Determination of Chlorofluorocarbons in Groundwater by Purge and Trap and Secondary Cold Trap Coupled with Gas Chromatography/Mass Spectrometry

A method was established to determine the chlorofluorocarbons (CFCs) in groundwater by purge and trap and secondary cold trap coupled with gas chromatography/mass spectrometry (GC-MS). The groundwater samples were processed with absorption/thermal desorption/cold trap/thermal desorption, and GC-MS was used for quantitative and confirmatory analysis. The results showed that the relative standard deviations of chlorotrifluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and 1,1,2-trichlorotrifluoromethane (CFC-113) were 1.1%, 0.9% and 1.5%. The method linearity range of the CFC-11, CFC-12 and CFC-113 were 0.09 × 10−12−3.0 × 10−12 M, 0.04 × 10−12−3.0 × 10−12 M and 4.0 × 10−17−4.0 × 10−14 M, respectively. The correlation coefficients were greater than 0.99. The detection limit of CFC-11, CFC-12, CFC-113 were 4.4 × 10−14 M, 1.6 × 10−14 M and 5.36 × 10−18 M, respectively. The average recovery of the spiked samples was 95.4%−102.0%. The method was quick, sensitive, easy and feasible for the detection of CFCs in groundwater. According to the analysis results, the apparent age of groundwater can be calculated.

The CFCs can be detected in the groundwater that accepting modern recharged by purge and trap and secondary cold trap coupled with GC-MS. According to the results of the samples measured, the apparent age of groundwater could be calculated through historical concentrations of CFCs in global atmosphere.Figure optionsDownload as PowerPoint slide