title: Microchip electrospray: cone-jet stability analysis for water-acetonitrile and water-methanol mobile phases.
abstract: Changes in mobile phase composition during high performance liquid chromatography (HPLC) gradient elution coupled to mass spectrometry (MS) sensitively affect electrospray operation modes. In this work, we identify the influences of dynamic changes in bulk conductivity on the cone-jet stability island for aqueous acetonitrile and aqueous methanol mobile phases commonly used in reversed-phase HPLC. Bulk conductivities of the mobile phases were varied by adding different amounts of formic acid. A commercial microchip-HPLC/ESI-MS configuration was modified to enable in situ electrospray diagnostics by frequency analysis of the microchip emitter current and spray imaging. This approach facilitated the detection of different spray modes together with their onset potentials. The established spray modes are described and the differences in onset potentials and stability regions explained by the physicochemical properties of the electrosprayed liquid.
authors.affiliation: Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Jung
authors.forename: Uwe
authors.initials: U
authors.lastname: Effelsberg
authors.forename: Ulrich
authors.initials: U
authors.lastname: Tallarek
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D055598:Chemical Phenomena; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004553:Electric Conductivity; D000432:Methanol / Q000737:chemistry*; D046208:Microchip Analytical Procedures / Q000379:methods*; D008956:Models, Chemical; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014867:Water / Q000737:chemistry*
chemical_list: D000097:Acetonitriles; D014867:Water; D000432:Methanol; C032159:acetonitrile