HPLC Simulation

 Programmed Version
Column
Diameter: Length: Packing fraction, Vs/(Vs+Vm):
Concentration of stationary phase sites: Plates:
Eluant The Mobile Phase Additive is M
Concentration for M: Flow rate: Run time:
   Programming: Change [M] to: from time: to time:
Injection
Volume: Sample [A]: [B]: [M]:

Partition Coefficients Equilibrium Constants
P   Pij  ABM
A A
B B
M M
Kij  ABM
A
B
M

  
Chromatogram:

In partition mode, the stationary phase is assumed to have a large active surface area and P=Cs/Cm. Cs is the concentration of a solute in the stationary phase. Cm is the concentration of a solute in the mobile phase. In competition mode, the stationary phase has a limited number of active sites and P=Cs/(Cm S). S is the concentration of unoccupied active sites on the stationary phase. This is equivalent to a Langmuir absorption isotherm.

To get comparable retention between a partitioning run and a competitive run, divide the partition coefficient for the partitioning run by the concentration of stationary sites. For example, if the partitioning partition coefficient for A is 0.1 and the concentration of stationary sites is 10 equiv/L, then divide the partition coefficient by 10 equiv/L to get the competitive partition coefficient, P(A)=0.01.

Colby College Chemistry, Thomas W. Shattuck