Modified Electrochemical Sensors for the Detection of Selected Food Azo Dyes: A Review

There are plenty of evidence that consuming high levels of azo dyes, such as Tartrazine, Sunset Yellow, Allura Red, Ponceau 4R, Amaranth, Sudan, and Azorubine, is associated with serious health problems. Therefore, electrochemical sensors have been developed for their effective detection, also offering low cost, portability, and the fact that they do not require harmful solvents. They are customarily employed in several electrochemical techniques, including cyclic voltammetry, differential pulse voltammetry, and square wave voltammetry. The most commonly employed materials in the manufacturing of electrochemical sensors are carbonaceous materials given their high stability, surface area, and conductivity. Employing these carbonaceous materials results in an enhanced sensitivity of electrochemical sensors when detecting azo dyes. To further improve the sensors, these materials are modified with metal oxides, polymers, polysaccharide, ionic liquids, and metal nanoparticles, allowing the detection of ultra-sensitive traces of azo dyes. Therefore, this review provides an overview of the characteristics of modified carbonaceous materials and their applications for the detection of food azo dyes, along with a summary of the currently employed electroanalytical detection methods. Additionally, this review discusses the development of novel nanomaterials and their technological advances, while exploring their potential environmental and health impacts within the food industry. A broad overview of carbon-based composite electrochemical sensors with metal oxides, polymers, metal complexes and metal-organic frameworks (MOFs), polysaccharides, ionic liquids, and metal nanoparticles, exploiting the conductivity, chemical stability, porosity, and functional groups present in these structures to provide enhanced current signals, then achieving submicromolar detection limits for azo food dyes.image