Gas-phase chemiluminescent determination of inorganic selenium in water samples following flow injection hydride generation and cryotrapping

Abstract

We describe a method for the determination of inorganic selenium in water samples via gas-phase chemiluminescence (GPCL). Se(IV) was first derivatized with 4-nitro-o-phenylenediamine to form 5-nitropiazselenol. The latter was decomposed by persulfate through photocatalytic oxidation to give Se(VI), which was reduced to Se(IV). Selenium hydride was generated from Se(IV) through reduction with sodium borohydride and then preconcentrated using cryotrapping. The cryotrapped hydride was evaporated and carried to a reaction chamber by a stream of helium, where it produced GPCL as a result of ozonation. The method exhibits a wide linear calibration range (from 0.5 μg L−1 to 1.0 mg L−1) with a detection limit of 0.12 μg L−1 (for n = 11), and a relative standard deviation of 3.90 % (at n = 11) at 5.0 μg L−1 level of selenium. The method was applied to the determination of inorganic selenium in water samples and gave satisfactory results.