Interference-free determination of selenium( IV ) by capillary gas chromatography–microwave-induced plasma atomic emission spectrometry after volatilization with sodium tetraethylborate

A method was developed for the direct determination of selenium in environmental waters. Improvement over gas chromatography-hydride generation atomic absorption spectrometry (GC-HGAAS) techniques was sought firstly by replacing sodium tetrahydroborate with sodium tetraethylborate as derivatizing agent, secondly by optimization of pH towards higher acidities, thirdly by cryotrapping the purged diethylselenide on a short capillary column and fourthly using capillary GC to separate the analyte from other potential interferent followed by atomic emission spectrometric (AES) detection. An essential increase in the selectivity of selenium(IV) determination was observed. Hydrochloric acid (4 M) was necessary to achieve maximal derivatization efficiency. A microwave-induced plasma was used as an atomizer. A detection limit of 8 ng per litre (for a 5 mg sample) in a fully automated system was achieved. The method was applied to the determination of selenium in natural waters. The possibility of selectively determining selenium(IV) in the presence of selenium(VI) is discussed. There are 32 references.