Reevaluation of Quantitative ESR Spin Trapping Analysis of Hydroxyl Radical by Applying Sonolysis of Water as a Model System
Reevaluation of Quantitative ESR Spin Trapping Analysis of Hydroxyl Radical by Applying Sonolysis of Water as a Model System
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DOI：
10.1246/bcsj.20100078
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发表时间：
2010-09-15
影响因子：
4
通讯作者：
Kohno, Masahiro
中科院分区：
文献类型：
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作者：
Nakamura, Keisuke;Kanno, Taro;Kohno, Masahiro
使用5,5 - 二甲基 - 1 - 吡咯啉N - 氧化物（DMPO）的电子自旋共振（ESR）自旋捕集通常用于羟基自由基的定量分析。为了更好地理解该分析，我们研究了与DMPO的羟基自由基自旋加合物的形成和衰减相关的动力学，并与3,3,5,5 - 四甲基 - 1 - 吡咯啉N - 氧化物（M4PO）和5 - （二苯基膦酰基） - 5 - 甲基 - 1 - 吡咯啉N - 氧化物（DPPMPO）进行了比较。在我们通过水的超声分解产生羟基自由基的研究中，我们发现：（1）即使羟基自由基持续产生，DMPO - OH的形成也会达到饱和；（2）在停止超声照射后，DMPO - OH的浓度与时间成反比下降，这表明衰减是二级反应。在过氧化氢光解产生DMPO - OH的实验中也得到了类似的结果。除了DMPO之外，M4PO和DPPMPO也能捕获羟基自由基，但自旋捕集效率低于DMPO。此外，M4PO - OH和DPPMPO - OH比DMPO - OH衰减得更快。由此，我们得出结论，DMPO比M4PO和DPPMPO更适合用于羟基自由基的定量，但定量分析的结果必须考虑与DMPO - OH的形成和衰减相关的动力学来解释，特别是在大量羟基自由基产生的定量分析中。
Electron spin resonance (ESR) spin trapping using 5,5-dimethyl-l-pyrroline N-oxide (DMPO) is commonly applied for quantitative analysis of hydroxyl radical. For better understanding of the analysis, we investigated kinetics related to formation and decay of hydroxyl radical spin adduct of DMPO compared with that of 3,3,5,5-tetramethyl-l-pyrroline N-oxide (M4PO) and 5-(diphenylphosphinoy1)-5-methyl-l-pyrroline N-oxide (DPPMPO). In our study where hydroxyl radical was generated by sonolysis of water, we found that (1) DMPO-OH formation was saturated even though hydroxyl radical was generated continuously and (2) the concentration of DMPO-OH decreased in inverse proportion to time after cessation of ultrasound irradiation, suggesting that the decay is a second-order reaction. Similar results were obtained in an experiment of DMPO-OH generated by photolysis of H2O2. Other than DMPO, M4PO, and DPPMPO also trapped hydroxyl radical but the spin trap efficiency was less than that of DMPO. Furthermore, M4PO-OH and DPPMPO-OH decayed more quickly than DMPO-OH. From this, we conclude that DMPO is more suitable for quantification of hydroxyl radical than M4PO and DPPMPO but results from the quantitative analysis must be interpreted with consideration of the kinetics related to formation and decay of DMPO-OH, especially in quantification of large amount of hydroxyl radical generation.