Determination of 1β-Hydroxylated Bile Acids and Related Compounds in Human Biological Fluids by Gas Chromatography-Mass Spectrometry

Abstract

A highly sensitive and specific quantitative assay of the 1β-hydroxylated bile acids and related compounds has been developed by gas chromatography-selected ion monitoring of their methyl ester-trimethylsilyl ether derivatives using the deuterium labeled internal standards: [2H7] DCA, [2H7] CA, [2H5] 3β-hydroxy- and [2H6] 3β, 12α-dihydroxy-5-cholen-24-oic acids. Calibration curves for these bile acids are useful over the range of 0.01-100μg in serum (0.2 ml), urine (5ml), or lyophilized meconium (1mg). Recoveries of the bile acids and their conjugates ranged from 92 to 101% of the added amounts of their standard samples. In the analysis of bile acids in human meconium by the developed method, novel 1β, 3α, 7α-trihydroxy- (II) and 1β, 3α, 7α, 12α-tetrahydroxy- (IV) 5β-cholan-24-oic acids were determined in significant amounts of 0.24μg/mg (5.3% of the total bile acids) and 0.27μg/mg (6.3%), respectively.