CHAPTER 6: Current Analytical Strategies and Techniques Related to Selenoproteins in Foods

The biological importance of selenium to ensure human health depends on the chemical forms of this element, as well as the key role of selenoproteins on the basic functions of life. Speciation of heteroelement-containing proteins is a rapidly developing area of detection, identification and quantification of these biomolecules in biological samples, and particularly in food. Hyphenated techniques based on the coupling of chromatographic separation with inductively coupled plasma spectrometry (ICP-MS) and its combination with organic mass spectrometry allows characterization and quantification of selenium species and selenoproteins. Sample preparation is a crucial step in Se speciation in food, in which cell and tissue disaggregation, analyte extraction, protein disulfide bridges prevention and proteases inhibition are key points of these treatments. In addition, some specific sample-preparation procedures based on enzymatic extraction, protein precipitation, ultrafiltration and sonication have been recently proposed. New analytical methodologies have been developed for the characterization of unknown selenium species and selenoproteins in food and other matrices, which exhibit essential or harmful functions, and play important biological roles depending on their bioavailability, mobility, interactions with other species and molecules and transport processes.