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ISRN Analytical Chemistry
Volume 2013 (2013), Article ID 805678, 6 pages
Research Article

Microwave-Assisted Derivatization of Bile Acids for Gas Chromatography/Mass Spectrometry Determination

1Departamento de Química, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627 Pampulha, 31270-901 Belo Horizonte, MG, Brazil
2Universidade Federal de São João Del Rei, Avenida Sebastião Gonçalves Coelho 400 Chanadour, 35501-296, Divinópolis, MG, Brazil

Received 8 July 2013; Accepted 7 August 2013

Academic Editors: D. J. Fletouris, R. K. Jyothi, A. Przyjazny, and I. Zhukov

Copyright © 2013 Maria José Nunes de Paiva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bile acids derived from cholesterol are produced in the liver, and their analysis is difficult due to their complex natures and their low concentrations in biological fluids. Mixtures of various derivatives, created via conventional heating, are used for such analyses. Microwave radiation is proposed to accelerate the derivatization process. This paper presents a mass fragmentation study and microwave-assisted derivatization (MAD) for the silylation of bile acids (cholic and ursodesoxycholic) prior to gas chromatography and mass spectrometry analysis. The derivatization was performed using the two-step process of methoximation and silylation. The reaction time, power, and quantity of N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TCMS) were optimized to improve the derivatization. The optimized derivatization conditions required 210 W for 3 min. The MAD method exhibited linearity with respect to cholic acid between 0.78 and 20.0 μg mL−1 with an LOQ of 0.23 μg mL−1 and a precision ranging from 1.08% to 9.32% CV. This optimized derivatization method is valid for the analysis of bile acids in different matrices.