Electroanalysis最新文献

Nicotinic acid (NA) is a free form of vitamin B3, and its altered levels in the human body can lead to serious clinical complications. Therefore, analytical methods to monitor this molecule must be developed. Voltammetric techniques have become viable because of their short analysis time and low associated cost. Thus, in this study, murumuru biochar (MBC) electrode was evaluated for NA determination using the differential pulse voltammetry (DPV) technique. The proportion of carbon paste was adjusted through the design of mixtures, resulting in proportions of 36.6% binder, 31.7% MBC, and 31.7% graphite. KCl (0.1 mol L⁻¹) acidified with HClO₄ at pH 2 was selected as the supporting electrolyte. DPV analyses were performed with a step of 5 mV, a pulse amplitude of 100 mV, a time interval of 75 ms, and a modulation time of 2 ms. The analytical curve presented an r² of 0.999 in a linear range from 4 to 100 μmol L⁻¹. The limit of detection (LOD) was 0.36 μmol L⁻¹, and the limit of quantification (LOQ) was 1.20 μmol L⁻¹. Based on the obtained analytical curve, NA was quantified in samples of multivitamins and synthetic urine, and satisfactory results were shown.

This work presents a novel automated voltammetric system that achieves a significant reduction in required sample volume while maintaining measurement quality for trace metal analysis in marine environments. Through modifications to a commercial voltammetric system, including a custom-designed measurement cell and miniaturized reference electrode, the system enables measurements with volumes as low as 1 mL, representing a 90% reduction compared to conventional setups. When integrated with automated sample handling, the system requires 3 mL for concentration measurements and 28.5 mL for complete organic complexation studies—a 70% and 78% reduction, respectively, from traditional methods. The system's performance was validated through copper measurements across diverse sample matrices, including certified reference materials, achieving an average deviation of 8.2% from certified values. Comparative measurements of copper-binding organic ligands in seawater samples demonstrated analytical quality comparable to manual measurements. The automation capabilities reduce analyst labor by up to 89% for concentration measurements and 87% for complexation studies. The system's modular design allows for easy component replacement and adaptation to different measurement procedures. This development particularly enables the investigation of trace metal speciation in sample-limited environments, such as marine porewaters, where traditional voltammetric methods have been constrained by volume requirements. Initial measurements of copper complexation in marine porewaters demonstrate the system's potential for expanding our understanding of sedimentary trace metal cycling.

This work presents a novel automated voltammetric system that achieves a significant reduction in required sample volume while maintaining measurement quality for trace metal analysis in marine environments. Through modifications to a commercial voltammetric system, including a custom-designed measurement cell and miniaturized reference electrode, the system enables measurements with volumes as low as 1 mL, representing a 90% reduction compared to conventional setups. When integrated with automated sample handling, the system requires 3 mL for concentration measurements and 28.5 mL for complete organic complexation studies—a 70% and 78% reduction, respectively, from traditional methods. The system's performance was validated through copper measurements across diverse sample matrices, including certified reference materials, achieving an average deviation of 8.2% from certified values. Comparative measurements of copper-binding organic ligands in seawater samples demonstrated analytical quality comparable to manual measurements. The automation capabilities reduce analyst labor by up to 89% for concentration measurements and 87% for complexation studies. The system's modular design allows for easy component replacement and adaptation to different measurement procedures. This development particularly enables the investigation of trace metal speciation in sample-limited environments, such as marine porewaters, where traditional voltammetric methods have been constrained by volume requirements. Initial measurements of copper complexation in marine porewaters demonstrate the system's potential for expanding our understanding of sedimentary trace metal cycling.

Over the past century, human activities have contributed to the widespread rise in tellurium contamination in the environment and water bodies. Certain forms of tellurium are toxic, and exposure to these forms can have adverse health effects. To address this issue, an electrochemical sensor was developed using a bare indium tin oxide (ITO) working electrode and square wave stripping voltammetry for the detection and quantification of Te(IV) ions. For Te(IV) detection, a deposition potential of −0.9 V was applied to the working electrode for 180 s. Calibration curves of peak current and peak area versus Te(IV) concentration were constructed in acetate buffer at pH 4.50. The electrochemical sensor achieved a detection limit of 0.5 ppb, comparable to other studies with different working electrodes. Interference studies were conducted to investigate the impact of other metal ions on the quantifiable stripping peak of Te(IV).

Polyanions have been introduced as replacements for poly(vinyl chloride) (PVC) and potassium tetrakis(4-chlorophenyl)borate (KTpClPB) in the preparation of solid contact potassium-ion selective electrodes (K⁺-ISEs). Partly carboxylated PVC (PVC-COOH) and a fully charged polyanion, sodium poly(4-styrenesulfonate) (NaPSS), were used, culminating in the fabrication of three-component ion-selective membranes (ISMs). The comparison with a PVC-based ISM showed significantly reduced potential drifts during conditioning (from ∼1.3 to ∼0.2 mV/h) and a constant drift rate. Reduced drift is attributed to the presence of counter-charges in the polymer and the large molecular weight of the polyanions, therefore decreasing the leaching of the components resulting in degradation of the membrane. The ISEs utilizing the hydrophilic and highly charged NaPSS as the polymer matrix exhibit similar water layer formation compared to the PVC-based ISEs, and maintained a sensitivity of 54 ± 1 mV/dec and a selectivity over sodium of −3.1 (log $$) after 1 week in solution, suggesting an alternative approach to the standard membrane preparation protocol.

Polyanions have been introduced as replacements for poly(vinyl chloride) (PVC) and potassium tetrakis(4-chlorophenyl)borate (KTpClPB) in the preparation of solid contact potassium-ion selective electrodes (K⁺-ISEs). Partly carboxylated PVC (PVC-COOH) and a fully charged polyanion, sodium poly(4-styrenesulfonate) (NaPSS), were used, culminating in the fabrication of three-component ion-selective membranes (ISMs). The comparison with a PVC-based ISM showed significantly reduced potential drifts during conditioning (from ∼1.3 to ∼0.2 mV/h) and a constant drift rate. Reduced drift is attributed to the presence of counter-charges in the polymer and the large molecular weight of the polyanions, therefore decreasing the leaching of the components resulting in degradation of the membrane. The ISEs utilizing the hydrophilic and highly charged NaPSS as the polymer matrix exhibit similar water layer formation compared to the PVC-based ISEs, and maintained a sensitivity of 54 ± 1 mV/dec and a selectivity over sodium of −3.1 (log $$) after 1 week in solution, suggesting an alternative approach to the standard membrane preparation protocol.

Over the past century, human activities have contributed to the widespread rise in tellurium contamination in the environment and water bodies. Certain forms of tellurium are toxic, and exposure to these forms can have adverse health effects. To address this issue, an electrochemical sensor was developed using a bare indium tin oxide (ITO) working electrode and square wave stripping voltammetry for the detection and quantification of Te(IV) ions. For Te(IV) detection, a deposition potential of −0.9 V was applied to the working electrode for 180 s. Calibration curves of peak current and peak area versus Te(IV) concentration were constructed in acetate buffer at pH 4.50. The electrochemical sensor achieved a detection limit of 0.5 ppb, comparable to other studies with different working electrodes. Interference studies were conducted to investigate the impact of other metal ions on the quantifiable stripping peak of Te(IV).

This study introduces, for the first time, a novel voltammetric strategy based on integrating a stencil-printed electrode (StPE) with a hydrogel (HG) serving as the electrolytic medium. The electrode was fabricated using a laboratory-made conductive ink composed of graphite (as the conductive material), glass varnish (as the polymeric binder), and an acetate sheet (as the substrate). The HG selected for this study consisted of sodium polyacrylate, a polymer commonly used for plant irrigation and decorative purposes due to its high water-retention capacity. The StPE sensors were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), while the HG was thoroughly characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). Additionally, the kinetic parameters of HG absorption were evaluated by fixing the hydration time at 6 h. As a proof of concept, uric acid (UA), a clinically relevant biomarker, was selected as the model analyte. A differential pulse voltammetry (DPV) method was developed to monitor UA in synthetic urine samples. The sensor exhibited a linear response in the concentration range of 2.0–10.0 µmol L⁻¹, with excellent detectability (limit of detection = 0.146 µmol L⁻¹). The method also demonstrated good precision (RSD < 4.4%) and accuracy, with recovery rates ranging from 94% to 105% in spiked samples. The sustainable characteristics of the StPE sensor, combined with its effective performance in the HG medium, highlight the potential of this platform for electrochemical analysis of other clinically, environmentally, and forensically relevant analytes, offering broad opportunities for future innovations.

This study introduces, for the first time, a novel voltammetric strategy based on integrating a stencil-printed electrode (StPE) with a hydrogel (HG) serving as the electrolytic medium. The electrode was fabricated using a laboratory-made conductive ink composed of graphite (as the conductive material), glass varnish (as the polymeric binder), and an acetate sheet (as the substrate). The HG selected for this study consisted of sodium polyacrylate, a polymer commonly used for plant irrigation and decorative purposes due to its high water-retention capacity. The StPE sensors were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), while the HG was thoroughly characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). Additionally, the kinetic parameters of HG absorption were evaluated by fixing the hydration time at 6 h. As a proof of concept, uric acid (UA), a clinically relevant biomarker, was selected as the model analyte. A differential pulse voltammetry (DPV) method was developed to monitor UA in synthetic urine samples. The sensor exhibited a linear response in the concentration range of 2.0–10.0 µmol L⁻¹, with excellent detectability (limit of detection = 0.146 µmol L⁻¹). The method also demonstrated good precision (RSD < 4.4%) and accuracy, with recovery rates ranging from 94% to 105% in spiked samples. The sustainable characteristics of the StPE sensor, combined with its effective performance in the HG medium, highlight the potential of this platform for electrochemical analysis of other clinically, environmentally, and forensically relevant analytes, offering broad opportunities for future innovations.

This study evaluates zinc anode substrate materials for zinc–nickel flow batteries, including stainless steel strip, Cu–Ni–Mn alloy, Monel alloy, and Nickel-plated strip. Monel alloy and Nickel-plated steel strip exhibit higher zinc deposition potential, with the Nickel-plated strip showing a low equilibrium potential (E₀ = −1.430 V) and minimal reaction resistance (0.110 Ω), similar to zinc. The Nickel-plated strip also maintains a higher battery capacity after cycling, likely due to the smooth zinc deposition and minimal grain distance, making it the preferred anode substrate.