Determination of ultra-trace amounts of selenium by continuous flow hydride generation AFS and AAS with collection on gold wire

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 Se-0 and collected by gold wire heated to similar to 200 degreesC. A device for trapping the selenium hydride was designed. On heating the trap at 600 degreesC 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.