I calculated the total exchange capacity of a column per gram of dry weight of resin to be 2.74 meq/g. This value comes from experimental values. However, the manufacturer's specifications for the number of exchange sites is 3.4 meq/g. 1. What's meq? I know this means milliequivalents of the anion/cation, but what does it mean? I think I'm contradicting myself by asking the question, but please help out to clarify if you can. 2. Why would there be such a big difference between the experimentally determined number of exchange sites and the manufacturer's specifications? I suspect that when the resin is packed in a column some surface area is compromised? Please help me out here Thanks, K.