Analytical approaches for selenium speciation in biological materials

Abstract

There is substantial evidence on the complexity of selenium speciation in living organisms and on the importance of the selective determination of the particular species of this element in order to understand its metabolism in environmental and clinical chemistry, ecotoxicology and nutrition. The major fields of interest include: (i) characterization of selenium species in plant and animal organisms with a special focus on edible tissues, (ii) speciation of metabolite products (selenoaminoacids, selenopeptides and selenoproteins) in organisms growing in selenium rich environment, (iii) speciation of selenium metabolites in body fluids, (iv) characterization of selenium enriched foodstuffs, food supplements and fodders available on the market. The myriad of selenium species with different physicochemical properties present in biological systems represents a challenge to the analyst. The most popular approach is the use of so called hyphenated techniques representing a unique analytical tool able to provide qualitative and quantitative information on element species at trace and ultratrace levels in complex matrices. The multiple areas of interest in the field selenium speciation require dedicated analytical approaches, both in terms of the separation technique and the element or molecule specific detection used. Since many selenium compounds have not been identified yet the role of molecular identification techniques such as GC MS for volatile species, ES MS/MS for selenopeptides and MALDI TOF for selenoproteins cannot be overestimated. The presentation discusses analytical chemistry of selenium species related to biological materials on the basis of the practical experience gathered in a decade of research in the field.