Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.
Lumex Ltd., ul. Obruchevykh 1b, 195220 St. Petersburg, Russia.
Molecules. 2022 Oct 13;27(20):6864. doi: 10.3390/molecules27206864.
Glow discharge (GD) source gained an increased level of attention in relation to the analysis of volatile organic compounds (VOCs) since past work showed that this soft ionization method allowed direct analysis of VOCs with minimal fragmentation, however, the issue of fragmentation was not previously studied in detail. The aim of the present work was to investigate the effect of discharge conditions on VOC fragmentation in the system consisting of the cell with pulsed glow discharge and a time-of-flight mass spectrometer. Ionization of VOCs of different classes (hydrocarbons, alcohols, esters, and carboxylic acids) was investigated. A copper cathode with flat geometry was used. VOCs were ionized in the afterglow of short pulse glow discharge in the air. The use of discharge afterglow significantly reduces or eliminates the effects of ionization mechanisms other than Penning process, in particular, electron ionization. This significantly reduced VOC fragmentation and provided rather low limits of detection. Specific cluster formation was observed for alcohols and esters, which may facilitate their identification.
辉光放电 (GD) 源在分析挥发性有机化合物 (VOCs) 方面受到了越来越多的关注，因为过去的工作表明，这种软电离方法允许对 VOCs 进行直接分析，几乎没有碎片，然而，以前并没有详细研究过碎片问题。本工作的目的是研究在由带有脉冲辉光放电的腔室和飞行时间质谱仪组成的系统中，放电条件对 VOC 碎片的影响。研究了不同类别 (烃类、醇类、酯类和羧酸类) 的 VOC 的电离。使用了具有平面几何形状的铜阴极。VOC 是在空气中的短脉冲辉光放电的余晖中被电离的。使用放电余晖可以显著减少或消除除彭宁过程以外的其他电离机制的影响，特别是电子电离。这显著减少了 VOC 的碎片，并且提供了相当低的检测限。对于醇类和酯类，观察到了特定的团簇形成，这可能有助于它们的识别。
