TitleInvestigation of the presence of OH radicals in electrolyzed NaCl solution by electron spin resonance spectroscopy.
Publication TypeJournal Article
Year of Publication2005
AuthorsStan, SD, Woods, JS, Daeschel, MA
JournalJ Agric Food Chem
Volume53
Issue12
Pagination4901-5
Date Published2005 Jun 15
ISSN0021-8561
KeywordsDisinfectants, Electrolysis, Electron Spin Resonance Spectroscopy, Hydrogen Peroxide, Hydroxyl Radical, Sodium Chloride
Abstract

In the anode side of a two-chamber electrolyzer, electrolysis of a NaCl solution generates acidic electrolyzed oxidizing (EO) water, which exhibits bactericidal effects against a large number of pathogens. This study was undertaken to investigate whether OH radical species are present in EO water or are formed when EO water reacts with iron ions. Electron spin resonance spectroscopy (ESR) coupled with the spin trapping technique was used for the detection of free radicals. Samples of EO water were collected at 0.5, 1, 2, 3, and 5 min of electrolysis and immediately mixed with the spin trapping agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The 5,5-dimethyl-2-hydroxypyrrolidine-N-oxyl (DMPO-OH) spin adduct, characteristic of OH radicals, was not observed. Starting with 2-min electrolysis, a seven-line spectrum characteristic of 5,5-dimethyl-2-pyrrolidone-N-oxyl (DMPOX) was formed. The reactions of EO water with Fe3+ and Fe2+ in the presence of DMPO yielded the spin adduct DMPO-OH. However, the addition of OH radical scavengers (ethanol and methanol) did not generate the characteristic DMPO-alkyl spin adducts. This indicated that the DMPO-OH spectrum was due to a nucleophilic addition of water to DMPO and not to trapping of OH radicals.

DOI10.1021/jf047920b
Alternate JournalJ. Agric. Food Chem.
PubMed ID15941333
Grant ListP30ESO7033 / ES / NIEHS NIH HHS / United States