Titration Curve of IEC CM-825
IEC CM-825 and Asahipak ES-502C are packed with weak cation exchange resins bonded with carboxymethyl groups. These groups have a pKa value of 5.7, therefore these bonded columns are suitable for the analysis of basic proteins. The base packing material of IEC CM-825 is polyhydroxymethacrylate and that of Asahipak ES-502C a polyvinyl alcohol. In some case of high molecular weight samples such as proteins not only the ion exchange mode, but also the reversed phase mode contribute to some degree to the separation, therefore a difference of packing material may play an important role.