真空紫外灯单光子电离源飞行时间质谱仪的研制

Vacuum Ultraviolet Single Photon Ionization Time-of-Flight Mass Spectrometer

研制了真空紫外灯单光子电离源飞行时间质谱仪(Vacuum ultraviolet single photon ionization timeof-flight mass spectrometer,VUV-SPI-TOFMS),包括真空系统、毛细管进样系统、真空紫外灯电离源、垂直加速反射式飞行时间质量分析器和数据采集系统等。仪器采用的真空紫外单光子电离方式,能够将电离能低于紫外单光子能量(10.6eV)的挥发性有机物(Volatile organic compounds,VOCs)电离。与电子轰击源比较,紫外光电离基本无碎片产生,比较适合样品定性分析。结果表明,仪器的质量分辨率优于800(Fullwidth at half maximum,FWHM),质量精度优于1.0×10-4。仪器能够检测出香烟主流烟气中的60多种化合物,对于丙酮、环己烷、乙酸乙酯和甲苯的定性检出限分别为0.33×10-6,0.27×10-6,0.42×10-6和0.11×10-6。本仪器能够实现对各种环境介质(气相、固相、液相)中挥发性有机物的实时、在线检测,若与膜富集、加热进样装置或吹扫捕集系统联用,仪器的灵敏度能得到有效提高。

A home-made vacuum ultraviolet single photon ionization time-of-flight mass spectrometer（VUV-SPI-TOFMS） was introduced,including vacuum system,sampling inlet system,vacuum ultraviolet ionization source,reflection time-of-flight mass analyzer and data acquisition system.Single photon ionization with vacuum ultraviolet light is a particularly soft ionization technique.Volatile organic compounds（VOCs） with ionization energy less than the photon energy（10.6 eV）,could be ionized into molecular ions.It was nearly fragmentation free compared with electron ionization,and very suitable for qualitative analysis.The mass resolution of instrument was higher than 800（Full width at half maximum,FWHM） and the mass accuracy was better than 1.0×10-4.The initial experiments showed that more than 60 components from cigarette mainstream smoke could be detected,and the limits of detection for acetone,cyclohexane,ethyl acetate and toluene were 0.33×10-6（V/V）,0.27×10-6（V/V）,0.42×10-6（V/V） and 0.11×10-6（V/V）,respectively.This instrument could be used for real-time and on-line analysis for VOCs in various environmental media（gas,solid,liquid）,and if combined with a membrane inlet system,heating device or purge and trap system,a higher sensitivity could be achieved.