Gas dynamics of the inductively coupled plasma mass spectrometry interface

Abstract

The documented properties of free jet expansions and molecular beam skimming have been applied to the sampling of an inductively coupled plasma (ICP) for mass spectrometry. It is shown that in the flow through the sampler and skimmer, the density and gas kinetic temperature of the plasma drop so rapidly that the degree of ionisation is frozen at that degree of ionisation of the source and little ion-molecule chemistry occurs. Provided the free jet is skimmed properly, a representative sample of ions from the ICP can be obtained.