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Oxidation of Flavonols in an Electrochemical Flow Cell Coupled Online with ESI‐MS
Author(s) -
Kummer Sina,
Ruth Wolfgang,
Kragl Udo
Publication year - 2016
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201501055
Subject(s) - flavonols , chemistry , myricetin , electrochemistry , redox , kaempferol , quercetin , cyclic voltammetry , electrospray ionization , mass spectrometry , antioxidant , inorganic chemistry , electrode , organic chemistry , chromatography
Flavonols, a class of flavonoids, are jointly responsible for antioxidant activities as free radical acceptors in flowers, fruits and vegetables. Due to their electroactive behaviour, the oxidation of chrysin, flavonol, kaempferol, morin, quercetin and myricetin in methanol was performed in an electrochemical flow cell with glassy carbon as the working electrode. This flow cell was coupled online with electrospray ionisation mass spectrometry to identify the possible oxidation products. Based on these experiments, it was concluded that when certain structural requirement are present, the initial electrode reaction of flavonols involves an electron delivery electrochemical step followed by a chemical step via methanol addition. The redox activity of the selected species explains the number of observed multiple methoxylation. Moreover, we identified a second two‐electron, two‐proton oxidation of the formed oxidation products of quercetin and myricetin for the first time.