Helium-argon inductively coupled plasma for plasma source mass spectrometry

Abstract

An He -Ar mixed gas inductively coupled plasma (ICP) was investigated for use as an ion source for plasma mass spectrometry (MS). The addition of He to Ar produces a plasma capable of ionising high ionisation potential elements more efficiently than the pure Ar plasma. The best signal to noise ratios for metallic elements were obtained with a 20% He plasma, and for halides with a 30% He plasma. The He -Ar mixed gas plasma shows an improvement of one order of magnitude in the detection limits of several metallic elements studied and an improvement of two orders of magnitude for non-metals in comparison with Ar ICP-MS. Figures of merit, including detection limits, linear dynamic ranges, metal oxide ratios and doubly to singly charged ion ratios, are reported and compared with those for Ar ICP-MS.

A status report on helium inductively coupled plasma mass spectrometry

“…Mass spectral interferences resulting from argon polyatomic species are reduced when He-based plasmas are applied as ionization sources, because He essentially is monoisotopic, and occurs at a low mass [11,12,20,24,25,27,30,35,36,[39][40][41][42]. The three isotopes of Ar ( 36 Ar + , 38 Ar + , and 40 Ar + ) along with polyatomic species containing Ar such as 40 Ar 16 O + , 40 Ar 40 Ar + , 40 Ar 35 Cl + interfere with the determination of certain isotopes, e.g.…”

Inductively coupled plasma mass spectrometry with ambient helium surrounding ion source

“…Finally, helium is of small size and light mass, so it easily diffuses into the plasma and collides with polyatomic ions. These collisions could result in the dissociation of polyatomic ions and the reduction of background signals [15]. For polyatomic ions that are weakly bound, they are easy to be fragment during collision processes.…”

Guideline of inductively coupled plasma mass spectrometry “ICP–MS”: fundamentals, practices, determination of the limits, quality control, and method validation parameters

“…It has great benefits; where it produces plasma to induce the ionization of some elements which have a high ionization potential efficiently more than the Argon gas only and also. The mixture of Argon and Helium show an improvement in detection limits for several elements [44].…”