Electrochemical detection and quantification of catechol based on a simple and sensitive poly(riboflavin) modified carbon nanotube paste electrode

Abstract

In the present research work, selective and sensitive catechol (CT) detection and quantification were shown in the presence of resorcinol (RS) in 0.2 M phosphate buffer (PB) solution by preparing a low-cost, simple, and green carbon nanotube paste electrode (CNTPE) surface activated with electropolymerized riboflavin (PRF). The morphological, conductivity, and electrochemical features of the modified electrode (PRFMCNTPE) and bare carbon nanotube paste electrode (BCNTPE) materials were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The PRF-activated electrode displays outstanding sensitivity, stability, selectivity, reproducibility, and repeatability for the redox feature of CT with improved electrochemical current and declined electrochemical potential compared to BCNTPE. The peak currents of CT are correlated to the different CT concentrations (CV method: 6.0-60.0 μM & DPV method: 0.5-7.0 μM), and the obtained detection limit (DL) and quantification limit (QL) are found to be 0.025 μM and 0.085 μM (CV method) and 0.0039 μM and 0.0132 μM (DPV method), respectively. The prepared PRFMCNTPE material was advantageous for the examination of CT in environmentally important tap water sample as a real-time application.

Keywords: Carbon nanotube paste electrode; Catechol; Electrochemical sensor; Poly(Riboflavin); Resorcinol; Voltammetry; Water sample analysis.

Graphical abstract

Fig. 1

FE-SEM images of (a) BCNTPE and (b) PRFMCNTPE.

Fig. 2

EIS plots for BCNTPE (curvature b) and PRFMCNTPE (curvature a).

Fig. 3

Cyclic voltammograms for 1.0 mM RF in PB solution (0.2 M & 6.0 pH) on BCNTPE at the scan rate of 0.1 V/s.

Fig. 4

(a) Cyclic voltammograms for the presence and absence (blank, curvature c) of CT in PB solution (0.2 M & 6.0 pH) on BCNTPE (curvature b) and PRFMCNTPE (curvature a) surfaces at the scan rate of 0.1 V/s. (b) Cyclic voltammograms for K₄[Fe(CN)₆] (1.0 mM) in KCl (0.1 M) on BCNTPE (curvature b) and PRFMCNTPE (curvature a) at the scan rate of 0.1 V/s.

Fig. 5

(a) Cyclic voltammograms for CT in PB solution (0.2 M & 6.0 pH) on PRFMCNTPE at variable scan rates ranging from 0.05 to 0.25 V/s. (b) The plot of I_pa v/s ʋ. (c) The plot of E_pa v/s log ʋ.

Scheme 1

The possible redox reaction mechanism of CT.

Fig. 6

(a) Cyclic voltammograms for CT in changed PB solution pHs (ranging from 5.5 to 8.0) at PRFMCNTPE at the scan rate of 0.1 V/s. (b) The plot of the pH v/s peak potential. (c) The plot of the pH v/s peak current.

Fig. 7

(a) Differential pulse voltammograms for CT and RS in PB solution (0.2 M & 6.0 pH) on PRFMCNTPE (curvature b) and BCNTPE (curvature a). (b) The plot of different interferents v/s % of signal change.

Fig. 8

(a) Cyclic voltammograms for different CT concentrations ranging from 2.0 to 60.0 μM in PB solution (0.2 M & 6.0 pH) on PRFMCNTPE at the scan rate of 0.1 V/s. (b) The plot of the concentration of CT v/s I_pa (CV). (c) Differential pulse voltammograms for different CT concentrations ranging from 0.5 to 7.0 μM in PB solution (0.2 M & 6.0 pH) on PRFMCNTPE. (d) The plot of the concentration of CT v/s I_pa (DPV).