The mass of solute removed (dm) is given by
where (Ct) is the concentration of solute in the vessel after time (t).
The mass change (dm) will result in a change in concentration (dCt)
and 
Integrating 
| where (Q) | is the flow rate, |
| (v) | is the volume flow of mobile phase through the system after time (t) |
| and (k) | is the integration constant. |
