Methods for the Determination of Selenium in Foodstuffs

The choice of the method for the determination of selenium in biological samples depends on the form of selenium present in the sample to be analyzed. The choice of method depends on whether the selenium is to be determined from the total organically bound selenium, total organically bound selenium in the protein fraction, or individual selenium amino acids, respectively. It is understood that the choice of method also depends on its content in the analyzed materials. Understanding the biochemical cycle, mobility, adsorption, and toxicity of selenium is important for developing reliable techniques for studying the selenium species in environmental and biological samples. Specific methods make it possible to determine the individual forms of selenium compounds present in the samples of various matrices, for example, inorganic forms of selenium such as selenite SeIV and selenate SeVI, trimethylselenonium ion TMSe+, selenium-containing amino acids, methylated forms such as DMSe and DMDSe. Since selenium is often present in biological and environmental samples at very low concentrations, very sensitive analytical methods should be used, and great care should be taken in the collection, storage, and transport of samples to avoid evaporative or contamination loss. The issue of selenium speciation is closely related to the content of low concentrations of each assayed form of selenium in biological samples.