Residue and decline study of emamectin benzoate in rice field

The residual dynamics and final residues of emamectin benzoate in paddy,rice,water and soil samples were determined by high performance liquid chromatography equipped with ultraviolet detector(HPLC-UVD).Water samples were extracted with methylene chloride and other samples were extracted with acetone/water (7∶ 3,V/V),the extracts were cleaned up by liquid-liquid extraction.Under the fortified level 0.050 to 1.0 mg/kg,the recovery ranged from 88.44% to 94.10% for water,86.29% to 101.1% for paddy,84.49% to 105.5% for rice,86.69% to 93.27% for soil with the relative standard deviations of 3.09% to 10.57% ,11.28% to 13.68% ,2.62% to 6.73% and 6.72% to 8.89% ,respectively.The limit of detection of the method was 0.018 mg/kg,the limit of quantification was 0.061 mg/kg for rice.The half-life of emamectin benzoate was 1.52 to 1.61 days in paddy,1.93 to 2.04 days in water and 2.01 to 2.14 days in soil,respectively.When sprayed for 4 successive times at application rate of 750 g/hm2,at interval time of 7 d after the last application,the final residues of emamectin benzoate in rice were lower than LOQ.