François Couderc | Université Paul sabatier (original) (raw)
Papers by François Couderc
Rapid Communications in Mass Spectrometry, 1987
Electrophoresis, 2004
Oxidative stress is present in cardiovascular diseases and hyperhomocysteinemia, an independant r... more Oxidative stress is present in cardiovascular diseases and hyperhomocysteinemia, an independant risk factor for these diseases. It may play a role by inducing production of oxygen free radicals. Reduced glutathione is the most abundant intracellular low-molecular-weight thiol and plays an essential role in protecting cells from toxic species. The thiol-containing compounds which are the most often considered in biological analysis, are homocysteine (Hcy), cysteine (Cys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), γ-glutamyl-cysteine (γGlu-Cys), and their derivatives. These aminothiols are present in body fluids or cells, associated with proteins or occur free (reduced and oxidized). These free forms may play a role in the pathogenesis of disease. Because Hcy (with Cys) exhibits pro-oxidative properties and GSH (with Cys-Gly) antioxidative properties, and because there is extensive interconversion between these metabolites, their simultaneous analysis in biological samples is necessary to examine their role in human disease. Capillary electrophoresis (CE) seems to be a solution to reach this goal. No extensive review reports the analysis of aminothiols using CE. This review describes the different CE approaches which have been used to separate and assay aminothiols, and the different obtained datas.
Journal of Chromatography A, 1997
A simple and reliable reversed-phase high-perfomance liquid chromatographic method has been devel... more A simple and reliable reversed-phase high-perfomance liquid chromatographic method has been developed and validated for the simultaneous determination of meloxicam and pridinol mesylate in their synthetic mixtures and combined tablet formulations. Both drugs were separated on a 250 mm × 4.6 mm C 18 column packed with 5 m particles. The mobile phase, optimized through an experimental design, was a 51:9:40 (v/v/v) mixture of methanol, isopropanol and 50 mM potassium phosphate buffer (pH 5.9), pumped at a flow rate of 1.0 ml min −1 . UV detection was performed at 225 nm. The method was validated in the sample concentration ranges of 33.7-61.8 mg l −1 for meloxicam and 8.8-16.8 mg l −1 for pridinol mesylate, where it demonstrated good linearity with r = 0.9989 and 0.9987 (n = 15), respectively. The assay was shown to be repeatable at concentration levels of 70%, 100% and 130%, with relative standard deviation values of 1.09% and 0.82% for meloxicam and pridinol, respectively. For independent 100% level samples, the intra-day precision was 0.4% and 1.0% while the intermediate precision was 0.7% and 1.0% for the drugs. The method demonstrated to be robust, resisting to small deliberate changes in pH, flow rate and composition (organic:aqueous ratio) of the mobile phase. The LOD values were 0.22 and 0.20 mg l −1 , while the LOQ were 1.7 and 1.1 mg l −1 , for meloxicam and pridinol, respectively. The applicability of the method was demonstrated by determining the drug content of two commercial pharmaceutical formulations, where it exhibited good performance.
Journal of Chromatography A, 1997
28 biogenic amines and amino acids were quantitated in red French wines over a 14 year period by ... more 28 biogenic amines and amino acids were quantitated in red French wines over a 14 year period by micellar electrokinetic chromatography separation and laser-induced fluorescence detection of fluorescein thiocarbamate derivatives. The grapes were grown in the same wine yard, under identical conditions, and the wines were made under fixed standard procedures. A pattern of evolution of amines and amino acids during wine aging is given. Principal component analysis indicates some correlations between the different amino acids and biogenic amines. A discussion on the behavior of amino acids during wine aging is presented.
Journal of Chromatography A, 1995
A ball-lens laser-induced fluorescence detector based on the conventional collinear arrangement i... more A ball-lens laser-induced fluorescence detector based on the conventional collinear arrangement is described for use with capillary electrophoresis. It allows better mechanical tolerances for capillary adjustment in front of the laser beam. Its sensitivity is equal to that of the conventional collinear arrangement. Micellar electrokinetic chromatographic determination of biogenic amines in dairy products is described as an application of this detector.
Electrophoresis, 2008
This paper describes a number of articles that have been published on amino acid (AA) analysis us... more This paper describes a number of articles that have been published on amino acid (AA) analysis using CE during the period from June 2005 to May 2007. This review article follows the format of the previous articles of Smith (Electrophoresis 1999, 20, 3078–3083), Prata et al.. (Electrophoresis 2001, 22, 4129–4138), and Poinsot et al.. (Electrophoresis 2003, 24, 4047–4062 and Electrophoresis 2006, 27, 176–194). Several new developments in AA analysis with CE are reported describing the use of laser-emitting diodes for LIF, MS, and chips. In addition, we describe articles concerning clinical studies and neuroclinical applications.
Journal of Chromatography A, 1995
Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to analyze ... more Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to analyze a 50-microliters sample of cerebrospinal fluid from leukaemic children treated with high doses of methotrexate. Free amino acids and primary amines are labelled with fluorescein isothiocyanate prior to analysis. Electropherograms containing more than 50 peaks were obtained in less than 22 min. Twenty-one peaks were identified, and 19 were quantitated. Observed differences in individual amino acid levels are compared with healthy reference values. The results indicate that CE-LIF is useful as a selective, rapid and sensitive tool for the determination of free amino acids and amines in clinical biology studies.
Journal of Chromatography A, 2000
In this publication we present results on the determination of enantiomers of amino acids at very... more In this publication we present results on the determination of enantiomers of amino acids at very low concentrations. A fluoresceine-based chiral dye was synthesized to allow the separation of diastereoisomers of D- and L-amino acids. We used capillary electrophoresis with different non-ionic surfactants (Brij). The separation parameters were optimized and separations of D- and L-isovaline, an unusual terrestrial amino acid, were obtained. The sensitivity limits were also determined using a commercial laser-induced fluorescence detector. The quantitation of these amino acids is very important to understand the process of chiral selection on Earth.
Electrophoresis, 2006
This paper describes a number of articles that have been published on amino acid analysis using C... more This paper describes a number of articles that have been published on amino acid analysis using CE during the period from June 2003 to May 2005. This review article follows the previous ones of Smith (Electrophoresis 1999, 20, 3078–3083), Prata et al.. (Electrophoresis 2001, 22, 4129–4138), and Poinsot et al.. (Electrophoresis 2003, 24, 4047–4062). Several new developments in amino acid analysis with CE are reported concerning UV detection, LIF, MS, and NMR. In addition, we describe articles concerning clinical and pharmaceutical studies, neuroclinical applications, and agricultural and food analysis.
Journal of Chromatography A, 1999
Laser-induced fluorescence (LIF) detection is now a well-known sensitive and selective detection ... more Laser-induced fluorescence (LIF) detection is now a well-known sensitive and selective detection mode for capillary electrophoresis (CE) analysis. It has been shown to be 100- to 100,000-times more sensitive than UV detection and little work has been done using LIF in conjunction with high-performance liquid chromatography (HPLC). The need for greater resolution and higher sensitivity for the analysis of anthracyclines (fluorescent chemotherapic drugs), prompted us to compare CE-LIF and HPLC-LIF, for the detection of these substances. CE-LIF sensitivity based on quantity of anthracycline injected is 50-times greater than that obtained with HPLC-LIF, because of the injected sample volume. Analysis of daunorubicin in Kaposy sarcoma tumors and in plasma are presented. The decrease of the concentration of daunorubicin in the tumor and in the plasma following time show the same behavior, indicating identical concentrations of the anthracycline in both samples.
Electrophoresis, 2005
Over the past few years, a large number of studies have been prepared that describe the analysis ... more Over the past few years, a large number of studies have been prepared that describe the analysis of peptides and proteins using capillary electrophoresis (CE) and laser-induced fluorescence (LIF). These studies have focused on two general goals: (i) development of automatic, selective and quick separation and detection of mixtures of peptides or proteins; (ii) generation of new methods of quantitation for very low concentrations (nm and subnanomolar) of peptides. These two goals are attained with the use of covalent labelling reactions using a variety of dyes that can be readily excited by the radiation from a commonly available laser or via the use of noncovalent labelling (immunoassay using a labelled antibody or antigen or noncovalent dye interactions). In this review article, we summarize the works which were performed for protein and peptide analysis via CE-LIF.
Electrophoresis, 1998
This review briefly presents the different laser-induced fluorescence detectors, outlines the dif... more This review briefly presents the different laser-induced fluorescence detectors, outlines the different dyes used to derivatize molecules which are used with capillary electrophoresis/laser-induced fluorescence (CE-LIF), and provides an overview and current status of CE-LIF in drug analysis.
Electrophoresis, 2003
Amino acids are studied extensively using capillary electrophoresis. In a previous article, we re... more Amino acids are studied extensively using capillary electrophoresis. In a previous article, we reviewed applications reported in the period 1999 – early 2001 (Prata, C., Bonnafous, P., Fraysse, N., Treilhou, M., Poinsot, V., Couderc, F., Electrophoresis 2001, 22, 4129–4138). In this article we follow on with this review for the period end of 2001 – beginning of 2003. We will report the developments of detection methods, separations of enantiomers, the new medical applications, and amino acids in food and plants. This review shows that CE is more and more important for the amino acid analysis.
Journal of Chromatography A, 2000
In recent papers, we presented a new analytical method for thiol quantification in serum. It is b... more In recent papers, we presented a new analytical method for thiol quantification in serum. It is based on the use of capillary electrophoresis and laser-induced fluorescence to analyze thiol 6-iodoacetamidofluoresceine (IAF) derivatives. Quantitative results of homocysteine, glutathione, cysteine-glycin, and cysteine were shown (Clin. Chem. 45 (1999) 412). A comprehensive comparison of the quantitation of homocysteine in serum, using high-performance liquid chromatography/conventional fluorescence detection and fluorescence polarization immunoassay was also used (E. Caussé et al., Electrophoresis 21 (2000) 2074). Sample preparation prior to derivatization with IAF had never been investigated. In this work we present the results of quantitation of thiols in serum and plasma with three different anticoagulants widely used: ethylenediaminetetraacetic acid (EDTA), heparin, and sodium citrate. We show that serum and EDTA plasma gave the same results. Then serum protein precipitations by acetonitrile, acetone, sulfosalicylic acid, perchloric acid and trichloracetic acid, prior to derivatization by IAF, were also investigated. Their influence on the concentrations of the thiols were determined. Sulfosalicylic acid and acetonitrile precipitations are well adapted, whereas acetone cannot be used.
Electrophoresis, 2007
Allantoin (All) is an oxidative end product of purines in mammals. The small amount of All presen... more Allantoin (All) is an oxidative end product of purines in mammals. The small amount of All present in human plasma or serum results from free radical action on urate and may provide a stable marker of in vivo free radical activity. Because free radicals have been implicated in the development and progression of atherosclerosis, this study focused on the metabolic compounds of the All pathway. We propose a new fast CE (CE/UV) method for the simultaneous determination of All, uric acid (UA), hypoxanthine (HX), and xanthine (X) in human plasma. These products were quantified in the plasma of patients with chronic renal failure before hemodialysis (n = 6), patients with chronic heart failure (n = 6) and controls (n = 6). The filtered plasma were diluted ten-fold before the direct injection in CE/UV (195 nm), which allows separating the four compounds in less than 13 min. The metabolites were detectable at concentrations of 0.3–0.6 μmol/L. The method was linear over the range 0.5–150 μmol/L for All, HX, and X and 10–1500 μmol/L for UA (r > 0.99). The analytical performance of this method is satisfactory with intra-assay CV < 3.4%, inter-assay CV < 5% (HX and X < 7%), and recovery (93–101%). The proposed CE-UV method appears to be a useful tool for studying physiological and pathological changes of HX, UA, and All levels in plasma samples, the latter being a possible indicator of free radical damage in vivo.
Electrophoresis, 2001
Amino acids are studied extensively using capillary electrophoresis. In this review we will repor... more Amino acids are studied extensively using capillary electrophoresis. In this review we will report the different researchs which have been done in the literature since 1998. We will describe the developments of, detection methods, separations of enantiomers, the new medical applications, and amino acids in food and plants.
Electrophoresis, 2000
We present a new analytical method for thiol quantification in plasma, based on the use of capill... more We present a new analytical method for thiol quantification in plasma, based on the use of capillary electrophoresis (CE) and laser-induced fluorescence (LIF) to analyze 6-iodoacetamidofluorescein derivatives. Quantitative results of homocysteine, glutathione, cysteinylglycine, and cystationine are presented. A comparison of the quantitation of homocysteine in plasma, using high performance liquid chromatography/fluorescence detection and fluorescence polarization immunoassay is proposed. The results indicate that these techniques for plasma total homocysteine (tHcy) determination can be used interchangeably. The major advantage of CE-LIF is that it can quantitate the thiols in one run while keeping the price of consumables reasonable.
Journal of Chromatography B-analytical Technologies in The Biomedical and Life Sciences, 2003
We have developed an automated large-volume sample stacking (LVSS) procedure to detect fluorescei... more We have developed an automated large-volume sample stacking (LVSS) procedure to detect fluorescein isothiocyanatelabeled peptides in the picomolar range. The injection duration is 10 min at 50 mbar to fill 62% of the capillary volume to the detection cell. The calculated limit of detection (S /N 5 3), filling 1% of the capillary volume, is 74 pM for bradykinin and 45 pM for L-enkephalin with samples diluted in water and analyzed in a 50 mM borate buffer, pH 9.2. With the automated LVSS system, the limits of detection are 7 pM for bradykinin, 3 pM for L-enkephalin and 2 pM for substance P. LVSS is shown to be quantitative from 500 to 10 pM.
Journal of Chromatography B-analytical Technologies in The Biomedical and Life Sciences, 2007
Journal of Chromatography B: Biomedical Sciences and Applications, 2000
Rapid Communications in Mass Spectrometry, 1987
Electrophoresis, 2004
Oxidative stress is present in cardiovascular diseases and hyperhomocysteinemia, an independant r... more Oxidative stress is present in cardiovascular diseases and hyperhomocysteinemia, an independant risk factor for these diseases. It may play a role by inducing production of oxygen free radicals. Reduced glutathione is the most abundant intracellular low-molecular-weight thiol and plays an essential role in protecting cells from toxic species. The thiol-containing compounds which are the most often considered in biological analysis, are homocysteine (Hcy), cysteine (Cys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), γ-glutamyl-cysteine (γGlu-Cys), and their derivatives. These aminothiols are present in body fluids or cells, associated with proteins or occur free (reduced and oxidized). These free forms may play a role in the pathogenesis of disease. Because Hcy (with Cys) exhibits pro-oxidative properties and GSH (with Cys-Gly) antioxidative properties, and because there is extensive interconversion between these metabolites, their simultaneous analysis in biological samples is necessary to examine their role in human disease. Capillary electrophoresis (CE) seems to be a solution to reach this goal. No extensive review reports the analysis of aminothiols using CE. This review describes the different CE approaches which have been used to separate and assay aminothiols, and the different obtained datas.
Journal of Chromatography A, 1997
A simple and reliable reversed-phase high-perfomance liquid chromatographic method has been devel... more A simple and reliable reversed-phase high-perfomance liquid chromatographic method has been developed and validated for the simultaneous determination of meloxicam and pridinol mesylate in their synthetic mixtures and combined tablet formulations. Both drugs were separated on a 250 mm × 4.6 mm C 18 column packed with 5 m particles. The mobile phase, optimized through an experimental design, was a 51:9:40 (v/v/v) mixture of methanol, isopropanol and 50 mM potassium phosphate buffer (pH 5.9), pumped at a flow rate of 1.0 ml min −1 . UV detection was performed at 225 nm. The method was validated in the sample concentration ranges of 33.7-61.8 mg l −1 for meloxicam and 8.8-16.8 mg l −1 for pridinol mesylate, where it demonstrated good linearity with r = 0.9989 and 0.9987 (n = 15), respectively. The assay was shown to be repeatable at concentration levels of 70%, 100% and 130%, with relative standard deviation values of 1.09% and 0.82% for meloxicam and pridinol, respectively. For independent 100% level samples, the intra-day precision was 0.4% and 1.0% while the intermediate precision was 0.7% and 1.0% for the drugs. The method demonstrated to be robust, resisting to small deliberate changes in pH, flow rate and composition (organic:aqueous ratio) of the mobile phase. The LOD values were 0.22 and 0.20 mg l −1 , while the LOQ were 1.7 and 1.1 mg l −1 , for meloxicam and pridinol, respectively. The applicability of the method was demonstrated by determining the drug content of two commercial pharmaceutical formulations, where it exhibited good performance.
Journal of Chromatography A, 1997
28 biogenic amines and amino acids were quantitated in red French wines over a 14 year period by ... more 28 biogenic amines and amino acids were quantitated in red French wines over a 14 year period by micellar electrokinetic chromatography separation and laser-induced fluorescence detection of fluorescein thiocarbamate derivatives. The grapes were grown in the same wine yard, under identical conditions, and the wines were made under fixed standard procedures. A pattern of evolution of amines and amino acids during wine aging is given. Principal component analysis indicates some correlations between the different amino acids and biogenic amines. A discussion on the behavior of amino acids during wine aging is presented.
Journal of Chromatography A, 1995
A ball-lens laser-induced fluorescence detector based on the conventional collinear arrangement i... more A ball-lens laser-induced fluorescence detector based on the conventional collinear arrangement is described for use with capillary electrophoresis. It allows better mechanical tolerances for capillary adjustment in front of the laser beam. Its sensitivity is equal to that of the conventional collinear arrangement. Micellar electrokinetic chromatographic determination of biogenic amines in dairy products is described as an application of this detector.
Electrophoresis, 2008
This paper describes a number of articles that have been published on amino acid (AA) analysis us... more This paper describes a number of articles that have been published on amino acid (AA) analysis using CE during the period from June 2005 to May 2007. This review article follows the format of the previous articles of Smith (Electrophoresis 1999, 20, 3078–3083), Prata et al.. (Electrophoresis 2001, 22, 4129–4138), and Poinsot et al.. (Electrophoresis 2003, 24, 4047–4062 and Electrophoresis 2006, 27, 176–194). Several new developments in AA analysis with CE are reported describing the use of laser-emitting diodes for LIF, MS, and chips. In addition, we describe articles concerning clinical studies and neuroclinical applications.
Journal of Chromatography A, 1995
Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to analyze ... more Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to analyze a 50-microliters sample of cerebrospinal fluid from leukaemic children treated with high doses of methotrexate. Free amino acids and primary amines are labelled with fluorescein isothiocyanate prior to analysis. Electropherograms containing more than 50 peaks were obtained in less than 22 min. Twenty-one peaks were identified, and 19 were quantitated. Observed differences in individual amino acid levels are compared with healthy reference values. The results indicate that CE-LIF is useful as a selective, rapid and sensitive tool for the determination of free amino acids and amines in clinical biology studies.
Journal of Chromatography A, 2000
In this publication we present results on the determination of enantiomers of amino acids at very... more In this publication we present results on the determination of enantiomers of amino acids at very low concentrations. A fluoresceine-based chiral dye was synthesized to allow the separation of diastereoisomers of D- and L-amino acids. We used capillary electrophoresis with different non-ionic surfactants (Brij). The separation parameters were optimized and separations of D- and L-isovaline, an unusual terrestrial amino acid, were obtained. The sensitivity limits were also determined using a commercial laser-induced fluorescence detector. The quantitation of these amino acids is very important to understand the process of chiral selection on Earth.
Electrophoresis, 2006
This paper describes a number of articles that have been published on amino acid analysis using C... more This paper describes a number of articles that have been published on amino acid analysis using CE during the period from June 2003 to May 2005. This review article follows the previous ones of Smith (Electrophoresis 1999, 20, 3078–3083), Prata et al.. (Electrophoresis 2001, 22, 4129–4138), and Poinsot et al.. (Electrophoresis 2003, 24, 4047–4062). Several new developments in amino acid analysis with CE are reported concerning UV detection, LIF, MS, and NMR. In addition, we describe articles concerning clinical and pharmaceutical studies, neuroclinical applications, and agricultural and food analysis.
Journal of Chromatography A, 1999
Laser-induced fluorescence (LIF) detection is now a well-known sensitive and selective detection ... more Laser-induced fluorescence (LIF) detection is now a well-known sensitive and selective detection mode for capillary electrophoresis (CE) analysis. It has been shown to be 100- to 100,000-times more sensitive than UV detection and little work has been done using LIF in conjunction with high-performance liquid chromatography (HPLC). The need for greater resolution and higher sensitivity for the analysis of anthracyclines (fluorescent chemotherapic drugs), prompted us to compare CE-LIF and HPLC-LIF, for the detection of these substances. CE-LIF sensitivity based on quantity of anthracycline injected is 50-times greater than that obtained with HPLC-LIF, because of the injected sample volume. Analysis of daunorubicin in Kaposy sarcoma tumors and in plasma are presented. The decrease of the concentration of daunorubicin in the tumor and in the plasma following time show the same behavior, indicating identical concentrations of the anthracycline in both samples.
Electrophoresis, 2005
Over the past few years, a large number of studies have been prepared that describe the analysis ... more Over the past few years, a large number of studies have been prepared that describe the analysis of peptides and proteins using capillary electrophoresis (CE) and laser-induced fluorescence (LIF). These studies have focused on two general goals: (i) development of automatic, selective and quick separation and detection of mixtures of peptides or proteins; (ii) generation of new methods of quantitation for very low concentrations (nm and subnanomolar) of peptides. These two goals are attained with the use of covalent labelling reactions using a variety of dyes that can be readily excited by the radiation from a commonly available laser or via the use of noncovalent labelling (immunoassay using a labelled antibody or antigen or noncovalent dye interactions). In this review article, we summarize the works which were performed for protein and peptide analysis via CE-LIF.
Electrophoresis, 1998
This review briefly presents the different laser-induced fluorescence detectors, outlines the dif... more This review briefly presents the different laser-induced fluorescence detectors, outlines the different dyes used to derivatize molecules which are used with capillary electrophoresis/laser-induced fluorescence (CE-LIF), and provides an overview and current status of CE-LIF in drug analysis.
Electrophoresis, 2003
Amino acids are studied extensively using capillary electrophoresis. In a previous article, we re... more Amino acids are studied extensively using capillary electrophoresis. In a previous article, we reviewed applications reported in the period 1999 – early 2001 (Prata, C., Bonnafous, P., Fraysse, N., Treilhou, M., Poinsot, V., Couderc, F., Electrophoresis 2001, 22, 4129–4138). In this article we follow on with this review for the period end of 2001 – beginning of 2003. We will report the developments of detection methods, separations of enantiomers, the new medical applications, and amino acids in food and plants. This review shows that CE is more and more important for the amino acid analysis.
Journal of Chromatography A, 2000
In recent papers, we presented a new analytical method for thiol quantification in serum. It is b... more In recent papers, we presented a new analytical method for thiol quantification in serum. It is based on the use of capillary electrophoresis and laser-induced fluorescence to analyze thiol 6-iodoacetamidofluoresceine (IAF) derivatives. Quantitative results of homocysteine, glutathione, cysteine-glycin, and cysteine were shown (Clin. Chem. 45 (1999) 412). A comprehensive comparison of the quantitation of homocysteine in serum, using high-performance liquid chromatography/conventional fluorescence detection and fluorescence polarization immunoassay was also used (E. Caussé et al., Electrophoresis 21 (2000) 2074). Sample preparation prior to derivatization with IAF had never been investigated. In this work we present the results of quantitation of thiols in serum and plasma with three different anticoagulants widely used: ethylenediaminetetraacetic acid (EDTA), heparin, and sodium citrate. We show that serum and EDTA plasma gave the same results. Then serum protein precipitations by acetonitrile, acetone, sulfosalicylic acid, perchloric acid and trichloracetic acid, prior to derivatization by IAF, were also investigated. Their influence on the concentrations of the thiols were determined. Sulfosalicylic acid and acetonitrile precipitations are well adapted, whereas acetone cannot be used.
Electrophoresis, 2007
Allantoin (All) is an oxidative end product of purines in mammals. The small amount of All presen... more Allantoin (All) is an oxidative end product of purines in mammals. The small amount of All present in human plasma or serum results from free radical action on urate and may provide a stable marker of in vivo free radical activity. Because free radicals have been implicated in the development and progression of atherosclerosis, this study focused on the metabolic compounds of the All pathway. We propose a new fast CE (CE/UV) method for the simultaneous determination of All, uric acid (UA), hypoxanthine (HX), and xanthine (X) in human plasma. These products were quantified in the plasma of patients with chronic renal failure before hemodialysis (n = 6), patients with chronic heart failure (n = 6) and controls (n = 6). The filtered plasma were diluted ten-fold before the direct injection in CE/UV (195 nm), which allows separating the four compounds in less than 13 min. The metabolites were detectable at concentrations of 0.3–0.6 μmol/L. The method was linear over the range 0.5–150 μmol/L for All, HX, and X and 10–1500 μmol/L for UA (r > 0.99). The analytical performance of this method is satisfactory with intra-assay CV < 3.4%, inter-assay CV < 5% (HX and X < 7%), and recovery (93–101%). The proposed CE-UV method appears to be a useful tool for studying physiological and pathological changes of HX, UA, and All levels in plasma samples, the latter being a possible indicator of free radical damage in vivo.
Electrophoresis, 2001
Amino acids are studied extensively using capillary electrophoresis. In this review we will repor... more Amino acids are studied extensively using capillary electrophoresis. In this review we will report the different researchs which have been done in the literature since 1998. We will describe the developments of, detection methods, separations of enantiomers, the new medical applications, and amino acids in food and plants.
Electrophoresis, 2000
We present a new analytical method for thiol quantification in plasma, based on the use of capill... more We present a new analytical method for thiol quantification in plasma, based on the use of capillary electrophoresis (CE) and laser-induced fluorescence (LIF) to analyze 6-iodoacetamidofluorescein derivatives. Quantitative results of homocysteine, glutathione, cysteinylglycine, and cystationine are presented. A comparison of the quantitation of homocysteine in plasma, using high performance liquid chromatography/fluorescence detection and fluorescence polarization immunoassay is proposed. The results indicate that these techniques for plasma total homocysteine (tHcy) determination can be used interchangeably. The major advantage of CE-LIF is that it can quantitate the thiols in one run while keeping the price of consumables reasonable.
Journal of Chromatography B-analytical Technologies in The Biomedical and Life Sciences, 2003
We have developed an automated large-volume sample stacking (LVSS) procedure to detect fluorescei... more We have developed an automated large-volume sample stacking (LVSS) procedure to detect fluorescein isothiocyanatelabeled peptides in the picomolar range. The injection duration is 10 min at 50 mbar to fill 62% of the capillary volume to the detection cell. The calculated limit of detection (S /N 5 3), filling 1% of the capillary volume, is 74 pM for bradykinin and 45 pM for L-enkephalin with samples diluted in water and analyzed in a 50 mM borate buffer, pH 9.2. With the automated LVSS system, the limits of detection are 7 pM for bradykinin, 3 pM for L-enkephalin and 2 pM for substance P. LVSS is shown to be quantitative from 500 to 10 pM.
Journal of Chromatography B-analytical Technologies in The Biomedical and Life Sciences, 2007
Journal of Chromatography B: Biomedical Sciences and Applications, 2000