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Generation of Hydrogen Radical in Water Irradiated by X-ray
https://repo.qst.go.jp/records/83244
https://repo.qst.go.jp/records/83244f501dc99-47c0-4239-9de3-c2e32a3f82da
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2021-05-14 | |||||
| タイトル | ||||||
| タイトル | Generation of Hydrogen Radical in Water Irradiated by X-ray | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Yusuke, Makino
× Yusuke, Makino× Megumi, Ueno× Yoshimi, Shoji× Ken-ichiro, Matsumoto× Ikuo, Nakanishi× Fukui, Koji× Yusuke, Makino× Megumi, Ueno× Yoshimi, Shoji× Kenichiro, Matsumoto× Ikuo, Nakanishi |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Local density of hydrogen radicals (•H) generated in water during X-ray irradiation to aqueous reaction mixtures were quantified by an electron paramagnetic resonance (EPR) spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin-trapping agent. During water radiolysis process (Eq. 1‒4), the •H could be generated by reaction of hydrated electron (e-aq) and hydrogen ions (H+), which were generated simultaneously with hydroxyl radical (•OH) from ionized water (H2O+). X-ray ~~> H2O → H2O+ + e-[1] e- + nH2O → e-aq[2] H2O+ → •OH + H+[3] H+ + e-aq → •H[4] Therefore, similar amount of •OH and •H should be expected, however, the G-values reported for •OH and •H are 0.28 and 0.06, respectively. To clarify what could make this difference of yields of •OH and •H, total amount and local densities of X-ray induced •OH and •H were compared. A concentration series of DMPO aqueous solutions (0.49 mM〜1700 mM) was prepared. The sample solutions were irradiated with 32 Gy of X-ray. Signal intensities of DMPO-OH and DMPO-H caused in the sample were measured by X-band EPR spectrometer. The decay of DMPO-OH and DMPO-H during irradiation was corrected and the net yield was observed [1]. The profiles observed by plotting concentrations of DMPO-OH and DMPO-H against the DMPO density (reciprocal of the intermolecular distance of DMPO) were analysed. When X-ray was irradiated to DMPO aqueous solutions under an aerobic condition, the profile of DMPO-OH generation showed 3-phase as reported previously [2], however; the profile of DMPO-H showed 2-phase. Both profiles observed for DMPO-OH and DMPO-H were almost overlapped except the DMPO-H lacked 3rd phase. Irradiation under hypoxic condition also showed similar results. The inflection point made by 1st and 2nd phases indicates relatively sparse (mmol/L-level) generation of the target radical. The yields of sparse generations of both •OH and •H were estimated as 200 mmol/L/Gy. Total yields of •OH and •H, which could be expected from end the plots, were 500 mmol/L/Gy or more for •OH and 200 mmol/L/Gy for •H. •H generation is available only from sparse ionization. References: [1] Matsumoto K, Ueno M, Shoji Y, Nakanishi I, Radiat. Biol. Res.Commun. 55, 303‒321 (2020). [2] Matsumoto K, Ueno M, Nakanishi I, Anzai K, Chem. Pharm. Bull.. 63, 195‒199 (2015). |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | ISMAR-APNMR-NMRSJ-SEST 2021 (a joint meeting of the 22nd International Society of Magnetic Resonance Conference, the 9th Asia-Pacific NMR Symposium, the 60th Annual Meeting of the Nuclear Magnetic Resonance Society of Japan (2021), and the 60th Annual Meeting of the Society of Electron Spin Science and Technology) | |||||
| 発表年月日 | ||||||
| 日付 | 2021-08-26 | |||||
| 日付タイプ | Issued | |||||
