Dispersion in Chromatography Columns - Resistance to Mass Transfer Dispersion > Diffusion Controlled Dispersion in the Mobile Phase > Page 34

Summarizing,, the rate theory provides the following equations that describe the variance per unit length (H) for four different columns.

1. The Open Tubular GC Column,

            (20)

(21)

This equation is basically that derived by Van Deemter et al. in 1956.

 

                           (22)

       (23)

It should be noted that all the equations assume that the mobile phase is incompressible which will not be true for equations (23) and (24). It follows that equations (23) and (24) will require modification in order to be applicable to practical situations.