A predictive model of plasma matrix effects in inductively coupled plasma atomic emission spectrometry

Abstract

Matrix effects in inductively coupled plasma atomic emission spectrometry (ICP-AES) due to metallic elements in solution are found to be largely due to plasma processes. The effects of such matrix elements on the sensitivities of analyte lines are evaluated. Most matrix elements give rise to considerably greater effects than do the frequently studied alkali metals, under operating conditions normally adopted for routine use. Analytes are affected to a degree dependent on the total excitation potential. Lines with high excitation potential are strongly affected. Different matrix elements produce widely varying effects on the sensitivity of a single line, depending on the energy required to dissociate and ionise the matrix. These observations are consistent with the hypothesis that the matrix effects are due to cooling of the plasma by the matrix. Such a model enables matrix effects to be quantitatively predicted for matrices at 0.05 M.