贮存方式对农残检测样品中有机氯类农药检测结果的影响

Effects of Storage Methods on Detection Results of Organochlorine Pesticides in Pesticide Residue Testing Samples

本试验以生菜为材料,研究了3种贮存方式(室温25℃、冷藏4℃、冷冻-20℃)对生菜中有机氯类农药(乙烯菌核利、联苯菊酯、甲氰菊酯)检测结果的影响。结果表明,联苯菊酯稳定性高于甲氰菊酯和乙烯菌核利;样品贮存3 d时,室温贮存效果最好;样品贮存5 d时,冷冻贮存效果优于冷藏;农药浓度为0.05 mg/kg时,表现出更好的稳定性,在样品贮存3~5 d后残留率在3个浓度中最高;随着样品冻融次数增多,农药降解的速度加快,检测结果偏低,冻融3次后,3种农药残留率在70%及以下,因而冻融3次后的样品不宜再作为农残检测样品进行检测。

In this experiment,lettuce was used as the material to study the effects of three storage methods(room temperature at 25℃,freezing at 4℃,and freezing at-20℃)on the detection results of organochlorine pesticides(vinclo-zolin,bifenthrin,fenothrin)in lettuce.The results showed that the stability of bifenthrin was higher than that of fenothrin and vinclozolin.When samples stored for 3 days,the storage effect at 25℃was the best,and when samples stored for 5 days,the storage effect at-20℃was better than that at 4℃.When the pesticide concentration was 0.05 mg/kg,it showed better stability,and the residue rate was the highest among the three concentrations after samples storaged for 3-5 days.As the number of freeze-thaw cycles of the samples increased,the degradation rate of pesticides accelerated,and the detection results were low.After 3 times of freeze-thaw,the residues of 3 pesticides were at or below 70%.Therefore,the samples after 3 times of freeze-thaw should not be used as pesticide residue testing samples for detection.