Titration Curve of 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.