Degradation pattern and risk assessment of imidacloprid in country bean using gas chromatography

Abstract

Abstract : The degradation pattern of Imidacloprid on country bean and its risk assessment for the safe consumption were studied. QuEChERS method was used for the extraction and cleanup of samples and the residues of Imidacloprid were estimated using Gas chromatography. The dissipation studies on country bean were carried out by application of Imidacloprid at five different dosages i.e. 100, 200, 300, 400, and 500 g a.i. haV Average initial deposits of Imidacloprid were 0.37, 0.73, 1.35, 2.15 and 3.52 mg.kg~‘, respectively. The residues reached below determination limit (BDL) of 0.01 mg kg'1 in nine days for recommended dose and 12 days for remaining higher doses . Half-life (T//2) of Imidacloprid on country bean was observed 2.47, 2.21, 1.90, 1.83 and 1.77 days, respectively, at 100, 200, 300, 400, and 500 g a.i. ha'1. The ehemodynamics study of Imidacloprid spray indicated that only 27.20 - 28.40% sprays were deposited to the target site (plant canopy) and 71.60-72.80% were lost to non-target site, such as soil and air. The drift of Imidacloprid to soil (39.47-40.20%) was higher than that of the air (32.13-32.60%). It was found that the theoretical maximum residue contribution (TMRC) values reached below maximum permissible intake (MPI) on 0 day (1 hour of treatment) in country bean samples treated with imidacloprid. This study, therefore, suggested that the use of Imidacloprid formulation at different dosages (up to five times than recommended doses) does not seem to pose any hazards to the consumers. The maximum Half-life (T1/2) of Imidacloprid was found 2.47 days. Therefore, a waiting period of three days might be suggested to reduce the risk before consumption of country bean grown in Imidacloprid contaminated soil.