Rapid chemical analysis of bear bile: 5 minute separation and quantitation of bile acids using UHPLC–qTOF-MS

Abstract

Bear bile is a precious traditional Chinese medicine containing abundant bile acids. The content of these bile acids varies significantly. In this study, a rapid and reliable method was established to simultaneously monitor major and minor bile acids, using ultra-high performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry. The samples were separated on a 1.8 μm Zorbax Eclipse-Plus C₁₈ column with acetonitrile and water (containing 4 mM of ammonium acetate) as the mobile phase. A 5 min analysis allowed the characterization of 21 steroids and the quantitation of two major constituents, taurochenodeoxycholic acid (TCDCA) and tauroursodeoxycholic acid (TUDCA). The contents of TUDCA and TCDCA in 8 commercial batches of bear bile were 39.04 ± 7.83% and 36.10 ± 9.42% (w/w; mean ± standard deviation), respectively, and the ratio of TUDCA/TCDCA ranged from 0.82 to 1.76. The simultaneous qualitative and quantitative analyses of bear bile powder was achieved, and minor steroid constituents were identified.