The application of multi-walled carbon nanotubes modified pencil graphite electrode for voltammetric determination of favipiravir used in COVID-19 treatment

Abstract

This study describes the first application of an improved procedure on a pencil graphite electrode decorated with functionalized multi-walled carbon nanotubes (f-MWCNTs/PGE) for the determination of the COVID-19 antiviral drug, favipiravir (FVP). The electrochemical behavior of FVP at f-MWCNTs/PGE was examined by cyclic voltammetry and differential pulse voltammetry (DPV) methods, and it was noted that the voltammetric response significantly increased with the modification of f -MWCNTs to the surface. The linear range and limit of detection from DPV studies were determined as 1-1500 µM and 0.27 µM, respectively. In addition, the selectivity of the method was tested toward potential interferences, which can be present in pharmaceutical and biological samples, and it was found that f-MWCNTs/PGE showed high selectivity for the determination of FVP in the presence of probable interferences. The results with high accuracies and precisions from the obtained feasibility studies also revealed that the designed procedure can be used for accurate and selective voltammetric determination of FVP in real samples.

Keywords: Electrochemistry; Favipiravir; Functionalized multi-walled carbon nanotubes; Sensors voltammetry.

Fig. 1

A CVs of 5.0 mM Fe(CN)₆^3−/4− + 0.1 M KCl solution recorded at PGE and f-MWCNTs/PGE (scan rate: 50 mV/s and potential range: −500 mV  -  1200 mV) and B EI curves (frequency range: 100,000–0.10 Hz and inset is circuit model, WE: working electrode, R_s: ohmic resistance, C: double layer capacitance, W: Warburg impedance, SEM images (100 nm × 30,000) recorded at C PGE, and D f-MWCNTs/PGE

Fig. 2

A CVs recorded for 0 mM (a, b) and 4.0 mM (c,d) FVP at PGE (a, c) and f-MWCNTs/PGE (b, d) (potential range: + 600 mV - 1500 mV and scan rate: 50 mV/s) and (B) recorded DPVs for pH 6 BRBS solution containing 0 µM (a, b) and 100 µM FVP (c, d) at PGE (a, c) and f-MWCNTs/PGE (b, d) (potential range: + 600 mV   ±   1300 mV; scan rate: 50 mV/s; E_Step: 5 mV and E_Amp: 10 mV)

Fig. 3

A CVs of 4.0 mM FVP at f-MWCNTs/PGE recorded in pH 3–8 BRBS solutions (potential scan range: + 600 - 1500 mV and scan rate: 50 mV/s), the plots of B pH–I_a and C pH–E_a generated from recorded CVs

Fig. 4

A Recorded CVs (potential scanning range: + 600 - + 1500 mV; red curve belongs to supporting electrolyte) of pH 6 BRBS containing 4.0 mM FVP at f-MWCNTs/PGE at various scan rates (20, 30, 40, 50, 75, 100, 200, 300, 400, 500, and 600 mV/s), B I(µA)–v^1/2, C LogI–Logv and D E_a–lnv plots generated from the recorded CVs

Fig. 5

DPVs recorded for increasing concentrations of FVP at optimized conditions at A PGE and B f-MWCNTs/PGE, the calibration plots for C PGE and D f-MWCNTs/PGE (red curves belongs to supporting electrolyte, n = 3)