土壤中多环芳烃单体碳同位素分析的分离净化方法研究  

Study on Separation of Polycyclic Aromatic Hydrocarbons in Soils for Compound-specific Carbon Isotope Analysis

作　　者：谢曼曼[1] 刘美美[1] 王淑贤[1] 凌媛 孙青[1] XIE Man-man;LIU Mei-mei;WANG Shu-xian;LING Yuan;SUN Qing(National Research Center of Geoanalysis,Beijing 100037,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]国家地质实验测试中心,北京100037 [2]中国地质科学院地质研究所,北京100037

出　　处：《岩矿测试》2021年第6期962-972,共11页Rock and Mineral Analysis

基　　金：国家自然科学基金青年基金项目(41302141);中国地质科学院基本科研业务费项目(CSJ202109)。

摘　　要：应用单体碳同位素组成追溯多环芳烃(PAHs)类污染物的来源越来越受关注。单体同位素分析中,利用样品预处理减少共流出和未分峰(UCM),是实现同位素比值准确分析的重要前提。已有分离净化研究较少关注环数小于3的PAHs;或需联合使用高效液相色谱(HPLC)技术,但对实验室条件要求较高。本文期望避免使用HPLC技术,仅通过简单的固相萃取法,实现16种PAHs的分离净化,满足包括低环数在内的PAHs单体碳同位素分析的要求。实验对比了氨基和硅胶两种填料的固相萃取(SPE)小柱,以及正戊烷等10种淋洗溶剂对PAHs的分离净化富集效果。结果表明:氨基小柱中有20%以上的萘和苊不能与烷烃和未分峰完全分离,硅胶SPE小柱除杂效果和分离效果优于氨基小柱。选择1000mg/6mL硅胶SPE小柱,利用6mL正戊烷淋洗UCM和烷烃,5mL正戊烷-二氯甲烷(70∶30,V/V)洗脱PAHs。利用气相色谱(GC)对分离净化效果进行初步检验,气体同位素质谱(GC-IRMS)进行单体碳同位素分析。16种PAHs的回收率为79%~128%,相对标准偏差为2%~13%(1σ,n=6),单体碳同位素比值(δ^(13)C)分析精度为0.1‰~0.75‰,大幅降低了其中UCM和共流出对PAH单体碳同位素分析的干扰,尤其减少了对低环数PAHs单体碳同位素分析的影响,而且净化过程没有造成PAHs单体碳同位素分馏,满足PAHs单体碳同位素分析的要求。BACKGROUND:Tracing the source of polycyclic aromatic hydrocarbons(PAHs)by the compound-specific carbon isotope is becoming increasingly popular.For precise carbon isotope analysis,a pretreatment process is required to reduce co-outflow and unresolved complex mixture(UCM).Some existing studies require more instrumentation,such as high-performance liquid chromatography(HPLC).In addition,little attention has been paid to PAHs with a ring number less than 3.OBJECTIVES:To establish a good separation method of 16 PAHs for meeting the requirements of compound-specific carbon isotope analysis.METHODS:The effects of solid phase extraction(SPE)cartridges with amino and silica fillers were compared,and 10 eluent solvents were used on the separation,purification and enrichment effects of PAHs.Gas chromatography(GC)was used to test the separation and purification effect,and gas chromatography-isotope ratio mass spectrometry(GC-IRMS)was used to analyze compound-specific carbon isotopes.RESULTS:More than 20%of the naphthalene and acenaphthene in the amino cartridge cannot be completely separated from the alkanes and unresolved peaks.The silica gel SPE cartridge has better impurity removal and separation effects than the amino cartridge.Choosing 1000mg/6mL silica gel SPE cartridge,using 6mL n-pentane to elute UCM and alkanes,and 5mL n-pentane-dichloromethane(70∶30,V/V)to elute PAHs,and GC to conduct a preliminary inspection of the separation and purification effect,and GC-IRMS for individual carbon isotope analysis.The recovery of 16 kinds of PAHs was 79%-128%,the relative standard deviation was 2%-13%(1σ,n=6),and the analysis accuracy of the single carbon isotope ratio(δ^(13)C)was 0.1‰-0.75‰.CONCLUSIONS:The method greatly reduces the interferences of co-outflow and UCM to compound-specific carbon isotope analysis of PAHs,especially the low cyclic PAHs.No significant carbon isotope fractionation of PAHs is observed during purification,which satisfies compound-specific carbon isotope analysis requirements.

关 键 词：土壤 多环芳烃 单体碳同位素 固相萃取 分离净化 气体同位素质谱法 

分 类 号：O657.63[理学—分析化学] S151.93[理学—化学]