EFFECT OF FURNACE ATOMIZATION TEMPERATURES ON SIMULTANEOUS MULTIELEMENT ATOMIC-ABSORPTION MEASUREMENT USING A TRANSVERSELY-HEATED GRAPHITE ATOMIZER

The sensitivities and signal-to-noise ratios (SNRs) of five elements (Cd, Pb, Cu, Cr, and V) were characterized for atomization by a commercially available transversely heated graphite atomizer (THGA) as a function of the atomization temperature, with and without a Pd-Mg(NO3)(2) matrix modifier, and with a standard furnace and an ''end-capped'' furnace to restrict diffusional loss of the analyte. These five elements were selected to provide a representative range of atomization temperatures. In general, the sensitivities of Cd, Pb, Cu, and Cr decreased with increasing atomization temperature and the sensitivity of the least volatile element, V, increased with temperature. The most suitable temperature for simultaneous determination of these elements was 2500 degrees C, as dictated by V. The loss in sensitivity for the atomization of Cd and Pb at 2500 degrees C was 25 to 35%, considerably less than predicted by mass diffusion. With use of the modifier and 'end-capped' THGAs, the temperature dependence of the sensitivity approached that predicted by mass diffusion. With photon shot noise and optimization of the integration interval, the best SNRs for all elements, in the simultaneous multielement mode or in the single element mode, are found at approximately 2500 degrees C and no compromise is necessary.