COMPARISON OF CHEMICAL MODIFIERS FOR THE DETERMINATION OF SELENIUM BYELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

Nickel, copper and palladium were investigated as chemical modifiers i n several modes of electrothermal atomic-absorption spectrometry for t he determination of selenium present in the samples in different valen ce states. Among the investigated metals, palladium alone, either ther mally reduced in the graphite furnace or electrodeposited on the graph ite surface, gave the best analytical performance for the determinatio n of selenium in the sample with organic matrix. In both cases the sen sitivity was nearly independent of the valence state of selenium and a characteristic mass (m(o)) of 50-55 pg (0.0044 s)(-1) was obtained. T he amount and the reduction conditions of the modifiers and the pyroly sis temperature for Se were optimized to find best conditions for perm anent modification. It is shown that thermally deposited palladium can serve for about ten firings. Tubes pretreated with electrodeposited p alladium exhibit had analytical lifetime, up to 500 firings without lo ss of sensitivity. (C) 1997 Elsevier Science B.V.