代森锌及其代谢物在小白菜中的残留及消解动态

Residues and Dissipation Dynamics of Zineb and Its Metabolites in Pakchoi

[目的]建立小白菜中代森锌及其代谢物的检测方法,评价代森锌在小白菜使用后的安全性。[方法]在密闭系统中与氯化亚锡盐酸溶液反应,释放出二硫化碳,经正己烷吸收,气相色谱检测;乙撑硫脲经甲醇提取,无水硫酸镁净化,高效液相色谱-串联质谱测定。[结果]在优化的条件下,二硫化碳和乙撑硫脲相关系数R^2大于0.99,2者在小白菜中的平均回收率分别为83.4%~84.7%和77.9%~87.9%,相对标准偏差分别为2.1%~3.2%和1.5%~2.0%。代森锌在湖南和安徽2地的小白菜上的降解半衰期分别为2.4、1.8 d。[结论]该方法简便、准确、灵敏、快速,可满足代森锌及其代谢物在小白菜的残留检测要求。

[Aims] To establish a method for the determination of zineb and its metabolites in pakchoi, and to evaluate the safety of zineb in pakchoi. [Methods] Sample was used to react with the SnCl2-HCl solution in the sample bottle by ultrasonic extraction. Then CS2 was extracted by n-hexane, which was detected by using GC, ethylenethiourea was extracted by methanol, purified by anhydrous magnesium sulfate, and determined by high performance liquid chromatography-tandem mass spectrometry. [Results] Under the optimized conditions, the correlation coefficient of zineb and ethylenethiourea were more than 0.99, the average recovery were 83.4-84.7% and 77.9-87.9%, the relative standards were 2.1-3.2% and 1.5-2.0%, respectively. The degradation half-lives of zineb on Chinese cabbage in Hunan and Anhui provinces were 2.4 and 1.8 d, respectively. [Conclusions] The method is simple, accurate, sensitive and rapid, and can meet the requirement of residue detection of zineb and its metabolites in Pakchoi.