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实验室研制了低能光电子磁场增强电离(MEPEI)和单光子电离(SPI)复合电离源,该电离源具有电离化合物范围宽、碎片离子少、质谱图简单等优点,结合飞行时间质谱(TOF-MS)实现了聚氯乙烯(PVC)热分解/燃烧产物的在线分析.针对不同的目标化合物,MEPEI/SPI复合电离源通过调节电离区电场强度,可以快速在SPI和SPI-MEPEI之间切换.PVC热分解/燃烧产物中电离能大于光子能量(10.60 eV)的HCl和CO2(12.74 eV、13.77 eV)利用MEPEI模式电离;而烯烃、二氯乙烯、苯系物、氯苯、苯乙烯、茚满及萘系物等可通过SPI-MEPEI复合模式电离.通过实时监测PVC主要燃烧产物的信号强度随温度的变化趋势可推断出,PVC燃烧产物主要是通过两种机制生成:①250～370℃时,PVC发生脱氯及分子内环化反应,产生大量的HCl、苯和萘;②380～510℃时,PVC发生分子间交联反应,生成烷基芳烃,如甲苯和二甲苯/乙苯等.实验结果表明,SPI/SPI-MEPEI复合离子源TOF-MS分析速度快,应用范围广,在在线分析中具有广泛的应用前景.
The laboratory has developed the low-energy photoelectron magnetic field enhanced ionization (MEPEI) and single-photon ionization (SPI) composite ionization source. The ionization source has the advantages of wide range of ionization compounds, few fragment ions and simple mass spectrum. Combined with time of flight mass spectrometry ) For on-line analysis of PVC thermal decomposition / combustion products.For different target compounds, MEPEI / SPI complex ionization source can quickly switch between SPI and SPI-MEPEI by adjusting the electric field intensity in the ionization region. HCl and CO2 (12.74 eV, 13.77 eV) in the thermal decomposition / combustion products with an ionization energy greater than 10.60 eV of photon energy are ionized using the MEPEI mode; while olefins, vinylidene chloride, benzene, chlorobenzene, styrene, And naphthalene compounds can be ionized by SPI-MEPEI composite mode. By real-time monitoring of the signal intensity of PVC main combustion products with temperature trend can be inferred, PVC combustion products are mainly generated by two mechanisms: ① 250 ~ 370 ℃, PVC dechlorination and intramolecular cyclization reaction, resulting in a large amount of HCl, benzene and naphthalene; ② 380 ~ 510 ℃, PVC intermolecular cross-linking reaction to generate alkylated aromatic hydrocarbons, such as toluene and xylene / ethylbenzene, etc. Experiment Results table , SPI / SPI-MEPEI complex ion source speed fast TOF-MS analysis, a wide range of applications, with a wide range of applications in online analysis.