EASILY IONIZED ELEMENT INTERFERENCE EFFECTS IN FURNACE ATOMIZATION PLASMA EMISSION-SPECTROMETRY

The effects of easily ionized element (EIE) matrices on the response in furnace atomization plasma emission spectrometry is reported. Using NaCl and CsCl as model matrices, interference on integrated emission intensity from Pb and Co was studied as a function of EIE mass and source pressure [200-1500 Torr (1 Torr = 133.322 Pa)] in a 50 W He r.f. plasma. Comparative response was measured in the same source using the AAS mode of operation. Radiative power losses from the plasma due to excitation of the EIE matrix species and probable alteration of the electron energy distribution function (due to EIE ionization and collisional dissociation of molecules) appear to be the major sources of interference. Classical analyte molecule formation, gas-phase expulsion and de-tuning of the plasma in the presence of large masses of EIE are not significant factors in determining the extent of interference.