中文摘要：

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10.3MPa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（35eV）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0.999 9,线性范围为0.2~400pg/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3~11pg/g。

英文摘要：

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.