Dispersion in Chromatography Columns - The Van Deemter Equation > Page 59


  or,                                            (45)

It is seen from equation (45) that the analysis time is proportional to the fourth power of the particle diameter and inversely proportional to the square of the diffusivity in the mobile phase. In a similar manner to column length, the analysis time is also directly proportional to the applied inlet pressure and inversely proportional to the mobile phase viscosity.

Summarizing, if a column is operated at its optimum velocity and the solute concerned is eluted at a relatively high k' value, and assuming the film thickness of the stationary phase is small compared with the particle diameter (a condition that is met in almost all LC separations) then,