Speciation of selenium compounds

The toxicity and essential nature of selenium in the environment depend on its concentration and on the chemical forms in which it is present. Dissolved inorganic selenium can be found in natural waters as selenides (Se-II), colloidal elemental selenium (Se-0), selenite (Se-IV) as well as selenate (Se-VI). Organic forms of selenium that may be found in organisms, air or in the aqueous environment are volatile methylselenides, trimethylselenonium ion and selenoamino acids. This review article intends to show some general ideas in speciation analysis of selenium and to highlight some important procedures.