5种农药在采收前和初烤后的烟叶及土壤中的残留量变化

Residues of five pesticides in tobacco leaves before harvesting and after flue-curing and soils

为研究采收前和初烤后烟叶及土壤中三唑酮、霜霉威、稻瘟灵、吡虫啉和仲丁灵残留量的变化,建立了烟叶和土壤中该5种农药残留的超高效液相色谱-串联质谱（UPLC-MS/MS）分析方法。样品经乙腈提取,N-丙基乙二胺（PSA）吸附剂净化,UPLC-MS/MS法检测,采用基质配制溶液绘制标准曲线,内标法定量。结果表明：1烟叶中5种农残的定量限在12.25～37.48μg/kg之间,加标回收率为74%～117%;土壤中5种农残的定量限在0.11～0.34μg/kg之间,加标回收率为78%～107%。2田间试验表明,于烟叶采收前15 d对烟草植株按最大许可使用量施药后,上部、中部叶中吡虫啉、三唑酮（含其残留的转化物三唑醇）和仲丁灵的残留量随时间逐渐减小;霜霉威和稻瘟灵的残留量随时间先增大后减小;初烤后烟叶中5种农药的最终残留量≤2.70 mg/kg,低于CORESTA规定的指导性残留限量（GRLs）。土壤中吡虫啉残留量随时间逐渐减小;三唑酮、稻瘟灵和霜霉威的残留量随时间先增大后减小;仲丁灵残留量随时间有所增加。

In order to study the variations of five pesticide residues in tobacco leaves before harvesting and afterflue-curing and soils,an ultra-high performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS） method was developed for the quantification of the residues in test samples.Samples were extracted withacetonitrile and cleaned up by primary secondary amine（PSA） sorbent,then detected by UPLC-MS/MS.Quantitative methods were established using matrix-matched calibration standards and internal standards.Theresults showed that：1） For tobacco samples,the limits of quantification（LOQs） ranged from 12.25 to 37.48 μg/kgand the recoveries were from 74% to 117% at three spiked levels.For soil samples,LOQs ranged from 0.11 to0.34 μg/kg and the recoveries were from 78% to 107% at three spiked levels.2） In field trails,the five pesticideswere applied to tobacco plants at their maximum permissible levels on the 15 th day before tobacco harvesting.The residues of imidacloprid,triadimefon（including the metabolite triadimenol of its residue） and butralin inupper and middle tobacco leaves gradually decreased with the proceeding of time.The residues of propamocarband isoprothiolane increased first and then decreased,and the final residues of the five pesticides in flue-curedleaves were lower than 2.70 mg/kg,which were below the guidance residue levels（GRLs） of CORESTA.For soilsamples,imidacloprid residue gradually decreased,triadimefon,isoprothiolane and propamocarb residuesincreased first and then decreased,and butralin residue slightly increased with the proceeding of time.