title: Electrochemically initiated tagging of thiols using an electrospray ionization based liquid microjunction surface sampling probe two-electrode cell.
abstract: This paper reports on the conversion of a liquid microjunction surface sampling probe (LMJ-SSP) into a two-electrode electrochemical cell using a conductive sample surface and the probe as the two electrodes with an appropriate battery powered circuit. With this LMJ-SSP, two-electrode cell arrangement, tagging of analyte thiol functionalities (in this case peptide cysteine residues) with hydroquinone tags was initiated electrochemically using a hydroquinone-doped solution when the analyte either was initially in solution or was sampled from a surface. Efficient tagging (approximately 90%), at flow rates of 5-10 microL/min, could be achieved for up to at least two cysteines on a peptide. The high tagging efficiency observed was explained with a simple kinetic model. In general, the incorporation of a two-electrode electrochemical cell, or other multiple electrode arrangement, into the LMJ-SSP is expected to add to the versatility of this approach for surface sampling and ionization coupled with mass spectrometric detection.
authors.affiliation: Organic and Biological Mass Spectrometry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6131, USA. vanberkelgj@ornl.gov
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Van Berkel
authors.forename: Vilmos
authors.initials: V
authors.lastname: Kertesz