A RADIOTRACER STUDY ON EFFECTIVENESS OF PLATINUM METALS AS CHEMICAL MODIFIERS IN ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY - BEHAVIOR OF SELENIUM IN A GRAPHITE-FURNACE

The effect of palladium, platinum, rhodium and iridium on the behaviou r of selenium in the graphite furnace for electrothermal atomic absorp tion spectrometry (ETAAs) has been investigated by the radiotracer tec hnique. These chemical modifiers have been used both in the chloride a nd in a reduced form, the latter being achieved by preliminary pyrolys is at 1000 degrees C. The losses of selenium were observed during the pyrolysis stage for every modifier studied. For prereduced Pd, Pt, Ph and Ir as chemical modifiers, at the pyrolysis temperature of 600 degr ees C these losses amount up to 13%, 32%, 41% and 65%, respectively. I n most instances, the effectiveness of chlorides of the platinum metal s is lower than that of the pre-reduced modifiers. It is postulated th at the dissolution of elemental selenium in palladium and platinum at relatively low temperatures diminishes losses of selenium in the pyrol ysis stage.