吡蚜酮在烟草中的残留降解及风险评估

利用高效液相色谱技术开发了鲜烟叶和干烟叶中吡蚜酮农药残留量的检测方法。样品经甲醇提取,C18、PSA固相萃取柱双柱净化,高效液相色谱-紫外检测器(HPLC-UV)检测,外标法定量。结果表明,0.02~5.0 mg/kg的添加水平,吡蚜酮在鲜烟叶和干烟叶中的平均回收率分别为94.0%~99.3%和89.0%~96.1%,相对标准偏差(RSD)分别为0.74%~3.88%和0.73%~3.03%。在鲜烟叶和干烟叶中定量限(LOQ)均为0.02 mg/kg。采用该方法测定了2012-2013年山东、湖南烟叶样品中吡蚜酮的消解动态及最终残留。吡蚜酮在烟叶中消解半衰期为4.2~8.8 d。按照150、225 a.i.g/hm²用量,于烟草现蕾初期至成熟期兑水喷雾施药2~3次,最后一次施药7 d后,烤后烟叶样品中吡蚜酮残留低于国际烟草合作研究中心指导性残留限量标准规定的MRL值(1.0 mg/kg)。

Dissipation and Residual Risk of Pymetrozine in Tobacco

A new method using high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed to analyze pymetrozine residue in fresh and cured tobacco leaves. Samples were extracted with methanol, cleaned up with Solid Phase Extraction Column (SPE) of C18 and PSA, analyzed and quantified using HPLC-UV with external standards. The average recovery rate at spiked levels of 0.02-5.0 mg/kg ranged from 94.0%-99.3% for fresh tobacco leaves and 89.0%-96.1% for cured tobacco leaves, with relative standard deviations (RSD) of 0.74%-3.88% and 0.73%-3.03%, respectively. The limit of quantification (LOQ) in fresh and cured tobacco leaves were both 0.02 mg/kg. Field experiments were performed in Qingdao, Shandong Province and Changsha, Hu'nan Province. Results from dynamic analysis showed that pymetrozine level declined quickly in green tobacco leaves with half-lives of 4.2-8.8 d. The final residues of pymetrozine in cured tobacco leaves were determined after the second and third application at levels of 150 and 225 a.i.g/hm², which were all below the MRL set by CORESTA (1.0 mg/kg).