Investigation of formation of superoxide anion radical in DMSO by ESR: Part 1. Influence of Fe2+ and Cu2+

The superoxide anion radical O-2(-.) can be produced by reactions between d issolved oxygen, DMSO and NaOH. The analysis of DMSO of chemical purity gra de showed that there are some ionic impurities such as Fe, Cu and Zn. A sys tematic study, by electron spin resonance, of the variation of the intensit y of the O-2(-.) radical as a function of the ion contents in DMSO showed t hat the amount of superoxide anion radical produced depends on the Fe2+ and Cu2+ contents in DMSO, but is independent of Zn2+ content. The presence of both Fe2+ and Cu2+ in a certain concentration range greatly favors radical formation. The mechanism of O-2(-.) generation in the presence of Fe2+ and Cu2+ in DMSO is discussed. Copyright (C) 2001 John Wiley & Sons, Ltd.