A high sensitivity adsorptive-electrochemical method for rapid and portable determination of hydroxychloroquine

On March 11, 2020, the World Health Organization declared the coronavirus disease pandemic, caused by the SARS-CoV-2 virus. This declaration propelled the drug hydroxychloroquine into the global spotlight, as it was identified as a potential early treatment for the disease. Consequently, there was a surge in its consumption worldwide, particularly in Brazil. This increased usage has raised concerns about the potential contamination of natural water sources. In response to this concern, the present study proposes an electroanalytical method for detecting hydroxychloroquine in pharmaceutical and drinking water samples. The method aims to study the effects of modifying the sensor with carbon black Super P for HCQ detection, as well as improving the reproducibility and repeatability of the SPCB/GCE. The detection method and sensor modification have been thoroughly optimized for hydroxychloroquine detection. The optimal analysis conditions were established with a concentration of 5.0 mg mL⁻¹ of SPCB, a pH of 7.00, and a preconcentration time of 2 min. The detection and quantification limits were determined to be 0.0093 µmol L⁻¹ and 0.0312 µmol L⁻¹, respectively, with a linear range between 0.10 and 10.0 µmol L⁻¹. Analyses conducted on fortified samples indicated recovery responses of 110% for tap water and 100.5% for drug samples, demonstrating the method’s high accuracy, particularly for pharmaceutical samples.