RAPID LOADING OF LARGE-SAMPLE VOLUMES, ANALYTE CLEANUP, AND MODIFIED MOVING BOUNDARY TRANSIENT ISOTACHOPHORESIS CONDITIONS FOR MEMBRANE PRECONCENTRATION-CAPILLARY ELECTROPHORESIS IN SMALL-DIAMETER CAPILLARIES

Using a removable membrane preconcentration (mPC) cartridge, large sam ple volumes can be loaded prior to final assembly of the mPC capillary electrophoresis (CE) capillary. For narrow-bore (less than or equal t o 25 mu m ID) uncoated mPC-CE capillaries, applied to peptide analysis , efficient moving boundary transient isotachphoresis (tITP) condition s at the onset of electrophoresis are described. The enhancement of mP C-CE-mass spectrometry (MS) technology afforded by rapid sample loadin g and modified moving boundary tITP conditions are demonstrated by ana lysis of major histocompatibility complex (MHC) class I peptides that were derived from a K-b precipitation of mouse EL-4 cells. Furthermore , we demonstrate the structural characterization of these immunologica lly significant molecules by mPC-CE-tandem mass spectrometry (mPC-CE-M S/MS).