A METHOD FOR THE DETERMINATION OF THE KINETIC ORDER AND ENERGY OF THE ATOM FORMATION PROCESS IN ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY (ETA-AAS)

A procedure for the determination of the kinetic parameters for the atom formation process in electrothermal atomizers is presented. From the kinetic equations of a mechanism where the rate of atom formation is assumed to have an arbitrary order m, we obtained that the rate constant for the non-isothermal generation of atomic vapor k1(t) is proportional to: [GRAPHICS] where k2(t) is the rate constant for the dissipation of the atomic vapor and A(t) is the absorbance signal. An Arrhenius type plot of log Wm(t), calculated with the experimental absorbance data, as a function of the inverse of the time dependent atomization temperature, gives a linear curve for the appropriate order m and allows the determination of the atomization energy E(a). A comparison with other methods is made and the deviations from linearity of the Arrhenius plots, commonly found in the literature, are discussed. The results obtained for the electrothermal atomization of Ru, Cu, Ni and Li are presented.