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Updated: Aug 11, 2026

Capillary Electrophoresis Separation of Monoclonal Antibody Isoforms Using a Neutral Capillary
Published on: January 16, 2017
Application of capillary isoelectric focusing with universal concentration gradient detector to the analysis of
1Department of Chemistry, University of Waterloo, Ontario, Canada.
Abstract:
The design of a new capillary isoelectric focusing (cIEF) instrument, composed of a rugged cartridge holding a short piece of capillary and a universal, inexpensive concentration gradient detector, was optimized and applied to the analysis of various protein samples. High-efficiency cIEF separations with sub-femtomole detection limits for absolute amounts were obtained using 10 microns I.D. capillaries with large O.D.-to-I.D. ratios. An electric field strength of 1 kV/cm applied in the focusing step resulted in a 10(-8) M on-column concentration detection limit, which corresponded to 10(2) amol absolute amount of proteins. The detection volume was estimated to be 2 pl, which is among the smallest values reported to date for any optical or spectroscopic detector. When a 6-cm long capillary was used, proteins with isoelectric points ranging from 4.7 to 8.8 could be analyzed in about 5 min, the shortest analysis time ever reported for cIEF. Compared with commercial cIEF instruments with UV-visible absorbance detectors, the instrument is easier to use and has lower detection limits and better resolution. Several protein mixtures and real samples were separated with this instrument.
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