Mass spectrometric determination of the temperature of an argon inductively coupled plasma from the formation of the singly charged monoxide rare earths and their known dissociation energies

Abstract

The effect of inductively coupled plasma (ICP) parameters on plasma temperature was studied by mass spectrometry using a commercially available SCIEX inductively coupled plasma mass spectrometer. Parameters varied include nebuliser gas flow, auxiliary gas flow, r.f. power and liquid sample uptake. The plasma temperatures were determined from the energy of formation of the singly positive charged monoxide ions from the singly charged positive metal ion and oxygen. As the nebuliser gas flow was changed, the measured plasma temperature varied from 12400 (nebuliser gas flow 0.6 l min^–1) to 5100 K (nebuliser gas flow 1.4 l min^–1). An increase in temperature from 9000 to 12700 K was observed as the power was increased from 1200 to 1500 W, or to 12500 K when the auxiliary gas flow was decreased from 2.0 to 1.0 l min^–1. A decrease in the liquid sample uptake from 1.0 to 0.2 ml min^–1 caused a temperature increase from 9000 to 11500 K.