Pulse polarographic determination of thiophanate methyl fungicide in relation to its soil adsorption study

Abstract

Background: The environmental pollution caused by the extensive use of the pesticide thiophanate methyl is of great concern, because it is a category III acute toxicant and a suspected carcinogen. Method: A remarkably sensitive differential pulse polarographic method for the determination of thiophanate methyl has been developed. The method is based on the reaction of the fungicide with copper(II) perchlorate in the presence of butylmethylimidazolium bromide (ionic liquid) in acetonitrile. Results: The reaction product exhibits an analytical useful diffusion controlled peak at −180 mV (vs SCE), and the thiophanate methyl has been determined in the linearity range 1.25 × 10−6 to 12.5 × 10−6 mol L−1 with a correlation coefficient of 0.997. To study the fate of this pesticide in soil and extent of surface and groundwater contamination, its adsorption on four soils of different soil characteristics has been studied using batch equilibrium technique. Conclusion: The leaching potential, a measure of ground and surface water contamination, has been evaluated in terms of groundwater ubiquity score (GUS) and the value obtained is in the range 0.87 to 0.97, classifying it as non-leaching pesticide.