The production of doubly charged sample ions by “charge transfer and ionization” (CTI) in analytical GD-MS

Sohail Mushtaq, Edward B. M. Steers, DeAnn Barnhart, Glyn Churchill, Martin Kasik, Silke Richter, Jens Pfeifer, Karol Putyera
  • Journal of Analytical Atomic Spectrometry, January 2017, Royal Society of Chemistry
  • DOI: 10.1039/c6ja00415f

What is it about?

In glow discharge mass spectrometry, the doubly charged ion current of a sample constituent is normally three or more orders of magnitude less than that of the singly charged ion. However, it has been observed that when a titanium sample is used with neon as the plasma gas, the Ti++ signal is of the same order of magnitude as the Ti+ signal. Whilst doubly charged ions may be produced by electron impact excitation, we show that this very large Ti++ signal is due to a little-known process, Charge Transfer and Ionization (CTI).

Why is it important?

This is the first time that 'Charge transfer and ionization' (CTI) process has been identified in analytical glow discharge mass spectrometry sources.


Mass Spectrometry Instruments Limited

An immediate analytical consequence of this work is that analysts need to be aware of the possible presence of additional doubly ionized species, which may lead to unexpected interferences. The possibility of high concentrations of Ba++ ions in an argon plasma is well known. The problem is still relatively mild when neon is used as the plasma gas, but will be much more severe if argon/helium mixtures are used.

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The following have contributed to this page: Dr SOHAIL MUSHTAQ