GAS TEMPERATURE INSIDE GRAPHITE FURNACES USED FOR ATOMIC-ABSORPTION SPECTROMETRY

A simplified model for heat transfer is used to calculate the gas temperature inside graphite furnaces used for atomic absorption spectrometry. In the absence of a convective flow through the furnace, the gas temperature follows the wall temperature of the heated furnace to within a few degrees. When a significant flow of protective cold gas is forced through the furnace, the gas temperature varies greatly along the furnace and its average value can be several hundred degrees lower than the wall temperature. These predictions are confirmed by the vapour temperatures which were measured experimentally by means of the two-line absorption technique. The results also demonstrate that analyte species volatilized in the furnace have the same temperature as the inert gas. The advantages of preheating the protective gas are indicated. © 1978.