TEMPERATURE-DEPENDENCE OF ATOMIZATION EFFICIENCIES IN GRAPHITE FURNACES

Measurements of characteristic masses, mo[exp], have been made using a spatially and temporally isothermal two-step atomizer for 14 elements (Ag, Al, Au, Bi, Cd, Ga, Ge, In, Mn, Pb, Se, Sn, Te, Tl) over broad temperature intervals. These mo[exp] values are compared with theoretical data, mo[calc], to assess the effect of temperature on the calculated atomization efficiency (ε{lunate}'A=100 × mo[calc]/mo[exp]) and to investigate the validity of the fundamental constants involved in the calculations. For some elements, comparative measurements were also made over a narrower temperature range using a Massmann-type atomizer (HGA-600) operated under stabilized temperature platform furnace (STPF) conditions. The following elements were found to have temperature dependent atomization efficiencies-Al, Au, Ga, Ge, In, Mn, Se, Sn and Te-and are thus susceptible to form stable volatile compounds at lower atomization temperatures. Improved ε{lunate}'A values were obtained for a selected number of these elements when a cool-down step was incorporated in the temperature programme prior to the atomization step using the HGA-600. The results with the two-step atomizer, in general, verify the validity of the method and fundamental constants used to calculate mo-values. It can also be concluded that efficient atomization conditions are provided in Massmann-type furnaces provided that the STPF concept is applied. A good criterion for evaluating furnace performance is to establish the atomization efficiencies for the elements of interest. © 1990.