A compound present in a standard sample of known concentration and volume which is
analysed separately from the unknown sample under identical conditions. It is used
to facilitate the qualitative indentification and/or quantitative determination of
the sample components. The volume of the external standard (standard sample) need
not to be known if it is identical to that of the unknown sample.
Source:
PAC, 1993, 65, 819
(Nomenclature for chromatography (IUPAC Recommendations 1993))
on page 837