A STUDY OF NICKEL ELECTROTHERMAL ATOMIZATION

The kinetic order of generation of the atomic vapor of Ni is determined as a function of the initial mass of analyte. For masses up to 3.0 ng, a kinetic order equal to 1 is obtained, with atomization energy and pulse half-width independent of the analyte mass. However, for sample mass in the range 4.0-8.0 ng, a kinetic order equal to 2 is determined with a constant atomization energy and a pulse width that increases as the initial mass increases. Accordingly, a first-order kinetic model is employed to describe the atomization profiles of analyte masses up to 3.0 ng. To determine the vapor formation and dissipation rate constants k1 and k2, the rate equations for this model were solved using boundary conditions at t(y), the time at which the rate of change of absorbance presents a minimum value and the temperature has already reached its maximum value. Employing the kinetic parameters of this model, a good description of the absorbance profiles is achieved and the theoretical behavior of the peak absorbance and the area of the pulse, as a function of the analyte mass, is predicted.