Bile acids are primarily produced in mammalians through cholesterol catabolism in the liver. Primary bile acids can be associated to taurine or glycine to form conjugates and transformed by gut bacteria giving secondary forms thereof. They constitute then a large family of molecules with several position isomer groups. Their role as digestive surfactants to promote lipids absorption is well-known. But these hormones are also involved in various metabolic pathway regulations. Blood enzyme activity tests (ALT, AST, etc.) and total bile acid test are widely conducted for the early diagnosis of liver disease and functional evaluation. However, although it can be confirmed that the liver function declines with the evaluation of total bile acid amount, it does not give much information in case of metabolic troubles. Therefore, clinical researchers could get more valuable information with a more precise and larger bile acids profiling. Due to their molecular structure, these compounds are also difficult to fragment by tandem mass spectrometry. Therefore, a good chromatographic separation is needed for accurate identification and quantification.
A newly developed method package (Shimadzu Corp., Kyoto, Japan) providing liquidchromatography and tandem-mass spectrometry conditions for the analysis of 28 bile acids and 10 internal standards was applied to human plasma samples.