Determination of selenite, selenate and selenomethionine by ion chromatography, microwave digestion and HGAAS.

An on-line system for the simultaneous determination of Se(IV), Se(VI) and selenomethionine (Se-Met) in aqueous samples was developed, consisting of separation by ion chromatography, microwave digestion and detection by hydride generation atomic absorption spectrometry. 8.3 mmol/l Na(2)HPO(4) (pH 9.2) was used as mobile phase for the ion chromatography, with a flow-rate of 1.5 ml/min. After the separation the sample was mixed with concentrated KBr-HCl solution and heated with microwave energy to digest Se-Met and reduce Se(VI) to Se(IV). The detection limits were 15 microg/l, 12 microg/l and 103 microg/l for Se(IV), Se(VI) and Se-Met, respectively.