Recovery of your biologically active target substance is a priority, and it’s important to check for its pH and ionic strength stability values...
As long as your target substance is stable over a wide pH range above and below the pI, you can use either an anion (e.g. Q or DEAE) or a cation exchanger (e.g. S). Otherwise, use a cation exchanger if your target is most stable below its pI and an anion exchanger if it is most stable above its pI.
