Simulated moving-column technique

Zhang, Y, McConnell, O. Simulated moving columns technique for chiral liquid chromatography. J. Chromatogr. A 2004, 1028, 227-238. 

A variant of this procedure has been commercialized under the name Cyclo-Jet (Merck, Germany). The same column switching technique is used as in the waUdng-column technique, but fresh sample is injected into the center of the sample band any time it passes from one column to the other. Also, the edges of tte band are collected as described in the peak-shaving technique mentioned above. Semicontinuous binary separations are possible with the Cyclo-Jet technique that are reminiscent of the simulated moving-bed technique described in the next section, but the technique is not as solvent eflBdent as the simulated moving bed. 

The performance of HPLC separations can be increased not only by the application of two- or multidimensional techniques but also by the use of simulated moving bed (SMB) [100-102] or true moving bed (TMB) techniques [103,104], SMB is a multicolumn separation technique allowing the continuous separation of analyses with higher productivity and smaller eluent consumption than the traditional single-column procedures. TMB... 

Simulated moving bed (SMB) processes are related to the separation of chemical products. Efficient purification techniques are crucial in chemical process industries. Liquid chromatographic separation has been widely used for products with an extremely high boiling point, or thermally unstable products such as proteins. In liquid chromatographic processes, a small amount of feed mixture is supplied to an end of a column which is packed with adsorbent particles, and then pushed to the other end with desorbent (water, organic solvent, or mixture of these). 

Simulated Moving-Bed Chromatography (SMBC) As the name suggests, this technique is based on the principle of liquid mobile phase and chromatography phase moving in opposite directions. Establishment of equilibrium helps in the improved efficacy of separation of the component of a mixture—often, a mixture of two enantiomers—which are fed into the middle of the column. The advantages are the continuous feeding of the sample... 

The simulated moving bed adsorption technique is based on the movement of the stationary phase. The front and back ends of a series of columns are connected to form a circle, and during rotation of the columns a countercurrent movement of the phase relative to the liquid stream in the system is developed [158]. Injections of the fresh chiral analyte and the solvent are made at various coimecting points, and the separated enantiomers are withdrawn simultaneously at certain time intervals. This is a continuous process that provides certain advantages for enantiodiscrimination. The chiral selectors used in this technique are the same as those utilized in liquid chromatography and capillary electrophoresis. 

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