A novel nanostructured poly(thionine)-deep eutectic solvent/CuO nanoparticle film-modified disposable pencil graphite electrode for determination of acetaminophen in the presence of ascorbic acid.

A new electrochemical sensor based on thionine (TH), an electroactive polymer, and CuO nanoparticle (CuONP)-modified pencil graphite electrode (PGE) has been developed. Poly(thionine) (PTH) was formed on the CuO/PGE surface by electropolymerisation in ethaline deep eutectic solvent (DES) containing acetic acid dopant to form PTHEthaline/CuO/PGE. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry were utilized to evaluate the fabrication process, electrochemical properties, and performance parameters of the modified electrodes. The analytical performance of the PTHEthaline/CuO/PGE was evaluated with respect to linear range, limit of detection, repeatability, and reproducibility for the detection of acetaminophen (APAP) by electrooxidation in the presence of ascorbic acid (AA). Analytical parameters such as pH were optimized. The combined use of PTH and CuONP led to enhanced performance towards APAP due to the large electroactive surface area and synergistic catalytic effect, with a wide linear working range and low detection limit. The reliability of the proposed sensor for the detection of APAP was successfully tested in pharmaceutical samples containing APAP and AA, with very good recoveries. Graphical abstract.