title: Methylene blue dye test for rapid qualitative detection of hydroxyl radicals formed in a Fenton's reaction aqueous solution.
abstract: A new procedure, the methylene blue dye test, qualitatively indicates the presence of hydroxyl radicals through the immediate, distinct bleaching of methylene blue dye on a paper test strip. This method employs a simple procedure requiring inexpensive materials, without the addition of competitive probe chemicals that potentially can interfere with the reaction. A Fenton's reaction with an Fe2+:H2O2 molar ratio of 1:20 generated hydroxyl radicals in Milli-Q water. The presence and absence of hydroxyl radicals were determined prior to and following quenching of the Fenton's reaction with 10% sodium sulfite, respectively. Bleaching of methylene blue dye, due to the presence of hydroxyl radicals in a sample,was indicated by a discoloration from a dark blue color to an almost white color, concentrated at the point of application, with a dark blue outline. A lack of bleaching indicated the absence of hydroxyl radicals in the sample. The presence of hydroxyl radicals was verified by benzoic acid chemical probe experiments with thin-layer chromatography (TLC) and spectrophotometric wavelength scans. The presence of hydroxyl radicals was indirectly determined by detection of hydroxylated benzoic acids on TLC plates and a violet solution color with a peak absorbance at a wavelength close to 520 nm.
authors.affiliation: Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Andrea Y
authors.initials: AY
authors.lastname: Satoh
authors.forename: James E
authors.initials: JE
authors.lastname: Trosko
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Masten
mesh_terms: D019817:Benzoic Acid / Q000737:chemistry; D002855:Chromatography, Thin Layer / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods; D006861:Hydrogen Peroxide / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry*; D013054:Spectrophotometry, Atomic
chemical_list: C045076:Fenton's reagent; D017665:Hydroxyl Radical; D019817:Benzoic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D008751:Methylene Blue