25%吡唑醚菌酯悬浮剂在7种蔬菜中的消解动态

Degradation Dynamics of 25%Pyraclostrobin Suspension Concentrate in Seven Vegetables

为评价吡唑醚菌酯在蔬菜中的安全性及其科学使用,采用高效液相色谱法测定了25%吡唑醚菌酯悬浮剂在7种蔬菜中的残留及消解动态。结果表明,在0.05、0.20和1.00 mg/kg添加水平下,吡唑醚菌酯蔬菜样品中的平均添加回收率为91.1%~99.5%,相对标准偏差为2.3%~4.1%。消解动态试验表明,25%吡唑醚菌酯悬浮剂在白菜、韭菜、黄心乌白菜、奶油小白菜、奶油生菜、香菜和萝卜菜中的消解动态均符合一级反应动力学模型;其中,吡唑醚菌酯在白菜中的消解速率较快,半衰期为1.36 d,在黄心乌白菜、奶油小白菜、香菜和萝卜菜中的消解次之,半衰期分别为2.10、2.31、2.67和2.89 d;而其在韭菜和奶油生菜中的消解较慢,半衰期分别为5.33和6.93 d,属于易降解农药。最终残留试验结果显示,施药14 d后,吡唑醚菌酯在7种蔬菜中的残留量均可降解至5 mg/kg以下,符合食品中农药最大残留限量。试验结果为吡唑醚菌酯在蔬菜生产中的科学安全使用提供依据。

In order to evaluate the safety of pyraclostrobin in vegetables and guide its scientific use,the residue and degradation dynamics of 25%pyraclostrobin suspension concentrate(SC)in seven vegetables were determined by high performance liquid chromatography(HPLC).The results showed that under the addition levels of 0.05,0.20 and 1.00 mg/kg,the average recovery of 25%pyraclostrobin suspension concentrate(SC)in vegetable samples was 91.1%~99.5%,the relative standard deviation was 2.3%~4.1%.The degradation dynamics of 25%pyraclostrobin SC in Chinese cabbage,leek,huangxinwu Chinese cabbage,cream Chinese cabbage,cream lettuce,coriander and radish conformed to the first-order reaction kinetic model.Among them,the degradation rate of pyraclostrobin in Chinese cabbage was faster with the half-life of 1.36 d,which followed by huangxinwu cabbage,cream cabbage,coriander and radish with the half-life of 2.10,2.31,2.67 and 2.89 d,respectively.While,its digestion in leek and cream lettuce was slow with the half-life of 5.33 and 6.93 d,respectively.Therefore,pyraclostrobin belonged to the easy degradation pesticide.After 14 d of last application,the residue of pyraclostrobin in seven vegetables could degrade below 5 mg/kg,which was in line with the maximum residue limit of pesticides in food.The test results provide a basis for the scientific and safe use of pyraclostrobin in vegetable production.