同位素稀释气相色谱-离子阱二级质谱法测定牛奶中残留的二恶英类多氯联苯

建立了气相色谱-离子阱二级质谱(GC-MS/MS)测定牛奶中12种二恶英类多氯联苯残留的分析方法。样品经冷冻干燥处理后用加速溶剂萃取方法提取、多层硅胶柱净化和GC-MS/MS测定。目标化合物先用二氯甲烷-正己烷-丙酮(体积比为4:4:2)混合溶剂在150 ℃和10.3 MPa条件下循环提取,再经酸性硅胶、硅胶和碱性硅胶复合柱净化及正己烷洗脱，最后用DB-5毛细管柱分离、电子轰击电离源(35 eV)多反应监测模式检测,同位素稀释内标法定量(定量离子为［M+2-72］+和［M+2-70］+)。12种化合物的标准曲线的线性相关系数均大于0.9999,线性范围为0.2～400 pg/μL;同位素内标的回收率范围为39%～129%,相对标准偏差为5%～22%;方法的检出限(以脂肪含量计)为3～11 pg/g。

Determination of dioxin like polychlorinated biphenyl residues in milk using isotope dilution gas chromatography-ion trap tandem mass spectrometry

A method for the determination of dioxin like polychlorinated biphenyl (DL-PCB) residues in milk has been developed using high resolution gas chromatography coupled with ion trap mass spectrometry (GC-MS/MS-IT). Analytical procedure consisted of accelerate solvent extraction (ASE), lipid removal with acidic silica and clean-up using anthropogenic isolation column packed with multilayer silica. The analytes were separated on a DB-5 capillary column, detected with multiple reaction monitor mode (MRM) and quantified using internal standard calibration curve of isotope dilution technique. The correlation coefficients of calibration standard solution were above 0. 999 9 for all the DL-PCBs. The recoveries and relative standard deviations of labeled compound solution were in the oranges from 39% to 129% and from 5% to 22%, respectively. The detection limits in the range from 3 to 11 pg/g (fat) were established for the 12 DL-PCBs.