异丙甲草胺在稻田环境中的降解与残留研究

Study about Decomposition and Residue of Metolachlor on the Rice Field

研究异丙甲草胺在水稻、土壤、田水中的残留分析方法及其消解动态和最终残留。样品以乙腈提取,净化后采用毛细管气相色谱法-电子捕获检测器进行测定。在0.005、0.05、1.00mg/kg3个添加水平,平均回收率为88.42%～101.25%,变异系数为1.49%～9.51%,符合农药残留分析的要求。运用上述方法,测定异丙甲草胺在稻田环境中的消解动态和最终残留。试验结果表明,异丙甲草胺在土壤和田水中消解较慢,在稻秆中消解则较快,在土壤、田水和稻秆的平均半衰期分别为42.63d、39.21d和17.42d;20%异丙甲草胺WP按有效成分用量950g/hm2,在直播水稻田水稻播种后施药1次,收获时异丙甲草胺在土壤、稻杆和稻谷中的残留量均低于0.05mg/kg。

The method of residue analysis of metolachlor,its degradation and residue in rice,soil and water were studied.Residues of metolachlor were extracted from straw,soil and water samples with acetonitrile.After been cleaned up,the final extract was injected into GC with ECD.The precision and recovery tests were made at the spike level of 0.005,0.05 and 1.00 mg/kg,and the results were as follows：recoveries in the range of 88.42%-101.25%,coefficients of variation 1.49%-9.51%.The dissipation rate was fast in straw than in water and soil,while,the residual dynamics had no evident difference between in water and soil.The average half-lives（T1/2） in soil,water and straw were 42.63 d,39.21 d and 17.42 d,respectively.The residue levels in soil,straw and rice seeds were lower than 0.05 mg/kg by the rice harvest,when 20% metolachlor WP was applied to the direct seeding rice fields dusting one time at 950 g/hm2（a.i.）.