采用MECC在线堆积同步检测茶叶中七种残留农药

    Synchronous detection of seven persistent pyrethroid pesticides in tea by MECC using reversed electrode polarity stacking concentration technique

    • 摘要: 为解决茶叶中的痕量农药残留的快速检测问题,建立了一种基于胶束毛细管电泳在线堆积技术的茶叶中7种拟除虫菊酯类农药痕量残留的一次进样同步检测方法。通过参数优化,得到最优的柱上在线堆积浓缩操作工艺:以15%异丙醇、20%乙腈、60 mmol/L十二烷基硫酸钠(SDS)和50 mmol/L tris的混合物为背景缓冲溶液(BGS)。茶叶的浸提液经过固相萃取净化吹干后,用1 mmol/L SDS溶解溶液残渣。进样100 s后施加反向电压,进行农药反向在线堆积,当电流恢复至正常分离时的95%时改变电压方向,进行正常分离。经过在线堆积浓缩,7种拟除虫菊酯类农药痕量残留堆积因子均高于17,回收率在82%以上,检测下限分别达到:功夫菊酯0.05 mg/kg、联苯菊酯0.05 mg/kg、百树菊酯0.05 mg/kg、高效氯氰菊酯0.05 mg/kg、溴氰菊酯0.2 mg/kg、二氯菊酯0.05 mg/kg、氰戊菊酯0.05 mg/kg,满足了2006年欧盟茶叶中拟除虫菊酯类农药残留的最低标准。

       

      Abstract: For rapid detection of trace residues of pesticides in tea, a synchronous detection method for seven kinds of pyrethroid pesticide residues in sample was established with micellar electrokinetic capillary chromatography(CMECC) based on the on-column stacking. The optimal operation condition of on-column stacking was described as follows: the background solution consists of 15% isopropyl alcohol, 20% acetonitrile, 60 mmol/L sodium dodecyl sulfate (SDS) and 50 mmol/L tris (hydroxymethyl) aminomethane (Tris). After the extract of tea was cleaned by solid phase extraction for removing some impurities, and dried by nitrogen, the sample residue was dissolved in 1 mmol/L SDS solution. Reverse voltage was imposed after the 100s injection, and then the polarity was exchanged when the current returned to 95% of the normal. After on-column stacking, the enrichment factors of seven pyrethroid pesticide residues were higher than 17, and their recoveries were more than 82%. Under the optimal operation condition, the detected concentration limits of seven kinds of pyrethroid pesticide residues in tea were 0.05 mg/kg for cyhalothrin, 0.05 mg/kg for bifenthrin, 0.05 mg/kg for yfluthrin, 0.05 mg/kg for alpha-cypermethrin, 0.4 mg/kg for deltamethrin, 0.05 mg/kg for permethrin and 0.05 mg/kg for fenvalerate, respectively.

       

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