Simplified kinetic model describing the analyte losses during pre-atomization thermal treatment in electrothermal atomic absorption spectrometry

Abstract

A proposed kinetic model for elucidating the analyte pre-atomization losses in electrothermal atomic absorption spectrometry has been extended and developed further. The apparent activation energies, E_a(loss), characterizing the process of analyte losses, have been derived from experimental data on absorbance and pre-treatment times at various pre-treatment temperatures for Sb, As, Pb and Sn, both in the absence and presence of a chemical modifier (20 µg of Mo^VI). In the presence of a modifier, the maximum thermal treatment temperatures and the E_a(loss) values were substantially increased and were of the same order, about 1300 K and 350 kJ mol^–1, respectively, for the analytes As, Sb and Sn. For Pb, the corresponding values were 973 K and 60 kJ mol^–1.