TEMPORAL EMISSION AND ABSORPTION CHARACTERISTICS OF SILVER, LEAD AND MANGANESE IN FURNACE ATOMIZATION PLASMA EXCITATION SPECTROMETRY

The temporal behaviour of the signal measured for Ag, Pb and Mn in furnace atomization plasma excitation spectrometry was studied using atomic emission and atomic absorption spectrometry. Analyte was deposited both on the wall and on the r.f. electrode with and without the r.f. power applied. Analyte condensation on the r.f. electrode is observed when no plasma is formed. When the plasma is formed inside the furnace it heats the electrode such that, for Ag and Pb, condensation is not observed except for large amounts of analyte. For Ag and Mn, the appearance temperatures and peak temperatures are not significantly affected by the plasma relative to the response obtained using a graphite furnace. For Pb, appearance and peak temperatures are shifted significantly earlier. For Pb, atom formation may be effected by the presence of CO in the gas phase generated from oxidation of the graphite furnace wall and electrode. The role of carbon in atom formation was studied by depositing the sample on both tungsten and graphite electrodes.