Recently glow discharge (GD) mass spectrometry, which is conventionally used to analyze solid samples, was successfully applied for ionization and the subsequent determination of volatile organic compounds (VOCs). In the present study, the possibility of direct determination of VOCs in ambient air using time-of-flight mass spectrometry with microsecond pulsed discharge in a copper hollow cathode was considered for the first time. The discharge cell of the mass spectrometer was modified for the direct analysis of gaseous samples by the introduction of a quartz capillary into the argon input channel. Various classes of compounds (aromatic and aliphatic hydrocarbons and derivatives of carboxylic acids) were studied. Particular attention was paid to the ionization mechanisms of VOCs. New mechanisms of chemical and electron ionization, resulting in the formation of associate ions with cathode material (copper) – CuM+, were demonstrated and implemented. Alternative mechanisms of organic compounds ionization in GD may be related to Penning process and proton transfer reactions. These processes are mainly responsible for the formation of molecular and protonated molecular ions. The relative contribution of all these mechanisms can be adjusted by operating parameters. In general, an extremely low degree of fragmentation of molecular ions or associates was observed. Due to its isotopic structure (only two isotopes 63Cu and 65Cu with comparable abundances), the use of copper as cathode material additionally increases the reliability of VOC identification in the form of their CuM+ associates. Such association shifts the detected ions to the region of large masses with fewer interferences and noise related to scattered ions.
Original languageEnglish
Article number105986
Number of pages8
JournalSpectrochimica Acta - Part B Atomic Spectroscopy
Volume173
DOIs
StatePublished - Nov 2020

    Scopus subject areas

  • Analytical Chemistry
  • Instrumentation
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy

    Research areas

  • Volatile organic compound, Time-of-flight mass spectrometry, Pulsed glow discharge, Hollow cathode, ionization, Ionization, HYDROCARBONS, QUANTIFICATION, ACQUISITION, POTASSIUM TITANYL PHOSPHATE, OXYGEN, ELEMENTS, FLIGHT MASS-SPECTROMETRY, PLASMA, FLUORINE, CRYSTAL MATERIALS

ID: 70814425