Octacyanomolybdate-doped-poly(4-vinylpyridine) ionomer film electrode for the electrocatalytic oxidation of <Emphasis Type="SmallCaps">l</Emphasis>-ascorbic acid |
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Authors: | R Thangamuthu S M Senthilkumar K Chandrasekara Pillai |
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Institution: | (1) Department of Physical Chemistry, University of Madras, Guindy Campus, Chennai, 600 025, India;(2) Present address: Department of Chemical Engineering, National Yunlin University of Science and Technology, Yunlin, Taiwan, ROC |
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Abstract: | Poly(4-vinylpyridine) (PVP)-based anion exchange polymers are not studied as much as cation exchange polymers Nafion and Eastman
Kodak AQ for electroanalytical applications. Similarly, octacyanomolybdate Mo(CN)8
4−] has not been studied much as a redox mediator. This communication presents results from examinations of the behaviour of
Mo(CN)8
4−-doped PVP ionomer film electrode to highlight the opportunities for realization of the application of this composite electrode
for l-ascorbic acid (AH2) estimation via electrocatalytic mediation in acidic medium. The modified electrodes were characterized by cyclic voltammetry
and rotating disc electrode voltammetry. PVP coatings possess strong anion-binding capacity for Mo(CN)8
4− mediator with an extraction coefficient of 990, and electrostatically cross-linked PVP films offer insignificant resistance
to permeation of AH2, facilitating a cross-exchange reaction between the substrate and the mediator in the entire film volume. They show effective
electrocatalytic oxidation of AH2, with the oxidation potential of AH2 decreased by ∼200 mV in overpotential compared to that at bare electrode. Mo(CN)8
4−/PVP composite electrode does not respond to the more common interferents of l-ascorbic acid estimation even at high positive potentials. These and several other attractive potentialities of the modified
electrode are demonstrated by direct determination of AH2 in a commercial vitamin C tablet without any special treatment, with the value closely agreeing (±0.75%) with the reference
method. |
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Keywords: | Ionomer-modified electrode Poly(4-vinylpyridine) Mo(CN)8 3− /4− l-ascorbic acid" target="_blank">l-ascorbic acid Electrocatalytic oxidation |
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