Determination of 10 Trace Benzene Series in Surface Water by Gas Chromatography-Mass Spectrometry with Solid Phase Micro-Extraction

Porous polyvinylidene fluoride membrane was used to wrap multi-walled carbon nanotubes (MWCNTs) to prepare a solid phase micro-extraction device. After water washing, methanol activating and drying, the device was put into 1 L of the sample, and the coating was stirred at a rate of 500 r·min^-1 for 30 min to adsorb and enrich trace benzene series. The coating was taken out and desorbed for 5 min in 1 mL of methanol to get the benzene series sample concentrated, in which 10 trace benzene series were analyzed by gas chromatography-mass spectrometry. 10 trace benzene series were identified by compared with NIST 14 spectrum library and the gas chromatographic retention time of the standards, and quantified by external standard method. As shown by the results, the application of self-made solid phase micro-extraction device could effectively remove the matrix interference of the system and improve extraction efficiency. Compared with NIST 14 spectrum library, the matching degree of 10 enriched benzene series was not less than 90%, indicating that qualitative analysis for this method was accurate. In quantitative analysis, linear relationships between values of peak area and mass concentration of 10 benzene series were found in the range of 1.000-1 000 ng·L^-1, with detection limits in the range of 0.010-0.013 ng·L^-1. Test for recovery was made by standard addition method, giving results in the range of 97.5%-100%, with RSDs (n=5) of the determined values ranged from 0.89% to 1.5%. This method was applied to determination of 12 actual water samples, among which the detection amount of chlorobenzene in one sample was 179.0 ng·L^-1 and that of paraxylene in the other sample was 151.0 ng·L^-1.