Highly sensitive determination of Sunset Yellow in drink using a poly (l-cysteine) modified glassy carbon electrode

Abstract

A voltammetric sensor for Sunset Yellow was fabricated by polymerizing L-cysteine on the surface of a glassy carbon electrode. The modified electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behavior and kinetic parameters of Sunset Yellow in phosphate buffer solution (pH 6.6) were investigated by cyclic voltammetry and chronocoulometry using the proposed sensor, and results showed that the electrochemical response of Sunset Yellow was significantly improved. The peak current (differential pulse voltammetry) of Sunset Yellow linearly increased with the concentrations in the range of 8.0 × 10⁻⁹–7.0 × 10⁻⁷ mol L⁻¹, and the minimum detectable concentration of Sunset Yellow was estimated to be 4.0 × 10⁻⁹ mol L⁻¹. Moreover, the linear relationship between the peak current and the concentration of Sunset Yellow in the presence of Lemon Yellow was 1.0 × 10⁻⁸–5.0 × 10⁻⁷ mol L⁻¹, with a minimum detectable concentration of 6.0 × 10⁻⁹ mol L⁻¹. The reported electrochemical sensor was excellent for the determination of Sunset Yellow because of merits such as extreme simplicity, low cost, high sensitivity, good stability and reproducibility.