Agreed method for determining one or more air quality characteristics where it is
not practical to produce a reference material
; the result obtained is defined as the measure of the air quality characteristic.
For example, a gas such as
may be somewhat unstable
when stored in a tank at low mixing ratios, so that the use of a more stableNO
standard mixture in
may be oxidized to
in a specified manner referred to as the
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2210
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook