The Effects of Column Efficiency

It is clear that the best conditions for a separation depend upon the nature of the separation problem. In order to isolate the earlier eluting impurity one could operate at high load and accept the loss in recovery as a cost of attaining a high production rate of the product, or one could reduce the load and improve the recovery at the 

2 The Practical Application of Theory in Preparative Liquid Chromatography 

For the majority of cases a moderate efficiency (in analytical terms) is necessary for preparative chromatography and plate counts in excess of 10000 are used only under special circumstances. One reason for this is that very high efficiencies can be 

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Equations 12.21 and 12.22 contain terms corresponding to column efficiency, column selectivity, and capacity factor. These terms can be varied, more or less independently, to obtain the desired resolution and analysis time for a pair of solutes. The first term, which is a function of the number of theoretical plates or the height of a theoretical plate, accounts for the effect of column efficiency. The second term is a function of a and accounts for the influence of column selectivity. Finally, the third term in both equations is a function of b, and accounts for the effect of solute B s capacity factor. Manipulating these parameters to improve resolution is the subject of the remainder of this section. 

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