土壤中不同极性污染物的亚临界水选择性萃取

Selected Extraction of Pollutants with Different Polarity by Subcritical Water in Soil

研究了用亚临界水萃取技术选择性萃取土壤中3种不同极性的污染物:2,4-二氯酚(2,4-DCP)、4-氯联苯(4-PCB)和六氯苯(HCB)。研究了在不同温度下亚临界水对分析物的萃取效率。125℃时,萃取物主要是2,4-DCP;250℃时,主要萃取4-PCB和HCB。同时,研究了亚临界水萃取时间、萃取体积对3种物质的萃取效率的影响,确定了土壤中HCB的最佳亚临界水萃取条件为萃取水体积4mL,萃取时间75m in,萃取温度250℃。本方法用于实际样品中的HCB萃取,通过改变萃取温度,可以去除其它污染物对HCB测定的影响,测定结果与索氏提取-GC分析结果吻合较好。与USEPA标准方法8081A相比,本方法可以显著缩短萃取时间、简化净化步骤及减少有机试剂的用量。

Three organochlorien compounds with different polarity, i. e. , 2,4-dichlorophenol （2,4-DCP）, 4- chlorobiphenyl （4-PCB） and hexachlorobenzene （HCB）, were extracted by subcritical water. Under the relative low extraction temperature （125℃）, the main extracted compounds was 2,4-DCP, and 4-PCB and HCB were quantitatively extracted under 250℃. The influence of the extraction time and water volume on the recoveries of analytes was also studied. The optimum conditions for HCB in the soil sample were extracting 75 min with 4 mL subcritical water under 250℃. This method has been applied to the determination of HCB in real soil sample. The result was agreement with that by standard method. Compared with the USEPA standard methods, the extraction time, volume of organic solvent and following extract clean-up steps can be shorten.