Here we will briefly discuss the concept of adsorption isotherms and its role in chromatography.
An adsorption isotherm is a plot of the concentration or amount of a specie on a surface as a function of its concentration in the bulk phase. In liquid chromatography, the bulk phase is, of course, the mobile phase.
In the simplest form of chromatographic theory,
it is assumed that the adsorption isotherm for the solute is linear, i.e.
Cs = K * Cm
where
Cs = the concentration of the solute on the surface
Cm = the concentration of the solute in the mobile phase.
K = adsorption constant of the solute to the stationary phase surface.