33%氯氟·吡虫啉悬浮剂在柑橘中的残留动态与膳食风险评估

Residual dynamics and dietary risk assessment of 33% λ-cyhalothrin-imidacloprid suspension in citrus fruits

采用QuEChERS前处理技术结合超高效液相色谱-串联质谱仪(UPLC-MS/MS)同时检测柑橘中33%氯氟·吡虫啉悬浮剂2种有效成分(高效氯氟氰菊酯和吡虫啉)的残留,并对该复配农药在柑橘田残试验中的残留消解动态规律进行了研究。试验结果表明:2种有效成分在柑橘全果上的消解规律均符合一级动力学关系,拟合优度r=0.9560~0.9923,高效氯氟氰菊酯、吡虫啉半衰期分别为8.2~9.8,5.5~7.6d,最终降解率均在92%以上;最终残留量表明,最终残留量与施药剂量、施药次数及采收间隔期呈正相关;2种有效成分的残留主要分布于果皮,其次为全果和果肉;距末次施药28d后,柑橘全果中吡虫啉和高效氯氟氰菊酯的残留量均低于国家标准(GB2763-2016)中规定的MRL值,膳食风险评估结果表明,其残留对6类典型人群的风险均在人体可接受范围内。因此建议33%氯氟·吡虫啉悬浮剂以1000倍稀释液(330mg/kg)施药,1个柑橘生产周期最多施药2次,施药间隔期10d,采收安全间隔期为28d对柑橘种植进行技术指导。

In this study, QuEChERS technology combined with UPLC-MS/MS was used to detect the active ingredients of 33%λ-cyhalothrin-imidacloprid suspension in citrus.Residue and degradation dynamics of the compound in citrus field residue test was studied for the first time.The residual digestion of λ-cyhalothrin and imidacloprid on whole fruit of citrus accorded with the first-order kinetic relationship, and correlation coefficient was 0.956 0~ 0.992 3.The half-lives of imidacloprid are 5.5~7.6 d while λ-cyhalothrin are 8.2~9.8 d, final degradation rate is above 92%.The terminal residues indicated that the amounts of final residues was positively correlated with the dosage, the number of application and the interval of harvesting.The residues of the two were mainly distributed in peel, followed by whole fruit and pulp.About 28 days later after the last application, the residues of imidacloprid and λ-cyhalothrin in fruits was lower than the MRL value specified in GB 2763-2016, and dietary risk assessment showed that risks of residues were acceptabled.Therefore, it is recommended that 33% imidacloprid-λ-cyhalothrin suspension should be applied in 1 000-fold dilution (330 mg/kg) and can be applied up to 2 times in one citrus production cycle with 10-days application interval and 28-days harvest interval.