A procedure in which the rate of flow of the mobile phase is changed systematically during a part or whole of the separation.
PAC, 1993, 65, 819
(Nomenclature for chromatography (IUPAC Recommendations 1993))
on page 827
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. doi:10.1351/goldbook