均质后芹菜抽检样品中7种拟除虫菊酯农药残留降解规律研究

选择7种拟除虫菊酯类农药作为研究对象，采用芹菜加标均质的制样方法制备抽检样品，研究不同储存条件（常温、冷藏和冷冻）下抽检样品中农药的降解规律，并将7种农药残留的检测结果通过拟合一级动力学模型预测其降解半衰期。结果表明：在常温条件下7种拟除虫菊酯类农药半衰期范围为3.1～12.6 d，冷藏条件下半衰期范围为5.9～23.1 d，冷冻条件下半衰期范围为28.9～63.0 d，其中，氰戊菊酯在各种储存条件下半衰期较长，化学性质相对稳定，而氯氰菊酯半衰期较短，容易降解。芹菜中7种拟除虫菊酯农药冷冻条件下的半衰期明显大于常温条件的半衰期。检出芹菜中7种拟除虫菊酯类农药超标在2倍以内的结果被复检机构推翻的风险较高。

Degradation Rules Study of Seven Pyrethroid Pesticide Residues in Celery Samples after Homogenization

Seven kinds of pyrethriod pesticides were selected as the research objects, celery with standard and uniform sample preparation method was adopted for the test samples preparation, then degradation rules of pesticides in samples under different storage conditions(normal temperature, cold storage and freezing) were studied, and the degradation half-lives of seven pesticide residues was predicted by fitting first-order kinetic model. The results showed that the half-lives of seven pyrethroids ranged from 3.1 d to 12.6 d at room temperature, 5.9 d to 23.1 d under cold storage, and 28.9 d to 63.0 d under freezing condition. Among them, fenvalerate showed longer half-lives and relatively stable chemical properties under various storage conditions, while cypermethrin presented relatively short half-lives and was easily degraded. The half-lives of seven pyrethroid pesticides in celery under freezing condition were obviously longer than that under normal temperature condition. The results of seven pyrethroids in celery exceeding the standard within 2 times had higher risk of being overturned by reinspection institutions.