ASSESSMENT OF THERMODYNAMIC BEHAVIOUR OF INSECTICIDES IN INDIAN SOILS BY DIFFERENTIAL PULSE POLAROGRAPHY

Abstract

The differential pulse polarographic method was developed and validated for the investigation of electrochemical and thermodynamic properties of imidacloprid in soil. In DPP method, electrochemical reduction behavior of imidacloprid was studied in Britton-Robinson buffer (pH 3.0-10) as a supporting electrolyte. The range of linearity (R2 = 0.996) of imidacloprid was found to be from 1.0 μgmL-1 to 12.0 μgmL-1, the limit of detection (LOD) is 0.6552 μgmL-1 and the limit of quantification (LOQ) is 2.184 μgmL-1. The validated differential pulse polarography method was successfully applied for the study of thermodynamic parameters. It was observed from Freundlich parameters that the value of Kf for selected insecticide is normalized with % organic matter in four soils. The value of 1/n for all soils is less than one which indicates a greater affinity of adsorption of insecticides on soils in the order of KS1>KS2>KS3>KS4. The proposed method is accurate, precise, fast and economical.