Fluorescence high-performance liquid chromatographic determination of free and conjugated bile acids in serum and bile using 1-bromoacetylpyrene as a pre-labeling reagent

Simultaneous determination of free and conjugated bile acids in human gastric juice by high-performance liquid chromatography

A high-performance liquid chromatographic procedure has been developed for the simultaneous assay of the major free bile acids and the corresponding glycine and taurine conjugates in man. No preliminary fractionation into the free, glyco- and tauro-conjugated forms was required. An Ultrasphere ODS column with UV detection at 210 nm and methanol-acetate buffer gradient elution were used. The retention volume of the conjugates was dependent on the sodium acetate concentration in the mobile phase. The method is applicable to the quantification of intragastric bile acids with satisfactory sensitivity, selectivity and precision. Unconjugated and conjugated bile acids present in the gastric juice of patients with bile reflux gastritis were determined directly after Sep-Pak C18 cartridge purification.

Rapid and sensitive on-line precolumn purification and high-performance liquid chromatographic assay for bile acids in serum

A simple and rapid technique for the simultaneous isolation and analysis of fifteen kinds of bile acid was developed using reversed-phase high-performance liquid chromatography with an automatic dual-precolumn switching system. The serum samples were directly injected onto a first precolumn (hydroxyapatite), which was flushed with 1 mM phosphate buffer. Serum proteins were strongly retained on the hydroxyapatite column, but bile acids were unretained. The bile acids were absorbed on a second precolumn (Serumout-25) and eluted onto the analytical column with solvent B (acetonitrile-methanol-30 mM ammonium acetate, 20:20:60, v/v/v). For the separation of each bile acid, the gradient elution technique was used (solvent A was acetonitrile-methanol-30 mM ammonium acetate, 30:30:40). After separation of the bile acids, NADH was produced by use of immobilized 3 alpha-hydroxysteroid dehydrogenase column and then determined fluorimetrically (gamma em = 460 nm, gamma ex = 350 nm). The recoveries of bile acids in serum generally approached 100%.

New preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for fatty acids and derivatives

A preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for carboxylic acids is described. 9-Anthraldehyde hydrazone is oxidized with an organic oxidant, N-chlorosuccinimide, in an organic solvent such as ethyl acetate to give ADAM, and then the reaction mixture is directly used as the reagent solution for the derivatization of carboxylic acids. Both the oxidation and the derivatization reaction are carried out at room temperature, and an aliquot of the derivatization mixture is directly injected into a chromatograph. 9-Anthrylmethyl ester derivatives formed from ADAM and various carboxylic acids are sufficiently separated on a reversed-phase column and are sensitively detected fluorometrically. The present method was applied to the high-performance liquid chromatographic determination of long and short chain fatty acids, keto acids, and hydroxy acids.

High-performance liquid chromatographic-fluorescence determination of human faecal bile acids

A high-performance liquid chromatographic method with fluorescence detection has been developed for the determination of human faecal bile acids, especially free faecal bile acids. Faecal bile acids were extracted using an Amberlite XAD-2 column and then fractionated into four groups (free, glycine-conjugated, taurine-conjugated and sulphated bile acids) on a piperidinohydroxypropyl Sephadex LH-20 column. The free bile acid fraction and free bile acids obtained after enzymatic hydrolysis and/or solvolysis of the three other fractions were derivatized with 1-bromoacetylpyrene and dicyclohexyl-18-crown-6-ether. The derivatized bile acids were separated stepwise on a Shim-pack CLC-ODS column using acetonitrilemethanol-water (100:50:30) (A), (100:50:20) (B), and (100:50:0) (C) as mobile phases with changing automatically from A to C using a solvent changer. Calibration curves of bile acid standards were linear in the range between 20 and 400 pmole, when monitored at 370 nm (excitation) and 440 nm (emission). Percent recoveries of bile acids from human faecal samples were between 80 to 95%. The method is applicable to clinical use and is sensitive, reliable, and useful for the detailed determination of human faecal bile acids, especially of free faecal bile acids.

High-performance liquid chromatographic analysis of bacterial fatty acid composition for chemotaxonomic characterization of oral streptococci

A high-performance liquid chromatographic method was developed to analyze the fatty acid composition of bacterial lipids. After saponification of lipids extracted from bacteria, the liberated fatty acids were labeled with a fluorescence reagent, 4-bromomethyl-7-acetoxycoumarin, followed by reversed-phase high-performance liquid chromatographic separation and fluorescence detection. All bacterial fatty acids were simultaneously separated within 30 min and sensitively determined. This method was applied to the chemotaxonomic characterization of oral streptococci. The fatty acid composition of phospholipids and total lipids distinguished Streptococcus mutans from any other species examined and showed that Streptococcus sanguis had a close taxonomic relationship with Streptococcus salivarius.

Rapid and accurate reversed-phase high-performance liquid chromatographic determination of conjugated bile acids in human bile for routine clinical applications. Therapeutic control during gallstone dissolution therapy

This paper introduces a new method to detect the taurine and glycine conjugates of five different bile acids (cholic acid, deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid and lithocholic acid) in human bile. Advantages of this method are sufficient separation of compounds within a short period of time and a high rate of reproducibility. Using a mobile phase gradient of acetonitrile and water, modified with tetrabutylammonium hydrogen sulphate (0.0075 mol/l), we were able to maximize the differentiation between ursodeoxycholic acid and lithocholic acid, which is of primary interest during conservative gallstone dissolution therapy. Use of this gradient reduced analysis time to less than 0.5 h. Recovery rates for this modified method ranged from 94% to 100%, and reproducibility was 98%, sufficient for routine clinical applications.

Determination of conjugated bile acids in human bile by isotachophoresis in a non-aqueous solvent using a.c. conductivity and UV detection

A method for the determination of conjugated bile acids in human bile using isotachophoresis in 95% methanol is described. The leading ion is 0.01 M chloride, the counter ion is hydroxylamine at its pK value and the terminating ion is N-2-hydroxyethylpiperazine-N'-2-ethanesulphonic acid (HEPES). The sample preparation consists of C18-silica cartridge adsorption. Microlitre amounts of the methanol eluate are injected and analysed within 20 min in a 0.2 mm I.D. PTFE capillary. The sensitivity of the method is better than 50 ng of each of the conjugated bile acids using a.c. conductivity detection.