Search

This work aims to allocate coffee grounds waste to the production of biochar from pyrolysis under different temperatures (350 °C and 500 °C), to add value to it. The resulting materials were characterized by immediate, elemental, thermogravimetric analysis, SEM, FT‐IR, XRD and Raman spectroscopy. Additionally, the need to activate the biochar produced for the desired use was evaluated. The obtained biochars were applied in electroanalysis in the manufacture of modified carbon paste electrodes. This choice was made due to the possibility of reaching a high sensitivity towards the determination of Cu2+ ions. The differential pulse adsorptive anodic stripping voltammetry technique was applied to perform the Cu2+ determination and, in this case, several parameters were optimized, including biochar' percentage, pH of pre‐accumulation step and reduction/stripping step, pre‐accumulation time, potential and time of reduction of adsorbed‐Cu2+. From this, the proposed modified electrode showed a linear voltammetric response towards Cu2+ in the range of 66.1 to 3997.3 ppb, with a limit of detection of 31.8 ppb, in addition to having been satisfactorily applied in the analysis of water samples (recoveries close to 100 %). Thus, demonstrating the potential for reuse of discarded coffee grounds for the preparation of activated biochar with outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

This study centers on the development and characterization of an innovative electrochemical sensing probe composed of a sensing mesoporous functional sol–gel coating integrated onto a glassy carbon electrode (sol–gel/GCE) for the detection of NH3 and/or NH4+ in water. The main interest for integrating a functional sol–gel coating onto a GCE is to increase the selective and sensing properties of the GCE probe towards NH3 and/or NH4+ ions. The structure and surface morphology of the newly developed sol–gel/GCE probe were characterized employing scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and Fourier-transform infrared (FTIR), while the electrochemical sensing properties were evaluated by Berthelot's reaction, cyclic voltammetry (CV), and adsorptive square wave–anodic striping voltammetry (Ads SW–ASV). It is shown that the newly developed sol–gel coating is homogeneously deposited on the GCE with a sub-micron and uniform thickness close to 630 nm and a surface roughness of 25 nm. The sensing testing of the sol–gel/GCE probe showed limits of detection and limits of quantitation of 1.7 and 5.56 nM of NH4+, respectively, as well as a probe sensitivity of 5.74 × 10−1 μA/μM cm−2. The developed probe was fruitfully validated for the selective detection of NH3/NH4+ in fresh and sea water samples. Computed Student texp (0.45–1.25) and Fexp (1.69–1.78) (n = 5) tests were less than the theoretical ttab (2.78) and Ftab (6.39) at 95% probability. [ABSTRACT FROM AUTHOR]

Background. Pollution of the environment with heavy metals, including mercury, poses a serious environmental hazard. Its determination, even in microconcentrations, is relevant. Purpose. Determination of Hg(II) ions by voltammetric method on a graphite electrode modified with anthranilic acid. Methodology. The object of the study is anthranilic acid and Hg(II) ions. The stripping voltammetric method for their analysis was used. Originality. A graphite electrode modified with anthranilic acid for the selective determination of Hg(II) by voltammetric method was used for the first time. Findings. Voltametric characteristics of the cathodic behavior of Hg(II) ions in the background electrolyte, with buffer solutions, at different pH, for different periods of electrolysis were recorded. [ABSTRACT FROM AUTHOR]

In the present work, we report the synthesis and evaluation of a graphite-supported bismuth film working electrode (BiFE) in the simultaneous quantification of Hg(II) and Pb(II) at ppb levels. The BiFE was synthesized in-situ by electrodeposition in 1 M HNO3 as the supporting electrolyte at −0.5 V potential. A design of experiments and a response surface model (RSM) were developed to optimize the parameter of bismuth concentration ([Bi]) and deposition time (tdep) in the synthesis of the BiFE. The electrodeposition conditions of [Bi] = 3 mM and tdep = 10s proved to be the optimal conditions for the highest sensitivity and selectivity of the synthesized working electrode. For the quantification of Hg(II) and Pb(II), the electrochemical technique of square wave anodic stripping voltammetry (SWASV) was used by applying a deposition potential of −1 V in 1 M acetic acid buffer solution. The optimization of the factors analyzed in the design of experiments allowed the simultaneous detection of Hg(II) and Pb(II) at limiting levels of 1 ppb and 10 ppb, respectively. The calibration curves of Hg(II) and Pb(II) present an R2 of 0.988 and 0.982, respectively.

AbstractFor the first time, Neutral Red (NR) has been used as a redox probe for comparative evaluation of the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with bismuth under different potentiostatic pre-plating conditions (Bi/SPCEs). It was shown that protonated NR undergoes quasi-reversible redox transformations at bare-SPCE and Bi/SPCEs in the pH range 5–6 in phosphate buffer solutions (PBS) in the potential range of (−0.2)–(−0.8) V, where bismuth is not electroactive. Bi/SPCEs have been characterized morphologically by scanning electron microscopy (SEM) and electrochemically by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) employing NR as a redox probe. The obtained SEM, CV, and EIS data are in good agreement. The highest charge transfer resistance (Rct) values (3.9 and 3.3 kΩ) were obtained at bare-SPCE and Bi/SPCE having low degree of bismuth coverage. Contrarily, the lowest Rct value (8 Ω) was recorded at Bi/SPCE, with the highest degree of bismuth coverage. CV experiments showed a significant increase in the electrochemical performances of Bi/SPCEs, whose surface is half or more covered with bismuth, in comparison to the bare-SPCE. Nickel (II) ions and formaldehyde (FM), in the form of formaldehyde hydrazone (FAH), were used as model analytes to determine the electroanalytical performance of Bi/SPCEs. A comparison of roughness factor and sensitivity toward both analytes for Bi/SPCEs with two-tailed Pearson’s criterion showed a high degree of correlation between their electrochemical and electroanalytical characteristics. The data acquired indicates that the use of NR as a redox probe may be quite helpful to control modification processes when developing novel bismuth-containing sensors. [ABSTRACT FROM AUTHOR]

A selective and reliable modified glassy carbon sensor, based on a 1.0% Cd zeolitic imidazole framework-67 modified glassy carbon sensor (GCS2), has been developed for ultrasensitive detection of dimethyl methyl phosphonate (DMMP) in human biological fluid. The synthesis of porous nanoparticles of Cd zeolitic imidazole framework-67 (Cd ZIF-67) was carried out via the hydrothermal method. The resulting Cd ZIF-67 powder emerges with good crystallinity, a rhombic dodecahedral morphology with particle size in the range 300 ~ 500 nm, and a specific surface area of 1780 m2·g−1. Furthermore, the fabricated sensor exhibited superior performance in the detection of DMMP with two linearity ranges of 0.02–2.0 nM and 2.0–9.0 nM and a limit of detection (LOD) of 0.06 pM. The fabricated sensor exhibited good reliability, long-term stability, and repeatability, which are favourable attributes for electroanalytical detection. In addition, the fabricated sensor displayed superior performance without significant interference during the assay of DMMP in a biological fluid (human serum sample) within two linearity ranges of 0.1–1.0 nM and 1.0–6.0 nM and a LOD of 0.03 nM. [ABSTRACT FROM AUTHOR]

Heavy metals are potent polluters of marine ecosystems. Consumption of contaminated seafood may lead to adverse health effects. In this work, thick film modified graphite sensors are used as working electrodes for the simultaneous determination of copper, lead, cadmium and zinc in mussel tissue from the Sea of Japan. The samples were prepared by HNO3 wet mineralization and analyzed in pH 4 acetate buffer by anodic stripping voltammetry. The analytical signal was studied as a function of accumulation potential, accumulation time, and sweep rate to determine the optimal electrolysis conditions. Standard addition method was used to evaluate the heavy metal concentrations to minimize matrix effects. The developed procedure is rapid, inexpensive, and reproducible, and has high selectivity and low limits of detection for the analytes. The relative standard deviations for the concentrations of Cu, Pb, Cd, and Zn are 13%, 21%, 7.7%, and 15%, respectively. The accuracy was confirmed by comparing the results with those obtained by inductively coupled plasma – optical emission spectrometry (ICP-OES) and inductively coupled plasma – mass spectrometry (ICP-MS). [ABSTRACT FROM AUTHOR]

Tin determination allows for the monitoring of pollution and assessment of the impact of human activities on the environment. The determination of tin in the environment is crucial for the protection of human health and ecosystems, and for maintaining sustainability. Tin can be released into the environment from various sources, such as industry, transportation, and electronic waste. The concentration of tin in the environment can be determined by different analytical methods, depending on the form of tin present and the purpose of the analysis. The choice of an appropriate method depends on the type of sample, concentration levels, and the available instrumentation. In this paper, we have carried out a literature review of electrochemical methods for the determination of tin. Electrochemical methods of analysis such as polarography, voltammetry, and potentiometry can be used for the determination of tin in various environmental samples, as well as in metal alloys. The detection limits and linearity ranges obtained for the determination of tin by different electrochemical techniques are collected and presented. The influence of the choice of base electrolyte and working electrode on signals is also presented. Practical applications of the developed tin determination methods in analyzing real samples are also summarized. [ABSTRACT FROM AUTHOR]

In quantifying NH3 and/or NH4+ ions, the wavelength-based spectrochemical methods involving formation of colored products of the Berthelot’s or Nessler reactions might be challenging due to auto-self absorbance, spectral overlap, and background scattering noise. Thus, the current study reports a renewable glassy carbon electrode (GCE) sensing probe combined with Berthelot’s reaction (indophenol formation) and adsorptive square - wave-anodic stripping voltammetry (Ads SWSV) at pH = 10 for detection of NH3 and/or NH4+ in water. The redox characteristics and the high surface coverage of the oxidation product of indophenol on the sensing platform suggested its use for NH3 and/or NH4+ detection. The electrochemical sensing probe for NH4+ displayed good linear relationship between 5.56 nM and 55.6 μM of NH4+ with limits of detection (LOD) and quantitation (LOQ) of 4.83 × 10-9 and 1.47 × 10-8 M, and sensing probe sensitivity of 1.27μA/μM−1 cm−2, respectively. The probe was applied for measuring NH3/NH4+ in fresh and seawater samples, and the results were validated using standard ion chromatography (IC) and micro spectrophotometry assays. The assembled probe was also tolerably selective against interfering of other contaminants in a comparable potential window. Additionally, the probe has exceptional selectivity, long-term stability, and repeatability, and has good capacity to detect NH3 and/or NH4+ ions with high accuracy (recovery range = 97.14 ± 4.12–102.9 ± 4.7) in environmental water samples. The calculated Student texp and Fexp values (n = 5) were less than the tabulated ttab (2.78) and Ftab (6.39) at 95 % probability (P = 0.05, n = 5). The study offer high reliability towards NH3 and/or NH4+ detection in complex environments.

This study compares the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with antimony (Sb/SPCEs) under different potentiostatic pre-plating conditions. Neutral Red (NR) was employed as a novel redox probe to evaluate the electrochemical performance of Sb/SPCEs. It was demonstrated that NR in the protonated form performs quasi-reversible redox transformations at bare SPCE and Sb/SPCEs in phosphate buffer solutions (pH 5.5±0.5) in the potential range of (−0.30)–(−0.75) V, where the antimony is not electroactive. Sb/SPCEs were studied electrochemically by cyclic voltammetry (CV) / electrochemical impedance spectroscopy (EIS), and morphologically by scanning electron microscopy (SEM). Cyclic voltammetry investigations revealed the dependence of the electrochemical performance of Sb/SPCEs on the degree of coverage of the substrate with the metal. The obtained CV, EIS, and SEM data are consistent. The lowest charge transfer resistance (Rct) value (6 Ω) was obtained at Sb/SPCE with the highest degree of antimony coverage. To investigate the electroanalytical performance of Sb/SPCEs, nickel (II) ions were utilized as a model analyte. A study of roughness factors and sensitivity towards nickel (II) ions for Sb/SPCEs using two-tailed Pearson's criterion revealed a high degree of correlation between their electrochemical and electroanalytical properties. The results show that using NR as a redox probe can help controlling modification processes during the development of innovative antimony-containing sensors.

The MONITOOL project (2017–2023) was carried out to describe the relationships between total dissolved and labile metal concentrations measured in spot water samples and in concurrently deployed Diffusive Gradients in Thin-films (DGTs) passive samplers, respectively. The ultimate aim was to adapt existing marine metal Environmental Quality Standards (EQS marine water) for DGTs, enabling their use in the context of the European Directives (the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD)). Time-integrated metal concentrations provided by DGTs, representing several days, are an advantage compared to conventional spot sampling, especially in highly dynamic systems, such as transitional waters. Hence, the MONITOOL project aimed to provide a robust database of dissolved and labile metal concentrations in transitional and coastal waters, based upon co-deployments of DGTs and collection of spot water samples at several sampling sites (England, France, Ireland, Italy, Northern Ireland, Portugal, Scotland and Spain), followed subsequently by DGT and water metal analysis. Samplings were carried out in 2018 and 2022, following agreed protocols developed in the framework of the project.The MONITOOL dataset includes metal concentrations from DGTs, measured with Inductively Coupled Plasma Mass Spectrometry (ICP-MS: Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) and in concurrently collected spot water samples by ICP-MS (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) and Anodic/Cathodic Stripping Voltammetry (ASV/CSV: Cd, Pb, Ni). Moreover, data on seawater physical-chemical parameters (salinity, temperature, dissolved oxygen, pH, turbidity, total suspended solids, dissolved organic carbon, and total organic carbon) is provided.This database presents the results obtained using, concurrently, different forms of sampling and analytical techniques, enabling the comparison of the results obtained by these strategies and allowing the adaptation of EQS in marine water (EQS marine water) to DGTs (EQS DGT), in the context of the WFD. Moreover, due to the large number of sampling sites, it could also be used for other types of research, such as those dealing with metal speciation or the determination of baseline levels.

This study centers on the development and characterization of an innovative electrochemical sensing probe composed of a sensing mesoporous functional sol–gel coating integrated onto a glassy carbon electrode (sol–gel/GCE) for the detection of NH3 and/or NH4+ in water. The main interest for integrating a functional sol–gel coating onto a GCE is to increase the selective and sensing properties of the GCE probe towards NH3 and/or NH4+ ions. The structure and surface morphology of the newly developed sol–gel/GCE probe were characterized employing scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and Fourier-transform infrared (FTIR), while the electrochemical sensing properties were evaluated by Berthelot’s reaction, cyclic voltammetry (CV), and adsorptive square wave–anodic striping voltammetry (Ads SW–ASV). It is shown that the newly developed sol–gel coating is homogeneously deposited on the GCE with a sub-micron and uniform thickness close to 630 nm and a surface roughness of 25 nm. The sensing testing of the sol–gel/GCE probe showed limits of detection and limits of quantitation of 1.7 and 5.56 nM of NH4+, respectively, as well as a probe sensitivity of 5.74 × 10−1 μA/μM cm−2. The developed probe was fruitfully validated for the selective detection of NH3/NH4+ in fresh and sea water samples. Computed Student texp (0.45–1.25) and Fexp (1.69–1.78) (n = 5) tests were less than the theoretical ttab (2.78) and Ftab (6.39) at 95% probability.

Stripping analysis was proposed for the voltammetric determination of trace cadmium and lead in local rice wine alcoholic beverages. A bismuth-antimony film electrode (Bi-SbFE) was employed for accumulative preconcentration of trace metals by adding 4 mg L−1 of bismuth and 1 mg L−1 of antimony directly to the sample solution and simultaneously depositing bismuth, antimony, and trace cadmium and lead target metals on the glassy carbon electrode by applying a fixed potential of –1.1 V versus the Ag/AgCl reference electrode for 300 s. Pre-treatment parameters for mineralization of the sample were optimized using the wet acid digestion procedure. Under the optimum conditions, linear calibration graphs ranging 20-200 μg L−1 for Cd and Pb were obtained with detection limits of 0.22 and 0.62 μg L−1 and limits of quantitation 0.73 and 2.07 μg L−1, respectively. Reproducibility values for seven replicate analyses of 50 μg L−1 Cd and Pb were 3.6 and 3.3%, respectively. The developed method was successful for Cd and Pb analyses in Thai rice wine samples and results were validated by the flame atomic absorption spectrometric method. Most samples were not contaminated with Cd and Pb. The amount of Cd contaminants in only one of rice wine sample was still lower than the maximum permitted level of Cd in wine.

In this research, graphene oxide (GO) was functionalized with D-penicillamine (DPA) and used to develop an electrochemical sensor for Cu(II) cation. For the successful synthesis of D-penicillamine-functionalized graphene oxide (DPA-GO), Fourier Transfer Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), X-ray diffraction pattern (XRD), and Transmission Electron Microscopy (TEM) are used. DPA-GO modified glassy carbon electrode (DPA-GO / GCE) was prepared and its electrochemical behavior was studied in the presence of Cu(II) cations by cyclic voltammetry, and the results showed the better performance of the DPA-GO-modified electrode compared to unmodified and GO-modified electrode, which related to GO nanostructure and complexing ability of sulfur, nitrogen, and oxygen-containing functional groups in the DPA structure. The prepared sensor was used for the selective and sensitive measurement of Cu(II) cations by square-wave anodic stripping voltammetry (SW-ASV) and the factors affecting the sensor performance were investigated and optimum conditions for sensor operation were determined. Under the optimal conditions, the prepared electrode has a linear response in the range of 1 pM to 0.1 µM and its detection limit was 0.31 pM. The proposed sensor was used satisfactorily to measure copper cation in real water samples with suitable reproducibility and stability.

Due to a great interest in the beneficial properties of polyphenolic antioxidant curcumin (CCM), sensitive and accurate methods for determining CCM are needed. The purpose of our research was to develop a very simple, fast, and sensitive differential pulse adsorptive stripping voltammetric (DPAdSV) procedure using an electrochemically activated screen-printed boron-doped diamond electrode (aSPBDDE) for the determination of CCM. The activation of the SPBDDE was accomplished in a solution of 0.1 mol/L NaOH by performing five cyclic voltammetric scans in the range of 0–2 V, at ν of 100 mV/s. The changes in surface morphology and the reduction of the charge transfer resistance due to the activation of the electrode resulted in the amplification of the CCM analytical signal on the aSPBDDE. As a result, an extremely sensitive measurement tool was formed, which under optimized conditions (0.025 mol/L PBS of pH = 2.6, Eacc of 0.3 V, tacc of 90 s, ΔEA of 100 mV, ν of 150 mV/s, and tm of 10 ms) allowed us to obtain a limit of detection (LOD) of 5.0 × 10−13 mol/L. The aSPBDDE has proven to be a highly effective tool for the direct determination of CCM in food samples with high accuracy and precision. The results are in agreement with those obtained using ultra-high-performance liquid chromatography coupled with mass spectrometry and electrospray ionization (UHPLC-ESI/MS). [ABSTRACT FROM AUTHOR]

A new anodic stripping voltammetry technique has been proposed for direct determination of zinc in seminal plasma of bulls. Two types of electrodes were used as working electrodes—a stationary glassy carbon electrode (GCE) and a thick-film-modified graphite electrode (TMGE) for comparison. The method is rapid, simple, and highly accurate, has high selectivity and low limits of detection (LODs) and limits of quantification (LOQs), and no sample pretreatment steps are also required. The data obtained in both cases agree well with each other and with the data obtained by the independent method of inductively coupled plasma optical emission spectrometry. The relative error of the zinc determination by anodic stripping voltammetry does not exceed 10%. The LOD and LOQ values obtained under optimized conditions were 3.0 and 8.0 µg L−1 for GCE and 2.0 and 5.0 µg L−1 for TMGE, respectively. In contrast to the GCE application, the TMGE application did not include the addition of toxic soluble mercury salts (II) in the electrolyte solution. The zinc content in seminal plasma of bulls is 6.1 ÷ 13.0 mg L−1. The mean values of zinc concentrations in the samples were 8.4, 11.9, and 9.0 mg L−1 for Red, Simmental, and Black-motley animals, respectively. All of these values are within physiological limits and agree well with literature data. [ABSTRACT FROM AUTHOR]

In the study, the electrochemical characteristics of carvedilol were determined by cyclic voltammetry and square wave voltammetry on carbon paste electrode with zinc oxide nanoparticles at pH 8.0 in Britton Robinson buffer. The adsorption characteristics of the molecule on the modified electrode and the electron number accompanying the electrode reaction were calculated. In addition, a new square wave anodic adsorptive stripping voltammetry process was suggested for the determination of carvedilol drug samples. The linear concentration range and detection limit of the process were found to be 0.07 µM–2.61 µM and 0.09 µM, respectively. Recovery studies of CAR in the pharmaceutical sample were performed to check the accuracy of the developed process. With the developed process, results with high reliability, reproduceability, accuracy and precision were obtained for the determination of CAR in pharmaceutical samples.

This paper describes a novel electrode material, diclofenac-impregnated mesoporous carbon modified with a cationic surfactant, cetyltrimethylammonium bromide (DF-CMK-3/CTAB), for ultratrace analysis of the arsenic drug roxarsone (ROX). DF-CMK-3 amorphous carbon is a material with a high specific surface area and well-defined, hexagonally ordered, thin mesopores. The functional groups attached to the carbonaceous surface, such as chromene and pyron-like oxygen groups, lactam, and aromatic carbon rings, have the basic character and they can donate electrons. Modification of DF-CMK-3 with a CTAB layer significantly increases the analytical signal due to electrostatic interactions between the cationic surfactant and the anion form of ROX in the acidic medium. The voltammetric procedure at the glassy carbon sensor modified with DF-CMK-3/CTAB exhibited excellent sensitivity (limit of detection of 9.6 × 10−11 M) with a wide range of linearity from 5.0 × 10−10 to 1.0 × 10−4 M. Analysis of real samples (treated municipal wastewater and river water) showed recoveries from 96 to 102% without applying the complicated sample pretreatment step. The sensor demonstrated excellent sensitivity in the analysis of the arsenic drug ROX in the presence of interferences in environmental water samples. [ABSTRACT FROM AUTHOR]

This article aims to investigate in detail to what extent surfactants affect the determination of cadmium by anodic stripping voltammetry. In recent years, the production and use of surfactants have been steadily increasing, so that their concentration in environmental water samples is rising. At the same time, it is known that organic compounds, such as surfactants, often hinder the voltammetric determination of trace elements by stripping. Non-ionic (Triton X-100, Brij 35, Tween 20, Tween 60, Tween 80), cationic (CTAB, CTAC, DTAB, HPC) and anionic (DSS, SDS) compounds were selected to investigate the effect of surfactants on the voltammetric signal of cadmium. At the same time, the extent to which the addition of Amberlite resins to the analysed solution eliminates the interfering effect of surfactants was tested. Three types of Amberlite resins XAD-2, XAD-7 and XAD-16 were selected for the study and the ratio of resin weight to solution volume was determined. Finally, the determination of cadmium in surfactant-enriched environmental samples was carried out. The recoveries obtained between 95.5 and 107%, with RSD between 3.4 and 6.2%, confirm the validity and correctness of the proposed procedure All measurements were carried out by anodic stripping voltammetry using a CNTs/SGC electrode modified with a bismuth film as the working electrode. [ABSTRACT FROM AUTHOR]

The stripping voltammetry at HMDE is proposed for Cd and Pb (undesirable ingredients) determination in the natural brine (CCl >43 g L−1). Samples with so high salinity have to be significantly diluted. For ICP MS, a 105–6 times dilution is required, which disqualifies this method. The proposed procedure allows to determine Cd (0.001 μg L−1) and Pb (0.005 μg L−1) after only 100 times dilution. The thermal chloride stripping or isolation by Chelex 100 increase the quality of obtained data. The recovery study was performed. The LOQs are below recommendations related to the use of brines in balneology. [ABSTRACT FROM AUTHOR]

The practical application of a novel, eco-friendly electrochemical sensor based on low-dimensional structures, spherical glassy carbon microparticles, and multiwall carbon nanotubes is described. This sensor, modified with a bismuth film, was used for the determination of Cd(II) by the anodic stripping voltammetric method. The instrumental and chemical factors influencing the sensitivity of the procedure were thoroughly investigated and their most favorable values were selected (acetate buffer solution pH = 3 ± 0.1; 0.15 mmol L−1 Bi(III); activation potential/time: −2 V/3 s; accumulation potential/time: −0.9 V/50 s). Under the selected conditions, the method exhibited linearity in the range of 2 × 10−9 to 2 × 10−7 mol L−1 Cd(II) with a detection limit of 6.2 × 10−10 mol L−1 Cd(II). The results obtained also showed that the application of the sensor for Cd(II) detection did not experience any significant interference in the presence of a number of foreign ions. The applicability of this procedure was evaluated using TM-25.5 Environmental Matrix Reference Material and SPS-WW1 Waste Water Certified Reference Material as well as river water samples through addition and recovery tests. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) Sb-modified screen-printed carbon nanofibers electrode (2D Sbexf-SPCNFE) was developed to improve the stripping voltammetric determination of Cd(II) and Pb(II), taking advantage of the synergistic effect between the two nanomaterials. The surface morphology of the 2D Sbexf-SPCNFE was investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The analytical performance of 2D Sbexf-SPCNFE was compared to those presented by screen-printed carbon electrodes modified with 2D Sbexf (2D Sbexf-SPCE) and the corresponding bare electrodes: screen-printed carbon nanofibers electrode (SPCNFEbare) and screen-printed carbon electrode (SPCEbare). After optimizing the experimental conditions, the 2D Sbexf-SPCNFE exhibited much better analytical parameters compared to the other assessed sensors. Analysis in 0.01 mol L−1 HCl (pH = 2) using 2D Sbexf-SPCNFE showed excellent linear behavior in the concentration range of 2.9 to 85.0 µg L−1 and 0.3 to 82.0 µg L−1 for Cd(II) and Pb(II), respectively. The limits of detection after 240 s deposition time for Cd(II) and Pb(II) were 0.9 and 0.1 µg L−1, and sensitivities between 1.5 and 3 times higher than those displayed by SPCEbare, SPCNFEbare, and 2D Sbexf-SPCE were obtained. Finally, the 2D Sbexf-SPCNFE was successfully applied to the determination of Cd(II) and Pb(II) traces in a certified estuarine water sample. [ABSTRACT FROM AUTHOR]

Herein, we proposed a cost-effective, eco-friendly, fast and sensitive square wave cathodic stripping voltammetry (SWCSV) and differential pulse cathodic stripping voltammetry (DPCSV) methods for the quantification of anti-ulcer drug cinitapride in pharmaceuticals. Cinitapride electrochemically reduced at pencil graphite electrode and gave an irreversible well-defined cathodic peak in cyclic, square wave, and differential pulse voltammograms. The effect of pH of buffer, scan rates, and drug concentration on peak current and peak potential were studied. The reduction of cinitapride at pencil graphite electrode was diffusion controlled and occurred via participation of two electrons and two protons (2e−/2H+). The various electro-kinetic parameters such as diffusion coefficient(Do), surface coverage (To)and electron transfer coefficient (α) were calculated, additionally, the mechanism of reduction of cinitapride at pencil graphite electrode was also proposed. The peak currents vary linearly in the concentration range 2.48 μmolL−1 to 17.39 μmolL−1 for all the voltammetric techniques. The obtained value of LOD for SWCSV and DPCSV techniques were2.48 μmolL−1 and 3.19 μmolL−1, respectively, which proved higher sensitivity of the proposed methods. [ABSTRACT FROM AUTHOR]

An anodic stripping voltammetric procedure for the determination of bismuth in the presence of excess of Cu2+ ions at two ex situ plated gold film electrodes was described. The procedure is based on utilization of two deposition and two stripping steps system. The presented procedure ensures increasing the sensitivity of Bi3+ determination and minimization of interferences related to peaks' overlapping. The calibration graph for bismuth determination was linear from 2.5×10−9 to 2×10−8 mol L−1 for deposition time of 300 s at both working electrodes while detection limit was 7.7×10−10 mol L−1. [ABSTRACT FROM AUTHOR]

A copper film-modified, carboxyl-functionalized, and multi-walled carbon nanotube (MWCNT-COOH)-modified screen-printed carbon electrode (CuF/MWCNTs/SPCE) was used for lead determination using anodic stripping voltammetry. The main parameters were investigated and optimized during the development of the research procedure. The most optimal electrolyte concentrations were determined to be 0.4 M HCl and 6.3 × 10−5 M Cu(II). The optimal parameters for voltammetric stripping measurements are as follows: an accumulation potential of −0.7 V; an accumulation time of 120 s; and a pulse amplitude and pulse time of 120 mV and 2 ms, respectively. The effect of surface active substances and humic substances as potential interferents present in aqueous environmental samples was investigated. The validation of the procedure was carried out using certified reference materials, like waste water SPS-WW1 and environmental matrix TM-25.5. In addition, the developed procedure was applied to investigate lead recovery from natural environmental water, such as rivers and lakes.

Tin determination allows for the monitoring of pollution and assessment of the impact of human activities on the environment. The determination of tin in the environment is crucial for the protection of human health and ecosystems, and for maintaining sustainability. Tin can be released into the environment from various sources, such as industry, transportation, and electronic waste. The concentration of tin in the environment can be determined by different analytical methods, depending on the form of tin present and the purpose of the analysis. The choice of an appropriate method depends on the type of sample, concentration levels, and the available instrumentation. In this paper, we have carried out a literature review of electrochemical methods for the determination of tin. Electrochemical methods of analysis such as polarography, voltammetry, and potentiometry can be used for the determination of tin in various environmental samples, as well as in metal alloys. The detection limits and linearity ranges obtained for the determination of tin by different electrochemical techniques are collected and presented. The influence of the choice of base electrolyte and working electrode on signals is also presented. Practical applications of the developed tin determination methods in analyzing real samples are also summarized.

Due to the risk of heavy metal pollution in infant milk powder, it is significant to establish effective detection methods. Here, a screen-printed electrode (SPE) was modified with nanoporous carbon (NPC) to detect Pb(II) and Cd(II) in infant milk powder using an electrochemical method. Using NPC as a functional nanolayer facilitated the electrochemical detection of Pb(II) and Cd(II) due to its efficient mass transport and large adsorption capacity. Linear responses were obtained for Pb (II) and Cd(II) in the range from 1 to 60 µg L−1 and 5 to 70 µg L−1, respectively. The limit of detection was 0.1 µg L−1 for Pb(II) and 1.67 µg L−1 for Cd(II). The reproducibility, stability, and anti-interference performance of the prepared sensor were tested as well. The heavy metal ion detection performance in the extracted infant milk powder shows that the developed SPE/NPC possesses the ability to detect Pb(II) and Cd(II) in milk powder. [ABSTRACT FROM AUTHOR]

Electrochemical determination of melatonin in the presence of tryptophan is a challenge because of the coincidence of voltammetric signals of these compounds when executing a voltammetric technique. The new method for selective determination of melatonin based on the square wave anodic stripping voltammetry determination of an electroactive product of melatonin was suggested here. This product is produced by previously applied positive pre‐potential to a carbon paste electrode, immersed in the test solution. By this means, the electrochemical signal of melatonin was separated effectively from that of tryptophan, making it possible to determine melatonin in the presence of a high concentration of tryptophan. The effect of important parameters on electrode performance was studied and optimized. The optimum response was obtained at pH=2 and utilizing the pre‐potential magnitude of +0.8 V, applied for 10 s. A linear relationship was found between peak current intensity and melatonin concentrations over the range of 5.00×10−7 to 8.00×10−5 mol L−1. A detection limit of 8.30×10−8 mol L−1 was calculated for the method (S/N=3). The selectivity of the method was considerably high, because of the independence of melatonin signal to the presence of higher amounts of some potentially interfering agents such as ascorbic acid, tryptophane glucose, etc. As an analytical application, the proposed sensor was used for the determination of melatonin in pharmaceutical and food samples. [ABSTRACT FROM AUTHOR]

In this work, we provide electrochemical and spectroscopic evidence of the conducting polymer-heavy metal ion interaction by comparing the electrochemical and spectroscopic behavior (FTIR) of two different conducting polymer-modified electrodes based on 3,4-alkoxythiophenes: 3,4-ethylenedioxythiophene (EDOT) and ortho-xylen-3,4-dioxythiophene (XDOT) during the potentiodynamic stripping of copper. By analyzing the electrochemical and spectroscopic results, it is possible to propose two different copper dissolution processes during the electrochemical stripping process, which depend on the conducting polymer used. With PEDOT matrix, stripping occurs in a two-step pathway, observed as two anodic peaks, involving the formation of the Cu+-PEDOT complex and the subsequent oxidation step of the Cu+ complex to release Cu2+ ions. On the other side, the experiments carried out let us propose the formation of a poorly stable Cu2+-PXDOT complex or a superficial mechanism for the Cu2+ release, characterized by a single stripping signal for this process. Thus, the incorporation of Cu ions into the matrix and the stripping release are intimately related to the chemical structure of the polymer used. [ABSTRACT FROM AUTHOR]

First time, the electro-oxidative behaviour and determination of acotiamide at a pencil graphite electrode have been investigated under different experimental conditions using cyclic voltammetry (CV), differential pulse anodic stripping voltammetry (DPASV), and square wave anodic stripping voltammetric (SWASV) techniques. The voltammetric responses of acotiamide have been analyzed at different scan rates, pH and concentrations. Oxidation of acotiamide at the surface of pencil graphite electrode gave two well defined irreversible peaks in the voltammograms in BR buffer of pH 7.0. The oxidation process is completely diffusion controlled. A linear response of peak current has been obtained between 15.5 to 124 μM in non-aqueous media for all the voltammetric techniques. The proposed DPASV and SWASV techniques show limit of detection at 18.58 and 13.36 μM, respectively. [ABSTRACT FROM AUTHOR]

I n this study, the electrochemical properties of carvedilol (CAR) were investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) on carbon paste electrode modified with zinc oxide nanoparticles (ZnONP/CPE) in pH 8.0 Britton Robinson (BR) buffer. The adsorption characteristics of the molecule on the modified electrode and the electron number accompanying the electrode reaction were calculated. Furthermore, a new square wave anodic adsorptive stripping voltammetry (SWAAdSV) method was proposed for the determination of CAR in drug samples. The linear concentration range and detection limit of the method were found to be 0.07 µM–2.61 µM and 0.09 µM, respectively. To test the accuracy of the developed method, recovery studies of CAR in the pharmaceutical sample were carried out. With the developed method, results with high reliability, reproducibility, accuracy, and precision were obtained for the determination of CAR in pharmaceutical samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Free-standing fiber made from SWCNT film is a new type of electrode material for electroanalysis. • Au/SWCNT fiber sensor for arsenic has a wide linear range and good repeatability. • Heat and chemical treatment of SWCNTs improves sensor performance. • Fabricated sensors have a long service life (were tested during a year). We developed a new method to produce fiber electrodes from single-walled carbon nanotube (SWCNT) films, which can be employed as a novel sensing platform for electrochemical investigations and analysis. By assembling SWCNT bundles in the form of a strong free-standing fiber with almost entire surface accessible to an analyte, we are able to avoid the interference of substrate and improve detection efficiency. We examined the influence of physical, chemical and electrochemical pretreatments of the new electrode SWCNT material on its properties. Transmission and scanning electron microscopy, Raman spectroscopy and cyclic voltammetry were used to characterize the SWCNT fibers. The modification of the SWCNT fiber electrode with gold nanoparticles provides the necessary analytical characteristics including high repeatability and sensitivity and low detection limit (1.3 – 2.1 μg L-1) for arsenic determination by anodic stripping voltammetry. Arsenic detection parameters such as deposition potential, deposition time and scan rate were optimized. Linear responses were found in concentration ranges from 3 to 210 μg L-1 and 7 to 125 μg L-1 for gold modified SWCNT fiber sensors (the SWCNTs were synthesized using CO or ethanol as precursors) at a relatively low deposition time of 60 s. The developed Au-SWCNT sensors allow rapid As determination in real samples and exhibit high durability and long service life. [ABSTRACT FROM AUTHOR]

[Display omitted] • The accurate measurement of creatinine (Ctn) in human biofluid samples is a challenge. • A stable carboxyl (C=O, COOH) groups were introduced on the electrode surface during electrochemical activation. • ePAD* was applied for the selective non-enzymatic detection of Ctn. • ePAD* detects Ctn in blood serum and urine samples with high reliability. • ePAD* is economic and accurate compared to existing methods for Ctn detection. Selective detection of creatinine (Ctn) is crucial for the clinical diagnosis of early-stage kidney dysfunction. A non-enzymatic electrochemical method for a highly selective and sensitive detection of Ctn in blood serum and urine samples was developed using an electrochemically activated carbon-coated paper-based analytical device (ePAD*). During activation, the growth of stable carboxyl (C = O, COOH) groups on the edge planes of the carbon surface was observed. The prepared ePAD* was characterized using various microscopic, spectroscopic, and electrochemical techniques. The ePAD* was utilized as a medium exchanger, and the voltammetric response of Ctn detection in the linear concentration from 0.03 to 45 mM with a detection limit of 5.41 µM was achieved. In addition, the selective detection of Ctn in the presence of potential interferences (i.e., uric acid, ascorbic acid, ammonia, and urea) was examined. The examination revealed a remarkable selectivity toward Ctn detection. Real-time detection of Ctn in blood serum and urine samples was performed. The results were correlated with the classical Jaffé colorimetric method. Our ePAD* exhibited a better electrochemical response. Thus, it is a highly potential diagnostic method for further development as a rapid and precise detection platform for point-of-care (POC) devices for examining patients with kidney disease. [ABSTRACT FROM AUTHOR]

The contamination of groundwater by arsenic is a serious concern due to the acute and long-term effects of arsenic toxicity on human health [...]

Due to a great interest in the beneficial properties of polyphenolic antioxidant curcumin (CCM), sensitive and accurate methods for determining CCM are needed. The purpose of our research was to develop a very simple, fast, and sensitive differential pulse adsorptive stripping voltammetric (DPAdSV) procedure using an electrochemically activated screen-printed boron-doped diamond electrode (aSPBDDE) for the determination of CCM. The activation of the SPBDDE was accomplished in a solution of 0.1 mol/L NaOH by performing five cyclic voltammetric scans in the range of 0–2 V, at ν of 100 mV/s. The changes in surface morphology and the reduction of the charge transfer resistance due to the activation of the electrode resulted in the amplification of the CCM analytical signal on the aSPBDDE. As a result, an extremely sensitive measurement tool was formed, which under optimized conditions (0.025 mol/L PBS of pH = 2.6, Eacc of 0.3 V, tacc of 90 s, ΔEA of 100 mV, ν of 150 mV/s, and tm of 10 ms) allowed us to obtain a limit of detection (LOD) of 5.0 × 10−13 mol/L. The aSPBDDE has proven to be a highly effective tool for the direct determination of CCM in food samples with high accuracy and precision. The results are in agreement with those obtained using ultra-high-performance liquid chromatography coupled with mass spectrometry and electrospray ionization (UHPLC-ESI/MS).

Here, we propose a stripping voltammetric method for Ag + ion determination in distilled water utilizing screen-printed Au electrodes coated with Nafion (Nafion/Au screen-printed electrodes). The concentration of Ag + in pure water was determined by linear sweep voltammetry (LSV) after silver deposition on the Nafion/Au electrode. The anodic stripping peak current increased linearly with the concentration of Ag +  ion in the range from 1 ppm to 22 ppm. The LSV oxidative peak current was increased by extending the silver deposition time from 300 s to 500 s. Repetitive LSV measurements revealed satisfactory reproducibility of the Nafion/Au screen-printed electrodes. The detection mechanism was elucidated by recording mass changes of the Nafion/Au electrode with a quartz crystal microbalance (QCM), and by determining changes in the low-frequency capacitance of the Nafion/Au electrode by electrochemical impedance spectroscopy (EIS). The observed changes in mass and capacitance confirmed Ag + accumulation and release processes at the Nafion/Au electrodes, in good agreement with stripping voltammetry. The combination of stripping voltammetry, QCM and EIS allowed a detailed characterization of the ion transfer, deposition and stripping processes at the Nafion/Au electrodes in presence of Ag + ions. The Nafion/Au screen-printed electrode enabled voltammetric determination of low Ag + concentrations in distilled water, without any sample pretreatment nor addition of supporting electrolyte., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This paper describes a novel electrode material, diclofenac-impregnated mesoporous carbon modified with a cationic surfactant, cetyltrimethylammonium bromide (DF-CMK-3/CTAB), for ultratrace analysis of the arsenic drug roxarsone (ROX). DF-CMK-3 amorphous carbon is a material with a high specific surface area and well-defined, hexagonally ordered, thin mesopores. The functional groups attached to the carbonaceous surface, such as chromene and pyron-like oxygen groups, lactam, and aromatic carbon rings, have the basic character and they can donate electrons. Modification of DF-CMK-3 with a CTAB layer significantly increases the analytical signal due to electrostatic interactions between the cationic surfactant and the anion form of ROX in the acidic medium. The voltammetric procedure at the glassy carbon sensor modified with DF-CMK-3/CTAB exhibited excellent sensitivity (limit of detection of 9.6 × 10−11 M) with a wide range of linearity from 5.0 × 10−10 to 1.0 × 10−4 M. Analysis of real samples (treated municipal wastewater and river water) showed recoveries from 96 to 102% without applying the complicated sample pretreatment step. The sensor demonstrated excellent sensitivity in the analysis of the arsenic drug ROX in the presence of interferences in environmental water samples.

The present study reports the development of a magnetic polyethylene glycol nanocomposite based on graphite reinforcement carbon paste electrode for the sensitive determination of perindopril L-arginine (PER L-Arg) using square wave stripping adsorptive voltammetry. The present strategy is based on two steps: firstly, the magnetic nanoparticles (MNPs) were fabricated with polyethylene glycol (PEG). In the next step, the functionalized magnetic beads (PEG-MNPs) were mixed with graphite reinforcement carbon paste to form PEG-MNPs assembly followed by loading PER L-Arg onto functionalized magnetic beads that had already been fixed at the surface of graphite reinforcement carbon paste electrode to facilitate oxidation. Scanning electron microscopy was used for the morphological characterization of the electrode prior to the modification and after the modification and utilization. The electrode showed good sensitivity, repeatability, and stability. The limits of detection and quantification were found to be 4 × 10–10 and 1.1 × 10–9 M, respectively. The electrode was successfully applied as an electrochemical sensor for the determination of PER L-Arg in pharmaceutical and biological samples, and recovery rates close to 100% were obtained. [ABSTRACT FROM AUTHOR]

In recent years, important efforts have been made to elucidate the mechanisms of epigenetic regulation, and one of the most studied epigenetic modifications was DNA methylation/demethylation. In this study, the voltammetric behaviour of 5-hydroxymethylcytosine was studied in the pH range of 2.00–11.00 using pencil graphite electrodes by differential pulse and square wave voltammetry. The effect of buffer solutions, scan rate, square wave voltammetry parameters, and stripping conditions on the voltammetric responses of 5-hydroxymethylcytosine were performed. The electrochemical oxidation process of 5-hydroxymethylcytosine on the pencil graphite electrode was realized under adsorption control. In human urine, by square wave stripping voltammetry, 5-hydroxymethylcytosine was quantified in a concentration range of 1.00 × 10−5 M-2.00 × 10−4 M. The proposed method was tested in the presence of cytosine in human urine. The recovery value of 5-hydroxymethylcytosine was found to be 99.57 %. [Display omitted] • SWAdSV technique developed for 5hmC detection. • 5hmC was detected for the first time on disposable PGE. • 5hmC analyzed in human urine in the presence of cytosine. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple and greener methods are used to achieve more reliability than conventional drop casting methods. • The first report based on EPD film for selective Pb2+ ions was achieved. • A facile EPD film enables precise alignment to ensure the selectivity and sensitivity of Pb2+ ions. • The synergistic effect of NS-rGO and Bi, which helps selectivity and sensitivity towards Pb2+ ions. • The EPD enables precise alignment to avert additive-free, irregular coating and stable film formation. Lead is very hazardous, as it is present in environmental samples, and it causes severe health problems affecting neurological, cardiac, genital, and mental illnesses owing to exposure to even a trace amount. The achievement of selective detection of Pb2+ ions is challenging due to interfering relevant metal ions. Hence, in this work, we have synthesized the Nitrogen and Sulphur N and S-doped reduced graphene oxide (NS-rGO) and fabricated it using electrophoretic deposition (EPD) in glassy carbon electrode (GCE) and Bi film deposition (Bi/EPD-NS-rGO/GCE) for selective detection of Pb2+ ions. The synthesized materials were characterized to confirm their functionalities, elemental analysis, and morphology. Further, the electrochemical behaviours were also carried out through Cyclic Voltammetry (CV) and Electrochemical Impedimetric spectroscopy (EIS) studies. The above-modified electrodes were utilized for selective detection of Pb2+ in the presence of Cd2+ ions using the differential pulse anodic stripping voltammetry (DPASV) method. The electrode modified with NS-rGO using the EPD method, along with a thin film of Bi that was electrodeposited, has better and more selective catalytic activity for sensing Pb2+ ions. The linear working response was found to be in the range of 100–2200 nM with a limit of detection (LOD) of 0.180 nM and verified as 144 times lower than the recommended level (26 nM) by World Health Organization (WHO) and United States Environmental Protection Agency (USEPA). The developed sensor was further applied to the selective detection of Pb2+ ions in tap water and river water, and it shows good recovery. The Bi/EPD-NS-rGO/GCE will explore a new pathway for the simple and selective detection of Pb2+ ions. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat acute and chronic inflammatory diseases. High consumption and indiscriminate use of DCF pose serious health issues, prompting the consideration of electroanalytical methods for detecting and controlling DCF levels in various samples. A sensitive and highly selective sensor was established for voltammetric determination of diclofenac (DCF) based on poly[cobalt(II) bis-(1,10-phenanthroline) complex] modified glassy carbon electrode (poly(Co(Phen) 2)/GCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the performance of a poly(Co(Phen) 2)/GCE sensor, revealing a negative oxidation potential shift and higher DCF peaks of current. CV and adsorptive stripping square wave voltammetry (AdSSWV) were used to evaluate the electrochemical behavior of DCF at poly(Co(Phen) 2)/GCE. Under the optimized experimental conditions, AdSSWV current signal of DCF at poly(Co(Phen) 2)/GCE provided linearity over the range of 1–250 μM with a limit of detection (LOD) and limit of quantification (LOQ) of 6.40 ×10−2 and 2.13 ×10−1, and 5.60 × 10−2 and 2.27 × 10−1 µM for Ip I and Ip II, respectively. The sensor for determining DCF was tested in pharmaceuticals, milk, serum, and urine samples, demonstrating excellent selectivity despite potential interferences like atorvastatin (ATS), chloroquine (CQ), and sulfamethoxazole (SMX). The detected DCF amounts ranged between 92.3% and 106.6%. The established sensor demonstrated excellent performance in determining DCF in real samples, with spiked recoveries exceeding 95.6%, demonstrating low LOD, high sensitivity, selectivity, repeatability, and long-term stability. These results confirm that the established method displays outstanding applicability for electrochemical determination of DCF in numerous real samples. [Display omitted] • A highly sensitive and selective electrochemical sensor was established for successful adsorptive striping voltammetric determination of (DCF). • Cobalt(II) bis-(1,10-phen) complex modified glassy carbon electrode was fabricated via electropolymerization. • The sensor exhibit excellent electrocatalytic sensing towards DCF. • The poly(Co(Phen) 2)/GCE sensor has shown excellent repeatability, reproducibility, and long-term stability. • This method was effectively employed for quantitative determination of DCF in pharmaceuticals and biological samples. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) Sb-modified screen-printed carbon nanofibers electrode (2D Sbexf-SPCNFE) was developed to improve the stripping voltammetric determination of Cd(II) and Pb(II), taking advantage of the synergistic effect between the two nanomaterials. The surface morphology of the 2D Sbexf-SPCNFE was investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The analytical performance of 2D Sbexf-SPCNFE was compared to those presented by screen-printed carbon electrodes modified with 2D Sbexf (2D Sbexf-SPCE) and the corresponding bare electrodes: screen-printed carbon nanofibers electrode (SPCNFEbare) and screen-printed carbon electrode (SPCEbare). After optimizing the experimental conditions, the 2D Sbexf-SPCNFE exhibited much better analytical parameters compared to the other assessed sensors. Analysis in 0.01 mol L−1 HCl (pH = 2) using 2D Sbexf-SPCNFE showed excellent linear behavior in the concentration range of 2.9 to 85.0 µg L−1 and 0.3 to 82.0 µg L−1 for Cd(II) and Pb(II), respectively. The limits of detection after 240 s deposition time for Cd(II) and Pb(II) were 0.9 and 0.1 µg L−1, and sensitivities between 1.5 and 3 times higher than those displayed by SPCEbare, SPCNFEbare, and 2D Sbexf-SPCE were obtained. Finally, the 2D Sbexf-SPCNFE was successfully applied to the determination of Cd(II) and Pb(II) traces in a certified estuarine water sample.

The practical application of a novel, eco-friendly electrochemical sensor based on low-dimensional structures, spherical glassy carbon microparticles, and multiwall carbon nanotubes is described. This sensor, modified with a bismuth film, was used for the determination of Cd(II) by the anodic stripping voltammetric method. The instrumental and chemical factors influencing the sensitivity of the procedure were thoroughly investigated and their most favorable values were selected (acetate buffer solution pH = 3 ± 0.1; 0.15 mmol L−1 Bi(III); activation potential/time: −2 V/3 s; accumulation potential/time: −0.9 V/50 s). Under the selected conditions, the method exhibited linearity in the range of 2 × 10−9 to 2 × 10−7 mol L−1 Cd(II) with a detection limit of 6.2 × 10−10 mol L−1 Cd(II). The results obtained also showed that the application of the sensor for Cd(II) detection did not experience any significant interference in the presence of a number of foreign ions. The applicability of this procedure was evaluated using TM-25.5 Environmental Matrix Reference Material and SPS-WW1 Waste Water Certified Reference Material as well as river water samples through addition and recovery tests.

A measurement and speciation procedure for the determination of total mercury (HgTOT), inorganic mercury (HgIN), and methylmercury (CH3Hg) was developed and the applicability for on-site determination was demonstrated. A simple, portable sample pretreatment procedure was optimized to extract the analytes. Home-made columns, packed with a new sorbent material called CYXAD (CYPHOS 101 modified Amberlite XAD), were used to separate the two forms of the analyte. HgTOT and CH3Hg were determined by anodic stripping voltammetry (ASV), using a solid gold electrode (SGE). Two certified reference materials (BCR-463 Tuna Fish and Tuna Fish ERM-CE 464) and eight fresh fishes were analyzed. Then, the results that were obtained following the optimized portable procedure were compared with the concentrations obtained, using a direct mercury analyzer (DMA). This quantification, using the two techniques, demonstrated the good performance of the proposed method. [ABSTRACT FROM AUTHOR]

Drug residues in water represent one of the most serious environmental problems because of their high toxicity to the biological system. Thus, this study reports a low-cost strategy for fast and precise analysis of β- blocker timolol maleate (TM) using differential pulse anodic stripping voltammetry (DP ASV) at a bare glassy carbon electrode (GCE). At the optimised solution pH 7.2 and other analytical parameters (accumulation time, deposition potential, scan rate, and pulse amplitude), a well-defined oxidation peak was observed at 0.85 V vs Ag/AgCl electrode. The linear calibration range for TM at 0.85 V vs. Ag/AgCl electrode was found to be 5.0 × 10−7 – 1.3 × 10−4 mol L−1 (0.21–56.2 μg mL−1) (R2 = 0.9947) with lower limits of detection (LOD) and quantitation (LOQ) of 2.7 × 10−7 (0.12) and 8.99 × 10−7 mol L−1 (0.39 μg mL−1), respectively. The developed assay was satisfactorily applied for trace determination of TM residues in biological fluids (urine), environmental water samples and eye drop with good recoveries (90.5 ± 0.66–106 ± 0.66%), demonstrating good accuracy and applicability of the proposed method as an effective and reliable electrochemical sensor for analysis of TM in complex matrices. Common organic and inorganic compounds did not interfere with TM in its determination. The established strategy was validated using the official HPLC method. Analysis results obtained by the present method were comparable to those obtained using the official method; indicating that the proposed method could be used as an alternative method for the routine quality control of the drug in complex matrices. Chromatographic methods are still more precise, while electrochemical sensors are promising for the analyte determination as they have reduced analytical time, low cost and reproducible. The proposed sensor also demonstrated excellent precision, selectivity, and reproducibility for TM determination. [ABSTRACT FROM AUTHOR]

The work reported here exploits the extraordinary features of graphene nanoribbons (GNR) and well‐known conductive polypyrrole (PPy) polymer to develop a very good electrochemically active composite for sensing metal ions. A strong hydrogen bond and π‐π interaction between the two components facilitates an enhanced conductive 3D network that has been used to design and fabricate an electrochemical sensor for selective and sensitive determination of Pb2+ ions by differential pulse voltammetry (DPV). The probe has been further extended to simultaneously detect Zn2+, Cd2+, As2+, Cu2+, Pb2+, Fe2+ and Hg2+ ions. Moreover, the larger effective surface area, higher porosity and chelating groups of composite promotes better adsorption‐stripping process of Pb2+ ions, leading to a high detection limit of 0.03 nM with a sensitivity of 0.7557 μA μM−1cm−2. This study is extended to detect heavy metal ions in lake water samples, demonstrating promising applications in real time (environmental) samples, and the study shows a deviation of ≈10 %, when validated with atomic absorption spectroscopy studies. [ABSTRACT FROM AUTHOR]

Heavy metal ions contamination is an ever‐growing threat to human health and ecosystems. Analytic sensing of heavy metal ions is a prerequisite step toward addressing this challenge. Electroanalytical technique is an effective and convenient way to detect heavy metal ions. Especially, stripping voltammetry techniques have been utilized for sensing metal ions at trace levels in different sample matrices. The choice of the working electrode materials plays a decisive role in the precision and sensitivity of stripping voltammetry. Post‐transition metals (including elements in group 12) are elements with low melting points, demonstrating unique properties including amalgamation with heavy metal ions that enhance the performance of stripping voltammetry during the pre‐concentration step, which make them particularly suitable for heavy metal ion sensing. Here, for better understanding the features and advantages of post‐transition metals in stripping voltammetry, eight classes of working electrodes based on zinc (Zn), mercury (Hg), gallium (Ga), indium (In), tin (Sn), lead (Pb), antimony (Sb), and bismuth (Bi), are reviewed, with their efficiency and effectiveness compared and recent progresses discussed. Additionally, liquid metal electrodes based on post‐transition metals and alloys are also presented. This review provides viable directions for future development of heavy metal ion sensors based on post‐transition metals. [ABSTRACT FROM AUTHOR]

The technical legal acts that regulate the quality and safety parameters of mineral waters out were analyzed. Seven samples of mineral waters produced in Belarus, Russia, and Georgia were studied. Analysis for heavy metals (Zn, Cd, Pb, Cu, and Hg) was performed by stripping voltammetry, for sulfates, by spectrophotometry, and for total mineralization, by conductometry. The pH values were measured by direct potentiometry. Comparative safety assessment of packaged mineral waters was performed. [ABSTRACT FROM AUTHOR]

Thin-film disposable screen-printed electrodes modified in situ with bismuth and mercury coatings to enhance the simultaneous sensitivities and the limits of detection of cadmium(II), lead(II), copper(II), and zinc(II) were prepared using anodic stripping voltammetry. Whether the films coated were properly adhered to the surface were checked by energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The optimum conditions for the best performance of the sensor were investigated. The modification with Bi/Hg film electrode exhibited good analytical performance, with excellent repeatability (RSD < 4.0%), reproducibility (RSD < 4.0%), and reasonable interferences by various inorganic species. Bi/Hg–SPC electrode also offers low detection limits for Zn(II), Cd(II), Pb(II), and Cu(II), i.e., 0.97 ppb, 0.16 ppb, 0.082 ppb, and 0.64 ppb, respectively. The developed method was applied to a certified reference water sample and a surface water sample taken from the environment by standard addition method and the results are satisfactory. Analytical results obtained with the sensor are comparable to those obtained by the inductively coupled plasma mass spectrometry. [ABSTRACT FROM AUTHOR]