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A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working standards. [1] [2] See Hierarchy of Standards.
Tris is also used as a primary standard to standardize acid solutions for chemical analysis. Tris is used to increase permeability of cell membranes. [ 13 ] It is a component of the Moderna COVID-19 vaccine [ 14 ] and the Pfizer-BioNTech COVID-19 vaccine for use in children 5 through 11 years of age.
A standard solution created from a secondary standard cannot have its concentration accurately known without stoichiometric analysis against a primary standard. An example of a secondary standard is sodium hydroxide , a hydroscopic compound that is highly reactive with its surroundings.
In chemistry, a reagent (/ r i ˈ eɪ dʒ ən t / ree-AY-jənt) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. [1] The terms reactant and reagent are often used interchangeably, but reactant specifies a substance consumed in the course of a chemical reaction. [1]
Reagents are "substances or compounds that are added to a system in order to bring about a chemical reaction or are added to see if a reaction occurs." [1] Some reagents are just a single element. However, most processes require reagents made of chemical compounds. Some of the most common ones used widely for specific reactive functions are ...
The primary result of TEM is a reaction curve which shows the elasticity over time when the clot forms or dissolves. This curve is also called a TEMogram. Four key parameters describe the clotting curve for clinical routine.
Reagent Chemicals [a] is a publication of the American Chemical Society (ACS) Committee on Analytical Reagents, [1] detailing standards of purity for over four hundred of the most widely used chemicals in laboratory analyses and chemical research. Chemicals that meet this standard may be sold as "ACS Reagent Grade" materials.
Pharmacopeial reference standards are available from various pharmacopoeias such as United States Pharmacopeia and the European Pharmacopoeia. Where pharmacopoeial tests or assays call for the use of a pharmacopoeial reference standard, only those results obtained using the specified pharmacopoeial reference standard are conclusive. [citation ...