DETERMINATION OF SELENIUM IN BIOLOGICAL TISSUE SAMPLES RICH IN PHOSPHORUS USING ELECTROTHERMAL ATOMIZATION WITH ZEEMAN-EFFECT BACKGROUND CORRECTION AND (NH4)(3)RHCL6 PLUS CITRIC-ACID AS A MIXED CHEMICAL MODIFIER

Spectral interferences from phosphorus on the determination of seleniu m in biological tissue materials were not observed when a Zeeman-effec t background correction was used with rhodium as a chemical modifier. A suppression effect on the selenium signal resulted when the concentr ation of phosphorus present was greater than 1.0 mg ml(-1). Rhodium wa s found to be more effective than palladium in overcoming the phosphat e: interference. Analytical procedures for the direct determination of trace selenium in standard reference materials by graphite furnace at omic absorption spectrometry following sample dissolution in nitric ac id and hydrogen peroxide using a microwave oven has been described. Th e results obtained agreed favourably with the certified values. (C) 19 98 Elsevier Science B.V. All rights reserved.