Selected ion flow tube mass spectrometry (SIFT-MS) and proton transfer reaction mass spectrometry with switchable reagent ion capability (PTR+SRI-MS) are analytical techniques for real-time qualification and quantification of compounds in gas samples with trace level concentrations. In the detection process, neutral compounds—mainly volatile organic compounds—are ionized via chemical ionization with ionic reagents or primary ions. The most common reagent ions are H₃O⁺, NO⁺ and O₂^+•. While ionization with H₃O⁺ occurs by means of proton transfer, the ionization via NO⁺ and O₂^+• offers a larger variety on ionization pathways, as charge transfer, hydride abstraction and so on are possible. The distribution of the reactant into various reaction channels depends not only on the usage of either NO⁺ or O₂^+•, but also on the class of analyte compounds. Furthermore, the choice of the reaction conditions as well as the choice of either SIFT-MS or PTR+SRI-MS might have a large impact on the resulting products. Therefore, an overview of both NO⁺ and O₂^+• as reagent ions is given, showing differences between SIFT-MS and PTR+SRI-MS as used analytical methods revealing the potential how the knowledge obtained with H₃O⁺ for different classes of compounds can be extended with the usage of NO⁺ and O₂^+•.

中文翻译：

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NO+ 和 O2+• 在可切换试剂离子质子转移反应飞行时间质谱中的潜力

选择离子流管质谱 (SIFT-MS) 和具有可切换试剂离子功能的质子转移反应质谱 (PTR+SRI-MS) 是用于对气体样品中痕量浓度化合物进行实时定性和定量的分析技术。在检测过程中，中性化合物（主要是挥发性有机化合物）通过离子试剂或一次离子的化学电离而电离。最常见的试剂离子是H ₃ O ⁺、NO ⁺和O ₂ ^+•。虽然H ₃ O ⁺的电离通过质子转移发生，但通过NO ⁺和O ₂ ^{+• 的}电离提供了更多种类的电离途径，因为电荷转移、氢化物提取等都是可能的。反应物在不同反应通道中的分布不仅取决于NO ⁺或O ₂ ^+·的使用，还取决于分析物化合物的类别。此外，反应条件的选择以及 SIFT-MS 或 PTR+SRI-MS 的选择可能对所得产物产生很大影响。因此，给出了作为试剂离子的NO ⁺和 O ₂ ^+•的概述，显示了 SIFT-MS 和 PTR+SRI-MS 所用分析方法之间的差异，揭示了如何利用 H ₃ O ⁺获得不同类别的知识的潜力化合物的数量可以通过使用NO ⁺和O ₂ ^+•来扩展。