Fast separation and analysis of reduced monoclonal antibodies with capillary zone electrophoresis coupled to mass spectrometry

• We developed a sample preparation protocol for reduced antibody CE–MS analysis.
• Heavy chain and light chain were baseline resolved for a single antibody within 10 min.
• Heavy chains and light chains were partially resolved for a mixture of two antibodies.

Capillary zone electrophoresis–electrospray ionization–mass spectrometry (CZE–ESI–MS) was used for analysis of reduced antibodies. We first developed a simple protocol to condition commercial linear-polyacrylamide coated capillaries for use in top–down proteomics. We then suspended reduced antibodies in a solution of 35% acetic acid, 50% acetonitrile in water. Heavy and light chains were baseline resolved within 10 min and with 3–30 µg/mL detection limits using a 0.1% aqueous formic acid background electrolyte. Quintuplicate runs of a two-antibody mixture produced relative standard deviations of ∼1% in migration time and 10% in peak amplitudes. Resolution was further improved for the two-antibody mixture by using 5% acetic acid as the background electrolyte, highlighting the potential of capillary electrophoresis–mass spectrometry for analysis of antibody mixtures.

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