Premium
DOPA and Adrenaline Oxidation Kinetics and Intermediates Identified by Electrospray Ionization Mass Spectrometry in Real Time
Author(s) -
Iftikhar Imran,
ElNour Kholoud Mohammed Abou,
BrajterToth Anna
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201701322
Subject(s) - chemistry , electrospray ionization , mass spectrometry , kinetics , electrochemistry , reactivity (psychology) , catechol , quinone , electrospray , photochemistry , redox , medicinal chemistry , chromatography , organic chemistry , electrode , medicine , physics , alternative medicine , quantum mechanics , pathology
Abstract DOPA and adrenaline (Adr) oxidation intermediates were identified using electrospray ionization mass spectrometry (ESI MS) by exploiting electrochemical oxidation reactions that occur during ESI. In addition, on‐line MS monitoring of the oxidations allowed evaluation of DOPA and Adr oxidation kinetics with approximately 3 ms time resolution. Kinetic information was confirmed by on‐line electrochemistry/ESI MS (EC/ESI MS). Application of an EC cell voltage in EC/ESI MS increased the oxidation rates and MS detection sensitivity of intermediates. During ESI and EC/ESI MS, oxidation rates were DOPA < Adr ≪ dopamine ( DA ) , cyclization rates of quinone oxidation products were Adr ≫ DOPA > DA , and cyclic leucochrome oxidation rates were DA>Adr>DOPA. Formation of radical semiquinones of Adr and DOPA through OH . radical‐initiated oxidation pathways was indicated, as reported for DA. Images of catecholamine oxidation pathways obtained with high time resolution, using MS, underscore the differences between the reactivity of DOPA, Adr, and DA.