Preparative chromatographic separation: Simulated moving bed and modified chromatography methods

Chromatography has been the method of choice for the separation of complex biological mixtures for analytical purposes, particularly for the last fifty years. Its use has recently been extended to preparative separation where the productivity relative to the amount of resin and solvent used is a matter of concern. To overcome the inherent thermodynamic inefficiency of batch chromatography, as exemplified by the partial temporal usage of the resin and dilution of the product with the solvent, chromatography has been continually modified by separation engineers. Column switching and recycling represent some of the process modifications that have brought high productivity to chromatography. Recently, the simulated moving bed (SMB) method, which claims a high separation efficiency based on counter-current moving bed chromatography, has become the mainstay of preparative separation, especially in chiral separation. Accordingly, this paper reviews the current status of SMB, along with several chromatographic modification, which may be helpful in routine laboratory and industrial chromatographic practices.