title: Dynamic pH junction preconcentration in capillary electrophoresis- electrospray ionization-mass spectrometry for proteomics analysis.
abstract: Capillary zone electrophoresis (CZE)-electrospray ionization (ESI)-mass spectrometry (MS) is an interesting complimentary technique to reversed phase liquid chromatography (RPLC)-ESI-MS for proteomics research. However, the low sample loading capacity of CZE (typically a few nL) can limit its application for large-scale proteomics. A number of on-line sample preconcentration methods have been developed to increase sample loading volumes. This review considers the dynamic pH junction as a simple on-line sample preconcentration method; this method is well suited for amphiprotic analytes. In the pH junction, these analytes are suspended in a basic buffer, injected by pressure into the capillary, and separated in an acidic background electrolyte, with no changes in either CZE-MS operations or instrumentation. We have demonstrated that the dynamic pH junction method can improve the sample loading volume to sub-μL volumes without significant loss of separation capacity for bottom-up proteomic analysis. The dynamic pH junction based CZE-ESI-MS system has been applied for a number of complex biological samples, including the E. coli proteome, impurities in recombinant antibody therapeutics, and the characterization of the phosphoproteome from a human cell line.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA. ndovichi@nd.edu.
authors.forename: Guijie
authors.initials: G
authors.lastname: Zhu
authors.forename: Liangliang
authors.initials: L
authors.lastname: Sun
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Dovichi
mesh_terms: D002460:Cell Line; D019075:Electrophoresis, Capillary; D004926:Escherichia coli; D006801:Humans; D006863:Hydrogen-Ion Concentration; D040901:Proteomics; D021241:Spectrometry, Mass, Electrospray Ionization