同位素稀释-气相色谱串联质谱法测定饲料中指示性多氯联苯

Determination of Ultratrace Indicator Polychlorinated Biphenyls in Animal Feed by Gas Chromatography-Triple Quadrupole Mass Spectrometry with Isotope Internal Standards

建立了气相色谱-串联质谱法(GC-MS/MS)测定动物饲料中6种指示性多氯联苯的痕量分析方法。样品中的多氯联苯经溶剂加速萃取,用44%酸性硅胶柱脱脂和复合硅胶柱净化,气相色谱-串联质谱法分析。采用DB-5MS毛细管柱分离,电子轰击电离源(EI)电离,多反应监测模式下(MRM)检测,同位素稀释法进行定量分析。结果表明,方法的线性范围为0.1～500.0 ng/m L,相关系数(R^2)均大于0.999,平均相对响应因子(RRF)为1.08～1.21;定量限为5.5～9.2 pg/g,样品添加回收率为92.8%～109.7%,RSD为1.6%～14.8%;定量内标的回收率为32.6%～90.2%。应用此方法对北京市周边地区采集的10个配合饲料样品进行检测,6种指示性PCBs均有检出,其中PCB28和PCB52为优势单体,总浓度范围为54.7～191.7 pg/g,远低于我国国标饲料限量标准(10μg/kg)。

A method was developed for determination of 6 kinds of indictor polychlorinated biphenyls in animal feed by chromatography-tandem mass spectrometry(GC-MS/MS).Analytical procedure consisted of accelerate solvent extraction(ASE),lipid removal with 44% acidic silica and clean-up using a column packed with multilayer silica.The analytes were separated on a DB-5MS capillary column,detected with electron ionization(EI)and multiple reaction monitor mode(MRM),and quantified using isotope dilution technique.The result showed that the calibration curves with good correlation coefficients(R^2>0.999)were obtained in the concentration range of 0.1-500.0 ng/mL.The average relative response factors of PCBs in calibration solvent were 1.08-1.21,and the limit of quantification were 5.5-9.2 pg/g.The average recoveries of PCBs in animal feed at two spiked concentration levels ranged from 92.8%to 109.7%with relative standard deviations(RSDs)of 1.6%-14.8%(n=5),and the average recoveries of quantitative internal standards were 32.6%-90.2%.Then the proposed method was successfully applied to detect the compound feed samples from the surrounding area of Beijing,and it was found that the 6 kinds of indictor PCBs were detected in all samples(n=10)with the total concentration ranges of 54.7-191.7 pg/g,which were far below the limit standard(10μg/kg)of Chinese National Standards.