# Plate Theory and Extensions - The Peak Capacity of a Chromatographic Column > Page 92

and the retention volume (V_{r})
given by V_{r} = n(v_{m} +
Kv_{s}).

Thus, a simple form of the peak capacity (S) could be given by

(S) is the number of peaks (assumed to have the same width as the last peak) that can be fitted into the chromatogram between the dead volume and the last peak. This expression does not give a valid number for the peak capacity, as even with very high efficiency columns, all those peaks eluted before the last will have significantly smaller widths. It follows a much greater number of peaks can be fitted into the chromatogram than the value of (S) calculated in this way might suggest.

The chromatogram in Figure 24 diagrammatically represents (r) resolved peaks, each peak being separated from its neighbor by 4s.

**Figure 24. Diagram of the
Separation of (r) Resolved Peaks**