Gas-Liquid Chromatographic Analysis of N-(4-Chlorophenyl-N′-2,6-difluorobenzoyl)urea Insecticide After Chemical Derivatization

The gas-liquid chromatographic analysis of TH 6040 (N-(4-chlorophenyl)-N′-(2,6-difluorobenzoyl)urea) was carried out after the insecticide was converted to its N,N′-dimethyl analog (N-methyl-N-(4-chlorophenyl)-N′-methyl-N′-(2, 6-difluorobenzoyl)urea). The methylation was accomplished in DMSO with sodium hydride and methyl iodide. The derivative was thermally stable and chromatographed as a single peak on 3% OV-1 at 235°C. Support for the structure of the product was given by mass spectrometry. The sensitivity of the product to electrolytic conductivity detection was approximately 50 ng for 50% full-scale deflection in the nitrogen mode and 70 ng for the same response in the chloride (reductive) mode. About 0.25 ng was required for 50% full-scale deflection by electron capture (at 1 × 10−9 amp standing current). Foliage samples were analyzed for TH 6040, using the proposed method.