Abstract
The pH dependence of the apparent rate constant kT
ap
for trapping by four nitrones was examined. In each case, kinetic curves were obtained after treatment of EPR spectra of the spin adduct formed using both singular value decomposition and pseudo-inverse deconvolution methods. Modelling these curves led to evaluate kT
ap
at various pH values. Analysis of the pH dependence of kT
ap
permitted the determination of the rate constants for the spin trapping of
and of
separately. Whatever the nitrone, our results clearly show that the EPR signals of the nitrone/superoxide spin adducts observed in aqueous media were essentially due to the trapping of the protonated species