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Biomedical subjects

G Guiochon

Publications and source records attributed to G Guiochon.

14 recordsLinked to original sources
PubMed1992

Enantiomeric separations using bovine serum albumin immobilized on ion-exchange stationary phases.

Bovine serum albumin (BSA) can be readily immobilized on ion-exchange stationary phases by frontal analysis of a proper solution. This provides a simple means of adjusting the amount of BSA contained in the column and of measuring it accurately. Although the immobilization is ionic and not covalent, the columns are stable for extensive periods of time. If needed, they can be easily regenerated by the same frontal analysis procedure.

Animals↗
PubMed1992

Contribution of ionically immobilized bovine serum albumin to the retention of enantiomers.

The retention of the enantiomers of mandelic acid and N-benzoylalanine was studied on columns prepared by immobilizing bovine serum albumin (BSA) on an anion exchanger. The amount of BSA fixed on the column is easy to adjust and measure. The adsorption isotherms were determined. For each enantiomer, the isotherm is well accounted for by a bi-Langmuir equation. One term of the isotherm (which is the same for both enantiomers) corresponds to non-selective interactions and the other term to the chiral selective interactions. The column saturation capacity of this second term is 8% larger for the less strongly retained enantiomer. This saturation capacity corresponds approximately to one enantiomer molecule adsorbed for five BSA molecules immobilized. This result is in agreement with the assumption of the hydrophobic cavity of BSA being the chiral selective site.

Alanine↗
PubMed1992

Factors affecting the separation and loading capacity of proteins in preparative gradient elution high-performance liquid chromatography.

The optimum conditions for the purification of proteins by gradient elution in reversed-phase liquid chromatography were studied, with emphasis on the column length. Because of the strong dependence of the retention of proteins on the mobile phase composition, very short columns can be used successfully to perform analytical separations. A similar conclusion is extended to preparative separations. Columns with different lengths and diameters were used. The dependence of the loading capacity for touching band separation on the column length, diameter and volume was studied, in addition to the regeneration time between successive runs, the starting mobile phase composition and the necessary column efficiency.

Animals↗
PubMed1990

Characterization of reversed-phase high-performance liquid chromatographic stationary phases using ribonuclease A.

The protein ribonuclease A (RNase A) represents a good model protein for studying reversible conformational refolding during gradient elution. Work is described utilizing RNase A under gradient conditions to evaluate several different reversed-phase materials. Columns (10 cm x 4.6 mm I.D.) were packed with Partisil C18, Vydac C18, Nucleosil C4, Nucleosil C18 and an adamantyl-modified Partisil silica. Measurements of the apparent first-order rate constant of refolding, as a function of temperature, are presented and compared for each stationary phase. Comparisons of peak shapes as functions of flow-rate and temperature are also discussed.

Chromatography, High Pressure Liquid↗
PubMed1989

Applications of preparative high-performance liquid chromatography to the separation and purification of peptides and proteins.

The basic differences between the problems encountered in the development of the analytical and preparative applications of high-performance liquid chromatography are analyzed and the principles of optimization of a preparative separation outlined. The application of these principles to the purification of peptides and proteins are discussed with emphasis on the specific problems raised by the separation of high-molecular-mass compounds. The relative advantages and inconveniences of displacement and overloaded elution are presented. The applications of the various retention modes of liquid chromatography (ion exchange, reversed-phase adsorption, hydrophobic interactions, size exclusion and bioaffinity) to the separation of various peptide and protein mixtures and/or to the extraction and purification of some of these compounds are reviewed. Separation performance reported in the literature are summarized in table form.

Chromatography, High Pressure Liquid↗
PubMed1984

Serum indole-3-acetic acid in control subjects and newly abstinent alcoholics after an oral loading with L-tryptophan: a preliminary study using liquid chromatography with amperometric detection.

Described in this paper is a rapid, isocratic assay for serum indole-3-acetic acid (IAA). The sample preparation involves only protein precipitation using sulfosalicylic acid, and the sensitivity of amperometric detection is in the picogram range. The chromatographic analysis time is approximately 4 min. The devised method was used for a longitudinal study of IAA levels in serum samples from control subjects and newly abstinent alcoholics. Dietary variations were eliminated by administering a 2.0-g loading dose of L-Trp to all subjects investigated. The results are presented in the form of cumulative frequency polygons. Preliminary data indicate no differences in IAA levels between newly abstinent alcoholics and control subjects.

Administration, Oral↗
PubMed1984

Analytical methodology for assays of serum tryptophan metabolites in control subjects and newly abstinent alcoholics: preliminary investigation by liquid chromatography with amperometric detection.

A rapid, isocratic assay for the determination of all major tryptophan metabolites in serum samples from control non-alcoholic subjects, recovered alcoholics and newly abstinent alcoholics is described. The sample preparation involves only precipitation of protein with sulfosalicylic acid. The complete liquid chromatographic analysis is short (25 min) and the sensitivity of amperometric detection permits the routine assessment of catabolites at the picogram level. This preliminary longitudinal study of the basal and post-tryptophan load serum metabolites revealed a considerable scatter of experimental results for kynurenine and serotonin in all groups examined, probably owing to the clinical heterogeneity of the sample populations.

Adult↗
PubMed1983

A strategy for source identification of organic pollutants in river water.

Sources of organic pollution in the Oise river, France have been identified using a "mutual search" strategy. This consisted of searching the characterized discharges for compounds found in the river water and, conversely, searching river water extracts for compounds found in the discharges. The "matches" were facilitated by comparisons of retention indices on two capillary gas chromatographic columns of widely differing polarity, response factors of selective detectors, and mass spectra. These assignments were verified by the geographical correlation of the selected pollutant's point of appearance in the river with the location of the suspected source.

Gas Chromatography-Mass Spectrometry↗