Validation of a spectrophotometric method for soil adsorption study of thiophanate-methyl

Department of Chemistry, Himachal Pradesh University, Shimla-171 005, Himachal Pradesh, India

E-mail : dksharma_dk@rediffmail.com Fax : 91-177-2633014

Manuscript received online 04 January 2012, revised 05 February 2012. accepted 07 February 2012

With a view to study the fate of thiophanate-methyl in soil and the extent of surface and ground water contamination, the soil-adsorption of the fungicide on four Indian soils of different soil characteristics has been studied by using a batch-equilibrium method. A spectrophotometric methodology based on the reaction of the fungicide with copper(n) acetate in aqueous DMF solution to form yellowish green solution showing maximum absorbance at 395 om has been validated for the purpose. The leaching behaviour of the fungicide in terms of ground ubiquity score (GUS) has the value below 1.8, classifying thiophanate-methyl as non-leaching pesticide and hence it does not represent hazard to ground water contamination.