High Resolution Capillary Isoelectric Focusing Mass Spectrometry Analysis of Peptides, Proteins, And Monoclonal Antibodies with a Flow-through Microvial Interface

Capillary isoelectric focusing directly coupled to high resolution mass spectrometry (cIEF–MS) provides information on amphoteric molecules, including isoelectric point and accurate mass, which enables structural interrogation of biopolymer pI variants. The coupling of cIEF with MS was facilitated by a flow-through microvial interface, made by stainless steel with high chemical resistance and mechanical robustness. Two on-column electrolyte configurations of cIEF–MS were demonstrated using peptide and protein pI markers. The pI resolution was 0.02 pH unit in the pH range of 5.5 to 7.0, with no anticonvective reagent (glycerol) added. High resolution Orbitrap detector provides mass spectra for midsized proteins (