螺螨酯和螺虫乙酯在覆膜金橘中的降解残留规律研究

Degradation of Spirodiclofen and Spirotetramat Residue in Kumquat with Film Mulching

为评价螺螨酯和螺虫乙酯在覆膜金橘中使用的安全性,研究了螺螨酯、螺虫乙酯及其代谢产物在覆膜金橘中的残留分析方法和残留动态规律,建立了金橘中螺螨酯、螺虫乙酯及其代谢产物的超高压液相色谱-串联质谱(UHPLC-MS/MS)检测方法。结果表明,在0.002~2.5 mg/kg添加水平范围内,螺螨酯、螺虫乙酯及其4种代谢产物在金橘中的添加回收率为86.9%~101.2%,相对标准偏差为2.3%~6.8%,方法检出限为0.1~5.0μg/kg,定量限为0.5~1.0μg/kg。螺螨酯和螺虫乙酯母体在覆膜金橘中的消解符合一级动力学方程,消解半衰期分别为14.1 d和23.1 d。最终残留实验结果表明,按照推荐的施药剂量使用,施药2次后15 d收获,螺螨酯和螺虫乙酯在覆膜金橘中的残留量均低于最大残留限量值(均为0.5 mg/kg)。

In order to evaluate the application safety of spirodiclofen and spirotetramat in kumquat with film mulching,the method for determination of the residue and dynamic change characteristics of spirodiclofen and spirotetramat residue in kumquat covered with plastic-film mulching was studied.A method for the simultaneous determination of spirodiclofen,spirotetramat and the four metabolites in kumquat was developed by ultra-high-performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS).The results showed that the average spiked recovery was in the range of 86.9%to 101.2%and the relative standard deviation was 2.3%–6.8%when the fortified levels were ranged from 0.002 to 2.50 mg/kg.The limit of detection(LODs)of spirodiclofen,spirotetramat and the four metabolites was in the range of 0.1 to 5.0μg/kg,while the limit of quantification(LOQ)was in range of 0.5 to 1.0μg/kg.The degradation dynamics of spirodiclofen and spirotetramat based on first-order reaction dynamic equations in kumquat covered with plastic-film mulching,the half-life of spirodiclofen and spirotetramat was 14.1 d and 23.1 d respectively.The results of the final residue experiment showed that spraying twice of spirodiclofen and spirotetramat in the dose of the highest recommended value,the residue of spirodiclofen and spirotetramat at 15 d after the last spray in kumquat covered with plastic-film mulching was all lower than China’s maximum residue limit of 0.5 mg/kg.