The Hydroxyl Radical is a Critical Intermediate in the Voltammetric Detection of Hydrogen Peroxide

摘要

Cyclic voltammetry is a widely used and powerful tool for sensitively and selectively measuring hydrogen peroxide (H_2O_2). Herein, voltammetry was combined with electron paramagnetic resonance spectros-copy to identify and define the role of an oxygen-centered radical liberated during the oxidation of H_2O_2. The spin-trap reagents, 5, 5-dimethyl-1-pyrroline N-oxide (DMPO) and 2-ethoxycarbonyl-2-methyl-3, 4-dihydro-2H-pyrrole-1-oxide (EMPO), were employed. Spectra exhibit distinct hyperfine patterns that clearly identify the DMPO~*-OH and EMPO~*-OH adducts. Multiple linear regression analysis of voltammograms demonstrated that the hydroxyl radical is a principal contributor to the voltammetry of H_2O_2, as signal is attenuated when this species is trapped. These data incorporate a missing, fundamental element to our knowledge of the mechanisms that underlie H_2O_2 electrochemistry.