Dissipation and decontamination of imidacloprid and lambda - cyhalothrin residues in brinjal

Residues ofimidacloprid at 20 g a.i. ha -1 and lambda -cyhalothrin at 15 g a.i. ha -1 were estimated quantitatively by HPLC/GLC in/on brinjal fruits. Initial deposits of insecticides were higher in imidacloprid than lambda -cyhalothrin. Initial deposits of 0.652 mg kg -1 of imidacloprid dissipated to 93.17 per cent on 10 th day. In lambda -cyhalothrin the initial deposits were 0.138 mg kg -1 which dissipated to 92.75 per cent on 10 th day. The degradation of imidacloprid was relatively higher as compared to lambda -cyhalothrin. Both imidacloprid and lambda -cyhalothrin had half -life values of 1.92 and 2.65 days, respectively on brinjal fruits. The safe waiting period for imidacloprid was found 4.70 days. In lambda -cyhalothrin, no waiting period is required after its application as the initial deposits were less than its MRL (0.3 mg kg -1 ).