Carbon based electrodes for the voltammetric determination of capsaicin in spicy samples

Abstract

A voltammetric sensor based on the modification of a screen-printed carbon electrode with reduced graphene oxide (rGO-SPCE) is presented for the cyclic voltammetric determination of capsaicin in a wide range of concentrations. Special attention was given to factors affecting sensitivity and repeatability in order to overcome common reported issues related to the voltammetric determination of capsaicin. Fouling associated to the adsorption of capsaicin was minimized using a simple and effective washing step, allowing sensors to be reused for at least 10 measurements with a repeatable signal. The developed rGO-SPCE presented two well-defined linear ranges (from 1.1 to 25.0 and from 25.0 to 150.3 µmol L−1) and provided an increased sensitivity as compared to the unmodified electrode as well as to other modified electrodes based on carbon nanomaterials commercially available. Furthermore, a low limit of detection of 0.3 µmol L−1 was achieved and the accuracy of the method was demonstrated for the determination of capsaicin in chilli pepper, paprika samples and Tabasco sauce, obtaining comparable results to those achieved by liquid chromatography with UV–vis detection.