Biopolymer Based Electrochemical Sensor for Ponceau 4R: An Insight into Electrochemical Kinetics

Utility of biopolymer [poly(L-Cysteine)] modified glassy carbon electrode for the determination of Ponceau 4R (P4R), a food colorant, was explored during the present study. On the probe [poly(L-Cys)/GCE], P4R behaved as perfectly reversible redox system with E-pa = 0.031 V and E-pc =-0.001 V (Delta E-p = 0.032 V). Significant decrease in the oxidation potential and remarkable increase in the current response of P4R on biopolymer modified GCE attests the excellent electron transfer capacity of the modified electrode towards the oxidation of P4R. Under optimal conditions, anodic peak current of P4R showed a linear behavior in the range 1.0 x 10(-5) to 1.0 x 10(-6) M, with minimum detectable concentration of 3.73 x 10(-8) M. Kinetic parameters viz., charge transfer coefficient (alpha) and heterogeneous rate constant (k(s)) have also been determined. Chronocoulometry was employed to calculate saturated adsorption capacity and diffusion coefficient (D) and values obtained were 5.54 x 10(-9) mol cm(-2) and 2.93 x 10(-6) cm(2) s(-1), respectively. Applicability of designed sensor was demonstrated in commercial soft drink samples. (C) 2018 The Electrochemical Society.