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

The superoxide anion radical O2−. can be produced by reactions between dissolved oxygen, DMSO and NaOH. The analysis of DMSO of chemical purity grade showed that there are some ionic impurities such as Fe, Cu and Zn. A systematic study, by electron spin resonance, of the variation of the intensity of the O2−. radical as a function of the ion contents in DMSO showed that 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 O2−. generation in the presence of Fe2+ and Cu2+in DMSO is discussed. Copyright © 2001 John Wiley & Sons, Ltd.