title: Chronocoulometry of wine on multi-walled carbon nanotube modified electrode: Antioxidant capacity assay.
abstract: Phenolic antioxidants of wine were electrochemically oxidized on multi-walled carbon nanotubes modified glassy carbon electrode (MWNT/GCE) in phosphate buffer solution. Three oxidation peaks were observed at 0.39, 0.61 and 0.83V for red dry wine and 0.39, 0.80 and 1.18 V for white dry wine, respectively, using differential pulse voltammetry at pH 4.0. The oxidation potentials for individual phenolic antioxidants confirmed the integral nature of the analytical signals for the wines examined. A one-step chronocoulometric method at 0.83 and 1.18 V for red and white wines, respectively, has been developed for the evaluation of wine antioxidant capacity (AOC). The AOC is expressed in gallic acid equivalents per 1L of wine. The AOC of white wine was significantly less than red wine (386 ± 112 vs. 1224 ± 184, p<0.0001), as might be expected. Positive correlations were observed between gallic acid equivalent AOC of wine and total antioxidant capacity, based on coulometric titration with electrogenerated bromine (r=0.8957 at n=5 and r=0.8986 at n=4 for red and white wines, respectively).
authors.affiliation: Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan Federal University, Kremlyevskaya 18, 420008 Kazan, Russian Federation. Electronic address: Ziyatdinovag@mail.ru.
authors.forename: Guzel
authors.initials: G
authors.lastname: Ziyatdinova
authors.affiliation: Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan Federal University, Kremlyevskaya 18, 420008 Kazan, Russian Federation.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Kozlova
authors.affiliation: Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan Federal University, Kremlyevskaya 18, 420008 Kazan, Russian Federation.
authors.forename: Herman
authors.initials: H
authors.lastname: Budnikov
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D004566:Electrodes; D005707:Gallic Acid / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010636:Phenols / Q000032:analysis; D014920:Wine / Q000032:analysis*
chemical_list: D000975:Antioxidants; D037742:Nanotubes, Carbon; D010636:Phenols; D005707:Gallic Acid
keywords: Antioxidant capacity; Carbon nanotubes; Chronocoulometry; Differential pulse voltammetry; Food analysis; Polyphenols; Wine