Persistence of Cypermethrin and Decamethrin Residues in/on Brinjal Fruits

Residues of cypermethrin and decamethrin were estimated in brinjal fruits by gas liquid chromatography following single application of Cymbush 25 EC @ 43.75 and 87.50 g a.i./ha and of Decis 2.8 EC @ 11.20 and 22.40 g a.i./ha at fruiting stage. The average initial deposits of cypermethrin 0.600 and 1.095 mg kg⁻¹ and of decamethrin 0.430 and 0.900 mg kg⁻¹ were observed for single and double dose, respectively. Residues reached below maximum residue limit (MRL) value of 0.2 and 0.05 mg kg⁻¹ on third and seventh day for cypermethrin and decamethrin, respectively. The half-life values (t_1/2) were worked out to be 1.16, 1.18 days for cypermethrin and 1.33, 1.42 days for decamethrin at single and double dose, respectively following first order kinetics. Washing and washing followed by boiling/cooking processes were found to be effective in reducing the residues of both the insecticides in brinjal fruits. Maximum reduction (31–42%) and (26–37%) was observed by washing followed by boiling/cooking for cypermethrin and decamethrin, respectively.