Gas chromatographic analysis of heptafluorobutyryl derivatives of some carbamate insecticides.

The gas chromatography (GC) of a number of carbamate insecticides as their heptafluorobutyryl derivatives has been studied. The reaction makes use of heptafluorobutyric anhydride with trimethylamine in benzene as a catalyst. Conversion of the insecticides to their products is complete in 15-20 min at room temperature. The same reaction proved satisfactory for trifluoroacetylation. The excess reagent and trimethylamine are removed by partitioning with water in the reaction test tube. An aliquot of the organic phase is used for analysis. The heptafluorobutyryl derivatives are stable for several days on the lab bench without removal of the aqueous phase from the test tube. GC detection was carried out with a Coulson conductivity detector in the halogen (reductive) mode. About 1.0 ng produced a 50% full-scale response for most of the carbamates (3 min retention time) on 3% OV-1. This method was applied to the analysis of several carbamates spiked in corn, mustard greens, turnip greens, lettuce and cabbage.