Let the volume
of sample injected be (Vi) ml, then the charge measured in 'plate
volumes' will be (
). Similarly, if the volume of mobile
phase passed through the column is (y) ml then that will be equivalent to 
plate
volumes. Assuming the sample that is injected onto the column contains solute
(S) at a concentration Xs1,
then from equation (25), the concentration of this solute (
)
leaving the (n) th plate in the column will be given by:-
Thus, for a chromatogram of (q) solutes, the elution curve equation will be given by,
. (64)
If pure mobile phase is injected onto the column, then Xs= 0 and equation (26) becomes
