This is the fundamental difference between the two types of column. The variance from a packed column is largely determined by the magnitude of the particle diameter, in contrast, the variance obtained from a capillary or open tubular column is determined by the magnitude of the radius
The Golay equation takes the following form:-
(52)
Where (H) is the variance per unit length of the column for the given
solute,
(k)' is the capacity factor of the solute,
(K) is the distribution coefficient of the solute between the two
phases,
(DM) is the diffusivity of the solute in the mobile phase,
(DS) is the diffusivity of the solute in the stationary phase,
(r) is the radius of the column,
and (u) is the linear velocity of the mobile phase.
If the solute is unretained (i.e. k'=0 ) then the Golay equation
reduces
to,
(53)
Figure 17. Graph of H against U for an Uncoated Capillary Column
