Indirect hydrogen monitoring by chemi-ionisation following an associative ionisation pathway after metastable helium atoms production by electron impact ionisation: Protonation and deuteration of carrier gas

摘要

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. However, hydrogen (H-2) detection after a GC separation is only possible with a Thermal Conductivity Detector (TCD), a Helium Ionisation Detector (HID) or expensive Atomic Emission Detector (AED). Recently, indirect H-2 detection by GC coupled to mass spectrometry (MS) was demonstrated but the mechanism of carrier gas protonation remained unclear. With electron impact as ionisation source of MS and helium (He) as GC carrier gas, H-2 is not ionised according the expected Penning ionisation neither according to the Associative ionisation. Rearrangement ionisation (RI) was found to be the main channel for H-2 and D-2 ionisation under GC-MS conditions used in most of laboratories using GC-MS, leading to the formation of [He-H](+) and [He-D](+) ions. (C) 2014 Elsevier B.V. All rights reserved.