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 the modifier mass and pyrolysis hold time on the integrated absorbance of selenium and the background absorbance has been investigated. Nickel and NH₄NO₃ allow the quantitative stabilization of selenium in the seawater matrix up to 1300° C as compared with 600° C without modifier. The modifier further reduces the background absorbance caused by seawater. The tolerable amounts of various inteferences such as chloride, sulphate and phosphorus in the presence of nickel plus NH₄NO₃ are evaluated for the determination of selenium in seawater. Received: 31 August 1995 / Revised: 21 December 1995 / Accepted: 6 January 1996