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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 Emily Braxton (13864461) David J. Fox (1909222) Ben Breeze (12369596) Joshua J. Tully (12975206) Katherine J. Levey (13864464) Mark E. Newton (1445038) Julie V. Macpherson (1517371) Electron paramagnetic resonance Electrochemistry Hydroxyl group Migrated from ePrints 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.<br><br>he file has been divided into two sections: 1 - Main Article Data Figure 1, Figure 2, Figure 3, Figure 4, Figure 5 and Figure 6 2 - Supporting Information Data Figure S1, Figure S2, Figure S3, Figure S4, Figure S5, Figure S6, Figure S8 and Figure S9 2022-10-07T00:00:00Z Dataset Dataset 10.82444/warw.33848521.v1 https://figshare.com/articles/dataset/Data_for_Electron_paramagnetic_resonance_for_the_detection_of_electrochemically_generated_hydroxyl_radicals_issues_associated_with_electrochemical_oxidation_of_the_spin_trap/33848521 CC BY-NC-ND 4.0