A radiotracer study on effectiveness of platinum metals as chemical modifiers in electrothermal atomic absorption spectrometry: Behaviour of selenium in a graphite furnace

The effect of palladium, platinum, rhodium and iridium on the behaviour of selenium in the graphite furnace for electrothermal atomic absorption spectrometry (ETAAs) has been investigated by the radiotracer technique. These chemical modifiers have been used both in the chloride and in a reduced form, the latter being achieved by preliminary pyrolysis 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 degrees C these losses amount up to 13%, 32%, 41% and 65%, respectively. In most instances, the effectiveness of chlorides of the platinum metals is lower than that of the pre-reduced modifiers. It is postulated that the dissolution of elemental selenium in palladium and platinum at relatively low temperatures diminishes losses of selenium in the pyrolysis stage.