Sheathless preconcentration-capillary zone electrophoresis-mass spectrometry applied to peptide analysis.

A reliable capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry system has been developed for the sensitive analysis and sequencing of peptides. The system comprises (1) a zero dead volume on-line sample preconcentration interface allowing over 100-fold increase in sample volume introduction and (2) a zero-dead volume, durable electrospray emitter yielding stable, low background electrospray signals, both proving not to compromize the electrophoretic performance. Sub-fmol sensitivities were obtained in applications to complex peptide samples derived from tryptic digestion of proteins and naturally processed major histocompatibility complex class I associated peptides.