A simple and quick gas chromatographic method for the determination of propham and chlorpropham in potatoes.

This study describes a gas chromatographic method for the quantitative determination of residual propham and chlorpropham in potatoes. Both herbicides are extracted from the foodstuff with methylene chloride. After centrifugation and concentration, propham and chlorpropham are quantitatively determined by gas chromatography thermionic detection using a fused silica capillary column CP Sil 5CB. 2-Chloraniline is used as internal standard. Recoveries of 100 +/- 15% and 99 +/- 10% have been obtained for propham and chlorpropham in blank samples spiked at the level of 0.5, 1.0 and 5.0 mg/kg. The absolute detection limit for both compounds is 1 ng corresponding to 0.1 mg/kg. Of the 161 samples of fresh potatoes analysed using this method, 136 contained residues of these herbicides and 18 of them (11%) exceeded the maximum tolerated value of 5 mg/kg.