Multivariate optimization of a novel electrode film architecture containing gold nanoparticle-decorated activated charcoal for voltammetric determination of levodopa levels in pre-therapeutic phase of Parkinson`s disease

•Activated charcoal (AC) is a low cost alternative material for electroanalysis.•A robust modified electrode is developed by immobilizing gold nanoparticle-decorated activated charcoal (AuNPs-AC) film.•A Doehlert matrix design experiment is used to optimize the electrode performance.•The AuNPs-AC based sensor presents enhanced response toward an antiparkinsonian drug sensing•The voltammetric method was successfully applied for levodopa determination in biological and environmental samples. Levodopa analysis is important to monitor progress of patients in Parkinson's disease, as well as to determine the treatment directions. In this way, the development of an electrochemical sensor based on a glassy carbon electrode modified with gold nanoparticles supported in activated charcoal with an epichlorohydrin-reticulated chitosan film was carried out under the assistance of a Doehlert matrix design experiment. The resulting electrode was subjected to a series of characterization techniques, including scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, for morphological analysis, as well as electrochemical impedance spectroscopy and cyclic voltammetry for electrochemical characterization. The active surface presented response for electrocatalytic oxidation of levodopa with high current response at reduced potential, which was applied, along with a square-wave adsorptive anodic stripping voltammetric methodology, for analysis of levodopa in different samples, presenting a three order of magnitude linear concentration range (50.0 nmol L−1 to 10.0 µmol L−1), low detection limit of 8.2 nmol L−1, good recovery analysis of spiked samples with low signal deviation under the presence of interfering species, and good accuracy front a comparative methodology. Schematic representation of experimental steps followed for determination of levodopa levels in pre-therapeutic phase of Parkinson`s disease by a square-wave adsorptive anodic stripping voltammetric method. [Display omitted]