A chemical confirmatory test for organophosphorus and carbamate insecticides and triazine and urea herbicides with reactive NH moieties

Article abstract of DOI:10.1021/jf60198a061

The effects of different solvents and temperatures on the base catalyzed reaction of O,O-diethyl N-methyl phosphoramidothioate and methyl iodide were studied. The N-methyl derivative was obtained in high yield in dimethyl sulfoxide at 50° for 10 min with sodium hydride as the base. This alkylation procedure was adapted to the microgram level and applied to 16 insecticides and herbicides which have an NH or NH₂ moiety. With carbamates, the best yields were obtained when the reaction was carried out at room temperature. The alkylated derivatives of organophosphorus and carbamate insecticides and triazine and urea herbicides all had better gc characteristics than the parent compounds. Thus, the alkylureas readily chromatographed on SE-30/QF-1 under conditions where the parent compounds decomposed. On this column, the alkylated phosphoramidothioates and carbamates also had shorter retention times. Alkylation of crude extracts of soil, plants, and blood plasma containing herbicides and insecticides illustrated the ability of the sodium hydride methyl iodide dimethyl sulfoxide procedure to confirm the identity of residues at the sub parts per million level.