Plate Theory and Extensions - The Retention Volume of a Solute > Page 12
Thus, Vr = n(vm + Kvs)
= nvm + KVs
The volume of mobile phase per plate (vm), multiplied by the number of plates (n), will give the total volume of mobile phase in the column (Vm). Similarly, the volume of stationary phase per plate (vs), multiplied by the number of plates (n), will give the total volume of stationary phase in the column (Vs).
Thus, Vr = Vm + KVS (13)
The function for the retention volume is indeed simple and depends solely on the distribution coefficient and the volumes of the two phases that are present in the column.
For an unretained beak K=0 and Vr(0) = Vm