Simulated moving bed (SMB) chromatography saves time and money in the lab

Simulated moving bed chromatography (SMBC) is increasingly applied as a separation technique in the pharmaceutical industry, production of fine chemicals, and in the field of bioengineering.

SMB is a method in process chromatography that enables substance mixtures to be continuously separated and extracted in two fractions. Its efficiency is significantly higher than batch chromatography, through better utilization of the column stationary phase.

Although in principle limited to two fraction separations, each partial fraction can be separated into a further fraction by repeated use of the SMB process – down to binary substance mixtures.

Typically, the SMB process is used for two component mixtures, like chiral separations or mixtures with a "leading" or a "trailing" key product peak in the chromatogram.

Due to their modular design, AZURA SMB systems can also be configured for other multi-column processes. KNAUER offers SMBC systems for purification up to 1000 kg/year.


How it works


The SMB process enables the separation of binary mixtures by means of a simulated countercurrent between the solid and liquid phases. This is accomplished with a series of chromatography columns arranged in a ring. An eluent flow circulates through this ring. Two inlets (for feed and eluent) and two outlets (extract/red and raffinate/blue) define four separation zones. By continuously feeding sample and synchronously switching the columns against the eluent flow direction, a countercurrent is achieved between the solid and liquid phases, leading to high purity of both target fractions.

The movement of the solid phase is realized by simultaneously switching seven multi-position valves (AZURA® SMB) or one central multi-position valve (former KNAUER SMB, CSEP®). The bulk of the eluent is continuously circulated in the system, making it necessary to replace only that small amount which is removed in the extract and raffinate, thereby enabling savings of up to 90% of the eluent in comparison to a batch process. Due to the simulated countercurrent, the stationary phase is significantly better utilized with the SMB technique as compared to the batch process technique. The number of theoretical plates might be also less important, making it possible to use cost-effective larger particle size for the stationary phases.

Introducing SMB chromatography

Simulated moving bed chromatography for continuous high-efficiency separations

How AZURA® SMB works

System configuration

The standard AZURA® SMB systems consists of four pumps and seven multi-position valves. The devices are arranged as follows:
• Three pumps (Extract, Raffinate, Eluent) are placed inside the SMB cycle.
• The feed pump is placed outside the SMB cycle.
• Four valves are placed at the pump outlets.
• Three valves are placed at the pump inlets. The feed pump inlet is not connected to a multiposition valve.

Due to this configuration the SMB system can be used very flexible for many different separation modes. Additionally to the process stability AZURA® SMB systems are outperforming every other SMB system on the market regarding material and configuration flexibility as well usable pressure range.

System solution for continuous purification

Solutions for continuous purification of xylitol

Simulated moving bed chromatography (SMBC) was applied for the purifi­cation of xylitol from fermentation mash of a fed batch culture. This process enabled to purify xylitol with nearly 100% purity and recovery. Thus, allowing large-scale purification of xylitol from the biological xylose-xylitol conversion process.

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