CHEMICAL MODIFICATION AND SPECTRAL INTERFERENCES IN SELENIUM DETERMINATION USING ZEEMAN-EFFECT ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

The role of chemical modification was studied with regard not only to thermal stabilization and atomization of selenium but also to the suppression of spectral interferences on Zeeman effect based background correction. Various amounts of palladium and nickel were used as modifiers at a series of pyrolysis and atomization temperatures for the direct determination of selenium and phosphorus in whole blood and urine reference materials. An attempt was made to correlate phosphorus atomization profiles and the occurrence of compensation errors in the determination of selenium. The smallest errors were measured for those conditions under which the atomization efficiency for phosphorus was enhanced or the volatilization of phosphorus-containing species was significantly delayed. Analytical procedures for the spectral interference-free determination of selenium in each of the matrices studied are described.