气相色谱法测定烟草中有机磷农药残留量

GC Determination of Residual Amounts of Organophosphorus Pesticides in Tobacco

提出了用气相色谱-脉冲火焰光度检测器(GC-PFPD)测定烟草中5种有机磷农药残留量的方法,采用乙腈超声提取烟草中残留的有机磷农药,提取液经蒸干等操作后,用凝胶渗透色谱法净化。用乙酸乙酯及环己烷(1+1)混合溶液作流动相淋洗凝胶柱,分取部分淋出液用HP-5弹性石英毛细管柱进行分离,GC-PFPD检测,外标法定量。所测5种农药的标准加入回收率在81.4%～99.8%之间,测得结果的相对标准偏差(n=6)在3.27%～8.42%之间。方法的检出限(3S/N)在0.02～0.04 mg.L-1之间。

Five organophosphorus pesticides as residues remained in tobacco were determined by gas chromatography with pulse flame photometric detector（PFPD）.The powdered tobacco sample,after dehydration,was extracted with acetonitrile ultrasonically for 1 h,and the extract was evaporated to near dryness with a rotary evaporator.The residue was taken up with ethyl acetate,cyclohexane and a mixture of NaCl and anhydrous Na2SO4（mixed in the ratio of 1 to 1 by mass）.The supernatant was taken and purified by gel permeation chromatography with a mixture of cyclohexane and ethyl acetate（mixed in the ratio of 1 to 1 by vol.） as mobile phase for elution.The eluate was collected,concentrated to 1 mL and diluted to 5.0 mL with ethyl acetate.One μL of the solution was taken for GC analysis.HP-5 elastic quartz capillary column was used for separation,and method of external standard was adopted in the determination.Detection limits（3S/N） for the 5 pesticides were in the range from 0.02 to 0.04 mg·L-1.Recovery and precision were tested and results of recovery obtained were in the range of 81.4% to 99.8%,with values of RSD′s（n=6） ranged from 3.27% to 8.42%.