Poly-adenine decorated pencil graphite electrode for the electrochemical quantification of indigo carmine

This work presents a simple and effective method for detecting indigo carmine using voltammetric analysis by modifying a pencil graphite electrode with a polyadenine biopolymer layer. The developed sensor offers selective and sensitive detection of this common synthetic dye used in food and textile industries, while also being low-cost and environmentally friendly. A biopolymer-modified pencil graphite electrode was successfully used as the sensing platform, and measurements were carried out using differential pulse voltammetry. The morphological and structural characterisation of the modified electrode was done using techniques such as scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. The fabricated electrode provides good performance, with a sensitivity of 434 A/µM/cm2. The sensor also shows a low limit of detection of 0.003 µM and a limit of quantification of 0.01 µM. In addition, it demonstrates good stability and reproducibility, making it suitable for practical applications such as monitoring indigo carmine in food samples and industrial wastewater.