SELENIUM AND THE ENVIRONMENT, THE METHODS OF ITS SEPARATIONS AND DETERMINATIONS
The chemical and physical properties of selenium and its compounds, in particular Se (IV), are described. The possibility and necessity of the presence of selenium in living organisms, including humans, in plants and in the natural environment is shown. Various schemes and methods for the determination of selenium (IV) are considered, the most representative of which are fluorimetric, extraction-photometric and titrimetric. From the analysis of the data presented, it becomes necessary to study the extraction of Se (IV) and its compounds in stratified aqueous systems without an organic solvent for subsequent determination by any instrumental method.