中文摘要：

研制了膜进样-单光子电离-飞行时间质谱仪,并应用于水中挥发性有机物（VOCs）的连续在线快速测量。以50μm硅橡胶膜为富集膜,用蠕动泵和电动切换阀,实现了水中VOCs的自动进样、富集和测量,无记忆效应。采用真空紫外灯发出的10.6eV的光子,对待测有机物实现单光子电离,无碎片离子,便于根据分子量进行定性分析。苯、甲苯、二甲苯和氯苯等样品的响应时间均低于100s;苯的检出限可达3×10-9（V/V）,且在10×10-9～1×10-6（V/V）范围内具有良好的线性。将仪器应用于某化工厂排污水的在线检测中,在200s时间内可检测到20多种10×10-9（V/V）量级的有机物。结果表明：膜进样-单光子电离-飞行时间质谱在水中VOCs在线检测方面具有广泛应用前景。

英文摘要：

A single photon ionization time of flight mass spectrometer with membrane inlet has been described and applied for on-line measuring volatile organic compounds （VOCs） in water. Automatic sampling, enrichment and measurement of VOCs were achieved by using a polyolimethyl siloxane （PDMS） membrane with a thickness of 50 μm, a peristaltic pump and electric switch valve. There is almost no memory effect in the membrane inlet system. Single photon ionization processes were accomplished with photons of 10.6 eV emitted from a commercial low pressure discharge krypton lamp, and almost no free fragment was found in mass spectrum. Thus, it can be used for chemical compounds identification according to their molecular weight. The response times for benzene, toluene, xylene and chlorobenzene were all shorter than 100 s. The detection limit of benzene is 3×10-9（volume fraction）, and an excellent linear response was observed in the range of 10×10-9（V/V） to 1×10-6（V/V）. The instrument was tested to analyze VOCs in the sewerage from a chemical plant, and more than twenty compounds of VOCs with concentration in 10×10-9（V/V） level were observed in 200 s. The results indicate that the single photon time-of-flight mass spectrometer with membrane inlet has a great application potential for on-line analyzing VOCs in water.