RESIDUE AND DISSIPATION KINECTICS OF ABAMECTIN IN COLE AND SOIL

Field trial was conducted to study the residue and dissipation kinetics of abamectin in cole and soil in Beijing and Shandong.A high performance liquid chromatography(HPLC) with fluorescence detector(FLD) was employed for the determination of abamectin.At fortified level of 0.005—0.1 mg·kg-1,average recoveries of abamectin in cole and soil were 88.3%—99.3% and 85.9%—95.9%,with relative standard deviation(RSD) of 4.0%—7.2% and 4.4%—6.5%,respectively.Results of dissipation study showed that the degradation of abamectin in cole and soil fit first-order model well and half lives derived were 1.7—1.8d and 3.5—3.9d,respectively in cole and soil.At doses of 13.5 g(a.i.)·ha-1 and 27.0 g(a.i.)·ha-1,sprayed 2—3 times,and a 7d interval,abamectin residue in cole was below the MRL of 0.05 mg · kg-1,A preharvest interval(PHI) of 3 days is therefore recommended based on our study.