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The word standard has several meanings:
Classically, standard referred to a flag or banner; especially, a
national or other ensign carried into battle; thus "standard bearer" indicates the one
who bears, or carries, the standard. The modern primary meaning evolved through symbolism: "a quality or measure which is
established by authority, custom, or general consent". In the phrase "light standard" it retains the older meaning of a vertical
support.
In technical use, a standard is a concrete example of an item or a specification against which all others may be measured. For
example, there are "primary standards" for length, mass, and other units of measure, kept by laboratories and standards organizations. Officially certified measuring
instruments must be checked for accuracy using such standards (or secondary standards made from the primary).
In analytical chemistry a standard is a
preparation containing a known concentration of a specified substance. A simple standard may be a dilute solution of the
substance; this serves as a reference to calibrate equipment used to measure a sample's composition in terms of elements. For accuracy, the standard concentration may be specially designed to be as close
to real samples as possible.
There are also certified reference materials available which contain independently verified concentrations of
elements available in different matrices (a matrix is bulk material of the sample, for example blood).
See Also
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