Determination of diagnostically important free and conjugated bile acids in blood plasma by high-performance liquid chromatography

A procedure was proposed for the determination of free bile acids and their conjugates in blood plasma by the reversed-phase HPLC using the column Lichrospher 100 RP-18 (250 + 4.6 mm) with gradient elution and UV-detection at 206 nm. The procedure allowed the simultaneous determination of diagnostically important cholic acids, tauro-and glyco-cholates in blood plasma of patients with no preliminary separation of the analytes into subtypes. The bile acids and their conjugates were isolated from the sample matrix by solid phase extraction in a Sep-Pack C18 cartridge. The limits of detection were 0.11–0.15 mM for free acids and 0.015–0.025 mM for conjugates.