Adsorption isotherms can be determined experimentally by using either static or dynamic measuring methods. The adsorption behavior of the system dichloromethane-n-hexane on two normal-phase silica-gels was measured both statically by using the circulation method and dynamically by using the frontal analysis and the perturbation method. As a matter of conformity, adsorption excess isotherms, which are the results of static methods, should have to be converted into loading isotherms. Analytical and different numerical conversion methods using different assumptions are presented and compared to each other. A conformity between the results of the analytical conversion method and the dynamically measured adsorption isotherms can be established if the decrease of the porosity with increasing loading is also taken into consideration.