RELATIONSHIP BETWEEN EFFECTIVE ATOMIC VAPOR TEMPERATURE OF SELENIUM AND MATRIX MODIFIERS IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

The effective atomic vapor temperature of Se, in the presence of different matrix modifiers, in the graphite furnace used for atomic absorption spectrometry was studied by the two-line method. In the presence of Pd or Rh, the effective atomic vapor temperature of Se at the beginning of atomization was raised by about 400-degrees-C compared to that in the presence of Mn. Pd and Rh make intermetallic compounds with Se, and it is presumed that the activity coefficients of Se became less than 1.0, thus atomization was raised to higher temperature. The effective atomic vapor temperature of Se atomized from the platform was raised by 200-degrees-C compared to atomization from the tube wall. Excitation interferences were investigated by using a urine sample, in which typical severe interferences exist. The effective atomic vapor temperature of Se in the presence of an oxidizing agent was raised to more than 8000-degrees-C, because the amount of Se in a ''metastable state'' was increased by an energy transfer process. This interference was lessened by increasing the amount of Pd or Rh, and by adding a reducing agent.