Electron Spin Resonance Studies of Reactions of Photo-generated Organic Radicals with Hydrogen Peroxide in Aqueous Solution

1971 ◽  
Vol 49 (24) ◽  
pp. 4005-4016 ◽  
Author(s):  
C. E. Burchill ◽  
P. W. Jones
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Free Radicals ◽  
Electron Spin Resonance ◽  
Organic Radicals ◽  
Chain Reaction ◽  
Direct Photolysis ◽  
Ketyl Radical ◽  
Γ Radiation ◽  
Spin Resonance

The reactions with H2O2 of free radicals derived from 2-propanol, methanol, dimethoxymethane, and tetrahydrofuran have been investigated by e.s.r. using in-cavity photolysis with acetone photosensitization to generate the radicals in flowing aqueous solutions. The variation in the concentrations of the radicals derived from a particular solute with addition of H2O2 is attributed to the selective oxidation of one radical by H2O2, propagating a secondary chain reaction, e.g.,[Formula: see text]The rate constant for the oxidation of the acetone ketyl radical ((CH3)2ĊOH) by H2O2 is estimated to be 5 × 105 M−1 s−1.The results and conclusions of this study are demonstrated to be consistent with the results of previous investigations employing γ-radiation, photolysis, and the reaction of Ti(III) with H2O2 for initiation.Results are also reported for the direct photolysis of aqueous malonic acid in the presence of H2O2.

Free radicals in the reaction between t-butyl hydroperoxide and titanous ion: Some observations by electron spin resonance spectrometry

1965 ◽  
Vol 18 (8) ◽  
pp. 1177 ◽  
Author(s):  
MFR Mulcahy ◽  
JR Steven ◽  
JC Ward
Keyword(s):  
Aqueous Solution ◽  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Peroxy Radicals ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Butyl Hydroperoxide ◽  
Spin Resonance ◽  
G Value

The reaction between t-butyl hydroperoxide and titanous ion in aqueous solution produces free methyl radicals detectable by electron spin resonance spectrometry (Dixon and Norman). However, the presence of titanous ion in concentrations greater than 0.01M broadens the spectrum of the methyl radical, causing it effectively to disappear at titanous concentrations greater than 0.1M. At hydroperoxide concentrations above 0.25M t-butyl peroxy radicals (identified by a strong single-line spectrum with g-value 2.0136) are produced by the reaction ���������� R. + (CH3)3COOH → RH + (CH3)3COO. Their concentration reaches a maximum about 1 sec after the concentration of the methyl radicals has fallen to an undetectable value and their half-life (≈ 5 sec) is about ten times that of the methyl radicals.

scholarly journals Estimation of the Postmortem Duration of Mouse Tissue by Electron Spin Resonance Spectroscopy

2011 ◽  
Vol 2011 ◽  
pp. 1-11
Author(s):  
Shinobu Ito ◽  
Tomohisa Mori ◽  
Hideko Kanazawa ◽  
Toshiko Sawaguchi
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Trap ◽  
Detection Sensitivity ◽  
Mouse Tissue ◽  
Spin Adduct ◽  
Simple Method ◽  
Oxidation Stress ◽  
Spin Resonance

Electron spin resonance (ESR) method is a simple method for detecting various free radicals simultaneously and directly. However, ESR spin trap method is unsuited to analyze weak ESR signals in organs because of water-induced dielectric loss (WIDL). To minimize WIDL occurring in biotissues and to improve detection sensitivity to free radicals in tissues, ESR cuvette was modified and used with 5,5-dimethtyl-1-pyrroline N-oxide (DMPO). The tissue samples were mouse brain, hart, lung, liver, kidney, pancreas, muscle, skin, and whole blood, where various ESR spin adduct signals including DMPO-ascorbyl radical (AsA∗), DMPO-superoxide anion radical (OOH), and DMPO-hydrogen radical (H) signal were detected. Postmortem changes in DMPO-AsA∗and DMPO-OOH were observed in various tissues of mouse. The signal peak of spin adduct was monitored until the 205th day postmortem. DMPO-AsA∗in liver (y=113.8–40.7 log (day),R1=-0.779,R2=0.6,P<.001) was found to linearly decrease with the logarithm of postmortem duration days. Therefore, DMPO-AsA∗signal may be suitable for detecting an oxidation stress tracer from tissue in comparison with other spin adduct signal on ESR spin trap method.

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