鱼肉样品中的手性多氯联苯对映体的分离测定研究

摘要

A method was developed for the separation and determination of 7 chiral polychlorinated biphenyls(PCBs) congeners(PCB 45,PCB 91,PCB 95,PCB 132,PCB 136,PCB 149 and PCB 174) in fish samples.The target chemicals were extracted by accelerated solvent extraction,cleaned up by gel permeation chromatography,acidified with silica gel column and multi-layer silica gel column,and were further fractioned with alkaline alumina columns.The chiral PCBs were identified and quantified by gas chromatography-mass spectrometry with electron impact ion source (GC-EI/MS).Five commercially available chiral capillary gas chromatography columns(BateDex-325,CP -Chirasil,BGB-172SE,Chirasil-Dex and Cyclosil-B) were evaluated for their ability to separate enantiomers of 7 chiral PCBs.Among the columns studied,Cyclosil-B capillary column obtained the best results,providing the simultaneous separation of 7 chiral PCBs with the enantioselective resolution of 0.8-2.3.The calibration curves of these seven chiral PCBs showed good linearities in the range of 10-200 μg · L-1 with correlation coefficients 0.998-1.000.The limits of detection (LOD,S/N =3) were all below 5.0 ng· g-1.The method was applied in the determination of the analytes in spiked fish samples,with recoveries of of 89.2％-114％ and relative standard deviations(RSDs,n =7) of 0.3％-2.1％,suggesting the high degree of accuracy and efficiency of the established method.The developed method was applied in fish samples which collected from a reservoir surrounded by several e-waste recycling workshops in Guangdong.PCBs and enantiomer franctions(EFs) of chiral PCBs(PCB 45,PCB 91,PCB 95,PCB132,PCB 136,PCB 149 and PCB 174) were analyzed in three kinds of fish samples.The concentrations of chiral PCBs ranged from 386.7 ng· g-1 to 602.8 ng · g-1in fish smaples.The EF values of chiral PCBs(PCB 45,PCB 91,PCB 95,PCB 132,PCB 136 and PCB 174) were significantly different with those in standard solution,which meaned that these chiral PCBs had enantioselective enrichment and metabolism in fish tissue.In addition,the EF values of chiral PCBs of PCB 45,PCB 91,PCB 95,PCB 132 and PCB 136 in three kinds of fish tissue were similar,with an exception of PCB 174.The declined EFs of PCB 174 in Cirrhinus moliorella and Cirrhinus moliorella were rebounded in Ophicephalus argu.This result may suggest that the Ophicephalus argu and Cirrhinus moliorella or Carassius auratus preferred to biotransform different enantiomers of PCB congeners.%该文建立了鱼肉样品中7种手性多氯联苯(PCB45,PCB91,PCB 95,PCB132,PCB 136,PCB 149和PCB 174)对映体的分离测定方法.样品经快速溶剂萃取技术萃取后,浓缩液经过凝胶渗透色谱除脂及大分子物质后再依次通过酸性硅胶柱、复合硅胶柱净化和碱性氧化铝柱分离得到PCBs组分.在气相色谱-质谱(GC-EI/MS)上对比研究了BateDex-325,CP-Chirasil,BGB-172SE,Chirasil-Dex和Cyclosil-B手性色谱柱的拆分效果,发现7种手性PCBs在Cyclosil-B毛细管柱上的分离效果最好,其分离度为0.8～2.3,可以实现基线分离在优化色谱条件下,7种手性PCBs在10 ～ 200 μg·L-1浓度范围内线性良好,相关系数为o.998～ 1.000,方法检出限(S/N=3)为0.4～5.0ng·g-1.在高、低2个加标水平下,7种手性PCBs的回收率为89.2％～114％,相对标准偏差为0.3％ ～2.1％,表明方法灵敏度高、回收率好、准确度高.采集广东电子垃圾拆解污染区鱼类样品验证方法的适用性,结果显示鱼肉样品中均检出7种手性PCBs,3种鱼肉样品中7种手性PCBs的总浓度为386.7 ～602.8 ng·g-1.对3种鱼肉组织中7种手性PCBs的EF值进行测定,发现PCB 45,PCB 91,PCB 95,PCB 132,PCB 136和PCB 174的EF值与标准品具有显著差异,表明这些手性PCBs在鱼类体内可能具有对映体选择性富集和代谢作用,此外PCB 45,PCB 91,PCB 95,PCB 132和PCB136在3种鱼肉组织中的分布特征相似,而PCB174的EF值在乌鳢体内大于标准品,而在鲮鱼、鲫鱼体内却小于标准品,表明PCB174在乌鳢和鲮鱼、鲫鱼体内的选择性代谢过程可能相反.