Natural deep eutectic solvent-supported exfoliated graphite nanoplatelet-based electrochemical sensor for the determination of tyramine in fermented beverages

Abstract

A novel electrochemical sensor was developed for the determination of tyramine. The sensor was constructed by modifying the surface of a glassy carbon electrode (GCE) with a film composed of exfoliated graphite nanoplatelets (xGnPs) dispersed in a natural deep eutectic solvent (NADES). The NADES was prepared by simply mixing equimolar amounts of caprylic acid and menthol and heating at 80 °C for 30minutes. Characterization studies confirmed the formation of a NADES through the attenuated total reflectance-Fourier transform infrared spectroscopy technique, while transmission electron microscopy demonstrated the ability of the NADES to disperse the xGnPs. Electrochemical impedance spectroscopy data showed that the modified sensor exhibited lower resistivity than the unmodified electrode. By optimizing the parameters of square wave voltammetry and experimental conditions to obtain the highest peak current values for tyramine oxidation, a calibration curve was constructed in a 0.1molL−1 phosphate buffer (pH 7.0), obtaining detection and quantification limits of 0.06 and 0.20mgL−1, respectively. Finally, the sensor was successfully applied to the determination of tyramine in fermented milk, beer, and non-alcoholic beer samples, with satisfactory recovery data.