Investigation of new indirect spectrophotometric method for the determination of dichlorvos in environmental and agricultural samples

A new and highly sensitive spectrophotometric method is developed for the determination of sub ppm levels of, widely used organophosphorus insecticide dichlorvos. The method is based on alkaline hydrolysis of dichlorvos to dichloroacetaldehyde, which react with p-aminoacetophenone in alkaline medium. The absorption maxima of the yellowish-orange compound formed is measured at 450 nm. Beer's law is obeyed over the concentration range of 5.3 to 42 mu g in a final solution volume of 25 ml (0.21-1.68 ppm). The lower limit of detection is 0.06 ppm. The molar absorptivity, Sandell's sensitivity and correlation coefficient were found to be 2.3 x 10(4) L mol(-1) cm(-1), 0.011 mu g cm(-2) and 0.9989 respectively. The standard deviation and relative standard deviation were found to be +/- 0.004 and 2.70% respectively. The method is simple, sensitive and free from interferences of other pesticides and diverse ions. Other organophosphorous pesticides do not interfere with the proposed method. The method has been satisfactorily applied to the determination of dichlorvos in environmental and agricultural samples.