Native online SCX-MS analysis of monoclonal antibodies

Cation exchange chromatography (CEX) is a non-denaturing technique used for separation and isolation of protein charge variants before characterisation via MS. This is usually a two step process, where the specific charge variant peak of interest has to be isolated prior to characterisation via mass spectrometry because in CEX mostly non-volatile buffers are used, which are not compatible with MS. The coupling of MS to CEX would save time and exclude possible artefacts of the long isolation process. In addition, it is possible to overlook minor species of e.g. monoclonal antibodies (MAb) that do not exhibit distinctive UV peaks in this two-step approach.