Selenium (Sodium Selenite)

Sodium selenite (disodium selenite, CAS 10102-18-8, EINECS 233-267-9) is the sodium salt of selenous acid, Na2SeO3, molecular weight 172.95. It is a white hygroscopic crystalline powder, forming white tetragonal crystals, freely soluble in water at approximately 85 g per 100 mL at 20 degrees C, insoluble in ethanol, and decomposing at about 710 degrees C. The anhydrous grade carries a theoretical 45.7% elemental selenium and is traded against a minimum 45% Se specification. The pentahydrate, Na2SeO3·5H2O (CAS 26970-82-1, molecular weight 263.03, approximately 30.0% Se), is the form covered by European Pharmacopoeia monograph 01/2008:1677, Sodium selenite pentahydrate. Sodium selenite is listed in Annex II of Directive 2002/46/EC, as amended by Commission Regulation (EU) No 1170/2009, as a permitted selenium source for food supplements, and is authorised in the European Union as feed additive 3b801 under Commission Implementing Regulation (EU) 2019/49, which characterises the additive as a powder with a minimum content of 45% selenium. Selenium is an essential trace element that is incorporated into selenoproteins such as glutathione peroxidase and thioredoxin reductase. Because the salt is potent at very low inclusion, formulators normally work with a triturated dilution or a mineral premix rather than dosing the neat powder. Thovek supplies sodium selenite in anhydrous and pentahydrate forms for supplement, food-fortification, cell-culture and feed applications. Each batch is certified for selenium content by titrimetry to the Ph. Eur. 1677 method or by ICP-OES, with total selenium in premixes and feed cross-checked by hydride generation atomic absorption spectrometry to EN 16159:2012. Heavy metals, moisture and microbiological limits are reported on a full Certificate of Analysis. Export documentation includes CoA, MSDS, Certificate of Origin, and allergen, GMO and BSE/TSE statements; consignments are declared as a toxic substance and moved in UN-certified outer packaging.