zone

in chromatography
https://doi.org/10.1351/goldbook.Z06749
A region in the chromatographic bed where one or more components of the sample are located. The term band may also be used for it.
Sources:
Orange Book, 2nd ed., p. 96 [Terms]
PAC, 1993, 65, 819. (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 824 [Terms] [Paper]