土壤样品中挥发性有机物的提取方法研究

挥发性有机物(VOCs)在土壤样品中残留浓度低且极易挥发,因此测定时选择合适的提取方法十分重要。文章研究优化了土壤样品中包括卤代烷烃、卤代烯烃和苯类的53种VOCs的提取方法。通过比较酸化、甲醇提取剂浓度和提取体积对土壤中挥发性有机物提取效率的影响,建立了使用4 mL 100%甲醇不酸化提取,顶空-气相色谱-质谱联用测定的分析方法,结果表明,0.10μg/g加标土壤53种VOCs的平均回收率为40.45%～119.73%,精密度(RSD,n=7)为1.26%～9.14%;1,1,2,2-四氯乙烷、三氯乙烯的回收率欠佳,主要是由于在碱性土壤条件下1,1,2,2-四氯乙烷分解造成的。该方法简便、快速,提取效果较好。但对土壤标准样品CRM 628-030进行提取,烯烃的回收率偏低,达不到给定区间浓度,且无法控制1,1,2,2-四氯乙烷的分解问题,有待于进一步研究。

Study on a Pretreatment Method for Volatile Organic Compounds in Standard Soil Samples

Volatile organic compounds(VOCs) have low concentrations and are readily volatile in soil samples.Therefore,it is very important to choose the appropriate extraction method.A method for the extraction of 53 kinds of VOCs in standard soil samples was established in this paper,including halogenated alkanes,halogenated alkenes and benzenes.After comparing the influence of pH with the concentration and volume of extract solvent,the method of Headspace-Gas Chromatography-Mass Spectrometry(GC-MS) was established to analyze volatile organic compounds by using 4 mL 100% methanol without acidification.Except for 1,1,2,2-tetrachloroethane and trichloroethylene,the average recoveries of 53 VOCs and 2 surrogates were between 40.45%-119.73% with 0.10 μg/g internal standard,and the relative standard deviations(RSD) for all the compounds ranged from 1.26% to 9.14%.The abnormal 1,1,2,2-tetrachloroethane and trichloroethylene was mainly caused by the decomposition of 1,1,2,2-tetrachloroethane in alkaline soil.This method was fast,simple,and effective in extraction.More research is necessary to address the problems of low recovery rate of alkenes for soil Standard Reference Sample CRM 628-030 and the decomposition of 1,1,2,2-tetrachloroethane.