Residue and Field Decline Study of Acetochlor in Rice Field

Gas chromatography equipped with an Electron-capture detector(GC-ECD) was conducted to reveal the residue dynamics and final residues of acetochlor in rice,water and soil samples.Soil samples were extracted with methanol and other samples were extracted with methylene chloride.The extracts were cleaned up by liquid to liquid separation.The recovery ranged from 87.2% to 96.8% for paddy,94.0% to 99.3% for water,83.6% to 93.7% for soil with the relative standard deviations of 3.80% to 7.66%,3.46% to 7.54% and 2.70% to 6.41% respectively.The limit of detection(LOD) of the method was 1.29×10-11 g.The limit of quantification(LOQ) was 1.3×10-3 mg/kg for rice.The half-life of acetochlor was 1.21 to 2.07 days in paddy,1.30 to 2.56 days in water and 1.22 to 2.41 days in soil,respectively.When applied once at the dosage of 90 g/hm2,the final residues of acetochlor in rice were lower than LOQ.