Nanocarbon Paste Electrodes

Comparative Electroanalytical Studies of Graphite Flake and Multilayer Graphene Paste Electrodes

In this paper, the fabrication, surface characterisation and electrochemical properties of graphite flake (GFPE) and multilayer graphene (MLGPE) paste electrodes are described. The Raman investigations and scanning electron microscopy were used to analyze and compare structure of both carbon materials. The electroanalytical performance of both electrodes was examined and compared on the basis of the square-wave and cyclic voltammetric behavior of acetaminophen and model redox systems. Results of those studies revealed that GFPE has a larger electroactive surface area and better conductive properties, whilst MLGPE demonstrate better analytical characteristic in case of acetaminophen (AC) determination. AC determination was developed using square wave voltammetry (SWV) and square wave stripping voltammetry (SWSV). For both working electrodes, the process of accumulation enabled us to obtain an extended linear range and to lower the detection limit. In pharmaceutical formulations, AC was determined with good recovery.

Carbon black as an outstanding and affordable nanomaterial for electrochemical (bio)sensor design

Advances in cutting-edge technologies including nanotechnology, microfluidics, electronic engineering, and material science have boosted a new era in the design of robust and sensitive biosensors. In recent years, carbon black has been re-discovered in the design of electrochemical (bio)sensors thanks to its interesting electroanalytical properties, absence of treatment requirement, cost-effectiveness (c.a. 1 €/Kg), and easiness in the preparation of stable dispersions. Herein, we present an overview of the literature on carbon black-based electrochemical (bio)sensors, highlighting current trends and possible challenges to this rapidly developing area, with a special focus on the fabrication of carbon black-based electrodes in the realisation of sensors and biosensors (e.g. enzymatic, immunosensors, and DNA-based).

A New Composite Electrode Applied for Studying the Electrochemistry of Insoluble Particles: α-HgS

The redox chemistry of solid α-HgS particles is revealed using a carbon/PVDF composite containing α-HgS, carbon black, polyvinylidene fluoride (PVDF). The electrochemical behaviour of the carbon/PVDF composite is first characterised with three water insoluble organic solids. Then the reduction of solid α-HgS particles is investigated and found to occur at a high negative potential, -1.82 V versus saturated mercury sulphate reference electrode, to form metallic mercury and sulphide ions. The subsequent oxidation of metallic mercury and sulphide occurs at +0.24 and -0.49 V versus MSE respectively.

Carbon Nanomaterials in Electrochemical Detection

This chapter overviews the use of carbon nanomaterials in the field of electroanalysis and considers why carbon-based nanomaterials are widely utilized and explores the current diverse range that is available to the practising electrochemist, which spans from carbon nanotubes to carbon nanohorns through to the recent significant attention given to graphene.

Absorptive stripping voltammetry for cannabis detection

BACKGROUND

Given that Δ(9)-tetrahydrocannabinol, the active constituent of cannabis, has been shown to greatly reduce driving ability, thus being linked to many drug driving accidents, its reliable detection is of great importance.

RESULTS

An optimised carbon paste electrode, fabricated from graphite powder and mineral oil, is utilised for the sensitive detection of Δ(9)-tetrahydrocannabinol (THC) in both aqueous solutions of pH 10.0 and in synthetic saliva solutions. "Absorptive Stripping Voltammetry" is exploited to that effect and the paste is used to pre-concentrate the carbon paste electrode with the target molecule. Practical limits of detection of 0.50 μM and 0.10 μM are determined for THC in stationary and stirred aqueous borate buffer solutions, respectively. Theoretical limits of detection are also calculated; values of 0.48 nM and 0.41 nM are determined for stationary and stirred THC aqueous borate buffer solutions, respectively. THC concentrations as low as 0.50 μM are detected in synthetic saliva solutions. The sensitivity of the sensor was 0.12 μA μM(-1), 0.84 μA μM(-1) and 0.067 μA μM(-1) for the stationary buffer, the stirred buffer and the saliva matrix, respectively.

CONCLUSIONS

"Absorptive Stripping Voltammetry" can be reliably applied to the detection of Δ(9)-tetrahydrocannabinol, after suitable optimisation of the assay. Usefully low practical limits of detection can be achieved.

Bifunctional redox tagging of carbon nanoparticles

Despite extensive work on the controlled surface modification of carbon with redox moieties, to date almost all available methodologies involve complex chemistry and are prone to the formation of polymerized multi-layer surface structures. Herein, the facile bifunctional redox tagging of carbon nanoparticles (diameter 27 nm) and its characterization is undertaken using the industrial dye Reactive Blue 2. The modification route is demonstrated to be via exceptionally strong physisorption. The modified carbon is found to exhibit both well-defined oxidative and reductive voltammetric redox features which are quantitatively interpreted. The method provides a generic approach to monolayer modifications of carbon and carbon nanoparticle surfaces.

Introducing absorptive stripping voltammetry: wide concentration range voltammetric phenol detection

“Absorptive stripping voltammetry”, a new electroanalytical method, is validated by phenol detection.