Detection of vanillin in food products over Cu - laser induced graphene nanocomposite using the combined electrochemistry and UV–Vis spectroscopy principles

Vanillin is the fragrant phenolic compound widely used as a food additive. However, an excessive consumption of vanillin can have adverse effects on human health. Therefore, the development of a sensor for the rapid and precise measurement of vanillin is essential. In this study, vanillin is successfully measured using the UV–Vis spectroelectrochemical (SEC) method. The method uses the laser induced graphene (LIG)-supported Cu nanoparticles coated over an indium tin oxide (ITO) as the electrode. The precursor material for Cu-LIG is synthesized using the suspension polymerization of phenol and formaldehyde, with the in-situ inclusion of Cu during gel formation step. The resulting polymeric film is subjected to calcination, hydrogen-reduction, and laser ablation to create a conductive Cu-LIG layer. The synthesized material exhibits a high electrochemical surface area of 0.907 cm²/cm² and electrical conductance of 0.002 S, rendering it a suitable electrocatalyst for the oxidation of vanillin. The Cu-LIG/ITO electrode is used in detecting the oxidized species of vanillin at 370 nm-wavelength post two cyclic voltammetry (CV) cycles over 0–1.3 V potential. The sensor shows an excellent linear response (R² value ∼ 0.993) over the concentration range 0.25–40 μg/mL, with 0.14 μg/mL limit of detection. Owing to the anti-interference ability of the SEC sensor, the intensity of UV–Vis absorbance at 370 nm remains unaffected against common interferents including glucose, fructose, ascorbic acid, and uric acid found in real food substances. This study has clearly shown the advantages of the combined electrochemistry and UV–Vis spectroscopy principles in quantitatively detecting oxidizable compounds in commercial food products.