Analytical Sciences

Separation and Detection of Bile Acid 24-Glucuronides in Human Urine by Liquid Chromatography Combined with Electrospray Ionization Mass Spectrometry

Shigeo IKEGAWA, Hiroko OKUYAMA, Junji OOHASHI, Naoaki MURAO and Junichi GOTO*

Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan

A method for the separation and determination of bile acid 24-glucuronides using liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometry (MS) has been developed. In the ESI mode, 24-glucuronides were characterized by an intense deprotonated molecule [M-H]^- with a fragment ion [M-H-176]^- formed by elimination of the glucuronic acid moiety. The ratio of these negative ions was significantly influenced by the orifice-1 and the ring lens voltages. Bile acid 24-glucuronides in human urine were extracted with an OASIS HLB cartridge and then subjected to the LC/ESI-MS analysis employing an ¹⁸O-labeled internal standard. The simultaneous separation was attained on a Develosil ODS-HG-5 column using 20 mM ammonium acetate (pH 6.0)-acetonitrile (3:1-> (Keywords: Bile acid, acyl-glucuronide, ester glucuronide, stable isotope labeling, electrospray ionization, liquid chromatography/mass spectrometry)

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