linear distribution isotherm

in chromatography
https://doi.org/10.1351/goldbook.LT06935
A distribution isotherm which can be approximated as cs=KC.cM where KC is a constant.
Note:
At low concentrations, all distribution isotherms tend towards being linear. KC is the distribution constant.
Source:
PAC, 1996, 68, 1591. (Nomenclature for non-linear chromatography (IUPAC Recommendations 1996)) on page 1593 [Terms] [Paper]