Simultaneous determination of ursodeoxycholic acid and its glycine-conjugate in serum as phenacyl esters using multidimensional liquid chromatography

Summary A narrowbore high-performance liquid chromatographic (HPLC) method using column switching is described for the simultaneous determination of ursodeoxycholic acid (UDCA) and glyco-UDCA (GUDCA) from serum samples as their phenacyl esters. Serum samples were subjected to a preliminary clean-up using octadecylsilane reversed-phase extraction and derivatized with phenacylbromide. The purification, fractionation and concentration of UDCA and GUDCA from the esterified serum sample were performed on-line by appropriate switching of columns. Limit of detection (LOD) of UDCA and GUDCA were 5 ng and the absolute mean recoveries averaged 84.4±8.2% and 85.2±8.4%, respectively. This method was successfully applied to the pharmacokinetic study of UDCA in rats and human.