Adsorptive-Stripping Voltammetry at PEDOT-Modified Electrodes. Determination of Epicatechin

Abstract

The food industry has a direct interest to bitter-tasting substances, either for the identification of negative off-flavors or for the monitoring of organoleptic quality. Polyphenols (such as catechins and epicathechins) are among the main molecular components responsible for the bitter taste of coffee/cocoa/chocolate-based products. The electrochemical detection of epicatechin through adsorptive stripping voltammetry on poly(3,4-ethylenedioxythiophene)-modified Pt electrodes has been investigated. The accumulation conditions were defined in order to record repeatable and reproducible electrochemical signals. Calibration plots were built in the 0.2-2.5 ppm concentration range of epicatechin in phosphate buffer solutions, pH 7. Preliminary tests in aqueous extraction solutions of biscuits containing different percentages of cocoa were performed; they confirmed, in principle, the effectiveness of the device and of the procedure proposed for the epicatechin determination by simple extraction from complex food matrice

Electrochemistry of White Wine Polyphenols Using PEDOT Modified Electrodes

“…After a period of accumulation, the oxidation of the phenol then occurs as an example of adsorptive stripping voltammetry, with complete oxidation of the adsorbed phenolic compound, and with a current much higher than that obtained at glassy carbon electrodes. In that study, the current peak for epicatechin reached a maximum after 25 min of accumulation time, and showed a linear response for epicatechin concentrations up to 1.5 ppm (2.0 µA for c. 0.005 mM) using differential pulse voltammetry, with linearity lost beyond 2.5 ppm [19]. A similar accumulation period was found to provide maximum oxidation current in the present study for white wine phenols.…”

“…In that study, the current peak for epicatechin reached a maximum after 25 min of accumulation time, and showed a linear response for epicatechin concentrations up to 1.5 ppm (2.0 μA for c. 0.005 mM) using differential pulse voltammetry, with linearity lost beyond 2.5 ppm [19]. A similar accumulation period was found to provide maximum oxidation current in the present study for white wine phenols.…”

“…By contrast, with a 20 min holding time, the response to the 20-fold diluted wine was over 50% of that of the 5-fold diluted wine. The analysis of phenolics on PEDOT electrodes after an accumulation time has also been described for the case of epicatechin, as found in products such as biscuits containing cocoa [19]. After a period of accumulation, the oxidation of the phenol then occurs as an example of adsorptive stripping voltammetry, with complete oxidation of the adsorbed phenolic compound, and with a Figure 3.…”

“…The analysis of phenolics on PEDOT electrodes after an accumulation time has also been described for the case of epicatechin, as found in products such as biscuits containing cocoa [19]. After a period of accumulation, the oxidation of the phenol then occurs as an example of adsorptive stripping voltammetry, with complete oxidation of the adsorbed phenolic compound, and with a The analysis of phenolics on PEDOT electrodes after an accumulation time has also been described for the case of epicatechin, as found in products such as biscuits containing cocoa [19]. After a period of accumulation, the oxidation of the phenol then occurs as an example of adsorptive stripping voltammetry, with complete oxidation of the adsorbed phenolic compound, and with a current much higher than that obtained at glassy carbon electrodes.…”

Preparation of Poly(pyromellitic Dianhydride-Co-Thionin) Modified Voltammetric Sensor for the Determination of Epicatechin

“…In recent years, polymer coating on electrodes namely electrode modification methods has shown considerable potential for application in the field of sensors (24). The electrochemical detection of epicatechin through adsorptive stripping voltammetry on poly(3,4ethylenedioxythiophene)-modified Pt electrodes was investigated (25). The mechanism of electrochemical oxidation of epicatechin (EC) on a glassy carbon electrode was investigated over a wide range of conditions, using cyclic and square-wave voltammetry (26).…”