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The voltammetric electrochemical sensing method combined with biosensors and multi-sensor systems can quickly, accurately, and reliably analyze the concentration of the main analyte and the overall characteristics of complex samples. Simultaneously, the high-dimensional voltammogram contains the rich electrochemical features of the detected substances. Chemometric methods are important tools for mining valuable information from voltammetric data. Chemometrics can aid voltammetric biosensor calibration and multi-element detection in complex matrix conditions. This review introduces the voltammetric analysis techniques commonly used in the research of voltammetric biosensor and electronic tongues. Then, the research on optimizing voltammetric biosensor results using classical chemometrics is summarized. At the same time, the incorporation of machine learning and deep learning has brought new opportunities to further improve the detection performance of biosensors in complex samples. Finally, smartphones connected with miniaturized voltammetric biosensors and chemometric methods provide a high-quality portable analysis platform that shows great potential in point-of-care testing.

Tetrahydroacridines arouse particular interest due to the potential possibilities of application in the medical field and protection against corrosion. Bis-tetrahydroacridines were newly synthesized by Pfitzinger condensation of 5,5′-(ethane-1,2-diyl) diindoline-2,3-dione with several cyclanones. NMR, MS, and FT-IR were used to prove their molecular structure. In addition, a computer-aided study was performed for the lowest energy conformers of each structure, in vacuum conditions, at ground state using DFT models to assess their electronic properties. UV–Vis and voltammetric methods (cyclic voltammetry, differential pulse voltammetry, and rotating disk electrode voltammetry) were used to investigate their optical and electrochemical properties. The results obtained for these π-conjugated heteroaromatic compounds lead to the conclusion that they have real potential in applications in different fields such as pharmaceuticals and especially as corrosion inhibitors.

8-Aminoquinoline (8AQ) is the building block for many medicinal molecules. However, the redox properties of 8AQ, which are important for understanding the redox stability of drugs based on 8AQ in the human body, have not been studied in detail before. We have used cyclic voltammetry and pulse voltammetric techniques to investigate the anodic as well as the cathodic electrochemical behavior of 8AQ in a wide pH range. We have also applied UV–Vis spectroscopy to get a better understanding of the deprotonation of 8AQ due to pH changes. In addition, quantum chemical studies exploring the energy landscapes of the possible oxidations and reductions were performed, advancing our understanding of the electrochemical phenomena. The results indicate that the oxidation pathway of 8AQ strongly depends on the pH of the solution while reduction occurs according to a single pathway.

Paracetamol (PCT) is an analgesic and antipyretic that is consumed on a large scale and frequently formulated in fixed-dose combinations to enhance therapeutic efficacy. In this study, an Eco-benign differential pulse voltammetric method using an unmodified glassy carbon electrode (GCE) was developed for the simultaneous micro-estimation of PCT in two binary mixtures: with Aceclofenac (ACL) and with Dicyclomine (DIC). In the Britton–Robinson buffer (BRB) at pH 2, PCT and ACL exhibited well-resolved anodic peaks at 0.62 and 0.81 V, respectively, while at pH 9, PCT and DIC demonstrated oxidation peaks at 0.41 and 0.58 V, respectively. The validation of the proposed method was conducted in accordance with ICH guidelines and they are applied to pharmaceutical tablet formulations successfully. Linearity was achieved over concentration ranges of 0.2–25 µg·mL⁻¹ for PCT and ACL, and 1–25 µg·mL⁻¹ for PCT and DIC, with coefficients of correlation that exceed 0.9995. The method adheres to Green and White Analytical Chemistry principles by minimizing reagent consumption, analysis time and environmental impact. A multihued sustainability assessment was conducted using several greenness and sustainability metrics and compared with reported techniques. In addition, alignment with the United Nations Sustainable Development Goals was evaluated using the innovative Need, Quality and Sustainability (NQS) index. The results demonstrate that the proposed voltammetric approach is simple, rapid, cost-effective and suitable for routine quality control analysis of paracetamol-based binary mixtures.

Novel chemically modified electrodes (CMEs) based on azulene were prepared by electrooxidation of guaiazulene derivative 4-((5-isopropyl-3,8-dimethylazulen-1-yl)methylene)-2-phenyloxazol-5(4H)-one (G). G is based on guaiazulene non-alternating aromatic hydrocarbon exhibiting a less symmetrical structure compared to naphthalene skeletal derivative. Therefore, it can be used as a building block for the preparation of novel materials. To evaluate the chemical structure and surface images, the CMEs based on G (G-CMEs) were characterized by ferrocene redox probe, X-ray photon spectroscopy (XPS), and scanning electron microscopy (SEM). They were also tested for the analysis of synthetic samples of heavy metal (HM) ions. The influence of preparation conditions (electric charge and potential) on the properties of these CMEs was examined. This paper highlights the importance of electropolymerization conditions on electrodeposited film surfaces, especially on their analytical properties vs. Cd(II), Pb(II), Cu(II), and Hg(II) investigated ions. This study is relevant for further design and development of advanced materials based on azulenyl-phenyloxazolone for the HM analysis in water. A linear dependence of the peak currents for Pb(II) ion on the concentration in test aqueous solutions was obtained between 10−7 M and 5·10−5 M. The detection limits of 5·10−6 M; 10−7 M; 5·10−6 M; and 10−5 M were estimated for Cd(II), Pb(II), Cu(II), and Hg(II), respectively, for G-CMEs.

Overexposure to nitrate, the most stable and prevalent form of dissolved inorganic nitrogen, harms the environment, causing soil acidification, eutrophication, and water contamination. Among various methods for nitrate detection, electrochemical sensors have attracted considerable attention due to their inherent simplicity, high sensitivity, and low cost. However, several challenges remain, including the overpotential for nitrate reduction reaction, which leads to poor selectivity, repeatability and stability. In this work, copper modified electrodes fabricated by pulse electrodeposition method were developed for the selective detection of nitrate. The electrode modification process that determines the sensing performance was investigated by machine learning approaches to understand the relationship between the sensors’ output and the copper deposition parameters. The developed networks successfully predicted the peak current, peak potential, and current stability for electrochemical reduction of nitrate based on the pulse electrodeposition parameters. Furthermore, the most important parameter that influenced the nitrate reduction peak current was revealed by the sensitivity analysis of the designed networks. The experimental results indicate that the proposed sensor achieved a sensitivity of 9.928 μA/mM and a linear range of 0.1 to 20 mM, along with satisfactory recoveries in real sample analysis. A copper‐based electrochemical sensor was developed via pulse electrodeposition for nitrate detection, achieving high sensitivity of 9.928 μA/mM, a wide linear range of 0.1 to 20 mM, and satisfactory recoveries in real sample analysis. Additionally, machine learning models were designed to predict sensing performance based on electrodeposition parameters, providing insights into the relationship between sensor fabrication process and its properties.

An aptasensor for electrochemical detection of carbendazim is reported with mulberry fruit-like gold nanocrystal (MF-Au)/multiple graphene aerogel (MGA) and DNA cycle amplification. HAuCl 4 was reduced by ascorbic acid in a CTAC solution containing KBr and KI and formed trioctahedron gold nanocrystal. The gold nanocrystal underwent structural evolution under enantioselective direction of l -cysteine. The resulting MF-Au shows a mulberry fruit-like nanostructure composed of gold nanocrystals of about 200 nm as the core and many irregular gold nanoparticles of about 30 nm as the shell. The exposure of high-index facets improves the catalytic activity of MF-Au. MF-Au/MGA was used for the construction of an aptasensor for electrochemical detection of carbendazim. The aptamer hybridizes with assistant strand DNA to form duplex DNA. Carbendazim binds with the formed duplex DNA to release assistant strand DNA, triggering one three-cascade DNA cycle. The utilization of a DNA cycle allows one carbendazim molecule to bring many methylene blue–labeled DNA fragments to the electrode surface. This promotes significant signal amplification due to the redox reaction of methylene blue. The detection signal is further enhanced by the catalysis of MF-Au and MGA towards the redox of methylene blue. A differential pulse voltammetric signal, best measured at − 0.32 V vs. Ag/AgCl, increases linearly with the carbendazim concentration ranging from 1.0 × 10 −16 to 1.0 × 10 −11  M with a detection limit of 4.4 × 10 −17  M. The method provides ultrahigh sensitivity and selectivity and was successfully applied to the electrochemical detection of carbendazim in cucumber. Graphical abstract This study reports on an ultrasensitive aptasensor for electrochemical detection of carbendazim in cucumber based on mulberry fruit–like gold nanocrystal–multiple graphene aerogel and DNA cycle double amplification.

The contents of heavy metals (HMs) in the soil and vegetables grown in the Amur region in the period of 2020–2023 were determined by voltammetry. The zinc, cadmium, lead, and copper contents in the soil do not exceed the background and approximately permissible concentrations. According to the total accumulated amount in vegetable produce, the heavy metals are arranged in the following order: Cu > Pb > Zn > Cd.

Chemically modified electrodes (CMEs) based on 2-phenyl-4-((4,6,8-trimethylazulen-1-yl)methylene)oxazol-5(4H)-one (M) were obtained by irreversible electrooxidation of M in millimolar solutions in 0.1 M tetrabutylammonium perchlorate (TBAP) in acetonitrile. These CMEs were characterized by a ferrocene redox probe, electrochemical impedance spectroscopy (EIS), X-ray photon spectroscopy (XPS), and scanning electron microscopy (SEM). The influence of the preparation conditions (charge and potential) was examined. The CMEs were finally used for the analysis of synthetic samples of heavy metal (HM) ions. The paper highlights the importance of potential and electropolymerization charge on the film properties, with accent on recognition of HMs, in order to identify the best conditions for their detection in water. The observed findings are relevant for further design and development of advanced materials based on azulenyl-phenyloxazolone for the analysis of HMs in water.

The Arctic Ocean is a unique biogeochemical environment characterized by low salinity surface waters, extensive sea-ice coverage, high riverine inputs, large shelf extension and the long residence time of deep waters. These characteristics determine the distribution of dissolved bio-essential trace metals, such as copper (Cu), and the dissolved organic-binding ligands capable of complexing it. This work reports the concentrations and conditional stability constants of dissolved Cu-binding ligands (L Cu and log K cond Cu2+L ) measured in samples from the Polarstern (PS94) expedition, as part of the international GEOTRACES program (cruise GN04). Full-depth profile stations from the Barents Sea, Nansen Basin, Amundsen Basin and Makarov Basin were analysed by competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-AdCSV). The basins and water masses presented a wide range of L Cu concentrations (range: 1.40 – 7.91 nM) and log K cond Cu2+L values (range: 13.83 – 16.01). The highest variability of Cu-binding ligand concentrations was observed in surface waters (≤200 m), and mean concentrations increased from the Barents Sea and Nansen Basin (2.15 ± 0.31 nM and 1.93 ± 0.35 nM, respectively) to the Amundsen (3.84 ± 1.69 nM) and Makarov Basins (4.40± 2.03 nM). The influence of the Transpolar Drift (TDP) flow path was observed in the Amundsen and Makarov Basins, especially on Cu-binding ligand concentrations (L Cu range: 3.96 – 7.91 nM). In contrast, deep waters (>200 m) showed no significant differences between basins and water masses in terms of L Cu concentrations (range: 1.45 – 2.78 nM) and log K cond Cu2+L (range: 14.02 – 15.46). The presence of strong Cu-binding ligands (log K cond Cu2+L >13) in surface waters stabilises the excess of dissolved copper (dCu) transported in the TPD and favours its export to the Fram Strait and Nordic Seas.