Voltammetric sensor based on carboxylated carbon nanotubes and poly(pyrogallol red) for determination of eugenol in essential oils

A voltammetric sensor based on a glassy cardon electrode with a layer-by-layer combination of carboxylated multi-walled carbon nanotubes and electropolymerized pyrogallol red has been developed for the determination of eugenol in essential oils. Optimal conditions for the preparation of poly(pyrogallol red) film in potentiodynamic mode in neutral medium were found to provide the best voltammetric response of eugenol. The electrode was characterized using scanning electron microscopy and a suite of electrochemical methods. A significant improvement in the voltammetric characteristics of eugenol on the polymer-modified electrode was shown. The parameters of eugenol electrooxidation were calculated and it was shown that the reaction proceeds with the formation of o-quinone. Under the conditions of differential-pulse voltammetry in Britton-Robinson buffer with pH 2.0, the range of detectable eugenol content is 0.75-100 μM with a detection limit of 0.73 μM. High selectivity of eugenol determination in the presence of inorganic ions and typical phenolic and terpene components of essential oils was shown. The approach was successfully tested on eugenol-containing essential oils and compared with an independent method.