Principles and Practice of Chromatography - Peak Dispersion in a Chromatographic Column > The Resistance to Mass Transfer in the Stationary Phase > Page 48
where (k') is the capacity ratio of the solute,
(df) is the effective film thickness of the stationary
(DS) is the diffusivity of the solute in the stationary
and the other symbols have the meaning previously ascribed to them.
Now, applying the law of Summation of Variances,
where () is the total variance/unit length of the column.
Thus substituting for (), (), () and () from equations (4), (5), (6) and (7), respectively,