Displacement chromatography shock layers

Thus, we can conclude that, as long as the mass transfer kinetics is reasonably fast, the equilibrium-dispersive model can be used as a first approximation to predict shock layer profiles. As a consequence, the results of calculations of band profiles, breakthrough curves, or displacement chromatograms made with this model can be expected to agree well vsdth experimental results. Conclusions based on the s) stematic use of such calculations have good predictive value in preparative chromatography. 

In the case of two components, the shock layer thickness is defined as in the singlecomponent case (Figure 14.3), with the help of threshold concentrations CJ and Cy, j = 1, 2), and the auxiliary parameter 6 (Eq. 14.21). hi displacement chromatography, there is a shock layer on each side of the isotachic bands, and we need to distinguish C (band rear) and cj (band front), and c. In the case... 

Figure 15.2 Definition of the parameters of the shock layer and the SLT in displacement chromatography, in an isotachic train. Reproduced with permission from J. Zhu and G. Guiochon,. Chromatogr. A, 659 (1994) 15 (Fig. 2).

Overdisplacement A phenomenon which takes place in displacement chromatography when the displacer concentration is too high, and, although the isotachic train forms, the band plateaus are very narrow or nonexistent, the retention times of the bands are dose to the holdup time and/or the shock layers are too thick. Little or no separation of the bands take place. 

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