title: The development of a counterflow-assisted preconcentration technique in capillary electrophoresis electrospray-ionization mass spectrometry.
abstract: A preconcentration approach for CE-MS using counterflow-assisted electrokinetic injection was proposed. The proposed preconcentration method was based on a counterflow-compatible sheathless interface. The interface was fabricated using a capillary-assembled PDMS microdevice that allowed the application of a counterflow and provided liquid-film electrical conduction. During electrokinetic injection, a hydrodynamic counterflow was introduced into the separation capillary to retard the movement of the stacking boundary to the CE outlet. Accordingly, a long injection time was achieved without a loss of CE separation. With the use of reverse polarity mode and a dynamic polybrene-coated separation capillary (filled with a 1% formic acid solution), a counterflow-assisted electrokinetic injection of peptide samples (in a aqueous solution containing 1% ammonia and 50% methanol) for 10 min provided a sensitivity enhancement of 750-1480 and a detection limit of 20 pM for the five peptide standards. The proposed technique was applied to the analysis of low nanomolar concentrations myoglobin tryptic peptides.
authors: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors: Che-Wei
authors: CW
authors: Wang
authors: Guor-Rong
authors: GR
authors: Her
mesh_terms: D004129:Dimethylpolysiloxanes; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006863:Hydrogen-Ion Concentration; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation* / Q000379:methods
chemical_list: D004129:Dimethylpolysiloxanes; D010446:Peptide Fragments; C013830:baysilon
keywords: CE-MS; Counterflow; Poly(dimethylsiloxane); Preconcentration; Sheathless