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建立了高效液相色谱法检测鲜烟叶和干烟叶中噻虫嗪残留量的方法。样品经乙腈提取,Cleanert NH2-SPE固相萃取柱净化,高效液相色谱-紫外检测器(HPLC-UV)检测,外标法定量。结果表明:在0.01~5 mg/kg添加水平下,鲜烟叶中噻虫嗪的平均回收率为92%~95%,相对标准偏差(RSD)为4.5%~9.2%,定量限(LOQ)为0.01 mg/kg;在0.05~5 mg/kg添加水平下,干烟叶中噻虫嗪的平均回收率为91%~94%,RSD为5.9%~6.8%,LOQ为0.05 mg/kg。采用所建立的方法,测定了山东、湖南2年2地烟叶样品中噻虫嗪的消解动态及最终残留量。结果表明:噻虫嗪在烟叶中的半衰期为1.3~8.1 d;按照噻虫嗪有效成分用量18.9和28.4 g/hm2,于烟草现蕾初期-成熟期对水喷雾施药2~3次,距末次施药7 d后,山东、湖南2年2地烟叶样品中噻虫嗪残留量为0.05~0.80 mg/kg,均低于国际烟草合作研究中心(CORESTA)指导性残留限量标准规定的MRL值(5.0 mg/kg)。
A method for the determination of thiamethoxam residues in fresh and dried leaves by HPLC was established. The samples were extracted with acetonitrile, cleaned up with Cleanert NH2-SPE cartridge and detected by HPLC-UV with external standard method. The results showed that the average recoveries of thiamethoxam in fresh tobacco leaves were 92% ~ 95% and the relative standard deviations (RSDs) were 4.5% ~ 9.2% at LO 0.01 ~ 5 mg / kg. The LOQ was 0.01 mg / kg. The average recoveries of thiamethoxam in dried tobacco leaves were 91% ~ 94%, the RSDs were 5.9% -6.8% and the LOQ was 0.05 mg / kg at 0.05-5 mg / kg. The established method was used to determine the digestion and the final residues of thiamethoxam in tobacco samples from two years in Shandong and Hunan. The results showed that the half-life of thiamethoxam in tobacco leaves ranged from 1.3 to 8.1 days. According to the active constituents of thiamethoxam at 18.9 and 28.4 g / hm2, the water spray was applied 2 to 3 times during the early stage of tobacco budding-maturity Seven days after the last application, the residues of thiamethoxam in tobacco samples from two years in Shandong and Hunan provinces were between 0.05 and 0.80 mg / kg, both of which were lower than the MRL values stipulated in the guidelines of the International Tobacco Cooperative Research Center (CORESTA) (5.0 mg / kg).