Therapeutic Monoclonal Antibody Intact Mass Analysis by Capillary Electrophoresis–Mass Spectrometry

The characterization of monoclonal antibody (mAb) therapeutics via mass spectroscopy is of important value in determining sequence integrity and identifying post-translational modifications. The monoclonal antibodies are commonly either reduced to generate heavy chain and light chain, or enzymatically cleaved to produce characteristic domains for subunit intact mass analysis. Toward this end, liquid chromatography coupled with mass spectrometry (LC-MS) is usually applied for the separation of these antibody subunits followed by on-line mass analysis. Capillary electrophoresis (CE) is an emerging separation technique that provides excellent protein separation efficiency at ambient temperature. The recent advancement on the coupling of capillary electrophoresis with mass spectrometer has essentially eliminated the technical obstacle for the broad application of CE-MS in the intact mass analysis of monoclonal antibody therapeutics. In this chapter, we will discuss several commercially available CE-MS interfaces and their applications, followed by demonstration of the CE-MS intact mass analysis procedure that has been developed for therapeutic protein characterization.