Simultaneous Adsorptive Stripping Voltammetric Analysis of Heavy Metals at Graphenated Cupferron Pencil Rods

Electroanalysis of heavy metal ions in the presence of cupferron ligands has been extensively studied due to its ability to form stable metallic coordination complexes. Herein, electrochemically reduced graphene oxide (ERGO) sheets were for the first time employed in conjunction with low-cost, disposable pencil graphite rods and in-situ plated thin mercury films (HgF) for the simultaneous detection of Cd2+, Cu2+, Pb2+, and Zn2+ in the presence of cupferron as a chelating agent by square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV). The technique is based on the catalytic reduction of adsorbed cupferron-metal ion complexes at the surface of the ERGO-HgF-PGE at 0.1 V for 60 s in 0.1 M acetate buffer solution (pH 4.6). Owing to the improved electronic and surface effects associated with ERGO inclusion, improved sensitivity was further achieved. Under optimized conditions, the ERGO-HgF-PGE showed a linear relationship from 20 to 200 µg.L-1 with detection limits below the US-EPA of 0.17 μg.L-1 , 0.02 μg.L-1 , 0.17 μg.L-1 and 0.14 μg.L-1 for Cd2+, Cu2+, Pb2+ and Zn2+, respectively at a deposition time of 60 s. The ERGO-HgF-PGE exhibited highly reproducible results with negligible intermetallic interferences and applied successfully to the determination of trace metals in tap water with satisfactory results.

Voltammetric Analysis of New Psychoactive Substances

New Psychoactive Substances (NPS) are synthetic drugs that create similar effects as various narcotic drugs and psychotropic substances. Different NPS such as mephedrone, synthacaine, synthetic cannabinoids, etc. are available today which are sold across numerous platforms like drug markets, head shops, the dark web, etc. They are emerging rapidly and becoming popular in society because of their variable nature and ease in avoiding breaking the law. Consequently, their analysis is extremely crucial in the prohibition of drug abuse and the development of laboratory methods. This review introduces a broad overview of the analysis of various new psychoactive substances by voltammetric techniques such as cyclic voltammetry, differential pulse voltammetry, square wave voltammetry, stripping voltammetry etc. It also focuses on various methodologies that were developed for the detection of these NPS which play a leading role in forensic investigation by providing a rapid, sensitive, and cost-effective platform of analysis. The need for the advancement of various detection methods and analysis of more drugs is additionally discussed.

Carbon Materials in Electroanalysis of Preservatives: A Review

Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical preparations. It was shown that for the electroanalysis of preservatives, mainly carbon electrodes modified with various modifiers are used. These modifications ensure appropriate selectivity, high sensitivity, low limits of detection and quantification, as well as a wide linearity range of voltammetric methods of their identification and determination.

Structural and Electrical Conductivity Studies of PVDF-HFP Film Filled with Tio2 and Nacl for Polymer Semiconductors

As prospective electrolyte membranes are fabricated using a conducting copolymer of poly (vinylidene difluoride-co-hexaf luoropropy lene) (PVDF-HFP) by a solution casting method. The prepared membranes were filled with an electrical conductor (NaCl) and semiconductor (TiO2) nanopowder in this method. The assimilated membranes were analytically characterized by scanning electron microscope (SEM) for surface morphology and X-ray diffraction (XRD) for crystalline nature of the TiO2 nanopowder present in the prepared membrane. The FTIR confirms the structural analysis of the copolymer and the NaCl and TiO2 incorporation nature into the PVDF-HFP membrane. Electrochemical stability of the fabricated membrane of PVDF-HFP was performed using thermo-gravimetric analysis (TGA). The cyclic voltammetric analysis conducted the charge and discharge tests of the filled and unfilled membrane. The addition of nano TiO2 particles and NaCl to the copolymer membrane was found to reduce the PVDF-HFP membrane's porousness and improve the ion conductivity and electrolyte/electrode interfacial stability of the filled membrane.

A Review on Impedimetric and Voltammetric Analysis Based on Polypyrrole Conducting Polymers for Electrochemical Sensing Applications

Conducting polymers have been widely used in electrochemical sensors as receptors of the sensing signal’s analytes and transducers. Polypyrrole (PPy) conducting polymers are highlighted due to their good electrical conductive properties, ease in preparation, and flexibility of surface characteristics. The objective of this review paper is to discuss the theoretical background of the two main types of electrochemical detection: impedimetric and voltammetric analysis. It also reviews the application and results obtained from these two electrochemical detections when utilizing PPy as a based sensing material in electrochemical sensor. Finally, related aspects in electrochemical sensor construction using PPy will also be discussed. It is anticipated that this review will provide researchers, especially those without an electrochemical analysis background, with an easy-to-understand summary of the concepts and technologies used in electrochemical sensor research, particularly those interested in utilizing PPy as a based sensing material.