# Plate Theory and Extensions - The Capacity Ratio of a Solute > Page 16

# The Capacity Ratio of a Solute

As (K) is a
unique property of a given solute its corrected retention volume, which is
calculated from its corrected retention time is used as a means of
identification. Thus the precision and accuracy of measurement depended on the
precision and accuracy of the flow rate measurement. To avoid errors associated
with flow rate measurement, the *capacity ratio* of a solute (k')
was introduced.

The capacity ratio of a solute is defined as the ratio of its distribution coefficient to the phase ratio (a) of the column, where

Thus,
_{ }and,
as V'_{r} = KV_{S}

_{ }

^{Then
} In
practice, (21)

_{ }

The value of (k') from experimental data, if not calculated by the data processing computer, is measured from the chart as,