Preparative-scale chromatography displacement

The Langmiur isotherm—used by Guiochon and others in the study of preparative scale chromatography—is based on the concept that adsorption nonlinearity occurs when there are so many molecules that they compete with one another for a limited number of adsorption sites. It is obvious that when two concentrated solutes are present at the same time, they will interfere with one another s adsorption. The one that adsorbs most strongly will almost totally displace the weaker adsorber. This is the basis of displacement chromatography, a nonlinear form developed by Tiselius in 1943 (17) and revived recently by Horvath [18]. 

Displacement chromatography is commonly used for preparative-scale separations, but, because of its focusing or concentrating effect, it also shows potential on the analytical scale, for example, for the concentration of minor components in complex mixtures.24,25 Operationally, displacement chromatography is similar to the step elution process, except that in the displacement process the mobile phase has a greater affinity for the stationary phase than for the sample components, and therefore the components are eluted ahead of the displacer front. The focusing effect of displacement chromatography is due to the fact that the concentration of the displacer determines the concentration of the product bands.26... 

Kalasz, H., and Horvath, Cs. (1981). Preparative scale separation of polymyxins by high performance displacement chromatography. J. Chromatogr. 215, 295-302. 

Displacement equilibrium is also known in chromatography, by which ligands compete for binding sites. This competition can be preferentially utilized for either analytical or preparative scale separations. 

Displacement chromatography offers an alternative to elution chromatography for preparative-scale separations under nonlinear conditions [10,66,82,83]. It has found limited success for the purification of biopolymers by reversed-phase [10,83,84] and ion-exchange chromatography [85-88], but is not widely used for the purification of small molecules [89-91]. It has the potential for greater use, but remains a minor technique compared with elution chromatography. 

Pumps are major components of all chromatography systems as they have to induce the driving force for the elution and separation process. In any case, process pumps should be able to maintain their set-point flow rate in a smooth manner. Positive-displacement pumps, such as diaphragm pumps, are often used in preparative and large-scale chromatography systems. 

This nonlinear multicomponent separation technique is eminently suitable for preparative/process scale applications. In displacement chromatography, the competition... 

Displacement chromatography has an enormous potential as a preparative bioseparation technique. In many situations from the mg to the kg scale and beyond the displacement chromatography may theoretically be the most practical, the most economic and the most efficient approach to a given separation problem. However, in order to exploit the full potential of displacement chromatography, suitable displacer/stationary phase systems must become available. This chapter is intended as an introduction to our current understanding of the requirements for systematic displacer design. 

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