Matrix effect of aluminium, calcium and magnesium in axially viewing inductively coupled plasma atomic emission spectrometry

The matrix effect due to Al, Ca and Mg in axial view mode ICP-AES was investigated over analyte lines with total excitation energy from 1.62 to 16.51 eV. A global qualitative explanation of the action of the matrix is proposed. The energy is directly transferred between matrix and analyte specimens ( atoms or ions) during inelastic collisions, which are particularly relevant in the 1.62-8 eV excitation energy range, where the direct action with argon specimens is less probable to occur. Concrete applications of this global qualitative explanation are given, taking into account the resonance energy effect and the spin conservation rule. The characteristic matrix effect of Al and Ca for lines excited by charge transference mechanism was observed. In the presence of Mg, other possible matrix-analyte interactions may reduce the efficiency of this mechanism. The particular behavior of the matrix effect for lines in the 10.5-11.5 eV energy range can be considered as experimental evidence of the Penning ionization-excitation mechanism, which probably actuates along other matrix-analyte interactions.