乙酰甲胺磷及其高毒代谢物甲胺磷在白菜中的残留动态

为明确乙酰甲胺磷在叶菜类蔬菜上使用后的环境安全性,采用气相色谱法比较研究了露地与设施栽培条件下乙酰甲胺磷及其高毒代谢物甲胺磷在白菜中的残留动态规律和最终残留。结果表明,按推荐使用剂量、2倍推荐使用剂量施药1次,乙酰甲胺磷在白菜中降解半衰期为2.060～3.203 d,大棚条件下降解速度慢于露地条件下降解速度;乙酰甲胺磷在降解过程中可代谢产生甲胺磷,作物中甲胺磷的残留量是乙酰甲胺磷代谢生成和甲胺磷本身降解两个过程共同作用的结果,施药几天后,出现一个甲胺磷残留的高峰;乙酰甲胺磷施用在白菜上可能会有较高的甲胺磷残留风险,尤其是大棚栽培方式、施药浓度高的情况下使用乙酰甲胺磷具有更高的甲胺磷残留风险。因此,在白菜等叶菜类蔬菜上应谨慎使用乙酰甲胺磷,露地栽培条件下的安全间隔期应延长为21 d,设施栽培条件下不宜使用。

Residue Dynamics of Acephate and Its Metabolite Methamidophos in Pakchoi

In order to definitude environmental safety and establish safe application standard,residue dynamics and final residue of acephate and its metabolite methamidophos were comparatively studied by the method of gas chromatography in open field and greenhouse vegetables.Meanwhile a safe application method of the insecticide was developed to provide a guidline for application of acephate in field,and to refine and update the residue data which was helpful to determine the harvest interval.The results showed that when the 30% acephate（EC） was applied one time by the dilution with 1∶1 000 and 1∶500,the half-lives of acephate in pakchoi were 2.060～3.203 d,respectively.The half-lives in greenhouse were longer than that in open field,which implied that acephate in greenhouse was more slowly degraded than that in open field.Acephate could be metabolized to methamidophos in the process of degradation,and the residue of methamidophos resulted from both degradation and metabolism.There was a distinct peak of methamidophos residue after several days of treatment.With the application of acephate on pakchoi,there could be a high methamidophos residue risk,and there was a higher residue risk under greenhouse conditions and higher concentration of the pesticide.It′s suggested that it should be careful to apply acephate on leafy vegetables.The safe interval of acephate should be extended to 21 days before harvest,and the quality of the products will meet the minimum requirement level（MRL） on pakchoi of China.The application of acephate is not recommended under greenhouse conditions.