Electroanalysis最新文献

Wine′s phenolic compounds present a group of hundreds of chemical compounds, contributing to the wine taste, color, and stability during the ageing. These compounds include phenolic acids, flavonols, anthocyanins, catechins, proanthocyanidins etc. They are very important because they offer numerous good benefits for human body. Electrochemical methods show a valuable technique for the determination of redox compounds in wine. In this review, a lot of attention is paid to carbon-based electrodes and to the voltammetric signals obtained in red and white wines using different modifiers for the electrode surface with nanoparticles and natural compounds used in the construction of biosensors. These electrodes are widely used due to their non-toxic properties, wide potential ranges, high conductivity and the possibility of use in aqueous and non-aqueous solutions. Different carbon electrodes are considered and briefly discussed. This review explores the current advancements in the electrochemical determination of most important polyphenolic compounds in wine using carbon electrodes. Also, this review gives a clear view about the oxidation peaks of various phenolic compounds in wine. It encompasses -the in-depth analysis of the different types of carbon electrodes used, such as glassy carbon, carbon paste, carbon nanotubes, screen-printed,graphene-based electrodes, biosensors and their respective benefits in polyphenolic compounds analysis. In conclusion, the electrochemical determination of polyphenolic compounds in wine using carbon electrodes offers a promising route for accurate and reliable analysis, with important implications for the wine industry and research. This review provides comprehensive information for researchers, winemakers and analytical chemists seeking to understand and apply these techniques for improving wine quality and advancing knowledge.

Low Li⁺ transference number in liquid electrolytes can lead to uneven lithium deposition and dendrite growth, reducing coulombic efficiency and cycle life of lithium metal batteries. In this study, metal-organic frameworks (MOFs) are used as electrolyte modulator to regulate Li⁺ transport. The -NH₂ group introduced into MOFs can form hydrogen bonds with anions in the electrolyte, immobilizing these anions and thereby facilitating the migration of cations. As a result, a uniform and dense deposition morphology of lithium was achieved. The Li⁺ transference number is increased from 0.26 to 0.57. The assembled Li||Li symmetrical cell can stably cycle for over for 900 h with an average overpotential below 20 mV. In addition, the rate performance of the battery can be enhanced.

The use of polymer additive manufacturing to produce electrodes is an increasingly popular area of electrochemical research. However, one downside of additively manufactured electrodes is the frequent need to remove polymer from the electrode surface to reveal a triple-phase boundary in order for improved electrode performance to be realized. A common way to achieve this, is surface activation via chronoamperometry within an aqueous sodium hydroxide solution. However, it has not been investigated whether the same activation can be carried out effectively in solutions of sodium hydroxide in simple alcohols. Therefore, in this work, we study the effect of performing common chronoamperometric additive manufacturing electrode activation methodologies in methanolic and ethanolic solutions of 0.05 M sodium hydroxide and compare these to activation carried out in standard aqueous solutions at concentrations of both 0.05 M and 0.5 M. We show that the alcoholic solutions are more effective in removing polymer from the additive manufacturing electrode surface, but that this does not lead to any improvement in electrode currents, and furthermore appears to hinder electron transfer kinetics at the additive manufacturing electrode surface, with the latter effect shown to be related to differences in the surface functionality of the exposed carbon black filler particles. As well as being interesting chemical experiments in their own right, these results may well be of interest to electrochemists who intend for their additive manufactured electrodes to be applied in these alcohols or indeed other non-aqueous solvents.

The combination of 3D-printing technology and microfluidics has garnered widespread interest for creating new designs and has opened a large window for creativity. However, some laboratories do not have the necessary technology to explore this potential advantage. In this paper, we demonstrate how to explore target technologies to fabricate a single version of a polydimethylsiloxane (PDMS)-based electroanalytical platform using a low-cost protocol and disposable materials. This protocol is cost-effective in terms of equipment and materials, allowing for the creation of a circular channel, a T-junction system, and two designs of electrochemical detectors customized onto a single platform. The interesting new device has some important characteristics, such as fabrication following green and sustainable protocols. Additionally, it can address the limitations associated with flow-based analysis, for which the classical three-electrode configuration is inadequate. It has also demonstrated the feasibility of using the device in analytical applications for the determination of salicylic acid in commercial dermocosmetic samples, including aqueous samples.

Neuropeptide Y (NPY) plays a central role in a variety of emotional and physiological functions in humans, such as forming a part of the body′s response to stress and anxiety. This work compares the impact of MCH and PEG spacer molecules on the performance of a potentiometric NPY sensor. An NPY-specific DNA aptamer with thiol termination was immobilized onto a gold electrode surface. The performance of the sensor is compared when either an MCH- or PEG-based self-assembled monolayer is formed following aptamer immobilization. Backfilling the surface with alkanethiol spacer molecules like these is key for proper conformational folding of aptamer-target binding. Non-specific adhesion of NPY to the MCH-based sensor surface was observed via surface plasmon resonance (SPR), and then confirmed via potentiometry. It is then shown that PEG improves the sensor′s sensitivity to NPY compared to the surfaces with an MCH-based SAM. We achieve the detection of picomolar range NPY levels in buffer with a sensitivity of 36.1 mV/decade for the aptamer and PEG-based sensor surface, thus demonstrating the promise of potentiometric sensing of NPY for future wearable deployment. The sensor′s selectivity was also studied via exposure to cortisol, a different stress marker, resulting in a 13x smaller differential voltage (aptamer-specific) response compared to that of NPY.

Herein, an eco-friendly, simple, inexpensive electrochemical sensor for the antibiotic ornidazole (ORN) was developed based on a carbon paste electrode modified by chitosan-CaO nanocomposite (Chi-CaO-NC/CPE). Eggshell waste was utilized to prepare CaO-NPs which were then combined with chitosan (Chi) to obtain Chi-CaO-NC/CPE. The prepared Chi-CaO-NC/CPE was characterized by different techniques such as XRD, FTIR, SEM, and EDX. The produced sensor showed higher electrocatalytic activity toward ORN in (0.1 M) PBS (pH 7.0) than the unmodified CPE. The influence of pH and scanning rate on the reduction peak of ORN implies that the reduction process of ORN at the Chi-CaO-NC/CPE surface was a diffusion-controlled reaction with four electrons and four protons. Additionally, under ideal conditions, differential pulse voltammetry (DPV) revealed that the cathodic current was directly proportional to ORN concentrations within two various detection ranges of 0.015–0.3 μM and 0.3–4.5 μM. The limit of quantification (LOQ), and the limit of detection (LOD) were 0.0138 μM and 4.13×10⁻³ μM, respectively. Moreover, the fabricated sensor provided acceptable selectivity towards ORN, good stability, and repeatable response, with recoveries ranging from 95.8 %–102.0 %; this electrode was also successful in detecting ORN in commercial tablets and milk samples.

Cover picture provided by Dr. Elena Benito-Peña and Dr. Susana Campuzano. Electroanalysis covers all branches of electroanalytical chemistry, including both fundamental and application papers as well as reviews dealing with analytical voltammetry, potentiometry, new electrochemical sensors and detection schemes, nanoscale electrochemistry, advanced electromaterials, nanobioelectronics, point-of-care diagnostics, wearable sensors, and practical applications.

Pb²⁺ ions are highly toxic to living beings because they tend to bioaccumulate in the body. For this reason, the development of simpler, low-cost, and easy-to-operate techniques that can detect and quantify low concentrations of metal ions would help to identify contaminating media and improve public health. This work proposes a Pb²⁺ voltammetric sensor based on a carbon paste electrode modified with hydrothermal biochar (hydrochar, HC) obtained from malt bagasse waste (HC/CPE). The obtained hydrochar was characterized by zero-charge point, FT-IR, XRD and thermogravimetry. The differential pulse adsorptive anodic stripping voltammetry (DPAdASV) technique was used to perform the Pb²⁺ determination. After optimizing important parameters for detecting Pb²⁺ ions and the parameters of the voltammetric technique employed, a linear response range of 0.50 to 7.06 μmol L⁻¹ with a limit of detection (LOD) and limit of quantification (LOQ) of 55.0 and 181.5 nmol L⁻¹ were achieved, respectively. The developed voltammetric procedure was applied towards the Pb²⁺ determination at tap water and river water samples, with excellent recoveries (ranging of 91.19 to 109.22 %), proving that the HC-based electrode has great potential for detecting Pb²⁺ ions. Hydrothermal carbonization allowed the biomass to be converted into functionalized hydrochar, eliminating the need for subsequent functionalization/activation steps for use as a Pb²⁺ adsorbing material on the electrodic surface. The proposed sensor also proved to be easy to assemble and environmentally friendly by using biomass waste as the carbon material. Thus, the proposed sensor adds to the literature the possibility of simple and easy detection of metal ions with a waste reuse bias.

Cover picture provided by Dr. Elena Benito-Peña and Dr. Susana Campuzano. Electroanalysis covers all branches of electroanalytical chemistry, including both fundamental and application papers as well as reviews dealing with analytical voltammetry, potentiometry, new electrochemical sensors and detection schemes, nanoscale electrochemistry, advanced electromaterials, nanobioelectronics, point-of-care diagnostics, wearable sensors, and practical applications.