The Multipath Process
In a packed column the solute molecules will describe a tortuous path through the interstices between the particles and obviously some will travel shorter paths than the average and some longer paths. Consequently, some molecules will move ahead of the average and some will lag behind thus causing band dispersion. The multipath effect is illustrated in figure (4)
Figure 4. Dispersion by the Multipath Effect
The Multipath
effect can be applied to the Random Walk Model. The average path length is
equivalent to the mean diameter of the particle (dp) and thus the
number of steps will be equivalent to the column length divided by the average
step i.e. 
.
Thus, applying
equation (1), 
