Ga. Zachariadis et al., SEM-EDXRF study of two chemical modifiers based on platinum and tungsten and their effect on ET-AAS atomization of lead, MIKROCH ACT, 136(3-4), 2001, pp. 115-122
The behavior of two chemical modifiers based on platinum and tungsten, is s
tudied in the two parts of this work. At first, the chemical and morphologi
cal alterations of these during pyrolysis and atomization stages in electro
thermal atomic absorption spectrometry are studied. The compounds were H2Pt
Cl6 and Na2WO4. A cylindrical graphite tube was used, and fixed shaped rect
angular graphite plates were put inside as platforms to prepare the specime
ns. The crystalline formations on the platforms were studied by scanning el
ectron microscopy and the energy dispersive X-ray spectra allowed the estim
ation of the chemical composition changes of the modifiers and the graphite
surface. According to the spectra and the images obtained, both modifiers
where found to change their crystalline form at temperatures between 500-12
50 degreesC. Severe corrosion of the graphite surface was observed in case
of H2PtCl6 at temperature higher than 750 degreesC, while minor damages wer
e observed in case of Na2WO4. In the second part of this work, the efficien
cy of these modifiers was tested for maximum loss-free pyrolysis temperatur
e and atomization of lead by electrothermal atomic absorption spectrometry.
The optimum results, concerning these parameters, obtained for medium conc
entration of the modifiers. The effect of each modifier on the atomization
signal is discussed, and the optimum concentration of each one is estimated
.