Colloidal palladium - a promising chemical modifier for electrothermal atomic absorption spectrometry

The efficiencies of chemical modifiers based on palladium for electrothermal atomic absorption spectrometry (ETAAS) were compared. The main attention was devoted to the comparison of two types of colloidal palladium with a mixture of palladium nitrate and magnesium nitrate or a mixture of ammonium dihydrogenphosphate and magnesium nitrate. The modifiers were applied to model solutions of the analytes Se, Cd, Te and Sn containing sodium sulphate, sodium chloride and glucose as matrix components. In general, no significant difference in effectiveness was found between the polymer-stabilized colloidal palladium and other chemical modifiers studied. Colloidal palladium stabilized with polyvinylpyrrolidone (M-r approximate to 360 000) has proved to be as effective as colloidal palladium stabilized with the surfactant lauryldimethylcarboxymethylammonium betaine. However, concentrated solutions of the former modifier can be prepared easily and kept for a long time at room temperature. The increase in the palladium particle size in solution from 2-10 nm to 20-2000 nm resulting from storage for 16 months did not significantly influence the effectiveness of the modifier. Colloidal palladium can be considered as a prospective aid to the investigation of processes in graphite atomizers. (C) 1997 Elsevier Science B.V.