Development and assessment of a helium inductively coupled plasma ionisation source for inductively coupled plasma mass spectrometry

Investigations were directed at the development of a He inductively coupled plasma (ICP) ionisation source for inductively coupled plasma mass spectrometry (ICP-MS). Earlier results, exhibiting simpler plasma gas mass spectral features coupled with higher sensitivities for high ionisation energy elements, indicated promise for this source as a supplement to the conventional Ar ICP ion source. However, existence of an intense plasma-sampler cone discharge and the possible need for modifications of the conventional ICP-MS interface may pose major impediments to the use of the He ICP as an atomic mass spectrometry ion source. Investigation of these problems involved measurements of ion energies in the He ICP and theoretical consideration of the interface gas flow dynamics with a He plasma. Empirical and theoretical results indicate promise for the ultimate compatibility of this source with existing ICP-MS designs.