# The Thermodynamics of Chromatography - Other Thermodynamic Methods that are Used for Studying Chromatographic Systems > Optimum Operating Conditions for Chiral Separations in Liquid Chromatography > Page 64

Now, (H_{min.}) (the minimum variance per unit
length of the eluted peak) to the first approximation, has been shown (see book
9 of this series) to be,

_{ (40)}

where (d_{p})
is the particle diameter of the packing.

The length (L) of the column is ,

L = nH_{min. }_{ }(41)

Substituting
for (n) from (39) and for (H_{min.})
from (40) in (41),

_{ } (42)

Similarly, it has been shown (15), the optimum mobile phase velocity is given by,