Determination of 30 Volatile Organic Compounds in Groundwater Samples by Purge and Trap-Gas Chromatography-Mass Spectrometry

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.