50%乙草胺水乳剂在油菜田的残留动态研究

A Study on Dynamic Changes of Acetochlore 50% EW Residue in Rape Field

采用气相色谱法测定了乙草胺在油菜植株、籽、籽壳及土壤中的消解动态和最终残留。油菜植株、籽、籽壳样品用二氯甲烷提取,土壤用甲醇提取,经弗罗里硅土净化,GC-ECD检测,外标法定量。结果表明:乙草胺的添加量在0.005～1.0mg/kg水平下,乙草胺在土壤、油菜植株、籽、籽壳中的平均回收率分别为85.3%～96.5%、86.9%～90.3%、83.3%～89.7%、87.9%～90.4%,相对标准偏差分别为3.9%～5.0%、3.9%～9.5%、6.6%～14.3%、6.4%～11.1%,乙草胺的最小检出量(LOD)为5×10-12g,油菜植株、籽及籽壳中的最低检测浓度(LOQ)为0.01mg/kg,土壤中的LOQ为0.005mg/kg。乙草胺在福建莆田和湖南长沙土壤中的半衰期分别为3.5、5.2天,在油菜植株中的半衰期分别为1.7、2.3天,油菜收获时(距施药60天),油菜田土壤、植株和油菜籽及壳中均未检测出乙草胺残留。

Gas chromatography was involved to reveal the dynamic changes of acetochlor residue and the final residue of aeetoehlor in rape plant, rape shell, rape kernel and soil samples. Soil samples were extracted with methanol and other samples were extracted with methylene chloride. The extracts were cleaned up by florisil. When samples were fortified with acetochlor at the levels between 0.005 mg/kg and 1.0 mg/kg, the recovery ranged from 85.3% to 96.5% for soil, 86.9% to 90.3% for rape plant, 83.3% to 89.7% for kernel, and 87.9% to 90.4% for shell, with the relative standard deviations of 3.9% 6.4% to 11.1% respectively. The limit of detection （LOD） quantification （LOQ） was 0.005 mg/kg for soil, and 0.01 mg/kg to 5.0%, 3.9% to 9.5%, 6.6% to 14.3%, and of the method was 5 ~ 10-n g. The limit of for other samples. The half-life of acetoehlor in Putian of Fujian province and Changsha of Hunan province was 3.5 days and 5.2 days in soil, and 1.7 days and 2.3 days in plant, respectively. No acetochlor residue was detected in rape plant, rape shell, rape kernel and soil samples in the treatments of 750-1125 g （a.i.）/hm2 at harvesting season （60 days after the treatment）.