Effect of furnace design on atomic absorption and emission signals in spectrochemical analysis

An examination has been made of several new furnace designs and applications for both atomic absorption and emission. Problems with current furnace designs are analyzed and experimental data from three new alternate designs are presented. These alternate furnace designs were developed specifically to increase the thermal energy available to analyte molecules before they diffused from the optical path. A two pronged support furnace was developed in which electric current passed across both ends of an 18mm long graphite tube. The tube center, where the sample was placed, heated by thermal conduction from the ends. Thus the analyte vapor always encountered walls hotter than the surface it left as it diffused toward the furnace ends. This heating mode resulted in ten-fold improvements in lead recoveries from some chloride salts compared to the CRA-63 atomizer. The dependence of lead recoveries on interferent/analyte ratios was also established for lead in magnesium chloride solutions. A double-walled furnace was also examined and compared to the twopronged support furnace. The heating of this furnace was spatially uniform during the atomization of lead and cobalt. Despite this, recoveries for lead and cobalt were equal or superior to those obtained with the two-pronged furnace. Recoveries for lead in ZnSO4, however, were lower in the double-walled design. Possible mechanism