title: On-column electrochemical reactions accompanying the electrospray process.
abstract: It is well-established that electrochemical reactions can occur within the capillary of an electrospray (ES) devise coupled to a mass spectrometer. In fact, such reactions must occur to maintain charge balance during the ES process. However, electrochemical reactions occurring distal to the capillary as a result of the high potential applied to the capillary have not been thoroughly investigated. In the present communication, we show that electrochemical processes can occur on a high performance liquid chromatography (HPLC) column coupled to an ES capillary. On-column solvent electrolysis is proposed to generate free radicals, which can subsequently initiate analyte oxidation. Oxidation of steroid sulfates possessing a reactive double bond between C-5 and C-6 is demonstrated. The possibility of similar reactions occurring within peptides possessing a site of unsaturation is also considered.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: Suya
authors.initials: S
authors.lastname: Liu
authors.forename: William J
authors.initials: WJ
authors.lastname: Griffiths
authors.forename: Jan
authors.initials: J
authors.lastname: Sjövall
mesh_terms: D002788:Cholesterol Esters / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019314:Dehydroepiandrosterone Sulfate / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D004563:Electrochemistry; D006801:Humans; D009842:Oligopeptides / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D010084:Oxidation-Reduction; D013256:Steroids / Q000032:analysis* / Q000737:chemistry; D013431:Sulfates / Q000032:analysis
chemical_list: D002788:Cholesterol Esters; D009842:Oligopeptides; D013256:Steroids; D013431:Sulfates; D019314:Dehydroepiandrosterone Sulfate; C007045:cholesteryl sulfate