A term which is equivalent to relative retention used in
column chromatography: the ratio of the

value of a component to the

value of a standard (reference) substance. Since the mobile phase front is common
for the two components, the

value can be expressed directly as the ratio of the distances travelled by the spot
of the compound of interest
(
) and the reference substance
(
) respectively:
In former nomenclatures the symbol

was used to express relative retardation in
planar chromatography. Because of its identity with the symbol for peak resolution the symbol

is suggested for relative retardation in
planar chromatography.
Source:
PAC, 1993, 65, 819
(Nomenclature for chromatography (IUPAC Recommendations 1993))
on page 845
Cite as:
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.