Voltammetric study of the hydrolysis product of fenthion at the Nafion®-modified glassy carbon electrode

The differential pulse voltammetric (DPV) method is proposed for the determination of phosphorothioate insecticide (fenthion) based on the oxidation of its hydrolysis product. A single peak at +0.65 V (vs. Ag/AgCl) is observed at the Nafion (R)-modified glassy carbon electrode in 0.1 M Britton-Robinson buffer solution (pH 4.0) as a supporting electrolyte. The voltammetric behavior of fenthion was investigated over a wide range of pH (2.0-8.0). The effect of the solution and operational parameters on the sensitivity of the DPV peak was carefully examined in order to select the optimum conditions for the determination of fenthion. Under optimum conditions, the oxidation response gives a linear calibration plot over a concentration range of 8.41 x 10(-7)-5.98 x 10(-6) M and the detection limit is found to be 7.6 x 10(-7) M. The effects of some diverse metal ions, anions, and some other organic molecules on the determination of fenthion were studied. The applicability of DPV for the determination of fenthion insecticide in a commercial sample as well as in some water samples was demonstrated.