Analysis of Bile Acid by GC-MS

Introduction

With active research on intestinal flora, analysis of the components produced by intestinal flora, which include bile acids, has attracted attention. “Bile acid” is a generic term for compounds having a cholanic acid skeleton, which is a steroid derivative. In general, LC-MS/MS is frequently used in analyses of bile acid, but because many of the individual compounds have similar molecular structures, GC- MS is also used in many cases when more reliable separation is required. In order to secure volatility in GC-MS analyses of bile acid, derivatization of hydrophilic side chains such as the carboxyl group and hydroxy group is necessary. This article introduces an example of quantitative analysis of bile acid by methylation of the carboxyl group and trimethylsilylation (TMS) of the hydroxy group. In this example, a dynamic range of 100 times or more and good linearity with a coefficient of determination R² ≥ 0.995 were confirmed in all of 22 bile acid compounds.

November 13, 2019 GMT