Factors Affecting Selenium Atomization Efficiency in Graphite Furnace Atomic Absorption

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Abstract
The effect of graphite furnace surface treatment, and the addition of “matrix modifiers” such as nickel or lanthanum on the observed selenium atomization siqnal in electrotherval atomic absorption analysis has been investiqated. The results indicate that the removal of signal depression caused by the addition of metal solution to analyte solution is not simply a devolatilization of the selenium. The effect appears to be a modification of the graphite surface which leads to more efficient atom formation. The role of the surface was investigated monitoring the atomic absorption signal generated from graphite furnaces which were untreated, pyrolytic graphite-coated, zirconium-or tantalum-coated, and metal-coated followed by pyrolytic graphite coating. The dependence of the analyte signal on the concentration of added metal was investigated for these surfaces. The optimum results obtained were the metal-coated/pyrolytic graphite-coated cuvettes. These cuvettes showed reduced effect of “matrix modifier,” suggesting that the surface treatment can replace the “matrix modifer,” Surface chemistry consistent with the atomic absorption observations and surface analysis data is presented.