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

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.

Electrocatalytic Determination of Hydroxychloroquine Using Sodium Dodecyl Sulphate Modified Carbon Nanotube Paste Electrode.

Selective, sensitive, easy, and fast voltammetric techniques were developed for the analysis of Hydroxychloroquine (HCQ). These analysis were carried out at sodium dodecyl sulphate modified carbon nanotube paste electrode (SDSMCNTPE) using an aqueous 0.2 M phosphate buffer solution as supporting electrolyte. The field emission-scanning electron microscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy were used for material characterization. A minute quantity of the SDS surfactant was sufficient to convey an outstanding electrocatalytic action to the electrochemical oxidation nature of HCQ. The HCQ molecule parades only electrochemical oxidation (irreversible) with the transfer of two electrons. The detection of HCQ was carried out through CV method at SDSMCNTPE and bare carbon nanotube paste electrode (BCNTPE). The corresponding analytical curve offered a decent linear nature in the considered HCQ concentration range (10-40 µM) and the detection limit was found to be 0.85 µM. The significant peak to peak split-up was observed between HCQ and interferents with a decent sensitivity and stability. The SDSMCNTPE to be an approachable electrode for the usage in the examination of HCQ independently and in the presence of paracetamol (PC) and ascorbic acid (AA). Thus, they were used to determine HCQ in pharmaceutical formulations and the results that showed good agreement with comparative methods. Furthermore, a mechanism for HCQ electro-oxidation was proposed.

Electro-oxidation of formoterol fumarate on the surface of novel poly(thiazole yellow-G) layered multi-walled carbon nanotube paste electrode.

The current study explicates the electro-oxidation behavior of formoterol fumarate (FLFT) in the presence of uric acid (UA) on the surface of poly thiazole yellow-G (TY-G) layered multi-walled carbon nanotube paste electrode (MWCNTPE). The modified (Poly(TY-G)LMWCNTPE) and unmodified (MWCNTPE) electrode materials were characterized through electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), and cyclic voltammetry (CV) approaches. The characterization data confirms the good conducting and electrocatalytic nature with more electrochemical active sites on the Poly(TY-G)LMWCNTPE than MWCNTPE towards the FLFT analysis in the presence of UA. Poly(TY-G)LMWCNTPE easily separates the two drugs (FLFT and UA) even though they both have nearer oxidation peak potential. The electro-catalytic activity of the developed electrode is fast and clear for FLFT electro-oxidation in 0.2 M phosphate buffer (PB) of pH 6.5. The Poly(TY-G)LMWCNTPE offered a well-resolved peak with the highest electro-oxidation peak current at the peak potential of 0.538 V than MWCNTPE. The potential scan rate and oxidation peak growth time studies show the electrode reaction towards FLFT electro-oxidation is continued through a diffusion-controlled step. The variation of concentration of FLFT in the range from 0.2 to 1.5 µM (absence of UA) and 3.0 to 8.0 µM (presence of UA) provides a good linear relationship with increased peak current and a lower limit of detection (LOD) values of 0.0128 µM and 0.0129 µM, respectively. The prepared electrode gives a fine recovery for the detection of FLFT in the medicinal sample with acceptable repeatability, stability, and reproducibility.