A GAS-CHROMATOGRAPHIC ANALYSIS OF FECAL SHORT-CHAIN FATTY-ACIDS, USING THE DIRECT-INJECTION METHOD

A simple, reproducible, and rapid gas chromatographic method for short -chain fatty acid determination in human feces was developed. It invol ves direct injection of fecal supernatants into the gas chromatograph, without any pretreatment. Contamination of the gas chromatographic co lumn with nonvolatile fecal material was prevented by the use of a gla ss liner in the injector. This liner, which acted as a precolumn, was stoppered with a glass wool plug at the lower end of the liner. Inject ion was performed against the glass wall of the liner, ensuring an imm ediate contact of the injected sample with the hot glass wall. More th an 100 injections of fecal supernatants could be carried out before th e liner had to be replaced by a new one. Peak tailing and ghosting was prevented by the use of formic acid in the fecal samples. The method gave sharp peaks with baseline separation for all the fatty acids. (C) 1996 Academic Press, Inc.