Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OHads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

Symmetrical Derivative of Anthrone as a Novel Receptor for Mercury Ions: Enhanced Performance of Modified Screen-Printed Electrode

Voltammetric sensor using a symmetrical derivative of anthrone3 (1,7-diamino-3,9-dibutyl benzo[1,2,3-de:4,5,6-d’e’]diquinoline-2,8(3H,9H)-dione) (SPE-A) has been developed as a probe for Hg(II) ions. Performance of the probe as screen-printed electrode modified with the receptor (SPE-A) has been compared with anthrone3 in solution phase, using 1:1 water-acetonitrile solvent system. Anthrone3 displayed an electrochemically quasi-reversible nature in voltammograms with both the systems and is presented as a novel disposable voltammetric sensor for mercury ions. Upon interaction with cations, both the electrode systems showed sensitivity towards Hg2+ ions with a lower detection limit of 0.61 µM. The magnitude of the voltammetric current with the SPE-A exhibited three times the current obtained with a bare glassy carbon electrode (GC). Kinetic performance of the SPE-A electrode is better than the GC electrode. The morphological studies indicate reusability of the electrodes.

Adsorptive Stripping Voltammetric Determination of Chloramphenicol Residues in Milk Samples Using Reduced Graphene Oxide Sensor

In this paper, the electrochemical response of chloramphenicol (CHL) was investigated on a bare glassy carbon electrode (GCE) and after modification with reduced graphene oxide (GCE/rGO). Preliminary studies by cyclic...

Simultaneous detection of hydroquinone and catechol with decreasing pH at a bare glassy carbon electrode surface

Hydroquinone (HQ) and catechol (CC) are two isomers, which often coexist and interfere with each other during their identification in samples.

A fast, direct, and sensitive analysis method for catechin determination in green tea by batch injection analysis with multiple-pulse amperometry (BIA-MPA)

A bioactive compound was quantified on a bare glassy carbon electrode by BIA-MPA. This method is simple, fast, and cost effective.

Cysteine determination via adsorptive stripping voltammetry using a bare glassy carbon electrode

Determination of cysteine by adsorptive stripping voltammetry at a bare GCE in an acidic electrolyte medium in the presence of copper(ii) ions.

Voltammetric detection of glutathione: an adsorptive stripping voltammetry approach

High sensitive detection of glutathione in presence of copper(ii) ions by cyclic voltammetry using a bare glassy carbon electrode is presented.

Novel Electrochemical Synthesis of Polypyrrole/Ag Nanocomposite and Its Electrocatalytic Performance towards Hydrogen Peroxide Reduction

A simple electrochemical method of synthesis of polypyrrole/silver (PPy/Ag) nanocomposite is presented. The method is based on potentiodynamic polymerization of pyrrole followed by electrodeposition of silver employing a single potentiostatic pulse. The synthesized PPy film has embedded Ag nanocubes. The morphology and structure of the resulting nanocomposite were characterized by field emission scanning electron microscopy and X-ray diffraction. Electron paramagnetic resonance studies showed that silver nanoparticle deposition on polypyrrole leads to an increase in carrier density, indicative of enhanced conductivity of the resulting composite. Electrocatalytic performance of the prepared composite was examined for reduction of hydrogen peroxide and was compared with corresponding PPy film and bare glassy carbon electrode.