Ultrasensitive and selective detection of indigo carmine in soft drink: A facile electrochemical approach based on Zr-MOF@MWCNTs nanocomposite

Abstract

Indigo carmine (IC), a widely used synthetic dye, possess significant risks to human health due to its high toxicity, carcinogenicity, teratogenicity, and mutagenicity. Given its widespread use in food, beverages, and pharmaceuticals, excessive IC exposure can lead to severe health issues, including allergic reactions, gastrointestinal disturbances, and potential carcinogenic effects. Therefore, stringent monitoring of IC content in food is essential to ensure public health and safety. In this study, we developed a novel electrochemical sensor for IC detection by synthesizing a nanocomposite of zirconium-based metal-organic frameworks (Zr-MOF) and multi-walled carbon nanotubes (MWCNTs). The Zr-MOF@MWCNTs composite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The sensor leverages the synergistic combination of the electrocatalytic properties of Zr-MOF and the superior conductivity of MWCNTs, demonstrating rapid response, excellent selectivity, high sensitivity (4.484 μA μM^-1 cm^-2), a broad detection range (0.005–30.0 μM), and a low limit of detection (LOD, 3.0 nM). The method showed good detection performance in both phosphate buffer solutions (PBS) and real beverage samples, achieving recoveries of 94.1 %–99.4 %. This study offers a promising approach for the rapid and accurate monitoring of IC in food products, contributing to improved food safety and public health.