Nanoparticles based on carbon dots and reduced graphene oxide as electrochemical sensor for voltammetric determination of hydroxychloroquine

The hybrid material was obtained from the synthesis of graphene oxide (GO) followed by GO chemical reduction with L‐ascorbic acid. Then hydrothermal synthesis was carried out to form and grow carbon dots (CDs) on the surface of reduced graphene oxide (rGO). The material obtained, CD@rGO, was characterized by transmission electron microscopy (TEM), the infrared (FTIR), Raman and UV‐visible (UV‐Vis) spectroscopy, in addition to X‐ray diffractometry (XRD), spectroscopy and electrochemical methods. The results indicated the formation of carbon dots on the surface of rGO. The study of the voltammetric determination of hydroxychloroquine (HCQ) was performed using adsorptive stripping voltammetry (AdSV) and employing a modified electrode with CD@rGO (ECR). Optimizations were kept in the electrolytic environment and AdSV technique parameters, making it possible to obtain a LOD and LOQ of 2.40 and 7.99 pmol L −1 , respectively. The evaluation of the ECR electrochemical stability, repeatability and reproducibility tests were performed with maximum variations of up to 2.79 and 2.03 %, respectively. Determinations in commercial samples of HCQ (tablets) and synthetic urine, recovery in the range of 101.55–106.83 % were obtained.