Spin trapping of hydroxyl in water: decay kinetics for the•OH and adducts to 5,5-dimethyl-1-pyrroline-N-oxide

A spin-trapping technique for distinguishing between free and bound hydroxyl radicals has been proposed in the literature. This technique relied upon observations of the steady-state concentrations of the spin-adducts of•OH and (from formate) to 5,5-dimethyl-1-pyrroline-N-oxide. In the present work, it is shown that the steady-state approach was only qualitatively correct. An alternative procedure is demonstrated which involves monitoring the growth of the spin-adducts after the start of radical generation. The latter approach is found to be quantitative.