title: Coumarin fluorometry to quantitatively detectable OH radicals in ultrasound aqueous medium.
abstract: When ultrasound (US) was exposed to aqueous coumarin solution in air atmosphere, the UV-visible and fluorescence spectra of the probe were measured at different US exposure times. The US exposure was carried out at 43 kHz and 500 kHz with different out-put power. It was found that the 500 kHz US produced umbelliferone fluorescence, while the 43 kHz US had no fluorescence. In addition, the coumarin absorbance at 270 nm maximum was decreased with in cases of the US exposure time. In contrary, the fluorescent intensity of umbelliferone at 460 nm increased with increasing of US exposure time. This exhibited that the coumarin probe was converted to umbelliferone by the US exposure, when the 500 kHz US was operated. This was facted that the coumarin framework was caused with addition of OH groups which was generated by the 500 kHz US. Therefore, the umbelliferone fluorescent became a probe to estimate OH radical in US medium. Furthermore, the chemo-fluorometry showed that the emission maximum of the formed umbelliferone could probe the bulk pHs in the US aqueous medium.
authors.affiliation: Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Hirano
authors.affiliation: Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan. Electronic address: takaomi@vos.nagaokaut.ac.jp.
authors.forename: Takaomi
authors.initials: T
authors.lastname: Kobayashi
mesh_terms: D003374:Coumarins / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000032:analysis*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D000069453:Ultrasonic Waves; D014468:Umbelliferones / Q000737:chemistry
chemical_list: D003374:Coumarins; D005456:Fluorescent Dyes; D014468:Umbelliferones; D017665:Hydroxyl Radical; C031477:7-hydroxycoumarin; C030123:coumarin
keywords: Chemo-fluorometry of the coumarin; Coumarin; Hydroxyl radical; Ultrasound; Ultrasound aqueous medium; Umbelliferone