Kinetic model for formation of DMPO-OH in water under ultrasonic irradiation using EPR spin trapping method

Masaki Kubo, Kazuhiro Sekiguchi, Naomi Shibasaki-Kitakawa, Toshikuni Yonemoto

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


The rate of the formation of the 2-hydroxy-5,5-dimethyl-1-pyrrolidinyloxy (DMPO-OH) radical in water during ultrasonic irradiation was evaluated both experimentally and theoretically. The hydroxyl radical (OH radical) was indirectly detected using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as the spin trapping compound, and the generated DMPO-OH by the reaction between the OH radical and DMPO was measured by an electron paramagnetic resonance. The rate of change in the concentration of the DMPO-OH decreased with time, suggesting that not only the formation reaction of DMPO-OH but also the degradation reaction would take place by ultrasonic irradiation. The formation rate of the DMPO-OH was higher with ultrasonic power intensity and lower with reaction temperature. Based on the experimental results, a kinetic model for the formation of the DMPO-OH was proposed by considering the formation reaction, the ultrasonic degradation, and spontaneous degradation of DMPO-OH. The model well described the effect of the ultrasonic power intensity and the reaction temperature on the formation rate of DMPO-OH. The rate of the formation of theDMPO-OH was evaluated with the aid of the kinetic model.

Original languageEnglish
Pages (from-to)2191-2204
Number of pages14
JournalResearch on Chemical Intermediates
Issue number9
Publication statusPublished - 2012 Nov


  • Electron paramagnetic resonance
  • Hydroxyl radical
  • Kinetic model
  • Spin trapping method
  • Ultrasonic irradiation


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