Dissipation kinetics of beta-cyfluthrin and imidacloprid in brinjal and soil under subtropical conditions of Punjab, India.

Dissipation of beta-cyfluthrin and imidacloprid was studied following three applications of a combination formulation of Solomon 300 OD (beta-cyfluthrin 9% + imidacloprid 21%) @ 60 and 120 g a.i. ha(-1) at 7 days interval. Samples of brinjal were collected at 0, 1, 3, 5, 7, 10 and 15 days after the last application and residues of beta-cyfluthrin and imidacloprid were estimated on gas liquid chromatography (GLC) and high performance liquid chromatography (HPLC), respectively. Half-life periods for beta-cyfluthrin were found to be 1.74 and 1.39 days and for imidacloprid these values were observed to be 2.31 and 2.18 days, respectively, at single and double the application rate. beta-Cyfluthrin residues dissipated below the limit of quantification (LOQ) of 0.01 mg kg(-1) after 5 and 7 days, respectively, at single and double the application dosages whereas imidacloprid residues took 10 days for both the dosages. Soil samples collected after 15 days after the last application did not show the presence of beta-cyfluthrin and imidacloprid at their detection limit of 0.01 mg kg(-1).