Permanent iridium modifier deposited on tungsten and zirconium-treated platforms in electrothermal atomic absorption spectrometry: vaporization of bismuth, silver and tellurium

The stabilizing role of permanent Ir modifier deposited on W-treated (WTP) and Zr-treated (ZrTP) platforms of transversely heated graphite atomizer (THGA) was studied in detail by electrothermal at. absorption spectrometry (ETAAS) and different surface techniques in model expts. for Ag, Bi and Te. The comparison of the stabilizing efficiency of permanent Ir modifier on WTP and ZrTP and each of the single components, reveals the better effect of Ir on WTP and Ir itself. The extent of analyte losses during pre-atomization and the strength of analyte assocn. with the modifier were estd. by the plotting of differential vaporization curves. The existence of double peaks of Ag, Bi and Te in WTP and Ir on WTP was confirmed and possible reasons for their formation are discussed. The absorbance profiles presented as differential curves reveal an existence of at least two different types of precursors detg. processes of atom generation. The obsd. differences in the behavior of Ir permanent modifier on WTP and ZrTP, resp., were explained by the different extent of Ir-W and Ir-Zr interaction and surface distribution. XRF, ESCA and SEM studies reveal nonuniform distribution of the modifier on the graphite substrate and the presence of oxide contg. species on the surface. [on SciFinder (R)]