAD and HPLC/MS methods in reagent water, surface water, and ground water. The average HPLC-DAD recoveries of the chloroacetanilide herbicide metabolites from water samples spiked at 0.25, 0.5 and 2.0 ??g/l ranged from 84 to 112%, with relative standard deviations of 18% or less. The average HPLC/MS recoveries of the metabolites from water samples spiked at 0.05, 0.2 and 2.0 ??g/l ranged from 81 to 118%, with relative standard deviations of 20% or less. The limit of quantitation (LOQ) for all metabolites using the HPLC-DAD method was 0.20 ??g/l, whereas the LOQ using the HPLC/MS method was at 0.05 ??g/l. These metabolite-determination methods are valuable for acquiring information about water quality and the fate and transport of the parent chloroacetanilide herbicides in water. Copyright (C) 2000 Elsevier Science B.V.

  11. Analyses of Indole Compounds in Sugar Cane (Saccharum officinarum L. Juice by High Performance Liquid Chromatography and Liquid Chromatography-Mass Spectrometry after Solid-Phase Extraction

    Directory of Open Access Journals (Sweden)

    Jean Wan Hong Yong

    2017-03-01

    Full Text Available Simultaneous quantitative analysis of 10 indole compounds, including indole-3-acetic acid (IAA, one of the most important naturally occurring auxins and some of its metabolites, by high performance liquid chromatography (HPLC and liquid chromatography-mass spectrometry (LC-MS after solid-phase extraction (SPE was reported for the first time. The analysis was carried out using a reverse phase HPLC gradient elution, with an aqueous mobile phase (containing 0.1% formic acid modified by methanol. Furthermore, a novel SPE procedure was developed for the pre-concentration and purification of indole compounds using C18 SPE cartridges. The combination of SPE, HPLC, and LC-MS was applied to screen for the indole compounds present in sugar cane (Saccharum officinarum L. juice, a refreshing beverage with various health benefits. Finally, four indole compounds were successfully detected and quantified in sugar cane juice by HPLC, which were further unequivocally confirmed by LC-MS/MS experiments operating in the multiple reaction monitoring (MRM mode.

  12. On-line comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for preparative isolation of Peucedanum praeruptorum.

    Science.gov (United States)

    Wang, Xin-Yuan; Li, Jia-Fu; Jian, Ya-Mei; Wu, Zhen; Fang, Mei-Juan; Qiu, Ying-Kun

    2015-03-27

    A new on-line comprehensive preparative two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was developed for the separation of complicated natural products. It was based on the use of a silica gel packed medium-pressure column as the first dimension and an ODS preparative HPLC column as the second dimension. The two dimensions were connected with normal-phase (NP) and reversed-phase (RP) enrichment units, involving a newly developed airflow assisted adsorption (AAA) technique. The instrument operation and the performance of this NPLC × RPLC separation method were illustrated by gram-scale isolation of ethanol extract from the roots of Peucedanum praeruptorum. In total, 19 compounds with high purity were obtained via automated multi-step preparative separation in a short period of time using this system, and their structures were comprehensively characterized by ESI-MS, (1)H NMR, and (13)C NMR. Including two new compounds, five isomers in two groups with identical HPLC and TLC retention values were also obtained and identified by 1D NMR and 2D NMR. This is the first report of an NPLC × RPLC system successfully applied in an on-line preparative process. This system not only solved the interfacing problem of mobile-phase immiscibility caused by NP and RP separation, it also exhibited apparent advantages in separation efficiency and sample treatment capacity compared with conventional methods. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Low-level flow counting of liquid chromatography column eluates

    International Nuclear Information System (INIS)

    Harding, N.G.L.; Farid, Y.; Stewart, M.J.

    1982-01-01

    The principal parameters which determine the operation of a high-resolution, high-sensitivity radioactive flow monitor are described: a) Sample preparation to ensure adequate recovery of radiolabelled sample, metabolites and internal standard. b) The instrument background count rate, when no sample or radiolabel is present in the flow cell, is a function of shielding and a reduction in noise obtained with a coincidence time below one microsecond. c) The minimum detectable amount of label depends upon the machine background, HPLC eluent and scintillator flow, whether or not packed flow cells are used, flow cell geometry, and the scintillator used. d) Three types of flow cell have been designed to cover the majority of HPLC and isotope applications. e) The performance of solid and liquid scintillators. It is shown that an instrument has been designed taking account of these parameters. The resulting design satisfies present high sensitivity counting requirements and maintains the resolution of current HPLC procedures when detection is by simultaneous flow radioassay and by optical methods. (orig.)

  14. Determination of Finasteride in Tablets by High Performance Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    K. Basavaiah

    2007-01-01

    Full Text Available A rapid, highly sensitive high performance liquid chromatographic method has been developed for the determination of finasteride(FNS in bulk drug and in tablets. FNS was eluted from a ODS C18 reversed phase column at laboratory temperature (30 ± 2°C with a mobile phase consisting of methanol and water (80+20 at a flow rate of 1 mL min-1 with UV detection at 225 nm. The retention time was ∼ 6.1 min and each analysis took not more than 10 min. Quantitation was achieved by measurement of peak area without using any internal standard. Calibration graph was linear from 2.0 to 30 μg mL-1 with limits of detection (LOD and quantification (LOQ being 0.2 and 0.6 μg mL-1, respectively. The method was validated according to the current ICH guidelines. Within-day co efficients of variation (CV ranged from 0.31 to 0.69% and between-day CV were in the range 1.2-3.2%. Recovery of FNS from the pharmaceutical dosage forms ranged from 97.89 – 102.9 with CV of 1.41-4.13%. The developed method was compared with the official method for FNS determination in its tablet forms.

  15. Hyphenated and comprehensive liquid chromatography × gas chromatography-mass spectrometry for the identification of Mycobacterium tuberculosis.

    Science.gov (United States)

    Mourão, Marta P B; Denekamp, Ilse; Kuijper, Sjoukje; Kolk, Arend H J; Janssen, Hans-Gerd

    2016-03-25

    Tuberculosis is one of the world's most emerging public health problems, particularly in developing countries. Chromatography based methods have been used to tackle this epidemic by focusing on biomarker detection. Unfortunately, interferences from lipids in the sputum matrix, particularly cholesterol, adversely affect the identification and detection of the marker compounds. The present contribution describes the serial combination of normal phase liquid chromatography (NPLC) with thermally assisted hydrolysis and methylation followed by gas chromatography-mass spectrometry (THM-GC-MS) to overcome the difficulties of biomarker evaluation. The in-series combination consists of an LC analysis where fractions are collected and then transferred to the THM-GC-MS system. This was either done with comprehensive coupling, transferring all the fractions, or with hyphenated interfacing, i.e. off-line multi heart-cutting, transferring only selected fractions. Owing to the high sensitivity and selectivity of LC as a sample pre-treatment method, and to the high specificity of the MS as a detector, this analytical approach, NPLC × THM-GC-MS, is extremely sensitive. The results obtained indicate that this analytical set-up is able to detect down to 1 × 10(3) mycobacteria/mL of Mycobacterium tuberculosis strain 124, spiked in blank sputum samples. It is a powerful analytical tool and also has great potential for full automation. If further studies demonstrate its usefulness when applied blind in real sputum specimens, this technique could compete with the current smear microscopy in the early diagnosis of tuberculosis. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Application of Homochiral Alkylated Organic Cages as Chiral Stationary Phases for Molecular Separations by Capillary Gas Chromatography.

    Science.gov (United States)

    Xie, Shengming; Zhang, Junhui; Fu, Nan; Wang, Bangjin; Hu, Cong; Yuan, Liming

    2016-11-08

    Molecular organic cage compounds have attracted considerable attention due to their potential applications in gas storage, catalysis, chemical sensing, molecular separations, etc. In this study, a homochiral pentyl cage compound was synthesized from a condensation reaction of ( S , S )-1,2-pentyl-1,2-diaminoethane and 1,3,5-triformylbenzene. The imine-linked pentyl cage diluted with a polysiloxane (OV-1701) was explored as a novel stationary phase for high-resolution gas chromatographic separation of organic compounds. Some positional isomers were baseline separated on the pentyl cage-coated capillary column. In particular, various types of enantiomers including chiral alcohols, esters, ethers and epoxides can be resolved without derivatization on the pentyl cage-coated capillary column. The reproducibility of the pentyl cage-coated capillary column for separation was investigated using nitrochlorobenzene and styrene oxide as analytes. The results indicate that the column has good stability and separation reproducibility after being repeatedly used. This work demonstrates that molecular organic cage compounds could become a novel class of chiral separation media in the near future.

  17. Application of Homochiral Alkylated Organic Cages as Chiral Stationary Phases for Molecular Separations by Capillary Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Shengming Xie

    2016-11-01

    Full Text Available Molecular organic cage compounds have attracted considerable attention due to their potential applications in gas storage, catalysis, chemical sensing, molecular separations, etc. In this study, a homochiral pentyl cage compound was synthesized from a condensation reaction of (S,S-1,2-pentyl-1,2-diaminoethane and 1,3,5-triformylbenzene. The imine-linked pentyl cage diluted with a polysiloxane (OV-1701 was explored as a novel stationary phase for high-resolution gas chromatographic separation of organic compounds. Some positional isomers were baseline separated on the pentyl cage-coated capillary column. In particular, various types of enantiomers including chiral alcohols, esters, ethers and epoxides can be resolved without derivatization on the pentyl cage-coated capillary column. The reproducibility of the pentyl cage-coated capillary column for separation was investigated using nitrochlorobenzene and styrene oxide as analytes. The results indicate that the column has good stability and separation reproducibility after being repeatedly used. This work demonstrates that molecular organic cage compounds could become a novel class of chiral separation media in the near future.

  18. Column liquid chromatography applied to concentrating, separating, and determining platinum metals

    International Nuclear Information System (INIS)

    Alimarin, I.P.; Basova, E.M.; Bol'shova, T.A.; Ivanov, V.M.

    1986-01-01

    The present survey deals with high-performance liquid chromatography (HPLC) in relation to the chromatographic behavior of the platinum metals, including separation and determination. The data shows that HPLC is the most promising and effective method of separating metals, including platinum ones. The method provides efficient separation of microgram amoounts of mixtures with a resolving power 3-20 times that of thin-layer chromatography. It is shown that the most promising line of advance in HPLC for inorganic systems lies in the separation and determination of metals as chelates by absorption or ion-pair chromatography. Examples of using HPLC for determining noble metals in particular cases indicate that the metrological characteristics are favorable

  19. Determination of oxyfluorfen herbicide and oxyfluorfen amine residues in garbanzo beans by liquid chromatography.

    Science.gov (United States)

    Zhou, M; Miles, C J

    1991-01-01

    Oxyfluorfen and oxyfluorfen amine were determined by liquid chromatography (LC) with ultraviolet (UV) and photoconductivity detection (PCD). A simple extraction procedure acceptably recovered both analytes from garbanzo beans over a wide range of fortifications (0.05 to 20 ppm) (83 +/- 4 for oxyfluorfen; 85 +/- 4 for oxyfluorfen amine). Percent recoveries decreased slightly as the fortification level decreased. Both analytes could be determined simultaneously at a concentration greater than 0.2 ppm in garbanzo beans. Detection limits were 3 ng for oxyfluorfen and 100 ng for oxyfluorfen amine using LC/UV, and 12 ng for both oxyfluorfen and oxyfluorfen amine with LC/PCD. Different knitted reaction coils and photoreactors were evaluated. Photoproduct yields and identification were determined by ion chromatography. The LC/PCD method measures oxyfluorfen and oxyfluorfen amine separately and has a shorter analysis time, while the standard method using gas chromatography measures total residues and is more sensitive.

  20. Phytochemical Profile of Erythrina variegata by Using High-Performance Liquid Chromatography and Gas Chromatography-Mass Spectroscopy Analyses.

    Science.gov (United States)

    Muthukrishnan, Suriyavathana; Palanisamy, Subha; Subramanian, Senthilkumar; Selvaraj, Sumathi; Mari, Kavitha Rani; Kuppulingam, Ramalingam

    2016-08-01

    Natural products derived from plant sources have been utilized to treat patients with numerous diseases. The phytochemical constituents present in ethanolic leaf extract of Erythrina variegata (ELEV) were identified by using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectroscopy (GC-MS) analyses. Shade dried leaves were powdered and extracted with ethanol for analyses through HPLC to identify selected flavonoids and through GC-MS to identify other molecules. The HPLC analysis of ELEV showed the presence of gallic and caffeic acids as the major components at concentrations of 2.0 ppm and 0.1 ppm, respectively, as well as other components. GC-MS analysis revealed the presence of 3-eicosyne; 3,7,11,15-tetramethyl-2-hexadecen-1-ol; butanoic acid, 3-methyl-3,7-dimethyl-6-octenyl ester; phytol; 1,2-benzenedicarboxylic acid, diundecyl ester; 1-octanol, 2-butyl-; squalene; and 2H-pyran, 2-(7-heptadecynyloxy) tetrahydro-derivative. Because pharmacopuncture is a new evolving natural mode that uses herbal extracts for treating patients with various ailments with minimum pain and maximum effect, the results of this study are particularly important and show that ELEV possesses a wide range of phytochemical constituents, as indicated above, as effective active principle molecules that can be used individually or in combination to treat patients with various diseases. Copyright © 2016. Published by Elsevier B.V.

  1. Gas chromatography-mass spectrometry and high-performance liquid chromatography-diode array detection for dating of paper ink.

    Science.gov (United States)

    Díaz-Santana, Oscar; Vega-Moreno, Daura; Conde-Hardisson, Francisco

    2017-09-15

    An extraction and determination method is shown for the analysis of dyes and solvents present in two types of ballpoint pen inks that are deposited onto paper. Ink extracts are analysed using a combination of gas chromatography with mass spectrometry (GC-MS), and high-pressure liquid chromatography with photodiode array detection (HPLC-DAD), within a single sample extraction procedure. Seventeen solvents and thirteen dyes contained in two Montblanc ® inks (black and blue) were monitored for 45 months at monthly intervals, in order to determine variations in the concentrations of the compounds over time. We also studied the relative variations between different compounds and the generation of degradation products such as phenol. The concentration data obtained from these compounds during their exposure have been analysed and a multiple regression model is developed for each ink type that allows an estimate of the exposure time of the ink on paper with a maximum error of between 4 and 7 months. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Pressurized planar electrochromatography, high-performance thin-layer chromatography and high-performance liquid chromatography--comparison of performance.

    Science.gov (United States)

    Płocharz, Paweł; Klimek-Turek, Anna; Dzido, Tadeusz H

    2010-07-16

    Kinetic performance, measured by plate height, of High-Performance Thin-Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Pressurized Planar Electrochromatography (PPEC) was compared for the systems with adsorbent of the HPTLC RP18W plate from Merck as the stationary phase and the mobile phase composed of acetonitrile and buffer solution. The HPLC column was packed with the adsorbent, which was scrapped from the chromatographic plate mentioned. An additional HPLC column was also packed with adsorbent of 5 microm particle diameter, C18 type silica based (LiChrosorb RP-18 from Merck). The dependence of plate height of both HPLC and PPEC separating systems on flow velocity of the mobile phase and on migration distance of the mobile phase in TLC system was presented applying test solute (prednisolone succinate). The highest performance, amongst systems investigated, was obtained for the PPEC system. The separation efficiency of the systems investigated in the paper was additionally confirmed by the separation of test component mixture composed of six hormones. 2010 Elsevier B.V. All rights reserved.

  3. Simultaneous achiral-chiral analysis of pharmaceutical compounds using two-dimensional reversed phase liquid chromatography-supercritical fluid chromatography.

    Science.gov (United States)

    Venkatramani, C J; Al-Sayah, Mohammad; Li, Guannan; Goel, Meenakshi; Girotti, James; Zang, Lisa; Wigman, Larry; Yehl, Peter; Chetwyn, Nik

    2016-02-01

    A new interface was designed to enable the coupling of reversed phase liquid chromatography (RPLC) and supercritical fluid chromatography (SFC). This online two-dimensional chromatographic system utilizing RPLC in the first dimension and SFC in the second was developed to achieve simultaneous achiral and chiral analysis of pharmaceutical compounds. The interface consists of an eight-port, dual-position switching valve with small volume C-18 trapping columns. The peaks of interest eluting from the first RPLC dimension column were effectively focused as sharp concentration pulses on small volume C-18 trapping column/s and then injected onto the second dimension SFC column. The first dimension RPLC separation provides the achiral purity result, and the second dimension SFC separation provides the chiral purity result (enantiomeric excess). The results are quantitative enabling simultaneous achiral, chiral analysis of compounds. The interface design and proof of concept demonstration are presented. Additionally, comparative studies to conventional SFC and case studies of the applications of 2D LC-SFC in pharmaceutical analysis is presented. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Analysis of anabolic steroids in body fluids by capillary gas chromatography with a two-channel detection system and a computer.

    Science.gov (United States)

    Uralets, V P; Semenova, V A; Yakushin, M A; Semenov, V A

    1983-11-25

    A method is described for analysis of multi-component mixtures of steroid metabolites in biological fluids by means of capillary gas chromatography with glass and fused-silica columns and simultaneous detection of methoxylamine-trimethylsilyl derivatives with universal flame-ionization and selective nitrogen alkali flameionization detectors. A data system was applied to the on-line treatment of the results. Computer programs were designed for precise calculation of Kováts retention indices from the known values for selected natural urinary steroids. The programs allow the selection of nitrogen-containing components, normalized chromatogram plotting for both detection channels and qualitative and quantitative analysis. Results are presented on the detection of metabolites of methandrostenolone, 17 alpha-methyltestosterone, 19-nortestosterone and fluoxymesterone.

  5. Simultaneous determination of polyamines, N-acetylated polyamines and the polyamine analogues BE-3-3-3 and BE-4-4-4-4 by capillary gas chromatography with nitrogen-phosphorus detection

    NARCIS (Netherlands)

    Dorhout, B; Kingma, AW; deHoog, E; Muskiet, FAJ

    1997-01-01

    We describe a method for the profiling of polyamines, N-acetylated polyamines and the polyamine analogues N-1,N-11 bis(ethyl)norspermine (BE-3-3-3) and 1,19-bis(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4) in L1210 murine leukaemia cells by capillary gas chromatography with nitrogen-phosphorus

  6. Trace analysis of halogenated hydrocarbons in gaseous samples by on-line enrichment in an adsorption trap, on-column cold-trapping and capillary gas chromatography. I.Method and instrumentation

    NARCIS (Netherlands)

    Noij, T.H.M.; Fabian, P.; Borchers, R.; Janssen, F.; Cramers, C.A.M.G.; Rijks, J.A.

    1987-01-01

    A method is described for the determination of halocarbons in gaseous samples down to the ppt level (1:1012, v/v), consisting of successive on-line sub-ambient enrichment on an adsorbent, on-column cryofocusing, capillary gas chromatography and electron-capture detection. The quantitative aspects of

  7. Novel preconcentration technique for on-line coupling to high-speed narrow-bore capillary gas chromatography: sample enrichment by equilibrium (ab)sorption, I: Principles and theoretical aspects

    NARCIS (Netherlands)

    Pham Tuan, H.; Janssen, J.G.M.; Cramers, C.A.M.G.

    1997-01-01

    In recent years, there has been substantial progress in the field of high-speed narrow-bore capillary gas chromatography (GC) in general, and in the development of (trans)portable gas chromatographs for fast and accurate analysis in field applications in particular. Due to the limited

  8. Analysis of polycyclic aromatic hydrocarbons I. Determination by gas chromatography with glass and fused silica capillary columns; Analisis de Hidrocarburos aromaticos policiclicos. I. Determinacion por cromatografia de gases con columnas capilares de vidrio de silice fundida

    Energy Technology Data Exchange (ETDEWEB)

    Perez, M M; Gonzalez, D

    1987-07-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (Author) 17 refs.

  9. Investigation of maltodextrin-based synergistic system with amino acid chiral ionic liquid as additive for enantioseparation in capillary electrophoresis.

    Science.gov (United States)

    Chen, Jiaquan; Du, Yingxiang; Sun, Xiaodong

    2017-12-01

    The combined use of chiral ionic liquids (ILs) and chiral selectors in capillary electrophoresis (CE) to establish a synergistic system has proven to be an effective approach for enantioseparation. In this article, tetramethylammonium-L-arginine, a kind of amino acid chiral IL, was applied to investigate its potential synergistic effect with maltodextrin in CE enantioseparation. The established maltodextrin-based synergistic system showed markedly improved enantioseparations compared with the single maltodextrin system. Parameters such as the chiral IL concentration, maltodextrin concentration, buffer pH, applied voltage, and capillary temperature were optimized. Satisfactory enantioseparation of the five studied drugs, including nefopam, duloxetine, ketoconazole, cetirizine, and citalopram was achieved in 50 mM Tris-H 3 PO 4 buffer solution (pH 3.0) containing 7.0% (m/v) maltodextrin and 60 mM tetramethylammonium-L-arginine. In addition, the chiral configuration of tetramethylammonium-L-arginine was also investigated to demonstrate the existence of a synergistic effect between chiral ILs and maltodextrin. © 2017 Wiley Periodicals, Inc.

  10. Rational approach to solvent system selection for liquid-liquid extraction-assisted sample pretreatment in counter-current chromatography.

    Science.gov (United States)

    Wang, Jiajia; Gu, Dongyu; Wang, Miao; Guo, Xinfeng; Li, Haoquan; Dong, Yue; Guo, Hong; Wang, Yi; Fan, Mengqi; Yang, Yi

    2017-05-15

    A rational liquid-liquid extraction approach was established to pre-treat samples for high-speed counter-current chromatography (HSCCC). n-Hexane-ethyl acetate-methanol-water (4:5:4:5, v/v) and (1:5:1:5, v/v) were selected as solvent systems for liquid-liquid extraction by systematically screening K of target compounds to remove low- and high-polarity impurities in the sample, respectively. After liquid-liquid extraction was performed, 1.4g of crude sample II was obtained from 18.5g of crude sample I which was extracted from the flowers of Robinia pseudoacacia L., and then separated with HSCCC by using a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v). As a result, 31mg of robinin and 37mg of kaempferol 7-O-α-l-rhamnopyranoside were isolated from 200mg of crude sample II in a single run of HSCCC. A scale-up separation was also performed, and 160mg of robinin with 95% purity and 188mg of kaempferol 7-O-α-l-rhamnopyranoside with 97% purity were produced from 1.2g of crude sample II. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Clinical applications of fast liquid chromatography: a review on the analysis of cardiovascular drugs and their metabolites.

    Science.gov (United States)

    Baranowska, Irena; Magiera, Sylwia; Baranowski, Jacek

    2013-05-15

    One of the major challenges facing the medicine today is developing new therapies that enhance human health. To help address these challenges the utilization of analytical technologies and high-throughput automated platforms has been employed; in order to perform more experiments in a shorter time frame with increased data quality. In the last decade various analytical strategies have been established to enhance separation speed and efficiency in liquid chromatography applications. Liquid chromatography is an increasingly important tool for monitoring drugs and their metabolites. Furthermore, liquid chromatography has played an important role in pharmacokinetics and metabolism studies at these drug development stages since its introduction. This paper provides an overview of current trends in fast chromatography for the analysis of cardiovascular drugs and their metabolites in clinical applications. Current trends in fast liquid chromatographic separations involve monolith technologies, fused-core columns, high-temperature liquid chromatography (HTLC) and ultra-high performance liquid chromatography (UHPLC). The high specificity in combination with high sensitivity makes it an attractive complementary method to traditional methodology used for routine applications. The practical aspects of, recent developments in and the present status of fast chromatography for the analysis of biological fluids for therapeutic drug and metabolite monitoring, pharmacokinetic studies and bioequivalence studies are presented. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Current practice of liquid chromatography-mass spectrometry in metabolomics and metabonomics.

    Science.gov (United States)

    Gika, Helen G; Theodoridis, Georgios A; Plumb, Robert S; Wilson, Ian D

    2014-01-01

    Based on publication and citation numbers liquid chromatography (LC-MS) has become the major analytical technology in the field of global metabolite profiling. This dominance reflects significant investments from both the research community and instrument manufacturers. Here an overview of the approaches taken for LC-MS-based metabolomics research is given, describing critical steps in the realisation of such studies: study design and its needs, specific technological problems to be addressed and major obstacles in data treatment and biomarker identification. The current state of the art for LC-MS-based analysis in metabonomics/metabolomics is described including recent developments in liquid chromatography, mass spectrometry and data treatment as these are applied in metabolomics underlining the challenges, limitations and prospects for metabolomics research. Examples of the application of metabolite profiling in the life sciences focusing on disease biomarker discovery are highlighted. In addition, new developments and future prospects are described. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Molecular differences between deuterated and protonated polystyrenes using reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Kayillo, Sindy; Gray, Michael J; Shalliker, R Andrew; Dennis, Gary R

    2005-05-06

    Isotopic substitution is a technique used to highlight particular bonds within a molecule for kinetic, spectroscopic and structure analysis. It is presumed that although some properties such as stretching frequencies will not be the same for substituted analogues, the chemical interactions will not vary appreciably as a function of labelling. Reversed-phase liquid chromatography has been used to demonstrate that there are significant differences between the chromatographic behaviour of a sequence of deuterated and protonated oligomeric polystyrenes. Two-dimensional reversed-phase liquid chromatography was used to show that even the diasteromers of the oligomers (n = 5) have retention mechanisms that are dependent on the subtle changes to the molecular conformation and electronic structure, which are a consequence of deuteration.

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

    Science.gov (United States)

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

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

  15. Liquid chromatography-mass spectrometry platform for both small neurotransmitters and neuropeptides in blood, with automatic and robust solid phase extraction

    Science.gov (United States)

    Johnsen, Elin; Leknes, Siri; Wilson, Steven Ray; Lundanes, Elsa

    2015-03-01

    Neurons communicate via chemical signals called neurotransmitters (NTs). The numerous identified NTs can have very different physiochemical properties (solubility, charge, size etc.), so quantification of the various NT classes traditionally requires several analytical platforms/methodologies. We here report that a diverse range of NTs, e.g. peptides oxytocin and vasopressin, monoamines adrenaline and serotonin, and amino acid GABA, can be simultaneously identified/measured in small samples, using an analytical platform based on liquid chromatography and high-resolution mass spectrometry (LC-MS). The automated platform is cost-efficient as manual sample preparation steps and one-time-use equipment are kept to a minimum. Zwitter-ionic HILIC stationary phases were used for both on-line solid phase extraction (SPE) and liquid chromatography (capillary format, cLC). This approach enabled compounds from all NT classes to elute in small volumes producing sharp and symmetric signals, and allowing precise quantifications of small samples, demonstrated with whole blood (100 microliters per sample). An additional robustness-enhancing feature is automatic filtration/filter back-flushing (AFFL), allowing hundreds of samples to be analyzed without any parts needing replacement. The platform can be installed by simple modification of a conventional LC-MS system.

  16. Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE): Lunar Advanced Volatile Analysis (LAVA) Capillary Fluid Dynamic Restriction Effects on Gas Chromatography

    Science.gov (United States)

    Gonzalez, Marianne; Quinn, Jacqueline; Captain, Janine; Santiago-Bond, Josephine; Starr, Stanley

    2015-01-01

    The Resource Prospector (RP) mission with the Regolith and Environment Science and Oxygen Lunar Volatile Extraction (RESOLVE) payload aims to show the presence of water in lunar regolith, and establish a proving ground for NASAs mission to Mars. One of the analysis is performed by the Lunar Advanced Volatiles Analysis (LAVA) subsystem, which consists of a fluid network that facilitates the transport of volatile samples to a gas chromatograph and mass spectrometer (GC-MS) instrument. The understanding of fluid dynamics directed from the GC to the MS is important due to the influence of flow rates and pressures that affect the accuracy of and prevent the damage to the overall GC-MS instrument. The micro-scale capillary fluid network within the GC alone has various lengths and inner-diameters; therefore, determination of pressure differentials and flow rates are difficult to model computationally, with additional complexity from the vacuum conditions in space and lack of a lunar atmosphere. A series of tests were performed on an experimental set-up of the system where the inner diameters of the GC transfer line connecting to the MS were varied. The effect on chromatography readings were also studied by applying these lines onto a GC instrument. It was found that a smaller inner diameter transfer line resulted in a lower flow rate, as well as a lower pressure differential across the thermal conductivity detector (TCD) unit of the GC and a negligible pressure drop across the mock-up capillary column. The chromatography was affected with longer retention times and broader peak integrations. It was concluded that a 0.050 mm inner diameter line still proved most suitable for the systems flow rate preferences. In addition, it was evident that this small transfer line portrayed some expense to GC signal characteristics and the wait time for steady-state operation.

  17. Simultaneous detection of six urinary pteridines and creatinine by high-performance liquid chromatography-tandem mass spectrometry for clinical breast cancer detection.

    Science.gov (United States)

    Burton, Casey; Shi, Honglan; Ma, Yinfa

    2013-11-19

    Recent preliminary studies have implicated urinary pteridines as candidate biomarkers in a growing number of malignancies including breast cancer. While the developments of capillary electrophoresis-laser induced fluorescence (CE-LIF), high performance liquid chromatography (HPLC), and liquid chromatography-mass spectroscopy (LC-MS) pteridine urinalyses among others have helped to enable these findings, limitations including poor pteridine specificity, asynchronous or nonexistent renal dilution normalization, and a lack of information regarding adduct formation in mass spectrometry techniques utilizing electrospray ionization (ESI) have prevented application of these techniques to a larger clinical setting. In this study, a simple, rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and optimized for simultaneous detection of six pteridines previously implicated in breast cancer and creatinine as a renal dilution factor in urine. In addition, this study reports cationic adduct formation of urinary pteridines under ESI-positive ionization for the first time. This newly developed technique separates and detects the following six urinary pteridines: 6-biopterin, 6-hydroxymethylpterin, d-neopterin, pterin, isoxanthopterin, and xanthopterin, as well as creatinine. The method detection limit for the pteridines is between 0.025 and 0.5 μg/L, and for creatinine, it is 0.15 μg/L. The method was also validated by spiked recoveries (81-105%), reproducibility (RSD: 1-6%), and application to 25 real urine samples from breast cancer positive and negative samples through a double-blind study. The proposed technique was finally compared directly with a previously reported CE-LIF technique, concluding that additional or alternative renal dilution factors are needed for proper investigation of urinary pteridines as breast cancer biomarkers.

  18. Polymer Analysis by Liquid Chromatography/Electrospray Ionization Time-of-Flight Mass Spectrometry.

    Science.gov (United States)

    Nielen, M W; Buijtenhuijs, F A

    1999-05-01

    Hyphenation of liquid chromatography (LC) techniques with electrospray ionization (ESI) orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (MS) provides both MS-based structural information and LC-based quantitative data in polymer analysis. In one experimental setup, three different LC modes are interfaced with MS:  size-exclusion chromatography (SEC/MS), gradient polymer elution chromatography (GPEC/MS), and liquid chromatography at the critical point of adsorption (LCCC/MS). In SEC/MS, both absolute mass calibration of the SEC column based on the polymer itself and determination of monomers and end groups from the mass spectra are achieved. GPEC/MS shows detailed chemical heterogeneity of the polymer and the chemical composition distribution within oligomer groups. In LCCC/MS, the retention behavior is primarily governed by chemical heterogeneities, such as different end group functionalities, and quantitative end group calculations can be easily made. The potential of these methods and the benefit of time-of-flight analyzers in polymer analysis are discussed using SEC/MS of a polydisperse poly(methyl methacrylate) sample, GPEC/MS of dipropoxylated bisphenol A/adipic acid polyester resin, LCCC/MS of alkylated poly(ethylene glycol), and LCCC/MS of terephthalic acid/neopentyl glycol polyester resin.

  19. Polarity-based fractionation in proteomics: hydrophilic interaction vs reversed-phase liquid chromatography.

    Science.gov (United States)

    Jafari, M; Mirzaie, M; Khodabandeh, M; Rezadoost, H; Ghassempour, A; Aboul-Enein, H Y

    2016-07-01

    During recent decades, hydrophilic interaction liquid chromatography (HILIC) ahs been introduced to fractionate or purify especially polar solutes such as peptides and proteins while reversed-phase liquid chromatography (RPLC) is also a common strategy. RPLC is also a common dimension in multidimensional chromatography. In this study, the potential of HILIC vs RPLC chromatography was compared for proteome mapping of human peripheral blood mononuclear cell extract. In HILIC a silica-based stationary phase and for RPLC a C18 column were applied. Then separated proteins were eluted to an ion trap mass spectrometry system. Our results showed that the HILIC leads to more proteins being identified in comparison to RPLC. Among the total 181 identified proteins, 56 and 38 proteins were fractionated specifically by HILIC and RPLC, respectively. In order to demonstrate this, the physicochemical properties of identified proteins such as polarity and hydrophobicity were considered. This analysis indicated that polarity may play a major role in the HILIC separation of proteins vs RPLC. Using gene ontology enrichment analysis, it was also observed that differences in physicochemical properties conform to the cellular compartment and biological features. Finally, this study highlighted the potential of HILIC and the great orthogonality of RPLC in gel-free proteomic studies. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Thermal-capillary analysis of Czochralski and liquid encapsulated Czochralski crystal growth. II - Processing strategies

    Science.gov (United States)

    Derby, J. J.; Brown, R. A.

    1986-01-01

    The pseudosteady-state heat transfer model developed in a previous paper is augmented with constraints for constant crystal radius and melt/solid interface deflection. Combinations of growth rate, and crucible and bottom-heater temperatures are tested as processing parameters for satisfying the constrained thermal-capillary problem over a range of melt volumes corresponding to the sequence occuring during the batchwise Czochralski growth of a small-diameter silicon crystal. The applicability of each processing strategy is judged by the range of existence of the solution, in terms of melt volume and the values of the axial and radial temperature gradients in the crystal.

  1. Metabolite Extraction from Saccharomyces cerevisiae for Liquid Chromatography-Mass Spectrometry.

    Science.gov (United States)

    Rosebrock, Adam P; Caudy, Amy A

    2017-09-01

    Prior to mass spectrometric analysis, cellular small molecules must be extracted and separated from interfering components such as salts and culture medium. To ensure minimal perturbation of metabolism, yeast cells grown in liquid culture are rapidly harvested by filtration as described here. Simultaneous quenching of metabolism and extraction is afforded by immediate immersion in low-temperature organic solvent. Samples prepared using this method are suitable for a range of downstream liquid chromatography-mass spectrometry analyses and are stable in solvent for >1 yr at -80°C. © 2017 Cold Spring Harbor Laboratory Press.

  2. Determination of preservatives in cosmetics, cleaning agents and pharmaceuticals using fast liquid chromatography.

    Science.gov (United States)

    Baranowska, Irena; Wojciechowska, Iwona; Solarz, Natalia; Krutysza, Ewa

    2014-01-01

    This paper reports the development of a method for simultaneously determining five preservatives in cosmetics, cleaning agents and pharmaceuticals by fast liquid chromatography. Methylisothiazolinone, methylchloroisothiazolinone, benzyl alcohol, sodium benzoate and methylparaben were separated on a Chromolith Fast Gradient reversed-phase 18e column using gradient elution with acetonitrile and a 0.1% aqueous solution of formic acid, with a run time of 3 min. The preparation of solid and liquid samples included ultrasonic extraction with methanol with recoveries ranging from 69 to 119%. The developed method was used to analyze samples of cosmetics (66 samples), cleaning agents (five samples) and pharmaceutical industry products (17 samples).

  3. Identification and Quantitation of Asparagine and Citrulline Using High-Performance Liquid Chromatography (HPLC)

    OpenAIRE

    Bai, Cheng; Reilly, Charles C.; Wood, Bruce W.

    2007-01-01

    High-performance liquid chromatography (HPLC) analysis was used for identification of two problematic ureides, asparagine and citrulline. We report here a technique that takes advantage of the predictable delay in retention time of the co-asparagine/citrulline peak to enable both qualitative and quantitative analysis of asparagine and citrulline using the Platinum EPS reverse-phase C18 column (Alltech Associates). Asparagine alone is eluted earlier than citrulline alone, but when both of them...

  4. DETECTION AND QUANTIFICATION OF PHYTOCHEMICAL MARKERS OF Ilex paraguariensis BY LIQUID CHROMATOGRAPHY

    OpenAIRE

    Pinto,Rodrigo M. C.; Lemes,Bruna M.; Zielinski,Acácio A. F.; Klein,Traudi; Paula,Fernado de; Kist,Airton; Marques,Anna S. F.; Nogueira,Alessandro; Demiate,Ivo M.; Beltrame,Flávio L.

    2015-01-01

    Ilex paraguariensis (yerba-mate) is used as a beverage, and its extract requires adequate quality control methods in order to guarantee quality and safe use. Strategies to develop and optimize a chromatographic method to quantify theobromine, caffeine, and chlorogenic acid in I. paraguariensis extracts were evaluated by applying a quality by design (QbD) model and ultra high-performance liquid chromatography (UHPLC). The presence of these three phytochemical markers in the extracts was evalua...

  5. Simultaneous Determination of Four Preservatives in Foodstuffs by High Performance Liquid Chromatography

    OpenAIRE

    Mohammad Faraji; Farzaneh Rahbarzare

    2016-01-01

    Background and objectives:  High concentration of preservatives in food may result in gastrointestinal disturbances whereby some patients suffering from asthma, rhinitis, or urticaria. The aim of this study is the introduction and optimization a new method for simultaneous determination of four preservatives (SB, PS, MP, PP) in foodstuff by high performance liquid chromatography. Materials and methods: Important factors in extraction, separation and determination process were optimiz...

  6. Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry.

    Science.gov (United States)

    Mämmelä, P; Savolainen, H; Lindroos, L; Kangas, J; Vartiainen, T

    2000-09-01

    Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid.

  7. Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications

    OpenAIRE

    Preti, Raffaella

    2016-01-01

    The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large am...

  8. RECENT ADVANCES IN ULTRA-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY FOR THE ANALYSIS OF TRADITIONAL CHINESE MEDICINE

    Science.gov (United States)

    Huang, Huilian; Liu, Min; Chen, Pei

    2014-01-01

    Traditional Chinese medicine has been widely used for the prevention and treatment of various diseases for thousands of years in China. Ultra-high performance liquid chromatography (UHPLC) is a relatively new technique offering new possibilities. This paper reviews recent developments in UHPLC in the separation and identification, fingerprinting, quantification, and metabolism of traditional Chinese medicine. Recently, the combination of UHPLC with MS has improved the efficiency of the analysis of these materials. PMID:25045170

  9. Toxic Compounds Analysis With High Performance Liquid Chromatography Detected By Electro Chemical Detector (Ecd)

    OpenAIRE

    Hideharu Shintaniq

    2014-01-01

    The principal area of application of high performance liquid chromatography-electrochemical detector (HPLC-ECD) has been in the analysis of naturally-occurring analytes, such as catecholamines, and pharmaceuticals in biological samples, HPLC-ECD has also applied to the analysis of pesticides and other analytes of interest to the toxicologist. In this paper, toxic area is described. In these, ammatoxins, aromatic amine, nitro-compounds, algal toxins, fungal toxins, pesticides, veterinary drug ...

  10. Resolution of the stereoisomers of baclofen by high performance liquid chromatography

    International Nuclear Information System (INIS)

    Weatherby, R.P.; Allan, R.D.; Johnston, G.A.R.

    1984-01-01

    The GABA analogue baclofen [3-(p-chlorophenyl)-4-aminobutanoic acid] has stereospecific actions on the peripheral and central nervous systems. This paper describes the resolution of tritium-labelled baclofen by high performance liquid chromatography on a reverse-phase C18 column using a chiral mobile phase. The method, which may have general application to certain other GABA analogues, affords optically pure (+)- and (-)-baclofen labelled with tritium to high specific activity suitable for ligand binding and other neurochemical studies. (Auth.)

  11. Quantitative analysis of cytokinins in plants by liquid chromatography single-quadrupole mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Novák, Ondřej; Tarkowski, Petr; Tarkowská, Danuše; Doležal, Karel; Lenobel, René; Strnad, Miroslav

    2003-01-01

    Roč. 480, č. 2 (2003), s. 207ů218 ISSN 0003-2670 R&D Projects: GA ČR GA522/01/0275 Grant - others:Volkswagen Stiftung(DE) I/76 865 Institutional research plan: CEZ:AV0Z5038910; CEZ:MSM 153100008 Keywords : Liquid chromatography mass spectrometry * Cytokinins Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.210, year: 2003

  12. Fingerprint analysis of Resina Draconis by ultra-performance liquid chromatography

    OpenAIRE

    Xue, Yudi; Zhu, Lin; Yi, Tao

    2017-01-01

    Background Resina Draconis, a bright red resin derived from Dracaena cochinchinensis, is a traditional medicine used in China. To improve its quality control approach, an ultra-performance liquid chromatography (UPLC) fingerprint method was developed for rapidly evaluating the quality of Resina Draconis. Methods The precision, repeatability and stability of the proposed UPLC method were validated in the study. Twelve batches of Resina Draconis samples from various sources were analyzed by the...

  13. Thermally and optically tunable lasing properties from dye-doped holographic polymer dispersed liquid crystal in capillaries

    Science.gov (United States)

    Chen, Maozhou; Dai, Haitao; Wang, Dongshuo; Yang, Yue; Luo, Dan; Zhang, Xiaodong; Liu, Changlong

    2018-03-01

    In this paper, we investigated tunable lasing properties from the dye-doped holographic polymer dispersed liquid crystal (HPDLC) gratings in capillaries with thermal and optical manners. The thermally tunable range of the lasing from the dye-doped HPDLC reached 8.60 nm with the temperature ranging from 23 °C to 50 °C. The optically tunable laser emission was achieved by doping azo-dye in HPDLC. The transition of azo-dye from trans- to cis-state could induce the reorientation of LC molecules after UV light irradiation, which resulted in the variation of refractive index contrast of LC-rich/polymer-rich layer in HPDLC. Experimentally, the emission wavelength of lasing showed a blueshift (about 2 nm) coupled with decreasing output intensities. The tunable laser based on HPDLC may enable more applications in laser displays, optical communication, biosensors, etc.

  14. 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.…

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

    Science.gov (United States)

    Wu, Yunli; Hu, Bin

    2009-11-06

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

  16. Applications of the solvation parameter model in reversed-phase liquid chromatography.

    Science.gov (United States)

    Poole, Colin F; Lenca, Nicole

    2017-02-24

    The solvation parameter model is widely used to provide insight into the retention mechanism in reversed-phase liquid chromatography, for column characterization, and in the development of surrogate chromatographic models for biopartitioning processes. The properties of the separation system are described by five system constants representing all possible intermolecular interactions for neutral molecules. The general model can be extended to include ions and enantiomers by adding new descriptors to encode the specific properties of these compounds. System maps provide a comprehensive overview of the separation system as a function of mobile phase composition and/or temperature for method development. The solvation parameter model has been applied to gradient elution separations but here theory and practice suggest a cautious approach since the interpretation of system and compound properties derived from its use are approximate. A growing application of the solvation parameter model in reversed-phase liquid chromatography is the screening of surrogate chromatographic systems for estimating biopartitioning properties. Throughout the discussion of the above topics success as well as known and likely deficiencies of the solvation parameter model are described with an emphasis on the role of the heterogeneous properties of the interphase region on the interpretation and understanding of the general retention mechanism in reversed-phase liquid chromatography for porous chemically bonded sorbents. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Characterization of the efficiency of microbore liquid chromatography columns by van Deemter and kinetic plot analysis.

    Science.gov (United States)

    Hetzel, Terence; Loeker, Denise; Teutenberg, Thorsten; Schmidt, Torsten C

    2016-10-01

    The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro-liquid chromatography system. Fully porous, core-shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub-2 μm fully porous as well as the 2.7 μm core-shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56-2.69) before correction for extra-column contribution compared to normal-bore columns. Moreover, the influence of extra-column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub-2 μm fully porous particle packed column for ultra-fast liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Separation of enantiomers of new psychoactive substances by high-performance liquid chromatography.

    Science.gov (United States)

    Kadkhodaei, Kian; Forcher, Lisa; Schmid, Martin G

    2018-03-01

    New psychoactive substances are defined as compounds with consciousness-changing effects and have been developed simultaneously with classical drugs. They arise through structural modifications of illegal substances and are mainly produced to circumvent laws. Availability is simple, since new psychoactive substances can be purchased from the Internet. Among them many chemical drug compound classes are chiral and thus the two resulting enantiomers can differ in their effects. The aim of this study is to develop a suitable chiral high-performance liquid chromatography separation method for a broad spectrum of new psychoactive substances using cellulose tris(3,5-dichlorophenylcarbamate) as a chiral selector. Experiments were performed by high-performance liquid chromatography in normal-phase mode under isocratic conditions using ultraviolet detection. Direct separation was carried out on a high-performance liquid chromatography column (Lux® i-Cellulose-5, 3.5 μm, Phenomenex®), available since 2016. Excellent separation results were obtained for cathinones. After further optimization, even 47 instead of 39 out of 52 cathinones showed baseline separation. For amphetamine derivatives, satisfactory results were not achieved. Further, new psychoactive substances from other compound classes such as benzofuranes, thiophenes, phenidines, phenidates, morpholines, and ketamines were partially resolved, depending on the polarity and degree of substitution. All analytes, which were mainly purchased from the Internet, were proven to be traded as racemates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Determination of veterinary antibiotic residues in foods of animal origin by liquid chromatography

    Directory of Open Access Journals (Sweden)

    Pedro Enrique La Rosa Zambrano

    2018-05-01

    Full Text Available TITLE: Determination of veterinary antibiotic residues in foods of animal origin by liquid chromatography Introduction: The presence of certain infectious agents makes necessary the use of antibiotics to ensure the welfare of animals destined for human consumption; however, the withdrawal time must be considered and respected since there is the possibility of finding residues above the permitted levels, which could constitute a risk to public health. Objective: Present a collection of information based on how is performed the detection and quantification of antibiotic residues in various products of animal origin using chromatography methods. Method: Review of databases in Elsevier, SciELO, Springer, Hindawi, FAO, EFSA, Senasa and Sanipes, using keywords such as “liquid chromatography”, “mass spectrometry”, “antibiotic residues” and “products of animal origin” in Spanish and English. Results: They were selected 71 references among articles, book chapters, norms and regulations published between 2000 and 2017, which it is emphasized that chromatographic methodologies for antibiotic residues monitoring must be sensitive, reproducible, reliable and identify volumes in mg/kg; likewise, they must follow the requirements of international standards for the maximum residue limits detecction. Conclusions: Liquid chromatography coupled to a mass spectrometer is the most used technique to allow the separation of complex matrices based on the molecular weight of the compound (antibiotic or its fragments; however, It is complex, expensive and requires highly trained personnel.

  20. Characterization of pitches by liquid chromatography using cellulose 3,5-dinitrobenzoate as the packing material

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K.; Judo, R.; Ota, E. [Gunma University, Gunma (Japan). Dept. of Chemistry

    1997-08-01

    Characterization of coal tar, petroleum and PVC pitches by a liquid chromatography using cellulose 3,5-dinitrobenzoate (DNB-cellulose) as the packing material was investigated. Separation mechanism based on charge-transfer interaction between the dinitrobenzoyl group and polyaromatic compounds was expected to be useful for separation of the constituents of the pitches. First, 26 model polyaromatic compounds were tested to examine the characteristic feature of the packing material by liquid chromatography. The compounds were found to be classified roughly into four groups with different retention volume, principally according to the number of condensed rings. The nonplanar structure and aliphatic side chain of the polyaromatic compounds also affected the separation behavior. Both benzene soluble-hexane soluble and benzene soluble-hexane insoluble fractions of the three pitches were separated on DNB-cellulose. It was found that coal tar pitch contains relatively large amounts of some highly condensed polyaromatic compounds with condensed rings of 4 to 5; petroleum pitch has small amounts of such specific highly condensed polyaromatic compounds, while PVC pitch has large amounts of less condensed polyaromatic compounds and there is no significant amount of highly condensed compound in it. Thus DNB-cellulose was useful as the convenient packing material for liquid chromatography to characterize pitches.