title: A sheathless nanoflow electrospray interface for on-line capillary electrophoresis mass spectrometry.
abstract: A novel, rugged capillary electrophoresis-electrospray ionization (CE-ESI) interface where the separation column, an electrical porous junction, and the spray tip are integrated on a single piece of a fused-silica capillary is described. ESI is accomplished by applying an electrical potential through an easily prepared porous junction across a 3-4-mm length of fused silica. A stable electrospray is produced at nanoflow rates generated in the capillary by electrophoretic and electroosmotic forces. The interface is particularly well suited for the detection of low-femtomole levels of proteins and peptides. The ruggedness of this interface was evident by the continuous operation of the same column for over a 2-week period with no detectable deterioration in separation or electrospray performance. The new interface was used for the LC-ESI-MS separation and analysis of peptides and proteins. Injection of 25 fmol of [Glu1]-fibrinopeptide B using the new device produced a CE-ESI-MS electropherogram with a signal-to-noise ratio of over 100 for this peptide.
authors.affiliation: Analytical Chemistry Laboratory, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, USA. Janini@mail.ncifcrf.gov
authors.forename: George M
authors.initials: GM
authors.lastname: Janini
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Conrads
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Wilkens
authors.forename: Haleem J
authors.initials: HJ
authors.lastname: Issaq
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Veenstra
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001059:Apoproteins / Q000032:analysis / Q000737:chemistry; D002853:Chromatography, Liquid; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D005345:Fibrinopeptide B / Q000032:analysis / Q000737:chemistry; D006736:Horses; D008969:Molecular Sequence Data; D009211:Myoglobin / Q000032:analysis / Q000737:chemistry; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D011506:Proteins / Q000032:analysis* / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
chemical_list: D001059:Apoproteins; D009211:Myoglobin; D011506:Proteins; C010857:apomyoglobin; D005345:Fibrinopeptide B