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氯酚类化合物是垃圾焚烧所产生的二噁英前生体之一,对二噁英的浓度有很好的指示作用。针对气相中氯酚类二噁英前生体的在线连续监测,自行研制了全自动富集进样-单光子电离-反射式飞行时间质谱仪。为实现低浓度氯酚的检测,设计了全自动的富集进样系统,利用3根阵列式Tenax TA吸附管,结合全自动控制的高温电磁阀,实现了气体样品连续自动的“富集-热解析-质谱进样”。研制的反射式单光子电离-飞行时间质谱仪采用10.6eV真空紫外灯作为光电离源,对气体样品分子进行软电离,避免了碎片离子的产生,所获得的样品分子离子经反射式飞行时间质量分析器完成检测,仪器分辨率达到3 000(m/z 78)。以3种典型的二噁英前生体氯酚类化合物(邻氯苯酚、2,4-二氯苯酚、2,4,6-三氯苯酚)为检测对象,对该仪器性能进行考察。富集进样系统对3种氯酚类化合物的富集倍数分别达到60、249、503,检测限分别达到66、120、125pg/L,动态线性范围分别为166pg/L~16.6ng/L、210pg/L~21ng/L、255pg/L~25.5ng/L。这些研究结果为今后开展垃圾焚烧烟气中二噁英的现场连续监测工作奠定了基础。
Chlorophenols are one of the precursors of dioxins produced by waste incineration and have a good indication of the concentration of dioxins. Aiming at the on-line continuous monitoring of chlorophenols and dioxins precursors in gas phase, a fully automated enrichment injection-single photon ionization-time of flight mass spectrometer was developed. In order to detect low concentration of chlorophenols, an automatic enrichment injection system was designed. With three arrays of Tenax TA adsorption tubes and a fully automatic control of high temperature solenoid valves, the gas sample was continuously and automatically enriched - Thermal Analysis - MS Injection ". The developed single-photon ionization time of flight mass spectrometer using 10.6eV vacuum ultraviolet lamp as a photo-ionization source, the gas sample molecules soft ionization to avoid the generation of debris ions, the sample molecular ions obtained by the reflection time-of-flight quality Analyzer to complete the test, the instrument resolution of 3 000 (m / z 78). Three representative samples of dioxins precursors chlorophenols (o-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol) were tested for their performance. Enrichment injection system for three kinds of chlorophenols enrichment multiple were 60,249,503, respectively, the detection limits were 66,120,125 pg / L, the dynamic linear range of 166pg / L ~ 16.6ng / L, 210pg / L ~ 21ng / L, 255pg / L ~ 25.5ng / L. These findings will lay the foundation for continuous monitoring of dioxins in waste incineration flue gas in the future.