Revisitation of the matrix effects in inductively coupled plasma atomic emission spectrometry: the key role of the spray chamber

Abstract

The level of matrix effects observed in ICP-AES linked to a change in the matrix concentration is usually low, with the matrix being either the major element or a reagent such as an acid. However, the magnitude of the matrix effects depends on the ICP operating conditions. Under so-called robust conditions,i.e., high power and low carrier gas flow rate, matrix effects resulting from a change in the plasma conditions, i.e., temperature, electron number density and spatial distribution of the various species, are minimized to the same extent, regardless of the element and line. Robust conditions can be verified by using the ratio of an ionic line intensity to an atomic line intensity, the Mg II/Mg I ratio being commonly used. The remaining depressive effect is assigned to the sample introduction system, and it can be demonstrated that the effect occurs during aerosol transport and filtering. This phenomenon emphasizes the key role of the spray chamber in the matrix effects.