Simulated moving bed chromatography (SMB) is a variation of conventional liquid chromatography, which provides continuous chromatographic separations, as opposed to batch separations, which account for the majority of chromatography systems. For the most part, the use of SMB in the laboratory is tied to a narrow scope of industrial applications, for which it offers a very attractive alternative.

SMB utilizes multiple high-pressure chromatographic columns and a complex series of valves to direct the flows of the feed, eluent, extract and raffinate streams. The complex configuration approximates the effect of actually being able to move the stationary phase counter to the flow of the mobile phase. SMB typically requires some significant mass-balance modeling and simulations to achieve the needed process.

SMB has existed since the 1960s, when it was developed for use in the sugar and sweetener industry. It is also used in the petroleum industry for xylene processing. There was no real market for laboratory SMB until the technique was seized upon by the pharmaceutical industry, which required more extensive study and methods development at smaller scales before implementing larger, more costly, production SMB systems.

The largest area of applications for SMB in the pharmaceutical market is chiral separations. One of the benefits of SMB is that it makes efficient use of chromatography media, which can be very expensive for chiral separation phases.

Because of the complexity of the systems, their continuous nature and the modeling and simulation required for a single separation, SMB is not a viable option for laboratory analytical or preparative applications. Thus, the market for laboratory SMB is driven almost exclusively by the need to model larger-scale industrial SMB separations or to conduct small-scale production runs. The more than $40 million laboratory SMB market represents only about 15% of the total worldwide market for SMB. Laboratory-scale SMB systems are limited to the use of columns with inside diameters of 100 mm and smaller. The cost of such systems can vary widely depending on size, number of columns and various options, and are generally highly customized.

There are few vendors that supply SMB systems that can fit into a laboratory. Novasep, which was recently bought out by its management (see IBO 12/15/06), is the leader in laboratory SMB. However, it is just one of several strong competitors in the industrial SMB market, which are each highly focused on separate industries. KNAUER, which is the other major vendor of laboratory SMB, is more focused on smaller-scale developmental systems than Novasep, but is not significantly involved in the larger-scale industrial SMB market.