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采用气相色谱-质谱联用技术,测定了良好农业规范(GAP)条件下3种常用拟除虫菊酯类杀虫剂高效氯氟氰菊酯、高效氯氰菊酯及溴氰菊酯在山东、四川、云南、辽宁和江西5地烟叶中的消解动态及最终残留。样品经乙腈提取,SPE-PSA柱净化,气-质联用、选择离子监测模式(GC-MS/SIM)下测定,外标法定量。结果表明:在0.01~1 mg/kg添加水平下,3种农药在鲜烟叶和干烟叶中的平均回收率分别在82.9%~110.9%和85.2%~108.3%之间,相对标准偏差(RSD)分别为1.7%~4.4%和2.3%~5.7%;3种农药在鲜烟叶和干烟叶中的定量限(LOQ)均为0.01 mg/kg;方法的准确度和精密度均符合农药残留检测要求。烘烤过程中残留农药消解明显,高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯的消解率分别高达78%、89%和91%。高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯乳油分别按有效成分450~675 g/hm2、600~900 g/hm2及450~675 g/hm2于烟叶采烤初期喷雾施药2次,距末次施药后14 d,干烟叶中3种农药的残留量分别为0.022~0.50、0.14~0.82和0.046~0.21 mg/kg,均低于国际烟草合作研究中心(CORESTA)提出的指导性农药残留限量标准(GRL)值(0.5、1和1 mg/kg),因此建议其安全间隔期可定为14 d。
Three pyrethroids, cyhalothrin and cypermethrin, which are commonly used pyrethroid insecticides under good agricultural practice (GAP) conditions, were determined by gas chromatography-mass spectrometry in Shandong, Sichuan, Yunnan, Digestion Dynamics and Residues in Tobacco Leaves in Liaoning and Jiangxi Provinces. The samples were extracted by acetonitrile, purified by SPE-PSA, GC-MS / SIM, and quantified by external standard method. The results showed that the average recoveries of three pesticides in fresh and dried leaves were between 82.9% -110.9% and 85.2% -108.3% at 0.01-1 mg / kg, respectively. The relative standard deviations (RSDs) (LOQ) of the three kinds of pesticides were both 0.01% and 4.4%, respectively. The accuracy and precision of the methods were in line with the requirements of pesticide residue detection . Residual pesticide digestion was obvious during the baking process. The digestion rates of lambda-cyhalothrin, beta-cypermethrin and deltamethrin were as high as 78%, 89% and 91% respectively. Lambda-cyhalothrin, beta-cypermethrin and deltamethrin EC were respectively sprayed by spraying the active ingredients 450-675 g / hm2, 600-900 g / hm2 and 450-675 g / hm2 on the initial stage of tobacco harvest, The residues of three pesticides in dried tobacco leaves were 0.022-0.50, 0.14-0.82 and 0.046-0.21 mg / kg, respectively, 14 d after the last application, which were all lower than those of the guidance pesticides proposed by CORESTA Residuals Standard Limits (GRL) values (0.5, 1, and 1 mg / kg) are therefore recommended and their recommended safety interval may be set at 14 days.