Gas-chromatographic determination of trace amounts of lower fatty acids in ambient air near and in exhaust gases of some odour sources

Abstract

The gas-chromatographic determination of trace amounts of the lower fatty acids (C₂—C₅) in ambient air near and in the exhaust gases of some odour sources was investigated. The sample for the gas-chromatographic determination was prepared by trapping in a pre-column packed with FFAP + orthophosphoric acid (H₃PO₄) on Carbopack C at 25 and 30 °C. The lower fatty acids were identified and quantitated from the difference between the chromatograms obtained using the FFAP + H₃PO₄ pre-column and that obtained using the FFAP + H₃PO₄ plus an alkaline pre-column. The method has been applied to the analysis of lower fatty acids in practical specimens, namely the ambient air near accumulated poultry manure, in a pig pen and a fish meal factory, and in the exhaust gases from a corn starch manufacturing factory and from a poultry manure dryer. The sample volume is as low as about 0.4 l and the method is sensitive (detection limit about 0.5 p.p.b.) and rapid (including the concentration and analysis of one sample, about 15 min are required). The coefficient of variation is less than 6%. This sensitivity and precision are adequate for use in odour pollution analysis.