Distinguishing the 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-OH radical quenching effect from the hydroxyl radical scavenging effect in the ESR spin-trapping method

Linxiang Li, Yoshihiro Abe, Kiyotada Kanagawa, Noriko Usui, Kazuhiro Imai, Tadahiko Mashino, Masataka Mochizuki, Naoki Miyata

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The spin-trapping method has been widely accepted to measure the hydroxyl radical scavenging activity in electron spin resonance (ESR) spectroscopy, however, the disappearance of the trapped signal of the 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-OH radical may lead to an erroneous conclusion, as the decreased signal must result from the rapid quenching of the DMPO-OH formed. The DMPO-OH quenching activity of a compound can be measured by tracing the signal decay resulting from its addition after the cessation of DMPO-OH formation. It was found that Fe(II) ions could quench the DMPO-OH radical quite rapidly, and phosphate ions could enhance the DMPO-OH radical quenching activity of the Fe(II) ions.

Original languageEnglish
Pages (from-to)121-124
Number of pages4
JournalAnalytica Chimica Acta
Issue number1
Publication statusPublished - 2004 Jun 4



  • DMPO
  • ESR
  • Fenton reaction
  • Hydroxyl radical
  • Spin-trapping

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

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