Temporal variations in gas temperature in an atomization stage of cadmium and tellurium evaluated by using the two-line method in graphite furnace atomic absorption spectrometry.

In order to discuss the atomization process of an analyte element occurring in a graphite furnace for atomic absorption spectrometry, we measured variations in the characteristic temperature with the progress of an atomization stage, by using a two-line method under the assumption of a Boltzmann distribution. For this purpose, iron was chosen as the analyte element. Also, the atomic absorption of two iron atomic lines, Fe I 372.0 nm and Fe I 373.7 nm, was simultaneously monitored as a probe for the temperature determination. This method enables variations in the gas temperature to be directly traced, yielding a temperature distribution closely related to the diffusion behavior of the probe element in the furnace. This temperature variation was very different from the furnace wall temperatures, which were monitored in conventional temperature control for atomic absorption spectrometry. Correlations between the gas temperature and the charring/atomizing temperatures in the heating program of the furnace were investigated. The atomization of cadmium and tellurium was also investigated by a comparison between the gas temperature with the wall temperature of the furnace. The atomic absorption of cadmium or tellurium appeared to be apart from the absorption of iron while the gas temperature was still low. Therefore, the analyte atoms could be atomized through direct contact with the wall of the graphite furnace, which has a much higher temperature compared to the gas atmosphere during atomization. Their atomization would be caused by conductive heating from the furnace wall rather than by radiant heating in the furnace.