气相色谱-三重四极杆质谱法测定绿茶中35种农药残留

Determination of 35 Pesticide Residues in Green Tea by Gas Chro⁃matography-Triple Quadrupole Mass Spectrometry

建立了QuEChERS/气相色谱-三重四极杆质谱同时测定绿茶中35种农药残留的分析方法。样品经85℃热水冲泡,放凉后加入乙腈提取,采用200 mg N-丙基乙二胺(PSA)、200 mg十八烷基硅烷(C_(18))、50 mg石墨化炭黑(GCB)为分散固相萃取剂净化后,以Agilent HP-5MS毛细管柱(30 m×0.25 mm×0.25µm)分离,采用电子轰击离子源,以多反应监测模式测定,基质匹配标准曲线外标法定量。35种农药在10~1000µg/L质量浓度范围内线性关系良好,相关系数(r^(2))大于0.99,方法检出限和定量下限分别为1~5µg/kg和5~15µg/kg。在20、40、200µg/kg 3个加标水平下,绿茶基质中35种农药的平均回收率为70.3%~112%,相对标准偏差为1.6%~12%。应用该方法对30份市售绿茶样品进行检测,在4份样品中检出6种农药。该方法简单快速,灵敏度和准确度高,适用于绿茶样品中35种农药残留的日常检测。

A method of QuEChERS/gas chromatography-triple quadrupole mass spectrometry was es-tablished for the simultaneous determination of 35 pesticide residues in green tea.The samples were brewed with water at 85℃,then extracted with acetonitrile after cooling down.After purified with 200 mg PSA,200 mg C_(18) and 50 mg GCB,the analytes were separated on an Agilent HP-5MS capil-lary column(30 m×0.25 mm×0.25µm).The analysis was performed in electron impaction source under multi-reaction monitoring mode,and quantified by matrix-matched standard curve and exter-nal standard method.There were good linear relationships for 35 pesticides in concentration range of 10-1000µg/L,with their correlation coefficients(r^(2))larger than 0.99.The limits of detection and limits of quantitation were 1-5µg/kg and 5-15µg/kg,respectively.The average recoveries for 35 pesticides in green tea at the spiked levels of 20,40 and 200µg/kg ranged from 70.3%to 112%,with relative standard deviations of 1.6%-12%.30 commercially available green tea were detected by the proposed method,and 6 pesticides were found in 4 samples.The method is simple,rapid,sensitive,and accurate,and could be adapted for daily analysis and planed monitoring of 35 pesticide residues in green tea samples.