联苯肼酯及其代谢物在草莓中的残留消解及储藏稳定性

Residues dissipation and storage stability of bifenazate and its metabolites in strawberry

目的采用超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)测定草莓样品中联苯肼酯及其代谢物联苯肼酯二氮烯残留,评价联苯肼酯及其代谢物在草莓中的残留消解和储藏稳定性。方法实验样品用乙腈提取,经N-丙基乙二胺(primary secondary amine, PSA)和无水硫酸镁净化, UPLC-MS/MS检测,采用基质匹配外标法定量。按照NY/T 788—2018《农作物中农药残留试验准则》进行残留消解试验,按照NY/T 3094—2017《植物源性农产品中农药残留储藏稳定性试验准则》进行储藏稳定性试验。结果本方法在0.0001~0.1mg/L范围内线性响应良好,相关系数大于0.9991。联苯肼酯及联苯肼酯二氮烯在0.01、0.5和2.0 mg/kg添加水平的平均回收率为78%~100%,相对标准偏差小于9.2%。联苯肼酯在草莓上的消解半衰期为6.4~10.4 d。储藏稳定性试验结果表明:草莓样品在-18℃储藏150 d,联苯肼酯及联苯肼酯二氮烯的降解率均小于30%。结论联苯肼酯在草莓中消解较迅速;最后一次喷施5 d后取样的草莓中联苯肼酯的最终残留量低于我国规定的最大残留限量值2 mg/kg;-18℃冷冻条件下,联苯肼酯及联苯肼酯二氮烯在草莓样品中储藏稳定期至少为150 d。

Objective To determine the residues of bifenazate and its metabolite bifenazate-diazene in strawberry samples by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),and to evaluate the residues dissipation and storage stability of phenylhydrazine ester and its metabolites in strawberries.Methods The experimental samples were extracted with acetonitrile,purified by N-propylethylenediamine(PSA)and anhydrous magnesium sulfate,detected by UPLC-MS/MS,and quantified by matrix matching external standard method.The residue digestion test was carried out according to NY/T 788—2018 Test criteria for pesticide residues in crops,and the storage stability test was carried out according to NY/T 3094—2017 Test criteria for storage stability of pesticide residues in plant derived agricultural products.Results The linear response of this method was good in the range of 0.0001‒0.1 mg/L,and the correlation coefficient was greater than 0.9991.The average recoveries of bifenazate and bifenazate-diazene at the levels of 0.01,0.5 and 2.0 mg/kg were 78%‒100%,and the relative standard deviations were less than 9.2%.The half-life of bifenazate on strawberry was 6.4‒10.4 d.The results of storage stability test showed that the degradation rate of bifenazate and bifenazate-diazene was less than 30%after 150 d storage at‒18℃.Conclusion Bifenazate is digested more quickly in strawberries.The final residue of bifenazate in strawberry sampled 5 d after the last spray was below the maximum residue limit(MRL)of China(2 mg/kg).Under freezing condition of‒18℃,the storage stability of bifenazate and bifenazate-diazene in strawberry samples is at least 150 d.