A dynamic reaction cell for inductively coupled plasma mass spectrometry (ICP-DRC-MS) - Part 1. The rf-field energy contribution in thermodynamics ofion-molecule reactions
Vi. Baranov et Sd. Tanner, A dynamic reaction cell for inductively coupled plasma mass spectrometry (ICP-DRC-MS) - Part 1. The rf-field energy contribution in thermodynamics ofion-molecule reactions, J ANAL ATOM, 14(8), 1999, pp. 1133-1142
The existing vast database of ion-molecule reaction kinetics may, with adva
ntage, be used to overcome spectral interference in ICP-MS. To be directly
applicable to an rf multipole reactor, it must be shown that the multipole
provides a controlled thermal environment. The contribution of the rf field
energy to the ion energy is modeled for a quadrupole reaction cell. It is
shown that the rf field contribution increases with increasing rf amplitude
and decreasing rf frequency (i.e., towards the high-q side of the quadrupo
le stability region). A thermodynamic ladder is proposed as a convenient me
asure of the thermal characteristics of the reactor, and should serve as a
benchmark for comparison of various reaction cell designs. Experimental res
ults for charge transfer reactions are presented. These indicate that the c
onfiguration reported is near-thermal, with an rf field energy contribution
less than about 0.4 eV. The rich variety of ion-molecule processes which m
ight be studied is demonstrated by examples of condensation, simple associa
tion and complex ligation reactions.