采用电子轰击(EI)和正化学(PCI)两种电离源技术,建立了气相色谱-串联质谱(GC-MS/MS)同时测定青菜和草莓中三环锡、三苯锡、苯丁锡农药残留的分析方法.样品经氢溴酸消解,丙酮-正己烷提取,经衍生后由Florisil固相萃取柱净化,分别采用EI和PCI两种电离源进行选择反应监测模式测定,采用基质匹配外标法定量.结果显示,在0.05～ 1.0 mg/L质量浓度范围内,3种有机锡农药呈良好线性,相关系数均大于0.998.两种方法中目标物的定量下限分别为0.019～0.042 mg/kg和0.009 ～0.042 mg/kg,均能满足国内外的限量要求.在0.05、0.10、0.20 mg/kg加标水平下,目标物的平均回收率为70.1％～ 93.9％,相对标准偏差(RSD)均小于10％.两种方法线性均较好,灵敏度较高,可用于水果蔬菜中有机锡农药的测定,且两种方法可实现互补,有助于提高定性和定量的可靠性.%A method was developed for the simultaneous determination of fenbutatin oxide,triphenyltin and cyhexatin pesticide residues in green vegetables and strawberry by gas chromatography-tandem mass spectrometry(GC-MS/MS) with two ionization techniques,i.e.electron impact ionization(EI) and positive chemical ionization(PCI).The samples were firstly digested with hydrobromic acid,then extracted with acetone-hexane,finally derived with sodium tetraethylborate.After purification with Florisil solid phase extraction column,the samples were analyzed by GC-MS/MS with EI and PCI sources under SRM mode.Three kinds of organo-tin pesticide residues showed good linear relationships in the range of 0.05-1.0 mg/L with correlation coefficients larger than 0.998.The limits of quantitation for the target objects were in the range of 0.019-0.042 mg/kg and 0.009-0.042 mg/kg,respectively,which could meet the requirements for the maximun residue limits (MRLs) of organotin pesticide residues at home and abroad.The average recoveries for three organotin residues at three spike levels of 0.05,0.10,0.20 mg/kg were in the range of 70.1％-93.9％with the relative standard deviations less than 10％.With good linearity and high sensitivity,the proposed methods could be used for the determination of organotin pesticide residues in green vegetables and strawberry.Forthermore,the two methods could complement each other to improve the reliabilities of qualitation and quantitation.
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