梨果实中百菌清的残留降解动态及安全性分析

The Residual Degradation Behaviors and Safety Analysis of Chlorothalonil in Pears

采用毛细管气相色谱（GC-ECD）法研究梨上百菌清的残留动态及套袋对百菌清残留的影响，测定方法的最低检出浓度为0．01mg／kg，其平均添加回收率为70．3％～96．2％，RSD为3．6％～6．2％。通过生长季节残留浓度的检测对北京郊区常规管理条件下百菌清的安全性进行分析。结果表明：百菌清在梨上的残留消解符合一级动力学方程。75％百菌清（chlorothalonil）可湿性粉剂推荐剂量稀释500倍液（A．I．1500mg／kg）施药1次，降解半衰期为3．22，1d后残留低于1．0mg／kg；加倍剂量稀释250倍液（A．I．3000mg／kg）施药1次，降解半衰期为3．53，3．30d后残留低于1．0mg／kg；A．I．1500mg／kg施药3次，7d后残留低于1．0mg／kg；A．I．3000mg／kg施药3次，14d后残留低于1．0mg／kg。百菌清主要残留于梨皮中，套袋后用药，采收时百菌清残留低于中国、欧盟、韩国最高残留限量（1．0mg／kg）。

The residual dynamics of chlorothalonil and effects of bagging on chlorothalonil residues in pear grown in open-fields were studied using gas chromatography with ECD. And the safety of chlorothalonil under the conventional management was analyzed through predicting residual concentrations during the growing season. The minimum detectable concentration by the GC method was 0.01 mg/kg, the average recovery rates were among 70. 3 % -96.2% ,and the RSD were 3.6%-6.2%. The results showed that the degradation dynamic equations of chlorothalonil were accorded with the first-order kinetics equation., With spraying 1 time of 75% chlorothalonil WP, the half-life was about 3.22 days （A. I. 1 500 mg/kg） at the dilution of 1：500 and 3.53 days （A. I. 3 000 mg/kg） at the dilution of 1： 250. And the residual concentrations were less than 1.0 mg/kg after 1 day and 3.30 days from the application. With spraying 3 times the residual concentrations were less than 1.0 mg/kg after 7 days and 14 days from the last application. Much of chlorothalonil residues were in pear peel, and the residues in pears with bagging at the harvest time were below the Maximum Residue Limit （MRL） from China, Europe and South Korea.