[Gas chromatographic analysis of C1-C6 fatty acids in rat fecal samples]

A gas chromatography procedure was performed to determine C1-C6 fatty acids in rat feces. Acidated fecal homogenate was extracted with ethyl ether-petroleum ether (1 + 1). After adding tetramethylammonium hydroxide to the extract, the quaternary ammonium salts of the fatty acids could react with ethyl bromide in the presence of N,N-dimethyl acetamide producing corresponding esters. The derived products were separated by the column packed with ethylene glycol succinate polyester and were determined with Flame ionization detector (FID). The extractive efficiencies of C1-C6 fatty acids from the fecal samples were 88.5%-100%, and the recoveries ranged from 82.4% to 110.8% with the coefficients of variation of 3.2%-10.9%. The detection limits were at 1ppm. The optimum conditions of esterification are discussed. The method is safe and rapid, and has been applied to the analysis of C1-C6 fatty acids in rat feces.