title: Highly selective colorimetric and electrochemical sensing of iron (III) using Nile red functionalized graphene film.
abstract: We report a highly selective method for identification and detection of iron (III) (ferric iron, Fe3+) using Nile red (NR) as a complexing agent. Fe3+preferentially binds with NR in dimethylformamide (DMF)/water (1:1) solution over other cations such as Fe2+, Cu2+, Pb2+, Hg2+, Mn2+, Ni2+, Zn2+, Co2+and Cd2+at room temperature. In the presence of Fe3+, the color of NR solution changes from purple to dark brown, which is detectable with bare eyes. Using UV-vis spectroscopy, we could measure the amount of Fe3+in the sample solution by monitoring changes in absorption from 540 to 580nm; the linear range and the limit of detection are 30-1000µM and 24.9µM, respectively. Taking advantage of the NR selectivity, we treated partially oxidized graphene sheets (po-Gr) with NR to obtain po-Gr-NR dispersion by ultrasonication. The NR-treated po-Gr flakes (po-Gr-NR) were characterized by UV-vis, FT-IR, and Raman spectroscopies and FE-SEM, which indicated attachment of NR on po-Gr sheets. The po-Gr-NR hybrid film deposited glassy carbon electrode (po-Gr-NR/GCE) served as the Fe3+sensor. Differential pulse voltammetry was used to investigate the detection of Fe3+in 0.05M HCl+0.05M KCl solution. The linear range and the limit of detection of Fe3+were from 37.5nM to 21.53µM and 18.7nM, respectively. Furthermore, this sensor was successfully used to measure Fe3+content in red wine samples.
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI 53706, United States.
authors.forename: Omer
authors.initials: O
authors.lastname: Sadak
authors.affiliation: Department of Biological Systems Engineering, University of Wisconsin-Madison, 460Henry Mall, Madison, WI 53706, Unites States. Electronic address: ashok.sundramoorthy@wisc.edu.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Sundramoorthy
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI 53706, United States; Department of Biological Systems Engineering, University of Wisconsin-Madison, 460Henry Mall, Madison, WI 53706, Unites States. Electronic address: guna@wisc.edu.
authors.forename: Sundaram
authors.initials: S
authors.lastname: Gunasekaran
mesh_terms: D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005290:Ferric Compounds / Q000032:analysis*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D007501:Iron / Q000032:analysis; D057230:Limit of Detection; D053761:Nanocomposites / Q000737:chemistry / Q000648:ultrastructure; D010078:Oxazines / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D005290:Ferric Compounds; D005456:Fluorescent Dyes; D010078:Oxazines; D006108:Graphite; D007501:Iron; C044808:nile red
keywords: Electrochemical sensor; Ferric iron; Nile red; Oxidized graphene; Visual detection; Wine