New possibilities for the determination of volatile organic compounds by their molecular ions in air using µs-pulsed gd tofms

A recent trend in glow discharge analysis, previously considered as a ‘purely inorganic’ technique, is related to the effective ionisation of volatile organic compounds (VOCs). This approach was demonstrated to be capable of analysing VOCs in both model gas mixtures and ambient air. In the current study, the possibility of the direct determination of VOCs of different classes of organic compounds (including toluene, p-xylene, chlorobenzene and 1,2,4-trimethylbenzene) in ambient air using microsecond pulsed glow discharge time-of-flight mass spectrometry (µs-Pulsed GD TOFMS) with copper hollow cathode was demonstrated. The ionisation processes with the formation of molecular ions M⁺, which can be used for quantification, were discussed. The fragmentation of detected molecular ions of VOCs was found to be quite low, which benefits both qualitative and quantitative determination. The ease of identification and relative simplicity of the mass spectrum is promising for the analysis of VOC mixtures. One of the possible applications of the designed method is the direct determination of VOCs in human exhaled breath for the diagnosis of lung diseases, including lung cancer. However, revealing its potential applicability for this purpose requires further research.