Azeotropic phenomena during separation of dilute mixtures of proteins by simulated moving bed chromatography

Recently, we have introduced the use of a salt gradient over a simulated moving bed system used for purification of proteins using ion exchange chromatography. This paper describes azeotropic phenomena in such a system, where complete separation of mixtures of proteins is not possible at certain salt concentrations, due to a reversing selectivity. These phenomena impose additional restrictions on the selection of the flow rates in each of the sections of the simulated moving bed which are discussed.