Evaluation of heating programs for electrothermal atomic absorption spectrometry using a tungsten coil

A tungsten coil atomizer was used to investigate the effect of heating programs with constant or variable drying temperatures on the atomization of Al, Cd, Cr and Pb, The variation of the surface temperature in the tungsten coil furnace can occur during each heating step due to the design of the power supply, that may apply constant voltages during a programmed time. For volatile elements (Cd), losses in sensitivity were observed when the program with a variable temperature was used. On the other hand, these effects are negligible for less volatile elements (Al and Cr) and any tested program, in different acidic media, could be used without appreciable changes in sensitivities. The results allow the establishment of proper heating programs for elements with different thermochemical behavior in the tungsten coil atomizer.