Electrochemical Analysis of Indigo Carmine in Food and Water Samples Using a Poly(Glutamic Acid) Layered Multi-walled Carbon Nanotube Paste Electrode

Some colourants are hazardous to living species; hence, a powerful and fast methodology is required for the analysis of those colourants in food and water samples. A modest electrochemically polymerised glutamic acid layered multi-walled carbon nanotube paste electrode [P(GA)LMWCNTPE] was functionalised for the sensing of indigo carmine (IC) by powerful differential pulse voltammetry (DPV) and cyclic voltammetry (CV) approaches. Within the optimised experimental conditions, the P(GA)LMWCNTPE holds an acceptable and high rate of electro-catalytic activity towards the redox behaviour of IC. The projected P(GA)LMWCNTPE shows a decent selectivity for IC in the presence of methyl orange. The modified sensor shows an acceptable linear growth between oxidative peak current and concentration in both CV and DPV methods with fine limit of detection values of 4.2 µM and 0.36 µM, respectively. Additionally, the developed sensor was effectively applied to detect IC in food and water samples. The morphological and surface activities of the modified and unmodified electrodes were determined through field emission scanning electron microscopy, electrochemical impedance spectroscopy, and CV techniques. The P(GA)LMWCNTPE requires a simple preparation procedure and is low-cost, with acceptable storage stability, sensitivity, and reproducibility.