Novel Electrodes Based on the Electropolymerized Nanocoatings for the Selective Voltammetric Quantification of Flavanones

Chemically modified electrodes are one of the most intensively developed areas in modern electroanalysis due to the appearance of a wide range of nanomaterials used as sensitive layers. One of the approaches for electrode surface modification is the coverage with the electropolymerized films based on phenolic compounds. Among a wide range of analytes, flavanones – flavonoids of Citrus fruits are less investigated in comparison to other natural phenolics and almost out of consideration in electroanalysis. The major natural flavanones are naringin and hesperidin which control in the real samples is required due to the possible prooxidant effect. Novel electrodes based on a layer-by-layer combination of carbon nanotubes and electropolymerized ellagic acid or aluminon were developed for the direct quantification of naringin and hesperidin. Conditions of monomers' potentiodynamic electropolymerization were optimized. SEM and electrochemical methods were used for the electrode surface characterization . The parameters of flavanones electrooxidation on the modified electrodes were found. A glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes and electropolymerized ellagic acid was developed for selective naringin determination. Simultaneous voltammetric quantification of naringin and hesperidin was shown for the first time using GCE modified with polyaminobenzene sulfonic acid functionalized single-walled carbon nanotubes and polyaluminon. The analytical characteristics obtained were significantly improved in comparison to other methods including electrochemical approaches. High selectivity of the electrodes’ response to flavanones in the presence of typical interferences and structurally related compounds was confirmed. The approaches developed were successfully applied for the analysis of citrus juices and a good agreement with the independent methods was shown. Thus, the novel highly sensitive and selective voltammetric methods for the direct flavanone quantification characterized by the simplicity of electrode fabrication, reliability, cost-efficiency can be applied for routine analysis as an alternative to chromatographic methods.