Recent advances in peptide fragmentation techniques and mass spectrometry have opened up the possibility of combining peptide sepn. techniques, such as capillary electrophoresis (CE) and capillary liq. chromatog., with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and electron capture dissocn. (ECD) in order to characterize peptide mixts. and protein digests. The results presented in this study show that CE/ECD-FT-ICR MS can be employed for peptide characterization in mixts. of std. peptides and in peptides resulting from the enzymic digestion of proteins. Furthermore, the technique has potential for the identification and localization of post-translational modifications in peptides and proteins. [on SciFinder (R)]