selenium

Selenium is a chemical element with atomic number 34, with the chemical symbol Se. Selenium occurs only rarely in the free state in nature. It is a nonmetal that is chemically related to sulfur and tellurium. It is toxic in large amounts, but trace amounts of it, forming the active center of certain enzymes such as glutathione peroxidase(GSH-Px), are necessary for the function of all cells in (probably) all animals. Selenium requirements in plants differ by species, with some plants apparently requiring none.

Isolated selenium occurs in several different forms, but the most stable of these is a dense purplish-gray semimetal (semiconductor) form that is structurally a trigonal polymer chain. It conducts electricity better in the light than in the dark, and is used in photocells (see allotropic section below). Selenium also exists in many nonconductive forms: a black glass-like substance, as well as several red crystalline forms built of eight-membered ring molecules, like its lighter cousin sulfur.

Selenium is found in economic quantities partially replacing sulfur in sulfide ores such as pyrite. Minerals that are selenide or selenate compounds are also known, but all are rare.



The term "selenium" was found in the following pages:

Instrument database: Analytik Jena GmbH - contrAAź 800 F - HRCS- Atomic absorption spectrometer for flame and hydride techniques
Material database: JRC - Joint Research Centre - BCR-032 - Trace elements in Moroccan phosphate rock
Material database: Laboratoire de toxicologie - QM-H-Q1412 - Human hair
Company database: Aqua Metrology Systems, Ltd.
Link database: National Research Council: Selenium in Nutrition
Material database: National Research Council of Canada (NRC - CNRC) - LUTS-1 - non defatted lobster hepatopancreas
Link database: Chemical Fact Sheet: Lanthanum
Speciomics as a concept involving chemical speciation and omics | EVISA's News
ESI-MS: The tool for the identification of chemical species | EVISA's News
Link database: Selenium and Livestock: Metabolism, Toxicity and Deficiency
Material database: RECIPE Chemicals + Instruments GmbH - ClinChek 8884 Control blood plasma, lyophilised, trace elements level II: LOT 129
ICP-OES sensitivity for silicon depends on silicon-species | EVISA's News
Material database: IRMM - Institute for Reference Materials and Measurements - BCR-277R - Estuarine Sediment
Material database: IRMM - Institute for Reference Materials and Measurements - BCR-288 - Lead
Flow-injection inductively coupled plasma mass spectrometry for speciation analysis | EVISA's News
Toxicity and bioavailability of different selenium metabolites | EVISA's News
Material database: RECIPE Chemicals + Instruments GmbH - ClinChek 8883 Control blood plasma, lyophilised, trace elements level I
Material database: JRC - Joint Research Centre - ERM-CA713: Trace elements in waste water
ICCST-11: 11th International Conference on the Chemistry of Selenium and Tellurium | EVISA's Agenda of Events
Determination of arsenic species in water by means of capillary electrophoresis coupled to electrospray mass spectrometry | EVISA's News