An easy procedure for determination of molar activity (or specific activity) of bile acids in bile

An easy procedure is described for determination of the molar activity of the major bile acids, labelled with 14C, in bile. The procedure involves initial enzymatic hydrolysis, by which the amino acid moieties are removed from the glycine and taurine conjugated bile acids by means of choloylglycine hydrolase, followed by thin-layer chromatographic separation of the unconjugated bile acids, cholic acid, chenodeoxycholic acid, and deoxycholic acid. Then the bile acids are eluted from the individual silica gel spots concerned. Finally, determination of the radioactivity by liquid scintillation counting and of the amount of substance by an enzymatic method using 3 alpha-hydroxysteroid dehydrogenase is performed in the eluates. The method requires only a small volume of sample and allows of separate determination of the molar activity of cholic acid and chenodeoxycholic acid, labelled with the same isotope, in the same sample.