沉积物中氯化石蜡与多氯联苯的分离及气相色谱-质谱检测

摘要

建立了沉积物中氯化石蜡(CPs)和多氯联苯(PCBs)的提取、分离和检测方法.沉积物样品用二氯甲烷索氏抽提,采用弗罗里硅土/硅胶复合柱纯化和分离.先用80 mL正己烷淋洗得到PCBs组分,再用60 mL二氯甲烷淋洗得到CPs组分,从而实现两者的有效分离.以气相色谱-低分辨质谱(负离子化学源)-选择离子监测技术测定CPs组分,气相色谱-质谱(电子轰击源)-选择离子监测技术测定PCBs,内标法定量,并对样品前处理条件和色谱质谱条件进行优化.在优化条件下,目标化合物(工业品CP52和22种PCB单体)的回收率为86％ ～ 99％,RSD＜10％.24种短链氯化石蜡(SCCPs)和24种中链氯化石蜡(MCCPs)的方法检出限分别为0.144 ～3.47 ng/g和0.530～2.24 ng/g.PCBs(一氯～七氯)的方法检出限为0.220 ～1.08 ng/g.应用该方法检测了东江6个沉积物中CPs和PCBs的含量,沉积物样品中SCCPs的含量为0.245～1.58 μg/g(干重),MCCPs的含量为0.538～1.83μg/g,PCBs的含量为1～ 100 ng/g.%A method was established for the separation and determination of chlorinated paraffin (CPs) and polychlorinated biphenyls ( PCBs) in sediment. CPs and PCBs were firstly extracted with dichloromethane from sediment, then CPs were separated from PCB via a cleanup procedure with complex Florisil/Silica column. The fraction containing PCBs was eluted with 80 mL hexane, followed by the elution of fraction containing CPs with 60 mL dichloromethane. CPs were determined by GC ECNCI LRMS under selective ion monitoring mode and PCBs were analyzed by GC El MS, and quantified by the internal standard method. The procedure of sample pretreatment, amount of dispersant and instrument conditions were also optimized. The result indicated that recoveries of technical mixture of CP52 and 22 PCB standards in spiked matrix ranged from 86% to 99% , with RSDs less than 10% . The method detection limits for short-chain chlorinated paraffin ( SCCPs) and medium-chain chlorinated paraffin( MCCPs) were in the ranges of 0. 144 - 3. 47 ng/g and 0. 530 - 2. 24 ng/g, respectively. The method was applied in the determination of CPs and PCBs in six sediments from Dongjiang River. The concentrations of SCCPs, MCCPs and PCBs were in the ranges of 0.245-1.58 μg/g, 0.538 -1.83 μg/g and 1 - 100 ng/g, respectively. Therefore, the method was rapid, sensitive and accurate, and was suitable for the reliable investigation of CPs and PCBs in sediment as well as in soil samples.