1978 Volume 27 Issue 7 Pages 381-386
The gas chromatographic determination of the traces of n-, iso-butyric and n-, iso-valeric acids in air at ppb level was performed using a precolumn. The chromatographic conditions were as follows: main analytical column packing, 0.3% FFAP +0.3% H3PO4 on Carbopack B (60/80 mesh) ; column size, 1.5 m × 3 mm i. d., glass; column temperature, 200°C; carrier gas, nitrogen flow rate, 65 ml/min. The four fatty acids were separated within 8 min without tailing. The precolumn packing, 0.3% SP-1000 + 0.3% H3PO4 on Carbopack B (60/80 mesh) ; column size, 18 cm × 4 mm i.d., glass. The trapping was operated at room temperature (about 20°C) and the temperature was elevated to 200°C in 24 s. The acids were detected with a flame ionization detector (FID). The coefficient of variation of the retention times and the peaks areas (as the counts of digital integrator) of (91000) ng of the four fatty acids in this method were less than 3.8% and 9.7%, respectively. The linear relationship was obtained between the peak areas and the amounts of four fatty acids over the range (24000 ) ng. The minimal detectable quantity of the four lower fatty acids was about 0.5 ng. The present method was applied to the determination of known concentrations {about (1113) ppb} of the four lower fatty acids in 10 m3 odor free room. The coefficient of variation of the determination was less than 11%.
