Packed and capillary column gas chromatographic analysis of fecal samples for volatile fatty acids

Abstract

Procedures for analyzing volatile fatty acids content of aqueous samples using packed and capillary chromatography columns are described and compared. A packed column system tolerant of aqueous samples was used that incorporated a formic acid vapor entrainment device. This permitted a simple sample preparation and concentration scheme. This system was compared to capillary column analysis with split, manual, or autosampler injection. The autosampler/capillary system used a solvent trapping technique not previously applied to aqueous sample chromatography. The capillary column gave greatly increased resolution, resulting in more precise quantitation and lower detection limits but with slightly longer analysis time. These procedures have been successfully applied to the analysis of volatile fatty acids in large numbers of fecal samples.Volatile fatty acids (VFAs), acetic through valeric, are common

Analysis of volatile fatty acids in biological specimens by capillary column gas chromatography

“…With subsequent injections, these constituents may be released, and this phenomenon has been referred to as "ghosting" or "memory effect." This type of absorption has been reduced by using glass columns in preference to stainless steel columns (5), by incorporating phosphoric acid into the packing materials (5) and by incorporating formic acid into the carrier gas stream (6). To some extent, these problems have been overcome by using capillary column chromatography (6).…”

“…This type of absorption has been reduced by using glass columns in preference to stainless steel columns (5), by incorporating phosphoric acid into the packing materials (5) and by incorporating formic acid into the carrier gas stream (6). To some extent, these problems have been overcome by using capillary column chromatography (6). Recently, these constituents were reported to be separable by employing a fused silica capillary column coated with OV-351, which is a Carbowax nitroterephthalic acid polymer, and a split injection mode chromatography procedure (6).…”

“…To some extent, these problems have been overcome by using capillary column chromatography (6). Recently, these constituents were reported to be separable by employing a fused silica capillary column coated with OV-351, which is a Carbowax nitroterephthalic acid polymer, and a split injection mode chromatography procedure (6). A similar technique has been used by others to analyze these constituents in human urine (7).…”

Energy metabolism of growing pigs

“…Formic acid prevents ghosting of VFA as they elute from the column as shown by Gray and Olson (1985). However, formic acid Is easily contaminated by acetic acid and therefore a more pure form would be necessary for this analysis.…”