Electronic tongue based on voltammetric electrodes modified with materials showing complementary electroactive properties.: Applications

An update of the work carried out by our group in the field of voltammetric sensors is presented. A simplified array formed by carbon paste electrodes (CPE) modified with three rare-earth bisphthalocyanines and three perylenes has been constructed. Chemical modifiers have been selected because of their complementary redox activity. Using square wave voltammetry, the array has provided a rich variety of voltammetric responses towards acids, bases, ionic solutions and antioxidants such as tannic acid or citric acid. This cross-selectivity is due to diffusion of ions inside the electrode to the sensitivity of the materials to protons and to the presence of oxidizing or reducing agents (i.e. perchlorate or tannins). The array of electrodes has been used to analyse white wines elaborated with different varieties of grapes. Principal component analysis conducted using Kernel functions demonstrated that the capability of discriminating white wines is similar to that observed in red wines. Loading plots confirm that the information provided by sensors modified with phthalocyanines and perylenes is highly complementary.