Abstract

This paper describes a method, which is similar to the mercury amalgamation pre-concentration technique, for the determination of ultra-trace amounts of selenium by combining hydride generation and gas-phase enrichment techniques. The method is based upon the fact that SeH₂ can be decomposed to Se⁰ and collected by gold wire heated to ∼200 °C. A device for trapping the selenium hydride was designed. On heating the trap at 600 °C or above, the selenium was released rapidly into an atomic fluorescence (or AAS) detector as the result of re-forming SeH₂ by the reaction between the selenium and the hydrogen carrier gas on the surface of the gold wire. A detection limit of 5 pg ml⁻¹ Se for a 5 min collection, and a relative standard deviation of 3.0% for 1 ng ml⁻¹ Se (n = 14) were obtained. The method was applied to the determination of selenium in mineral water samples and materials of a complex nickel-based alloy.