factor (also called "capacity ratio") is symbolized by k'
(USP terminology) or k (IUPAC/ASTM terminology). It is a
measure of the retention of a peak that is independent of column
geometry or mobile phase flow rate.
The capacity factor
is calculated as:
k' = (tR - t0)/t0
where tR is the retention time of
the peak, and t0 is the dead time of the column.
Note that the
capacity factor cannot be calculated in this manner from a gradient
chromatogram. The "apparent" capacity factor obtained when this is done
is meaningless chromatographically.