Residues of OO‐dimethyl S‐(N‐methylcarba moylmethyl) phosphorothiolothionate (dimethoate) in sprayed crops

Abstract A method for the determination of residues of the insecticide OO‐dimethyl S‐(N‐methyl‐carbamoylmethyl) phosphorothiolothionate (dimethoate) in crops is described. Radio‐chemical and biochemical investigations indicate that the method can be applied to growing crops without interference from metabolites in the plant derived from dimethoate. The limit of sensitivity of the method is about 5 °. of dimethoate, equivalent to o‐I p.p.m. in the plant tissue by the method described. Harvest residues found in many British and overseas crops 1–3 weeks after spraying with dimethoate are given.