A review on recent electroanalytical methods for the analysis of COVID-19 drugs

Currently, there are no specific drugs for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, designated as coronavirus disease 2019 (COVID-19). Several therapeutic options including antiviral, antithrombotic, immunosuppressive, and anti-rheumatic drugs are researched all over the world. Analytical methods are needed in every step of innovation, research, development, and manufacturing process of pharmaceuticals, therefore new analytical methods for pharmaceuticals are developed and validated increasingly over time. In this review, recent reports on electroanalytical techniques for the determination of selected COVID-19 drugs, favipiravir (FAV), remdesivir (REM), lopinavir (LOP) / ritonavir (RIT), and hydroxychloroquine (HCQ) were emphasized. Electroanalysis of antiviral active pharmaceutical ingredients carried out at various modified or non-modified electrodes by cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) were compiled from the literature. The effects of supporting electrolyte and pH on the current and potential of the analytical signal were evaluated. Scan rate results obtained by the CV method showed whether the redox process of the drug active ingredient diffusion or adsorption controlled at the electrode used in the selected solvent-supporting electrolyte and pH systems. Linearity range and the limit of detection (LOD) of applied electroanalytical methods were compared by combining the results obtained from drug active ingredients given in references.