Detection of fast capillary electrophoresis peptide and protein separations using electrospray ionization with a time-of-flight mass spectrometer.

Fast capillary electrophoresis (CE) separations on bare and coated fused silica have been detected on-line using a time-of-flight mass spectrometer which is capable of acquiring spectra at a rate suitable for the narrow peaks generated by CE. Protein and peptide separations producing peaks 1-2 s in width have been detected with an integration time of 0.125 s/spectrum, each spectrum being the sum of 1024 complete m/z range scans. The effects of the liquid sheath flow rate, electric field strength, and integration time on sensitivity and peak shape have been examined. A sensitivity limit of 8 fmol has been established for leucine enkephalin.