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The Moving Bed Continuous Chromatography System

The idea of a continuous moving bed extraction process as a means of large scale separation is almost as old as gas chromatography itself. The first description of a continuous gas-solid extraction process that was reported in the chromatography literature was in 1956 by Freund et al. (10). However, much of the experimental work had been reported considerably earlier but in the 'not readily available' Hungarian technical literature. Shortly afterwards, the use of a moving bed for the continuous preparative scale product isolation using gas-liquid chromatography was reported by Scott (11,12)

The principle of the moving bed separating system is basically simple, but can be quite difficult to carry out in practice. Considering the separation from a theoretical aspect, the moving bed is depicted, diagramatically in figure 23.

Let the column have a length (L) and with the packing static let the retention volume and retention time of a solute eluted through the column be (Vr) ml, and (to) sec. respectively. When moving through the column from right to left, let the packing have a velocity (U). Let the mobile phase pass through the column from left to right at a flow rate (Q) ml / min..

Figure 23. Diagrammatic Representation of a Moving Bed Separation System