National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China.
Anal Chem. 2013 Dec 17;85(24):11993-2001. doi: 10.1021/ac402955k. Epub 2013 Nov 25.
A newly developed, qualitative and quantitative method based on tunable synchrotron radiation vacuum ultraviolet photoionization time-of-flight mass spectrometry (SR-VUV-PI-TOFMS) and photoionization efficiency (PIE) curve simulation was applied for the online analysis of isomers and isobaric compounds in the gas phase of mainstream cigarette smoke. After blocking the particulate phase components by the Cambridge filter pad, a puff of fresh gas-phase cigarette smoke was immediately introduced into a vacuum ionization chamber through a heated capillary, then was photoionized, and analyzed by a TOF mass spectrometer. The PIE curves for the mass peaks up to m/z = 106 were measured between 8.0 and 10.7 eV. Some components could be directly identified by their discriminated ionization energies (IEs) on the PIE curve. By simulating the PIE curve with the sum of scaled absolute photoionization cross sections (PICSs), complex isomeric/isobaric compounds along with their mole fractions could be obtained when the best-fitting was realized between experimental and simulated PIE curves. A series of reported toxic compounds for quantification, such as 1,3-butadiene (m/z = 54), 1,3-cyclopentadiene (m/z = 66), benzene (m/z = 78), xylene (m/z = 106), 2-propenal (m/z = 56), acetone and propanal (m/z = 58), crotonaldehyde (m/z = 70), furan and isoprene (m/z = 68), were all found to have other isomers and/or isobaric compounds with considerable abundances. Some isomers have never been reported previously in cigarette smoke, like C5H6 isomers 1-penten-3-yne, 3-penten-1-yne, and 1-penten-4-yne at m/z = 66. Isomeric/isobaric compounds characterization for the mass peaks and mole fraction calculations were discussed in detail below 10.7 eV, an energy value covering several conventional used VUV light sources.
一种新开发的基于可调谐同步辐射真空紫外光电离飞行时间质谱（SR-VUV-PI-TOFMS）和光电离效率（PIE）曲线模拟的定性和定量方法，被应用于主流香烟烟雾气相中异构体和等质量异位体化合物的在线分析。在用剑桥滤片阻断颗粒物成分后，通过加热毛细管将一口新鲜的气相香烟烟雾立即引入真空电离室，然后进行光电离，并由飞行时间质谱仪进行分析。在 8.0 至 10.7 eV 之间测量了质量峰高达 m/z = 106 的 PIE 曲线。一些成分可以通过它们在 PIE 曲线上的分辨电离能（IE）直接识别。通过用比例绝对光电离截面（PICS）的总和模拟 PIE 曲线，可以在实验和模拟 PIE 曲线之间实现最佳拟合时获得复杂的异构体/等质量异位体化合物及其摩尔分数。为了定量分析，还测定了一系列报道的有毒化合物，如 1,3-丁二烯（m/z = 54）、1,3-环戊二烯（m/z = 66）、苯（m/z = 78）、二甲苯（m/z = 106）、2-丙烯醛（m/z = 56）、丙酮和丙醛（m/z = 58）、巴豆醛（m/z = 70）、呋喃和异戊二烯（m/z = 68），这些化合物都发现存在其他异构体和/或等质量异位体化合物，而且丰度相当高。有些异构体在香烟烟雾中从未被报道过，例如 m/z = 66 的 C5H6 异构体 1-戊烯-3-炔、3-戊烯-1-炔和 1-戊烯-4-炔。在低于 10.7 eV 的能量值下（涵盖了几个常用的 VUV 光源），详细讨论了质量峰和摩尔分数计算的异构体/等质量异位体化合物特征。
