Dispersion in Chromatography Columns - Experimental Validation of the Van Deemter Equation > Page 95
It follows that, if suitable experimental data was available, a graph relating, , against, , should provide a straight line.
Katz and Scott (26), in their work involving the development of a method for the measurement of solute molecular weight from chromatographic data, generated sufficient data to test the relationship given in equation (71). Furthermore, the equation could be tested against the two alternative values for the capacity factor (k') calculated by employing the fully permeating dead volume, or (k'e) derived by employing the excluded dead volume. The graph relating,, to, should provide a straight line. This graph is shown in two forms figure 27. It is clear that the upper curve is not a linear curve and the use of (k') values derived from the fully permeating dead volume can not be used in the kinetic studies of LC columns. In contrast, the lower linear curve shown in figure 27, is the same basic graph but, in this case, the ordinate values were calculated using (k'e) values based on the excluded dead volume.