The LEA model has been analyzed by comparing to other chromatographic theoretical approaches. In the LEA model a layer of equilibrium adsorption, L_e, serves as an effective kinetic constant. For the layer L_e, the concentration issuing from this layer is in equilibrium with the average value of adsorption on the whole layer at any moment of time. The value of L_e, is determined from all factors which broaden the chromatographic zone. Such an approach permits us to combine the features of the mass balance (solute continuity in a chromatographic column), of the mass transfer phenomenon, and of the adsorption isotherm into a single first order differential equation. Apart from other layer-by-layer models, the LEA model supposes that over the whole column a continuous (real) distribution of adsorption a(L, t) and concentration c(L, t) is observed. The usefulness of the LEA model in developing a chromato-graphic theory has been disussed.