The Stochastic Theory of Chromatography describes the migration of a single solute molecule into a chromatographic medium as a complex chain of sorption-desorption steps between mobile and stationary phase.This description, firstly proposed by Giddings and Eyring [1] in the case of infinite dilution and on a homogeneous surface, was extended by using the characteristic Function approach [2].By using Monte Carlo simulation techniques, the stochastic description of chromatography was extended to non linear conditions [3, 4].