Ion exchange column estimate

Question

The question is: Suppose another student attempts to do an ion exchange on a column that is already nearly saturated with Co2+ and Zn2+. Will his calculated % Co be high or low?

Answer 1

It is difficult to answer this without knowing what the experiment is trying to accomplish.  If the column is being used to capture Co2+ and Zn2+ and then elute them off later, the second student could have recovery that is is higher than expected because of elution of ions that were not actually in the applied sample.  But, if if there is no elution involved, then the ions in the applied sample will come through the column in the void volume and the % may appear to be too low.  Can't really tell without knowing more about the actual experiment.