Equilibrium relations for the glucose-sucrose-sorbitol-water system (a quaternary system) on 13X zeolite molecular sieves have been determined by an extension of the method suggested for a ternary system. The quaternary and the constituent ternary adsorption equilibrium relations derived from chromatographic retention time measurements of binary systems are verified by comparing experimental retention times with that obtained from simulations and the equilibrium theory of bisolute systems respectively. The accuracy of the adsorption equilibria is further verified by the adsorbed phase concentrations predicted by the ideal adsorbed solution theory and potential theory.