Capillary gas chromatographic separation of bile acid acyl glycosides without thermal decomposition and isomerization

A direct method for the capillary gas chromatographic (cGC) separation of the acyl glycosides of bile acids was successfully attained. The free acyl glycosides were derivatized to their complete trifluoroacetyl (TFA) derivatives with N-methyl-bis(trifluoroacetamide). The highly volatile TFA derivatives were chromatographed on a short-length (10 m), narrow-bore (0.1 mm) capillary column coated with a thin film (0.1 μm) of 5% phenyl polysilphenylene-siloxane at a column temperature below 280 °C. Each exhibited a single, well-separated peak of the theoretical shape without any accompanying peaks due to the thermal decomposition and isomerization. The bile acid 24α-glucosides were always eluted faster than the corresponding 24β-glucosides, which eluted before the corresponding 24β-galactosides. The method could be usefully applied to biosynthetic and metabolic studies of bile acid acyl glycosides in biological materials.