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Peptide mapping using capillary electrophoresis offline coupled to matrix‐assisted laser desorption ionization time of flight mass spectrometry
Author(s) -
Bachmann Stefan,
Bakry Rania,
Huck Christian W.,
Polato Fabio,
Corradini Danilo,
Bonn Günther K.
Publication year - 2011
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201000653
Subject(s) - capillary electrophoresis , chromatography , chemistry , capillary electrophoresis–mass spectrometry , mass spectrometry , capillary action , analyte , analytical chemistry (journal) , time of flight mass spectrometry , matrix (chemical analysis) , sample preparation , capillary electrochromatography , desorption , electrophoresis , ionization , electrospray ionization , materials science , ion , organic chemistry , adsorption , composite material
Abstract This article reports the results of a study carried out to evaluate the offline hyphenation of capillary zone electrophoresis with matrix‐assisted lased desorption ionization time of flight mass spectrometry (MALDI‐TOF‐MS) for the analysis of low‐abundant complex samples, represented by the tryptic phosphorylated peptides of phosphoproteins, such as α‐casein, β‐casein, and fetuin. The proposed method employs a latex‐coated capillary and consists in the online preconcentration of the tryptic peptides by a pH‐mediated stacking method, their separation by capillary zone electrophoresis, and subsequent deposition of the separated analytes onto a MALDI target for their MS analysis. The online preconcentration method allows loading a large sample volume (∼150 nL), which is introduced into the capillary after the hydrodynamic injection of a short plug of 1.0 M ammonium hydroxide solution and is sandwiched between two plugs of the acidic background electrolyte solution (BGE) filling the capillary. The sample spotting of the separated analytes onto the MALDI target is performed either during or postseparation using an automatic spotting device connected to the exit of the separation capillary. The proposed method allows the separation and identification of multiphosphorylated peptides from other peptides and enables their identification at femtomole level with improved efficiency compared with LC approaches hyphenated to MS.