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Data for Electron paramagnetic resonance for the detection of electrochemically generated hydroxyl radicals : issues associated with electrochemical oxidation of the spin trap
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Braxton, Emily, Fox, David J., Breeze, Ben, Tully, Joshua J., Levey, Katherine J., Newton, Mark E. and Macpherson, Julie V. (2022) Data for Electron paramagnetic resonance for the detection of electrochemically generated hydroxyl radicals : issues associated with electrochemical oxidation of the spin trap. [Dataset]
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README.txt - Published Version Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0. Download (4Kb) |
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WRAP DMPO EPR paper.zip - Published Version Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0. Download (6Mb) |
Official URL: http://wrap.warwick.ac.uk/168380/
Abstract
For the detection of electrochemically produced hydroxyl radicals (HO·) from the oxidation of water on a boron-doped diamond (BDD) electrode, electron paramagnetic resonance spectroscopy (EPR) in combination with spin trap labels is a popular technique. Here, we show that quantification of the concentration of HO· from water oxidation via spin trap electrochemical (EC)-EPR is problematic. This is primarily due to the spin trap oxidizing at potentials less positive than water, resulting in the same spin trap-OH· adduct as formed from the solution reaction of OH· with the spin trap. We illustrate this through consideration of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap for OH·. DMPO oxidation on a BDD electrode in an acidic aqueous solution occurs at a peak current potential of +1.90 V vs SCE; the current for water oxidation starts to rise rapidly at ca. +2.3 V vs SCE. EC-EPR spectra show signatures due to the spin trap adduct (DMPO-OH·) at potentials lower than that predicted thermodynamically (for water/HO·) and in the region for DMPO oxidation. Increasing the potential into the water oxidation region, surprisingly, shows a lower DMPO-OH· concentration than when the potential is in the DMPO oxidation region. This behavior is attributed to further oxidation of DMPO-OH·, production of fouling products on the electrode surface, and bubble formation. Radical scavengers (ethanol) and other spin traps, here N-tert-butyl-α-phenylnitrone, α-(4-pyridyl N-oxide)-N-tert-butylnitrone, and 2-methyl-2-nitrosopropane dimer, also show electrochemical oxidation signals less positive than that of water on a BDD electrode. Such behavior also complicates their use for the intended application.
Item Type: | Dataset | ||||||||||||||||||
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Subjects: | Q Science > QC Physics Q Science > QD Chemistry |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||||||||||||||||
Library of Congress Subject Headings (LCSH): | Electron paramagnetic resonance, Electrochemistry, Hydroxyl group | ||||||||||||||||||
Publisher: | University of Warwick, Department of Chemistry | ||||||||||||||||||
Official Date: | 7 October 2022 | ||||||||||||||||||
Dates: |
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Status: | Not Peer Reviewed | ||||||||||||||||||
Publication Status: | Published | ||||||||||||||||||
Media of Output (format): | .txt, .opd | ||||||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | ||||||||||||||||||
Copyright Holders: | University of Warwick | ||||||||||||||||||
Description: | he file has been divided into two sections: 1 - Main Article Data |
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Date of first compliant deposit: | 3 October 2022 | ||||||||||||||||||
Date of first compliant Open Access: | 7 October 2022 | ||||||||||||||||||
RIOXX Funder/Project Grant: |
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