A Simple Electroanalytical Method for Detecting Carminic Acid in Foods through a Glassy Carbon Electrode Modified with Chitosan in the Presence of Allura Red

Abstract

In this report, a new method involving glassy carbon electrodes modified with chitosan (Cs) was tested for the detection of carminic acid (CA) in the presence of allure red by square wave voltammetry. The modified electrode (Cs/GCE) presented activity toward the oxidation of CA at potential values less than 0.3 V The signal is generated from the oxidation of carboxylic acid in the chemical structure of CA. Compared to that of the unmodified electrode, the anodic peak current of the Cs/CGE electrode increased by more than 500 %, and the oxidation potential shifted to a lower potential. This result indicates that the sensitivity increases and the energy to oxidize CA decreases with the Cs/GCE. The optimal parameters were pH 3.0 and PBS buffer, the square wave voltammetry with accumulation time was t_ACC 30 s, the accumulation potential was E_ACC 0.0 V, the oxidation signal was proportional to the concentration of CA between 0.99 and 10.90 μmol/L, and the detection limit was 0.20 μmol/L. The relative standard deviation (R.S. D) was 5.0 % using five different electrodes. The Cs/GCE was used for food samples spiked with CA with consistent results