Considerations in the spin trapping of superoxide and hydroxyl radicals in aqueous ystems using 5,5-dimethyl-l-pyrroline-l-oxide

SUMMARY: The superoxide radical spin adduct of the spin trap 5,5-dimethyl-l-mine-l-oxide was found to be relatively unstable in aqueous solution. The half-life of the electron spin resonance signal is approximately 80 set at pH 6 and only about 35 set at pH 8. These observations as well as the possible reaction products of 0 ' that may develop in the time course of an experiment, must be considered whe a planning or interpreting data from a spin trapping experiment. INTRODUCTION: The technique of spin trapping (1) has recently been applied to studies of free radicals in biological systems (2-6). Much of this increased interest results from studies on the role of the oxygen centered radicals 0; and *OH in biological systems. Our studies using the spin trap 5,5-dimethyl-l-pyrroline-l-oxide have revealed some potential limitations in the technica