Thus,                             (44)

It is seen that the column length varies inversely as the product of the solute diffusivity in the mobile phase and the mobile phase viscosity in much the same way as the column efficiency does when operating at the optimum velocity. As would be expected the column length is directly proportional to the inlet pressure but, less obviously is also proportional to the cube of the particle diameter.

The analysis time for a solute mixture in which the last peak is eluted at a capacity ratio of k'_F is given by,

Substituting for (u_opt) and (l) from equations (36) and (44),