Stencil-printed graphene electrodes for affordable electrochemical sensing of capsaicin

[Display omitted] •Stencil printing provides competitive and reproducible electrochemical responses.•Great electrical and electrochemical properties with commercial graphene ink.•Compared to paper substrates, PVC offers better ink adherence and analytical signal.•Electrochemical measurements are conducted with only 80 µL of solution.•A cost-effective method for capsaicin determination in pepper extract and sauce. Disposable electrochemical sensors have gained popularity due to their low cost and manufacturing simplicity. Herein, electrochemical sensors were fabricated on different substrates using commercially available graphene ink. The substrates include watercolor paper (300 g/m2), kraft paper (300 g/m2), office paper (A4), polyvinyl chloride (PVC) and overhead sheets. The fabrication process involved the application of the conductive ink on a geometrically defined mask, generating a three-electrode electrochemical system. PVC plastic substrates provided better electrochemical performance to the devices and ink adhesion on this substrate. Such features were associated with each evaluated substrate’s morphologic aspects. The reproducibility of the manufacturing process was evaluated for five PVC devices, resulting in a relative standard deviation (RSD) of 9.2 % for [Ru(NH3)6]3+. Response repeatability was also tested for 10 consecutive measurements, yielding consistent electrochemical response with an RSD of only 2 %. The analytical performance of the resulting sensors was assessed for capsaicin (CAP) quantification, achieving limits of detection (LOD) and quantification (LOQ) of 0.10 and 0.31 µmol L−1, respectively. In addition, the proposed sensors showed competitive electrochemical performance compared to previously reported carbon electrodes, highlighting their feasibility for analytical applications with sample microvolumes, as demonstrated through analyses of pepper extract and sauce. Therefore, this work offers a promising alternative to fabricating affordable graphene electrodes for capsaicin electrochemical sensing in real samples.