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 sample volumes can be loaded prior to final assembly of the mPC capillary electrophoresis (CE) capillary. For narrow-bore (≤ 25 μm ID) uncoated mPC-CE capillaries, applied to peptide analysis, efficient moving boundary transient isotachphoresis (tITP) conditions at the onset of electrophoresis are described. The enhancement of mPC-CE-mass spectrometry (MS) technology afforded by rapid sample loading and modified moving boundary tITP conditions are demonstrated by analysis 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 immunologically significant molecules by mPC-CE-tandem mass spectrometry (mPC-CE-MS/MS).