A new method for the determination of some organophosphate insecticides

Department of Chemistry, University of Allahabad, Allahabad-211 002, India
Manuscript received 17 May 2002, revised 27 November 2002, accepted 10 February 2003

A quick and convenient method has been developed for milligram determination of some organophosphate insecticides. The sample is allowed to react with a calculated excess of (0.1 N) chloramine-T reagent in the presence of glacial acetic acid for 10-15 min at room temperature. After the reaction is over, KI solution (10%) is added and the unreacted reagent is backtitrated with 1 N solution of sodium thiosulfate to starch end-point. The method is applied for the determination of technical preparations of malathion (95%), dimethoate (90%), ethion (95%) and phorate (97%). The results are within the error of ±1.0%.