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Critical evaluation of potentiometric redox titration in enology

Comtat, Maurice and Durliat, H. Critical evaluation of potentiometric redox titration in enology. (2005) Analytica Chimica Acta, Vol. 545 (n°2). 173 -181 . ISSN 0003-2670

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Official URL: http://dx.doi.org/10.1016/j.aca.2005.04.084

Abstract

Measurements of the zero current potential of a platinum electrode immersed in solutions of tanins or in wines of various origins, were performed during the additions of a solution of Ti(III), or of a solution of dichlorophenolindophenol (DCPIP), in order to obtain a global indication for the resistance to oxidation of some wines. The steady state intensity–potential curves on a platinum electrode highlight the occurrence of mixed potentials between the oxidation of ethanol or catechin and the reduction of oxygen present at very low concentrations, as well as the irreversibility of the redox system Ti(IV)/Ti(III). The adsorption of various species on the platinum and the slowness of the oxidation reactions by DCPIP exclude use of potentiometric titration theory. The shape of the potential–reagent volume curves depends on the nature of the solution and on the rate of reagent introduction. Generally, due to the slowness of the oxidation reactions with DCPIP it is impossible to find a linear relationship between the volume of titrant solution necessary to reach the inflexion point of the curves and the solution composition.

Item Type:Article
Additional Information:This article is available at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-4G94HW2-7&_user=1072870&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=965294731&_rerunOrigin=google&_acct=C000043979&_version=1&_urlVersion=0&_userid=1072870&md5=bd1c785662fed0d510bd252bfc7ebc67
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Guylène Abadie
Deposited On:23 Jul 2009 14:59

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