distribution isotherm

in chromatography
The equilibrium relation between the concentration of a sample component in the @[email protected] \(c_{\text{S}}\), and in the @[email protected] \(c_{\text{M}}\), expressed as a function \(c_{\text{S}}=f(c_{\text{M}})\). In some versions of @[email protected], a distribution isotherm can be seen as a @[email protected], an @[email protected], or a combination of these, depending on the mechanism of separation.
The relation can be influenced also by concentrations of other sample components. \(c_{\text{S}}\) and \(c_{\text{M}}\) are usually expressed per unit volume of the phase; \(c_{\text{S}}\) may also be expressed per mass of the dry solid phase or per unit surface area.
PAC, 1996, 68, 1591. (Nomenclature for non-linear chromatography (IUPAC Recommendations 1996)) on page 1592 [Terms] [Paper]
This definition supersedes an earlier definition of distribution isotherm.