DETERMINATION OF SELENIUM IN SEAWATER BY ZEEMAN GFAAS USING NICKEL PLUS NH4NO3 MODIFIER

The effectiveness of nickel plus NH4NO3 as a chemical modifier for the determination of selenium in seawater by Zeeman electrothermal atomic absorption spectrometry has been evaluated. The effect of changing th e modifier mass and pyrolysis hold time on the integrated absorbance o f selenium and the background absorbance has been investigated. Nickel and NH4NO3 allow the quantitative stabilization of selenium in the se awater matrix up to 1300 degrees C as compared with 600 degrees C with out modifier. The modifier further reduces the background absorbance c aused by seawater. The tolerable amounts of various interferences such as chloride, sulphate and phosphorus in the presence of nickel plus N H4NO3 are evaluated for the determination of selenium in seawater.