气相色谱-三重四极杆质谱同位素内标法测定鱼样中20种多氯联苯

建立了一种气相色谱-三重四极杆质谱结合双稳定性同位素内标检测鱼样中多氯联苯的方法。采用自动索氏提取器提取样品中的多氯联苯，经一根复合净化柱净化后，采用质谱多反应监测模式检测，选取两个独立的离子对。分析了20种多氯联苯，包含7种指示性多氯联苯，从三氯联苯到八氯联苯每族3个化合物，九氯联苯和十氯联苯各一个，每族使用一个相同氯代程度的¹³C₁₂标记多氯联苯作为定量内标、2种回收内标。20种多氯联苯在33 min内流出，分离良好，线性范围为0.05~10 μg/L，相关系数r均在0.99以上，低、中、高3种水平的加标回收率均在80.3%~117.6%之间，相对标准偏差（RSD，n=6）在5.09%~18.5%之间，方法检出限为0.01~0.02 μg/kg。20种多氯联苯总量在1.2~8.8 μg/kg（湿重）范围内，7个指示性多氯联苯总量在0.68~6.4 μg/kg（湿重）范围内。该方法缩短了分析时间，减少了有机溶剂的使用量，适合鱼样中多氯联苯的测定。

Determination of 20 polychlorinated biphenyls in fish samples by gas chromatography-triple-quadrupole mass spectrometry isotope dilution method

An improved method based on the isotope dilution technique was developed for the determination of 20 polychlorinated biphenyls (PCBs) in fish samples, including seven indicator polychlorinated biphenyls. The analysis was performed by gas chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) in the multiple reaction monitoring (MRM) mode. Two MRM transitions were monitored for each PCB congener for quantitation and qualification purposes. The edible parts of the fish samples were shattered, frozen, and dried. ¹³C-PCB surrogate standards were spiked into the fish samples. The PCBs in fish samples and the surrogate standards were extracted by auto-Soxhlet extraction. The extract was cleaned-up by a disposable multi-layer column packed with acidic silica gel and basic alumina. ¹³C-PCB recovery standards were spiked into the extract before injection. The separation was performed on a TG-5MS capillary column. Quantitation was performed by the internal standard method. Every group of PCBs used a same number chlorinated ¹³C-isotope PCBs congener as the internal standard. The calibration curves of 20 PCB congeners were linear (correlation coefficient (r)>0.99) within the range of 0.05-10 μg/L. For the recovery test, three levels were spiked in matrices. The average recoveries obtained by this method were 80.3%-117.6% and the relative standard deviations (RSDs, n=6) were 5.09%-18.5%. The limits of determination (LODs) were 0.01-0.02 μg/kg. Contents of the 20 PCBs in the fish samples were in the range 1.2-8.8 μg/kg (wet weight), while those of the seven indicator PCBs were in the range 0.68-6.4 μg/kg (wet weight). The method is suitable for determining polychlorinated biphenyls in fish samples.