title: Merits of online electrochemistry liquid sample desorption electrospray ionization mass spectrometry (EC/LS DESI MS).
abstract: A new online electrochemistry/liquid sample desorption electrospray ionization mass spectrometry (EC/LS DESI MS) system with a simple electrochemical thin-layer flow-through cell was developed and tested using N,N-dimethyl-p-phenylenediamine (DMPA) as a model probe. Although oxidation of DMPA is observed as a result of ionization of LS in positive ion mode LS DESI, application of voltage to the online electrochemical (EC) cell in EC/LS DESI MS increases yields of oxidation products. An advantage of LS DESI MS is its sensitivity in aqueous electrolyte solutions, which improves efficiency of electrochemical reactions in EC/LS DESI MS. In highly conductive low pH aqueous buffer solutions, oxidation efficiency is close to 100%. EC/ESI MS typically requires mixed aqueous/organic solvents and low electrolyte concentrations for efficient ionization in MS, limiting efficiency of electrochemistry online with MS. Independently, the results verify higher electrochemical oxidation efficiency during positive mode ESI than during LS DESI.
authors.affiliation: Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA.
authors.forename: Wen Donq
authors.initials: WD
authors.lastname: Looi
authors.affiliation: Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA.
authors.forename: Blake
authors.initials: B
authors.lastname: Brown
authors.affiliation: Faculty of Chemistry, University of Strasbourg, 1 Rue Blasie Pascal, 67008, Strasbourg, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Chamand
authors.affiliation: Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA. atoth@chem.ufl.edu.
authors.forename: Anna
authors.initials: A
authors.lastname: Brajter-Toth
keywords: Aqueous electrolyte sample solutions; Electrochemistry; Liquid sample desorption electrospray ionization; Mass spectrometry; N,N-Dimethyl-p-phenylenediamine