Detection of sunset yellow by adsorption voltammetry at glassy carbon electrode modified with chitosan

The simple modification of the surface of a glassy carbon electrode with chitosan (CS) allowed the development of a electroanalytical method useful for the detection and quantification of sunset yellow (SY-E110) by square wave adsorption voltammetry (SWAdV). The electrode surface was characterized with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results showed that the presence of CS on the surface of the electrode, allowed the oxidation of the SY to 1.01 V in a process controlled by adsorption. Under optimal conditions (pH 2.5, t_ADS 60s, E_ADS 0.10 V) the anodic peak current was proportional to the concentration of SY between 0.25 to 3.25 μmol L^-1, with a limit of detection of 0.098 μmol L^-1. The relative standard deviation (RSD) for a solution with 0.080 mmol L^-1 of E110 was 2.5% for five different electrodes (n=5). The method was validated with unflavored gelatin samples spiked with known amounts of SY. The potential interferences of other synthetic dyes were studied and finally the method was tested with real samples of foods containing SY and other synthetic dyes. The results were equally acceptable compared to previous reports.