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Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. [7] In 2000, the US Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/day. [8]
Selenium trioxide is produced in the laboratory by the reaction of anhydrous potassium selenate (K 2 SeO 4) and sulfur trioxide (SO 3). [7] Salts of selenous acid are called selenites. These include silver selenite (Ag 2 SeO 3) and sodium selenite (Na 2 SeO 3). Hydrogen sulfide reacts with aqueous selenous acid to produce selenium disulfide:
[3] [4] It is suitable for food and laboratory uses. Reagent grade is almost as stringent as the ACS grade. USP grade meets the purity levels set by the United States Pharmacopeia (USP). USP grade is equivalent to the ACS grade for many drugs. NF grade is a purity grade set by the National Formulary (NF). NF grade is equivalent to the ACS grade ...
Sodium selenate is produced by oxidation of selenium, first with nitric acid, producing selenous acid. The selenous acid is neutralized to form sodium selenite. The sodium selenite is oxidized in a basic medium hydrogen peroxide to form a selenate, which is then spray-dried. [3] Se + 2HNO 3 → H 2 SeO 3 + NO + NO 2 H 2 SeO 3 + Na 2 CO 3 → Na ...
USP establishes documentary (written) and reference (physical) standards for medicines, food ingredients, dietary supplement products, and ingredients. These standards are used by regulatory agencies and manufacturers to help to ensure that these products are of the appropriate identity, as well as strength, quality, purity, and consistency.
An electronic lab notebook (also known as electronic laboratory notebook, or ELN) is a computer program designed to replace paper laboratory notebooks. Lab notebooks in general are used by scientists , engineers , and technicians to document research , experiments , and procedures performed in a laboratory.
[25] [26] CRMs are typically monitored at a range of temperatures and the results are used to predict the rate of change at a proposed, usually low, storage temperature. Often, the prediction uses a well known degradation model such as an Arrhenius model. [9]
Similarly, sodium selenide is readily oxidized to polyselenides, a conversion signaled by off-white samples. Sodium selenide reacts with acids to produce toxic hydrogen selenide gas. Na 2 Se + 2 HCl → H 2 Se + 2 NaCl. The compound reacts with electrophiles to produce the selenium compounds.