Ce-western applications for antibody development

A method for detecting and/or discriminating between variants of an antibody in a sample by a physical parameter, comprising:

• separating protein components of a sample comprising an antibody of interest by molecular weight or charge in one or more capillaries using capillary electrophoresis, wherein the antibody of interest is conjugated to biotin;
• immobilizing the protein components of the sample within the one or more capillaries;
• contacting the protein components within the one or more capillaries with one or more primary antibodies that specifically bind to the antibody of interest and with streptavidin conjugated to a detectable label;
• and
• detecting the binding of the one or more primary antibodies and the binding of the streptavidin conjugated to a detectable label, thereby detecting and/or discriminating between size variants or charge variants of the antibody of interest in the sample.