Page 46 - Tandem Techniques

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cell of the associated instrument would provide confused data and make identification very difficult, if
not impossible.

The retention volume, VR(A), of solute A is given by

where (Vo) is the dead volume, that is the volume of mobile phase between the injection point and the
detector,

(K (A) ) is the distribution coefficient of solute (A) between the two phases,

and (V ) is the volume of stationary phase in the is the volume of stationary phase in the
L

and for solute B,

where (K(B)) is the distribution coefficient of solute (B) between the two phases.

It is seen that the retention of a solute depends only on the volume of mobile phase and stationary phase
in the column, and the distribution coefficient of the solute between the two phases. It is independent of
the mobile phase velocity and the particle size of the packing.

The volume between the peaks, which is one measure that describes the magnitude of the resolving
power of the column, is given by

It is seen that for any given pair of solutes the volume between the peaks increases with the volume of
stationary phase in the column. Thus, as a packed column contains one to two orders of magnitude
more stationary phase than the capillary column then, for columns of equal length, the packed column
will give the greater separation. However, it must also be