We present an effective procedure to differentiate instrumental artefacts, such as parasitic ions, memory effects, and real trace impurities contained in inert gases. Three different proton transfer reaction mass spectrometers were used in order to identify instrument-specific parasitic ions. The methodology reveals new nitrogen- and metal-containing ions that up to date have not been reported. The parasitic ion signal was dominated by [N2 ]H+ and [NH3 ]H+ rather than by the common ions NO+ and O2 + . Under dry conditions in a proton transfer reaction quadrupole interface time-of-flight mass spectrometer (PTR-QiTOF), the ion abundances of [N2 ]H+ were elevated compared with the signals in the presence of humidity. In contrast, the [NH3 ]H+ ion did not show a clear humidity dependency. On the other hand, two PTR-TOF1000 instruments showed no significant contribution of the [N2 ]H+ ion, which supports the idea of [N2 ]H+ formation in the quadrupole interface of the PTR-QiTOF. Many new nitrogen-containing ions were identified, and three different reaction sequences showing a similar reaction mechanism were established. Additionally, several metal-containing ions, their oxides, and hydroxides were formed in the three PTR instruments. However, their relative ion abundancies were below 0.03% in all cases. Within the series of metal-containing ions, the highest contribution under dry conditions was assigned to the [Fe(OH)2 ]H+ ion. Only in one PTR-TOF1000 the Fe+ ion appeared as dominant species compared with the [Fe(OH)2 ]H+ ion. The present analysis and the resulting database can be used as a tool for the elucidation of artefacts in mass spectra and, especially in cases, where dilution with inert gases play a significant role, preventing misinterpretations.

中文翻译：

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质子转移反应飞行时间质谱仪中的伪像的阐明。

我们提出了一种有效的程序来区分仪器伪像，例如寄生离子，记忆效应和惰性气体中所含的实际痕量杂质。为了鉴定仪器特有的寄生离子，使用了三种不同的质子转移反应质谱仪。该方法揭示了迄今尚未报道的新的含氮和金属离子。寄生离子信号主要由[N2] H +和[NH3] H +决定，而不是由普通离子NO +和O2 +决定。在干燥条件下，质子转移反应四极杆界面飞行时间质谱仪（PTR-QiTOF）中，[N2] H +的离子丰度与存在湿度的信号相比有所提高。相反，[NH3] H +离子没有显示出明显的湿度依赖性。另一方面，两种PTR-TOF1000仪器显示[N2] H +离子没有明显贡献，这支持了在PTR-QiTOF的四极界面中形成[N2] H +的想法。鉴定出许多新的含氮离子，并建立了三个显示相似反应机理的不同反应序列。此外，在三种PTR仪器中还形成了几种含金属的离子，它们的氧化物和氢氧化物。但是，在所有情况下，它们的相对离子丰度都低于0.03％。在一系列含金属的离子中，在干燥条件下贡献最大的是[Fe（OH）2] H +离子。与[Fe（OH）2] H +离子相比，仅在一种PTR-TOF1000中，Fe +离子作为主要物质出现。本分析和所得的数据库可以用作阐明质谱中的伪像的工具，并且