Microwave assisted reduction of Se(VI) to Se(IV) and determination by HG/FI-ICP/MS for inorganic selenium speciation

Speciation of inorganic selenium using hydride generation method is a widespread analytical method nowadays. However, a reduction step of Se(VI) to Se(IV) is necessary as the hydride-forming species is HSeO(3)(-) (oxydation state+IV). This paper describes the development of a batch assisted microwave system allowing a rapid (<5 min) conversion of Se(VI) to Se(IV). Hydride generation is performed by a flow injection system and detection by ICP/MS. Detection limits of 6 and 8 pg for Se(IV) and for Se(VI) (by using a sample loop of 200 mul) respectively have been achieved. This method has been validated by participating in a European certification exercise for inorganic Se speciation in aqueous solutions.