A novel method for the assessment of methyl parathion by using coupling agents in environmental and commercial samples

A sensitive and rapid spectrophotometric method for the determination of reduced methyl parathion (=O,O-dimethyl O-(4-nitrophenyl) phosphorothioate) is described. The method is based on the interaction of diazotized reduced methyl parathion with 8-hydroxyquinoline (quinolin-8-ol; 8-HQ) and 3-aminophenol (3-AP) as new coupling agents. Absorbances of the resulting chromophores are measured at 430 and 440 nm, respectively, and colored products were stable for at least 2 days. Beer's law is obeyed over the methyl parathion concentration range 0.2-5.5 mu g ml(-1) for 8-HO and 0.5-6.0 mu g ml(-1) for 3-AP. From the data, it was confirmed that the two coupling agents can be effectively applied for the determination of methyl parathion in environmental and commercial samples.