Determination method of bile acids in biological materials by mass fragmentography (author's transl)

Abstract

A new method was developed for quantitative analysis of deuterium-labelled and endogenous bile acids in human serum, urine, bile and feces. The conventional extraction method was modified to improve the recovery of the sulfated bile acids. The sulfated and nonsulfated bile acids were adsorbed on an Amberlite XAD-2 column, eluted with methanol containing 20 mM NaOH, and separated on a Sephadex LH-20 column. Sulfated bile acids were dissolved in ethanol (pH 1)-acetone (1 : 9, v/v) and solvolysed for 3 hr at 37°. A new alkaline hydrolysis method was also devised ; bile acids were dissolved in 4 N NaOH-methanol (1 : 1, v/v) and hydrolyzed in a screw-capped Pyrex glass tube at 80° for 16 hr. After extraction with ether, bile acids were converted to methyl ester propionate derivatives. The determination of endogenous and deuterium-labelled bile acids was accomplished by gas chromatography-mass fragmentography. The reproducibility of the present method was good (3-8% of relative standard deviation for endogenous bile acid in serum) and 11, 12-2H2-chenodeoxycholic acid was determined up to 1% of the coexisting chenodeoxycholic acid. Endogenous bile acid levels in biological materials were measured and compared with previously reported results. The present method was sensitive and useful for the quantitation of minute amounts of bile acids. Further, this was a recommendable method for the determination of pool size of bile acids by using deuterium-labelled bile acids.