An attempt to differentiate HPLC-ICP-MS selenium speciation in natural and selenised Agaricus mushrooms using different species extraction procedures
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Total determination and speciation analysis of Se in commercial and selenised Agaricus mushrooms have been performed to investigate the Se species naturally occurring in non-enriched mushrooms as well as those present in specimens grown in a Se-enriched medium. Mushroom aqueous and enzymatic extracts have been analysed by three complementary chromatographic separation mechanisms (size-exclusion, anion-exchange and reversed-phase) coupled to an inductively coupled plasma mass spectrometer with an octopole reaction system. Post-column isotope dilution analysis has been used on-line with the separations for quantification of the Se species eluted. The 78Se-to-77Se isotope ratio was monitored after adequate corrections for both total determinations and Se species quantitative speciation. The results showed marked differences not only in total Se contents but also in Se species found in the two types of Agaricus mushrooms investigated. Selenomethionine was detected in both of them (free in commercial mushrooms and incorporated into proteins in selenised ones) together with a number of unknown selenocompounds.
KeywordsAgaricus Mushroom Se speciation Hybrid high-performance liquid chromatography inductively coupled plasma mass spectrometry Isotope dilution analysis
The authors gratefully acknowledge the financial support of project MCT-00-BQU2003–04671. Thanks are also due to Peter Fodor (Szent István University, Budapest, Hungary), who provided us with the selenised Agaricus mushrooms.