Direct Detection of Small & IT;n & IT;-Alkanes at Sub-ppbv Level by Photoelectron-Induced O-2(+) Cation Chemical Ionization Mass Spectrometry at kPa Pressure
Direct Detection of Small & IT;n & IT;-Alkanes at Sub-ppbv Level by Photoelectron-Induced O-2(+) Cation Chemical Ionization Mass Spectrometry at kPa Pressure
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直接检测小
DOI：
10.1021/acs.analchem.8b00595
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发表时间：
2018
影响因子：
7.4
通讯作者：
Li Haiyang
中科院分区：
文献类型：
--
作者：
Wang Yan;Hua Lei;Li Qingyun;Jiang Jichun;Hou Keyong;Wu Chenxin;Li Haiyang
饱和烃类，特别是小分子正构烷烃，由于其碱性低，缺乏可电离的官能团，直接质谱测量仍然是一个很大的挑战。在这项工作中，一种新型的高压光电子诱导O2+阳离子化学电离源（HPPI-OCI）在kPa的基础上的10.6 eV氪灯的飞行时间质谱仪（TOFMS）的发展。在双电场电离区，空气分子通过光电子电离产生高强度O2+反应物离子。当离子源压力从88 Pa提高到1080 Pa时，C3-C6正构烷烃的准分子离子[M-H]+在质谱中逐渐占据主导地位，信号强度提高了3个数量级以上。其结果是，达到的检测限降低到0.14，0.11，0.07，和0.1 ppbv的丙烷，正丁烷，正戊烷，和正己烷，分别。HPPI-OCI TOFMS的性能首先通过分析健康吸烟者和非吸烟者呼出的小正构烷烃来证明。分析4名健康志愿者饮酒后呼出气中小分子正构烷烃的浓度变化，探讨酒精肝毒性相关的氧化应激。总之，本工作提供了新的见解，控制O2+参与的化学电离，通过调整离子源的压力，并开发了一种新的直接质谱方法灵敏的测量malln-烷烃。
Direct mass spectrometric measurements of saturated hydrocarbons, especially smalln-alkanes, remains a great challenge because of low basicity and lack of ionizable functional groups. In this work, a novel high-pressure photoelectron-induced O2+cation chemical ionization source (HPPI-OCI) at kPa based on a 10.6 eV krypton lamp was developed for a time-of-flight mass spectrometer (TOFMS). High-intensity O2+reactant ions were generated by photoelectron ionization of air molecules in the double electric field ionization region. The quasi-molecular ions, [M–H]+, of C3–C6n-alkanes, gradually dominated in the mass spectra when the ion source pressure was elevated from 88 to 1080 Pa, with more than 3 orders of magnitude improvement in signal intensity. As a result, the achieved limits of detection were lowered to 0.14, 0.11, 0.07, and 0.1 ppbv for propane,n-butane,n-pentane, andn-hexane, respectively. The performance of the HPPI-OCI TOFMS was first demonstrated by analysis of exhaled smalln-alkanes from healthy smokers and nonsmokers. Then the concentration variations of exhaled smalln-alkanes of four healthy volunteers were analyzed after alcohol consumption to explore the alcohol-hepatoxicity-related oxidative stress. In summary, this work provides new insights for controlling the O2+-participating chemical ionization by adjusting the ion source pressure and develops a novel direct mass spectrometric method for sensitive measurements of malln-alkanes.