National Institute of Chemistry, Ljubljana, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
Radially resolved emission profiles of Sr, Mn and Zn analyte lines have been used to study the matrix effects in the presence of potassium chloride and phosphoric acid in inductively coupled plasma atomic emission spectrometry. The effects of these two matrices on the excitation temperature at a forward power of 1.3 kW and 1.6 kW is discussed. It is shown that both matrices influence the radially resolved excitation temperature and the analyte emission line profiles. At a higher operating power an increase in the excitation temperature of about 1000 K is observed for a potassium matrix. There are no simple relationships between the variations in the excitation temperature and changes in the analyte emission intensities. The differences in the radially resolved emission intensity profiles between Zn with a higher ionisation potential and Sr and Mn with lower and moderate ionisation potentials in the presence of potassium and phosphorous matrices at 1.3 kW are significant. However, in the vicinity of the central channel of the plasma, at 1.6 kW, these differences are lower indicating that the increase in excitation temperature plays a role in minimising matrix effects.