A rapid spectrophotometric assay of some organophosphorus pesticide residues in vegetable samples

A rapid and sensitive spectrophotometric method for the determination of some organophosphorus insecticides, i.e. malathion, dimethoate and phorate is described. It is based on the oxidation of organophosphorus pesticide with slight excess of N-bromosuccinimide (NBS) and the unconsumed NBS is determined with rhodamine B (lambda max: 550 nm). Beer's law is obeyed in the concentration range 0.108–1.08, 0.056–0.56 and 0.028–0.28 μg mL−1 for malathion, phorate and dimethoate, respectively. The method has been successfully applied for the determination of organophosphorus pesticide residues in various vegetable samples.