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.