Author(s): S .R. BARIK, S. MAJUMDER AND A. BHATTACHARYYA

Abstract: Imidacloprid 0.3% G is a new insecticide formulation having Imidacloprid [1-(6-chloro-3 pyridylmethyl) – N – nitroimida-zolidinimine] as active ingredient. A laboratory experiment was undertaken to determine the dissipation pattern as well as residue level of Imidacloprid 0.3% G exist in water maintained at different pH and soils of different agro-climatic zones following application at 1 ppm and 2 ppm. Samples were processed for analysis of Imidacloprid residues at intervals of 0 (2h after application), 5, 15, 30, 60 and 90 days after application. Imidacloprid 0.3% G was extracted from water by partitioning with dichloromethane. In case of soil samples the residue was extracted with acetonitrile: water (8:2) mixture. The extracts in acetonitrile were concentrated in rotary vacuum evaporator. The concentrated extract was subjected to solvent partitioning with dichloromethane. In both the cases, dichloromethane part after collection was evaporated to dryness in rotary vacuum evaporator. Final volume was reconstituted with acetonitrile for HPLC analysis. The residue of Imidacloprid 0.3% G in spiked water samples of pH 4.0, 7.0 and 9.2 as well as soils of different agro-climatic zones gradually decreased with time following first order kinetics in all the cases. The calculated half life (T1/2) values in water were found to be in the range of 66.9 to 94.07 days and in case of different soils these values were range of 59.03-75.26 days. The dissipation of Imidacloprid 0.3% G appeared to be faster in acid medium than neutral but slower in alkaline medium.

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