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吡虫啉在烟草中的残留分析及调制对其残留的影响

Analysis of imidacloprid residue and influences of curing methods on its residue in flue-cured and air-cured tobacco

  • 摘要: 为了解吡虫啉在烟草中的残留行为及调制对该药残留的影响,采用乙腈作为提取液、N-丙基乙二胺(PSA)等作为净化吸附剂,建立了吡虫啉在烟叶中残留量的快速样品前处理(QuEChERS)-HPLC检测方法。结果表明:①该法的最低检出限为0.02 mg/kg,以0.1、0.5、1.0 mg/kg吡虫啉的添加量分别添加到烟叶空白样品中,回收率为88.6%~96.6%,变异系数为2.05%~3.42%。②当药剂使用量为4 mg(a.i)/株时,吡虫啉对一般刺吸式口器害虫的持效期在15 d左右。③通过对调制前后烟叶样品钙质量分数的测定以消除因调制过程中烟草干物质消耗产生的影响,对调制后烟样中吡虫啉的残留量进行了校正,经计算得出烘烤与晾制过程中吡虫啉分别降解了47.96%和48.66%。

     

    Abstract: In order to study the imidacloprid residue and the influences of curing methods on its residue in tobacco, a method was developed for determining the imidacloprid residues in tobacco by QuEChERS-HPLC. A pre-treatment approach known as QuEChERS was followed:leaf samples were extracted with acetonitrile, and cleaned up with N-propyl ethylenediamine sorbent before analysis by HPLC. The results showed that:1) The detection limit(LOD) of imidacloprid was 0.02 mg/kg, its average recoveries at three fortified levels(0.1, 0.5, 1.0 mg/kg) ranged from 88.6% to 96.6% with relative standard deviation of 2.05%-3.42%. 2) When the application rate of imidacloprid was 4 mg(a.i)/plant, the persistent period for controlling pests with piercing-sucking mouthparts was about 15 days. 3) After eliminating the influences of dry matter (matrix) consumption via determining the calcium mass fraction before and after tobacco curing, the imidacloprid residues in cured leaves were calibrated, and the calculated results indicated that the imidacloprid residues reduced by 47.96% and 48.66% after flue-curing and air-curing, respectively.

     

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