Determination of Selenium in Drinking Water by Electrothermal Atomic Absorption Spectrometry after Photochemical Generation, Distillation, and Preconcentration of Its Gaseous Compounds in a Graphite Furnace

Abstract

A highly sensitive scheme of the determination of selenium in drinking water by electrothermal atomic absorption spectrometry with the on-line preconcentration of gaseous analyte compounds obtained by the UV treatment of an analyzed solution in a graphite furnace (GF) is implemented. A photochemical generator of original design of the type “UV lamp in a hollow cylindrical reactor” is used. The conditions of the photochemical generation and sorption of gaseous selenium compounds are optimized. The efficiency of a number of permanent sorbent modifiers, such as, metallic iridium, tungsten and zirconium carbides, and mixtures of tungsten and zirconium carbides with activated carbon, at the sorption stage in the GF is estimated. The maximum analytical signals of selenium are recorded using graphite tubes modified by iridium. The analytical scheme is verified by a spike recovery test, the recovery of element additives was 90%. The attained limit of detection for Se(IV) is 4.1 ng/L; the relative standard deviation of the results of replicate determinations is no more than 4.0% at the concentration of Se(IV) in water samples 0.1 µg/L.