吹扫捕集-气相色谱-质谱联用法测定地下水中27种挥发性有机物

建立了DB-624和DB-FFAP双柱定性,吹扫捕集-气相色谱-质谱联用法测定地下水中卤代烃、苯系物、氯代苯等27种挥发性有机物的分析方法。考虑到环境介质的复杂性及干扰的不确定性,选择DB-624柱和极性较强的DB-FFAP柱优化了分离条件;采用分流进样模式,确定了目标组分灵敏度较高时的分流比10∶1;选择离子监测(SIM)方式扫描,提高了各扫描周期内组分的灵敏度;DB-624和DB-FFAP双柱定性,确保了结果的准确性,在DB-FFAP柱上可实现间二甲苯和对二甲苯异构体的完全分离。方法检出限为0.02～0.10μg/L,基体加标回收率为93.3%～109.5%,精密度(RSD,n=7)为0.9%～8.5%。对外部监控样品和实际水样进行测定表明,方法准确,灵敏可靠,可以满足地下水中痕量挥发性有机物的分析要求,适合于批量样品分析。

Determination of 27 Volatile Organic Compounds in Groundwater by Gas Chromatography-Mass Spectrometry with Purge and Trap Sampling

A method has been developed for the simultaneous detection of 27 volatile organic compounds(VOCs) including halogenated hydrocarbons,benzene series compounds and chlorinated benzenes in groundwater by Gas Chromatography-Mass Spectrometry(GC-MS) with purge and trap sampling.The double capillary columns of DB-624 and DB-FFAP were used for identifying the target compounds based on the complexity of the environmental medium and uncertainty of interference.Parameters affecting the accuracy and precision,such as separation conditions,injection mode and mass spectrometry scanning mode,were tested and optimized.The peak shape of target compounds in two different injection modes was compared and the results show that the split injection mode is significantly better than the non-split mode.The split injection with a ratio of 10:1 was selected to determine the target analytes with high sensitivity.The selected ion monitoring(SIM) scan mode improved the sensitivity of the components within the scan cycle.The double capillary columns of DB-624 and DB-FFAP were used to identify the target compounds,which ensured the accuracy for the analysis results.Meanwhile the m-xylene and p-xylene were totally separated by DB-FFAP capillary columns.The detection limits of the method for the target compounds were 0.02-0.10 μg/L.The recovery rates were 93.3%-109.5% with RSD of 0.9%-8.5%(n=7).The method has the advantages of lower detection limits,good precision and is suitable for the determination of trace VOCs in groundwater for a large number of samples.