超声波萃取-分散固相萃取净化-气相色谱电子捕获法测定土壤或底泥中的多氯联苯

Determination of Polychlorinated Biphenyls in Soil or Sediment by Gas Chromatography-Electron Capture Detection Combined with Ultrasonic Extraction and Dispersive Solid Phase Extraction Cleanup

采用超声波萃取、分散固相萃取净化结合气相色谱电子捕获检测法,建立了快速测定环境土壤或底泥中7种指示性多氯联苯（Polychlorinated biphenyls,PCBs）的方法。根据提取液的颜色,灵活选择是否增加浓H2SO4净化步骤,并对分散固相萃取净化过程中吸附剂的种类和用量进行了优化。当提取液颜色基本无色透明时,仅选用150 mgN-丙基乙二胺（Primary-secondary-amine,PSA）吸附剂进行分散固相萃取净化（即一步净化）,否则提取液先经过浓H2SO4净化再采用100 mg PSA吸附剂进行分散固相萃取净化（即两步净化）。整个分散固相萃取净化过程不超过5 min,前处理时间显著缩短。结果表明在1.25-100μg/L浓度范围内7种PCBs峰面积与浓度呈线性相关,相关系数为0.9990-0.9999舱出限为0.02-0.03μg/kg,样品经两步净化和一步净化时,7种PCBs不同浓度加标水平回收率分别为72%-107%和88%-115%,相对标准偏差分别为3.5%-5.8%和3.7%-6.9%（n=5）,已成功应用于舟山朱家尖某菜地土壤样品和岱衢洋海域底泥样品检测,且检测结果与国家标准方法保持一致。本方法简单快速,高效,基体干扰小,灵敏度、准确度、精密度均满足土壤或底泥中PCBs的定量分析要求。

A simple,rapid,efficient,sensitive and low matrix interference method for the determination of 7specified polychlorinated biphenyls（PCBs） in soil or sediment samples using gas chromatography-electron capture detection（GC-ECD） combined with ultrasonic extraction and dispersive solid phase extraction（DSPE） cleanup was described.The step of concentrated sulfuric acid purification could be chosen flexibly according to the color of the extract,and the kinds and amounts of adsorbent were optimized.If the extract was basically colorless transparent,only 150 mg of primary secondary amine（PSA） was used for DSPE cleanup（one-step purification process）,otherwise it needed a purification for the extract by concentrated sulfuric acid and 100 mg of PSA for the DSPE cleanup（two-step purification process）.The whole DSPE cleanup process only needed less than 5 min,which significantly shortened the sample pretreatment time.The linearity of the method ranged from 1.25 μg/L to 100 μg/L for 7 PCBs,with correlation coefficients ranging from 0.9990 to0.9999.The detection limits for 7 PCBs were 0.02-0.03 μg/kg.The recoveries of spiked PCBs at different concentration levels in samples with two-step purification process（concentrated sulfuric acid purification and DSPE cleanup） and one-step purification process（only DSPE cleanup） were 72%-107%,and 88%-115%,respectively,with relative standard deviations（RSDs） of 3.5%-5.8%,and 3.7%-6.9%（n = 5）,respectively.The performance of the proposed method was compared with national standard methods on the real water samples（i.e.,soil samples in certain vegetable patch of Zhujiajian,Zhoushan,sediment samples in waters of Daiquyang,Zhoushan,etc.） and comparable efficiencies were obtained.It was concluded that this method could be successfully applied for the determination of PCBs in soil or sediment with good accuracy and precision.