Speciation of organic selenium compounds by high-performance liquid chromatography–inductively coupled plasma mass spectrometry in natural samples

Abstract

The importance of selenium in the environment and in biological systems is now well recognized. Its biochemical functions, e.g., its anti-oxidant role and therefore cell protecting function, as an essential constituent of the enzyme glutathione peroxidase, has provoked a growing interest in the determination of this element. Selenoamino acids are essential for the understanding of the biogeochemical cycle of Se and TMSe⁺ is a known urinary metabolite present at high levels when Se is taken in excess. In this work we present a hyphenated technique (HPLC–ICP-MS) available for the separation of the organic Se compounds (selenocystine, selenomethionine and trimethylselenonium ion). The choice of column and solvents has been a critical parameter. Good repeatability and excellent detection limits (less than 1 µg l^–1 for each species) have been reached for standard solutions and the application to some natural samples (enriched yeast, human serum and urine) has shown quite promising results.