The Experts below are selected from a list of 3378 Experts worldwide ranked by ideXlab platform
Jonas Bergquist - One of the best experts on this subject based on the ideXlab platform.
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quantitation of tryptophan kynurenine and kynurenic acid in human plasma by Capillary Liquid Chromatography electrospray ionization tandem mass spectrometry
Journal of Chromatography B, 2002Co-Authors: Ardeshir Amirkhani, Eva Heldin, Karin E Markides, Jonas BergquistAbstract:Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by Capillary Liquid Chromatography - electrospray ionization tandem mass spectrometry
Ardeshir Amirkhani - One of the best experts on this subject based on the ideXlab platform.
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quantitation of tryptophan kynurenine and kynurenic acid in human plasma by Capillary Liquid Chromatography electrospray ionization tandem mass spectrometry
Journal of Chromatography B, 2002Co-Authors: Ardeshir Amirkhani, Eva Heldin, Karin E Markides, Jonas BergquistAbstract:Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by Capillary Liquid Chromatography - electrospray ionization tandem mass spectrometry
Pavel Coufal - One of the best experts on this subject based on the ideXlab platform.
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monolithic columns based on a poly styrene divinylbenzene methacrylic acid copolymer for Capillary Liquid Chromatography of small organic molecules
Journal of Chromatography A, 2011Co-Authors: Adela Svobodova, Tomas Křižek, Jakub Sirc, Petr Salek, Eva Tesařova, Pavel Coufal, Karel StulikAbstract:Abstract A very simple and readily performed method is described for the preparation of poly(styrene-divinylbenzene-methacrylic acid) monolithic columns for Capillary Liquid Chromatography. The effect of the methacrylic acid content on the morphological and chromatographic properties has been investigated. Methacrylic acid is shown to be essential for isocratic separations of small organic analytes by Capillary Liquid Chromatography. Column efficiencies of about 28,000 theoretical plates/m have been obtained for all the test compounds. The batch-to-batch and run-to-run repeatability of the retention times is better than 1.5%.
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Hydroxymethyl methacrylate-based monolithic columns designed for separation of oligonucleotides in hydrophilic-interaction Capillary Liquid Chromatography
Journal of Biochemical and Biophysical Methods, 2006Co-Authors: Petra Holdšvendová, Jana Suchánková, Martin Bunček, Veronika Bačkovská, Pavel CoufalAbstract:Hydroxymethyl methacrylate-based monolithic columns for separation of oligonucleotides by Capillary Liquid Chromatography (CLC) were prepared. We optimized composition of the polymerization mixture, which contained the monomer mixture consisting of N-(hydroxymethyl) methacrylamide (HMMAA) and ethylene dimethacrylate (EDMA), and the porogenic system composed of propane-1-ol, butane-1,4-diol and α, α′-azoisobutyronitrile (AIBN) as initiator. Separations of oligonucleotides were performed in HILIC (hydrophilic-interaction) mode using 100 mM triethylamine acetate (TEAA) in acetonitrile and in water as eluents. The influence of steepness of the mobile phase gradient on separation of the oligonucleotides was evaluated as well as the reproducibility of HMMAA monolith preparation.
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Optimization of binary porogen solvent composition for preparation of butyl methacrylate monoliths in Capillary Liquid Chromatography.
Journal of chromatography. A, 2004Co-Authors: Jan Grafnetter, Pavel Coufal, Jana Suchánková, Eva Tesarova, Zuzana Bosáková, Juraj SevcíkAbstract:Butyl methacrylate monolithic columns in 320 microm i.d. fused silica capillaries for reversed-phase Capillary Liquid Chromatography were prepared by radical polymerization initiated thermally with azobisisobutyronitrile (AIBN). Polymerization mixture contained butyl methacrylate (BMA) as the function monomer and ethylene dimethacrylate (EDMA) as the crosslinking agent with 1,4-butanediol and 1-propanol as a binary porogen solvent. Ratio of 1,4-butanediol to 1-propanol in the porogen solvent was optimized regarding the monolithic column efficiency and performance. Total porosity, column permeability, separation impedance, Walters hydrophobicity index, retention factors, peak asymmetry factors, height equivalents to a theoretical plate and peak resolutions were used for characterization of the prepared monolithic columns. The polymerization mixture consisting of 17.8% of BMA, 21.8% of EDMA, 18.0% of 1,4-butanediol, 42.0% of 1-propanol and 0.4% AIBN generated monolithic columns of the best performance having a sufficient permeability and the lowest separation impedance. It was also demonstrated that monolithic columns of this composition exhibited good preparation reproducibility and an excellent pressure resistance when applied in Capillary Liquid Chromatography.
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Separation and Quantification of Enkephalin and Vasopressin Related Peptides in Reversed-Phase Capillary Liquid Chromatography
Chromatographia, 2004Co-Authors: Jana Suchánková, Eva Tesarova, Zuzana Bosáková, K. Soukupova, Pavel CoufalAbstract:A method for determination of some biologically active penta- and nona-peptides under isocratic conditions in Capillary Liquid Chromatography was developed. Separation system consisting of XTerra C18 stationary phase and mobile phase composed of a mixture of acetonitrile with 0.1% trifluoroacetic acid (TFA) and water with 0.1% TFA in the ratios 75/25 (v/v) and 85/15 (v/v) was suitable not only for a good resolution of enkephalin and vasopressin related peptides, respectively, but it also enabled separation of the respective biopeptides from other constituents of human urine. Calibration curves for the studied peptides were linear in the measured concentration range from 1.00 to 1.57×10−2 mg mL−1. The limit of detection and limit of quantification were in the range of units of μg mL−1 and tens of μg mL−1, respectively; slightly higher values were obtained for nonapeptides. Determination of certain biologically active peptides in urine can serve in future as a tool for diagnosis of various diseases, e.g. autism.
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Method of Determination of 9-(Alkylthio)Acridines in Urine by Capillary Liquid Chromatography
Chromatographia, 2004Co-Authors: Jan Srbek, Pavel Coufal, Jana Suchánková, Eva Tesarova, Zuzana Bosáková, I. NěmcováAbstract:Reversed-phase Capillary Liquid Chromatography was applied for quantification of thioderivatives of acridine. Ten 9-(alkylthio)acridines, three containing and seven lacking amino groups, were analyzed on Nucleosil C18 with acetonitrile-water-triethylamine (90.0:9.0:1.0, v/v/v) mixture as the mobile phase. The presence of triethylamine in the eluent greatly improved the peak shape and markedly shortened the analysis time. Calibration curves of all the studied acridine derivatives were measured over a concentration range of 1.0·10−6 – 1.0·10−3 mol. L−1 at two parallel detection wavelengths, 265 and 270 nm. Detection and quantification limits were evaluated for all the derivatives. The detection limits were in the region of μmol. L−1 for most of the thioacridines. The calibration curves were used for quantification of the derivatives in human urine. No pretreatment of the real biological samples was necessary. The optimized CLC method enabled a good separation of the individual thioacridines from other compounds present in human urine samples and their quantification in a reasonable analysis time.
Angelo Visconti - One of the best experts on this subject based on the ideXlab platform.
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identification of allergenic milk proteins markers in fined white wines by Capillary Liquid Chromatography electrospray ionization tandem mass spectrometry
Journal of Chromatography A, 2010Co-Authors: Linda Monaci, Ilario Losito, Francesco Palmisano, Angelo ViscontiAbstract:Abstract A method based on Capillary Liquid Chromatography combined with electrospray ionization-tandem mass spectrometry (CapLC–ESI-MS–MS) for the detection and identification of casein deriving peptides in fined white wine is described. This is the first step towards the development of a Liquid Chromatography mass spectrometric method for the detection/identification of markers of potentially allergenic milk proteins used as wine fining agents. The method demonstrated to be capable of detecting some peptides arising from α and β casein (with the relative aminoacidic sequences elucidated) in extracts of white wine fined with casein at 100 and 1000 μg/mL. This MS based approach appears to be a useful tool for screening purposes as well as a confirmatory tool for the unequivocal identification of caseins in ELISA positive samples.
Jing Dong - One of the best experts on this subject based on the ideXlab platform.
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Recent progress of polar stationary phases in CEC and Capillary Liquid Chromatography
Electrophoresis, 2020Co-Authors: Xiaoli Dong, Ren’an Wu, Jing Dong, Minghuo WuAbstract:The stationary phases including the nonpolar and polar stationary phases in microscale separations have been greatly developed. This review describes the recent progress of the polar stationary phases (PSPs) with the focus on their preparation and the interesting applications in the field of CEC and Capillary Liquid Chromatography (CLC) covering the literatures from the middle of 2006 to the middle of 2008. The PSPs described herein were summarized into three types as open-tubular, particle-packed and monolithic stationary phases for either CEC or CLC, and the separation mechanisms are of hydrophilic interaction, chiral selection, ion-exchange and/or electrostatic interaction, etc. After overviewing the literatures published in the last 2 years, the research efforts on PSPs for CEC and CLC have been remaining in the fabrication of open-tubular and monolithic Capillary columns; whereas, the research endeavor of PSPs on particulate-packed format seemed to decline most likely due to the commercial availability of various packing particles for CEC and CLC.
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thiol epoxy click polymerization for preparation of polymeric monoliths with well defined 3d framework for Capillary Liquid Chromatography
Analytical Chemistry, 2015Co-Authors: Junjie Ou, Hongwei Wang, Jing DongAbstract:A facile approach was developed for direct preparation of organic monoliths via the alkaline-catalyzed thiol-epoxy click polymerization. Two organic monoliths were prepared by using tetraphenylolethane glycidyl ether as a multiepoxy monomer, and trimethylolpropane tris(3-mercaptopropionate) and pentaerythritol tetrakis(3-mercaptopropionate) as the multithiol monomer, respectively, in the presence of a ternary porogenic system (DMSO/PEG200/H2O). The obtained organic monoliths showed high thermal, mechanical and chemical stabilites. Benefiting from the step-growth polymerization process, two organic monoliths possessed well-defined 3D framework microstructure, and exhibited high permeabilities and column efficiencies in Capillary Liquid Chromatography. A series of neutral, basic and acidic small molecules were used to comprehensively evaluate the separation abilities of these monoliths, and satisfactory chromatographic performance with column efficiencies ranged from 35 500 to 132 200 N/m was achieved, demo...
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Preparation of a butyl–silica hybrid monolithic column with a “one-pot” process for bioseparation by Capillary Liquid Chromatography
Analytical and Bioanalytical Chemistry, 2012Co-Authors: Zhenbin Zhang, Fangjun Wang, Junjie Ou, Jing DongAbstract:A butyl–silica hybrid monolithic column for bioseparation by Capillary Liquid Chromatography (cLC) was prepared with butyl methacrylate and alkoxysilanes through a “one-pot” process. The effects of polycondensation temperature, volume percentage of N,N′-dimethylformamide, and content of cetyltrimethylammonium bromide and butyl methacrylate on the morphologies of the hybrid monolithic columns prepared were investigated in detail. Baseline separations of proteins and small peptides on the hybrid monolithic column were achieved by cLC with gradient elution. In addition, the resulting hybrid column was also applied for analysis of tryptic digests of bovine serum albumin by cLC coupled with tandem mass spectrometry. The results demonstrate its potential application in separation of complex biological samples.
