摘要:
在测定地下水中有机污染物时,捕集阱的填料对分析结果有很大的影响。本文采用吹扫捕集/气相色谱-质谱联用技术,建立了适用于地下水中卤代烃、氯代苯、苯系物等30种挥发性有机污染物的分析方法。对11#捕集阱(VOCARB3000)和10#捕集阱(Tenax/硅胶/碳分子筛)进行比较实验和捕集阱的填料进行选择优化,结果表明,以氮气为吹扫气,11#捕集阱的检出限比10#捕集阱的检出限低,富集效率和响应值更高,更适合分析低含量的地下水样品; Rtx-502.2毛细柱(60 m×0.32 mm×1.8 μm)对目标组分有更好的分离效果,且柱流失小、色谱峰响应高; 利用选择离子扫描方式对目标物进行扫描,采用内标法定量,提高了方法灵敏度,消除了组分的干扰以及整个分析过程中存在的系统误差。方法检出限为0.031~0.059 μg/L,精密度(RSD)为1.02%~5.19%(n=7),回收率为87.7%~118.0%(n=7),各组分相关系数均在0.9991以上。方法操作简便,对环境污染小,可满足大批量地下水中痕量挥发性有机物的分析要求。
Abstract:
The packing of the Trap has crucial influence to the results when measuring the volatile organic compounds (VOCs) in groundwater samples. The determination of 30 kinds of VOCs including halohydrocarbons, chlorobenzene, benzene series, and so on, in groundwater samples was developed by using Purge and Trap-Gas Chromatography-Mass Spectrometry. The fillings of the trap were optimized with the comparison study of Trap 10# and Trap 11#. Results indicated that Trap 11# had lower detection limit, high enrichment and response compared with Trap 10# when nitrogen was the purge gas. The Trap 11# was suitable for low level groundwater samples. The Rtx-502.2 capillary column (60 m×0.32 mm×1.8 μm) was good for separating target components with small column erosion and high peak response. Selected Ion Monitoring (SIM) and the internal standard method were used for the quantitative analysis, which increased the sensitivity of the method, eliminated the matrix effect and the systematical error for the whole procedure. The detection limits of the method were 0.031-0.059 μg/L, and the mean recoveries were between 87.7%-118.0% with precision of 1.02%-5.19% (n=7). The correlation coefficients of the calibration curve equations were higher than 0.9991 for all compounds. The method provided the advantage of simple operation and low environment pollution, and was suitable for batch determination of trace VOCs in groundwater samples.
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