Studies on bile acids: The microquantitative separation of cellular bile acids by gas-liquid chromatography

Abstract

1. A method is described for the quantitative isolation of bile acids from cellular material. Homogenates of rat liver are freeze-dried and extracted exhaustively with 95% (v/v) ethanol containing 0.1% (v/v) of aq. ammonia (sp.gr. 0.88) and purified by anion-exchange chromatography on Amberlyst A-26. 2. The extracted bile acid conjugates are subjected to either of two hydrolytic procedures, one involving chemical and the other enzymic agents. A unique feature in this study is the introduction of an enzyme, a clostridial peptide-bond hydrolase, for the rapid cleavage of bile acid conjugates, replacing the classical drastic chemical hydrolysis with strong alkali. 3. After hydrolysis, free bile acids are methylated and converted into their trifluoroacetates for final determination by gas-liquid chromatography on a triple component column, FS-1265-SE30-NGS. 4. For the purpose of identification of peaks, bile acid methyl esters are converted into their trimethylsilyl ethers by allowing the methyl esters to react with a new and potent silyl donor, bis(trimethylsilyl)acetamide. 5. The technique affords us a means of studying the metabolism of bile acids at the cellular and subcellular levels in tissues.