If you're using paper chromatography, you can vary the solvent. Let's say one particular ion has a high solubility in acetone or something, then you could use acetone to keep that ion in solution, and it will travel farther than say, an ion that doesn't "like" acetone. Using different solvents, you can somewhat resolve different ions. The BEST way to do this is by using ion-exchange chromatography. Where you have polymer beads in a column and their charged ends are outward on the spherical(or nearly spherical) beads. You control the charge with pH and the cations bind/unbind based on size/charge density. It works best for transition metal elements. But you can resolve main group elements using this technique as well. Hope this helps.
Imtiaz
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