关键词: 环境空气, 挥发性有机物, 气相色谱-三重四极杆串联质谱, 热脱附

Abstract:

A method was established for the simultaneous determination of 23 volatile organic compounds (VOCs) in ambient air with combination of thermal desorption (TD) and gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). The air samples were collected by active sampling method using Tenax-TA sorbent tubes, and desorbed by thermal desorption. The analytes were determined by GC-MS/MS in selected reaction monitoring (SRM) mode, and internal standard method was applied to quantify the VOCs. The results of all the 23 VOCs showed good linearities in low level (0.01-1 ng) and high level (1-100 ng) with all the correlation coefficients (r²) more than 0.99. The method quantification limits were between 0.00008-1 μ g/m³. The method was validated by means of recovery experiments (n=6) at three spiked levels of 2, 10 and 50 ng. The recoveries between 77% and 124% were generally obtained. The relative standard deviations (RSDs) in all cases were lower than 20%, except for chlorobenzene at the low spiked level. The developed method was applied to determine VOCs in ambient air collected at three sites in Shanghai. Several compounds, like benzene, toluene, ethylbenzene, m-xylenes, p-xylenes, styrene, 1,2,4-trimethylbenzene and hexachlorobutadiene were detected and confirmed in all the samples analyzed. The method is highly accurate, reliable and sensitive for monitoring the VOCs in ambient air.

Key words: ambient air, gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS), thermal desorption (TD), volatile organic compounds (VOCs)