Sensitive Spectrophotometric Determination of Chlorpyrifos in Different Environmental and Biological Samples

A highly sensitive spectrophotometric method was developed for the determination of organophosphorous insecticide, chlorpyrifos, which is widely used. This method is carried out on the basis of alkaline hydrolysis of chlorpyrifos to 1, 2, 4-trichloropyridine (TCP), followed by coupling with diazotized 2-amino-8-hydroxy quinoline in alkaline medium. The absorption maxima of the orange dye formed was measured at 420 nm. Beers law was obeyed over the concentration range of 1 g to 8 g (0.01-0.08 mgL-1) in a final solution of 10 mL. The molar absorptivity, Sandells sensitivity and Correlation coefficient was found to be 9.04 x 109 mol-1 cm-1, 0.010 g cm-2 and 0.897 respectively. The Standard deviation and Relative standard deviation are 0.00811 and 2.45 %. The method was simple, cheap, sensitive and selective. The method was satisfactorily applied to the determination of chlorpyrifos in various environmental and biological samples.