Electrochemical Study of Carminic Acid Determination in Foodstuffs. Investigation of the Reaction Mechanism and Electrochemical Parameters

A new electrochemical sensor was designed to discriminate and determine Carminic Acid (CA) utilizing a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs). Using this electrode, CA showed an anodic peak at around 0.24 V. The mechanism of the electrochemical process on the surface of the modified electrode was analyzed by obtaining cyclic voltammograms at various potential scan rates. Different electrochemical parameters of present experiments were calculated such as charge transfer coefficient α as 0.46 and diffusion coefficient D as 3.25 × 10^–7 cm² s^–1. After studying the electrocatalytic behavior of the CA, differential-pulse voltammetry (DPV) was subsequently applied as a very sensitive electro-analytical method for the determination of sub-micromolar amounts of CA. Under the optimized conditions, the anodic peak current enhanced with the CA between 0.41 to 5.55 µM. The detection limit was calculated to be 0.24 µM (S/N = 3). The modified electrode was successfully applied for the accurate determination of minor amounts of CA in strawberry milk samples with adequate results.