Principles and Practice of Chromatography - Factors Controlling Retention > Page 14
or V'_{r = } KV_{S}_{ (1)}
_{ }
where | |
(V_{m}) | is the volume of mobile phase in the column |
(V_{S)} | is the volume of stationary phase in the column, |
(K) | is the distribution coefficient of the solute between the phases, |
and (V'_{r}) | is the corrected retention volume i.e., (V_{r }- V_{m)} |
_{ }
From equation (1) it is seen that the corrected retention volume is controlled by two parameters: firstly the distribution coefficient of the solute between the two phases and secondly, the amount of stationary phase that is available to the solute.
Consequently, the magnitude of (V'_{r) }is determined by (K) or (V_{s}) or both.
From equation (1) the conditions necessary to separate two solutes (A) and (B) can be deduced.
To separate solutes (A) and (B), V'_{r(A)} <> V'_{r(B), }
which can be achieved by making either K_{(A) } <> K_{(B)}
or V_{S(A)} <> V_{S(B) }or an appropriate combination of both.
Thus, to separate a mixture, either the values of (K) for all components, or the amount of stationary phase (V_{S}), available to each component, must be made to differ or, again, appropriate adjustments must be made to both.