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Updated: Oct 11, 2026

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method
Published on: September 19, 2018
Capillary isoelectric focusing-electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry
L Yang1, C S Lee, S A Hofstadler
1Department of Chemistry and Ames Laboratory, USDOE, Iowa State University 50011, USA.
Abstract:
On-line combination of capillary isoelectric focusing (CIEF) with electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is demonstrated for high-resolution analysis of model proteins, human hemoglobin variants, and Escherichia coli proteins. The acquisition of high-resolution mass spectra of hemoglobin beta chains allows direct identification of hemoglobin variants A and C, differing in molecular mass by 1 Da. Direct mass determination of cellular proteins separated in the CIEF capillary is achieved using their isotopic envelopes obtained from ESI-FTICR. The factors which dictate overall performance of CIEF-ESI-FTICR, including duty cycle, mass resolution, scan rate, and sensitivity, are discussed in the context of protein variants and cell lysates analyzed in this study.
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