Differential Pulse Anodic Stripping Voltammetry Research Articles

Co-electrodeposition of poly(Eriochrome black T) and copper oxide nanocomposite on the graphenized pencil electrode for enhanced anodic stripping voltammetric analysis of cadmium and lead in water samples

In this study, poly(Eriochrome Black T) /copper oxide nanocomposites were simultaneously electrodeposited on a graphenized pencil electrode (GPE/PEBT/CuO) for sensitive determination of Cd2+ and Pb2+ in water samples. Active surface area of the prepared electrode was remarkably increased in comparison with GPE/Cu and GPE/PEBT. Under the optimized conditions including accumulation time of 200 s, accumulation voltage of −1.0 V and pH 6, the prepared GPE/PEBT/CuO was utilized for Cd2+ and Pb2+ determination by differential pulse anodic stripping voltammetry with good linearity in the concentration range of 7.8–78 µg/L and 22–220 µg/L, detection limit of 1.8 µg/L and 6.85 µg/L and sensitivity of 0.1081 µA µg−1 L and 0.0394 µA µg−1 L respectively. The method was properly utilized for Cd2+ and Pb2+ detection in tap and river water samples with satisfactory results.

Co-Deposition of Bimetallic Au-Pt with L-Cysteine on Electrodes and Removal of Copper by Iron Powder for Trace Aqueous Arsenic Detection

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal ions (especially copper ions). In this study, bimetallic AuPt nanoparticles are electrochemically modified with screen printing electrodes. What’s more, L-cysteine also self-assembles with AuNPs through Au-S bond to enhance the electrochemical performance. To overcome the interference of Cu (II) in the sensing process, the reduced iron powder was chosen to remove Cu (II) and other oxidizing organics in aqueous solutions. The lowest detectable amount is 0.139 ppb, a linear range of 1~50 ppb with superlative stability by differential pulse anodic stripping voltammetry. Fortunately, the reduced iron powder could eliminate the Cu (II) with no effect on the As (III) signal.

Ultra-sensitive detection of cadmium and lead in water using crown ether gel electromembrane extraction coupled with miniaturized electrochemical system

This study presents the development of an electrochemical technique combined with gel electromembrane extraction (G-EME) for the simultaneous detection of cadmium and lead in environmental water samples. Crown ether (18C6) was added to the gel as a complexing agent and cationic carrier. The electrochemical responses were evaluated using differential pulse anodic stripping voltammetry (DPASV) across various pH levels and deposition times. The most sensitive response (acetate buffer pH 4, deposition time 90 s) was selected for the development of the G-EME process. By applying a 30 V electrical potential across the gel membrane containing 1 % (w/v) of 18C6 for 10 min, positively charged Cd2+ and Pb2+ ions migrated from the donor phase (pH 5.0) through the 18C6@gel membrane (pH 5.0) into the acceptor phase (pH 5.0). This resulted in a linear range from 0.3 to 5 µg/L for Cd2+ and 0.5 to 5 µg/L for Pb2+, with detection limits of 0.10 µg/L and 0.19 µg/L, respectively— up to 120 times more sensitive than direct electrochemical measurements. Furthermore, the proposed technique maintained selectivity for cadmium and lead, despite the presence of other potential heavy metal ions in the environment.

A Nafion/BiVO4-COOH-MWCNTs/GCE for the sensitive determination of Cd2+ and Pb2+ by DPASV

BiVO4 was hydrothermally prepared and then ultrasonically mixed with carboxylated multiwalled carbon nanotubes (COOH-MWCNTs) to yield a BiVO4-COOH-MWCNTs composite. The composite were cast-coated on a glassy carbon electrode (GCE) to yield a BiVO4-COOH-MWCNTs/GCE, and then a Nafion solution was cast-coated on the BiVO4-COOH-MWCNTs/GCE to yield a Nafion/BiVO4-COOH-MWCNTs/GCE. The related materials and electrodes were characterized by field emission scanning electron microscopy, X-ray diffractometer and electrochemical methods. Under the optimal experimental conditions, Cd2+ and Pb2+ were analyzed by differential pulse anodic stripping voltammetry on the Nafion/BiVO4-COOH-MWCNTs/GCE, giving a linear detection range (LDR) from 10.0 nM to 2.00 μM and a limit of detection (LOD, S/N = 3) of 0.5 nM for Cd2+, as well as a LDR from 10.0 nM to 1.00 μM and a LOD of 0.9 nM for Pb2+. The Nafion/BiVO4-COOH-MWCNTs/GCE exhibited good selectivity, stability and reproducibility and returned satisfactory results of determining Cd2+ and Pb2+ in seafood samples.

Stable sandwich-type electrochemical lead ions sensor based on bismuth-metal organic framework and Mxene

For electrochemical Pb2+ detection, high sensitivity and stability are essential owing to the mutagenicity, carcinogenicity, and teratogenicity of aqueous Pb2+ ions. Herein, a three-dimensional bismuth-containing metal-organic framework (Bi-MOF) was synthesized using a hydrothermal method, followed by post-synthetic functionalization with thiol (-SH) groups. A sandwich-type Bi-MOF-SH/Mx/Bi-MOF-SH/GCE multilayer sensitive electrochemical sensor was then constructed on the surface of the glassy carbon electrode for Pb2+ detection. Differential pulse anodic stripping voltammetry (DPASV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to evaluate the performance of the sensor. The developed multilayer sensor demonstrated an exceptionally high current response, good sensitivity (0.03–20.0 μg/L), and an ultra-low level of detection of 0.012 μg/L (S/N=3) towards Pb2+ ions. The as-prepared electrode showed high stability, repeatability, and selectivity among possible interfering ions (Na+, Ca2+, Cu2+, Zn2+, K+, Mg2+, Al3+, and Cd2+), suggesting potential for use in real-world applications.

Highly sensitive determination of trace arsenic(III) onto carbon paste electrode modified with graphitic carbon nitride decorated Fe-MOF

An effective electrochemical sensor was developed to detect and determine of the As(III) by modifying the carbon paste electrode (CPE) with graphitic carbon nitride decorated with iron-based metal-organic frameworks (Fe-MOF/g-C3N5). The differential pulse anodic stripping voltammetry (DPASV) method was used to analyze As(III) ions in a phosphate buffer solution (0.10 M, pH = 5). Fe-MOF/g-C3N5/CPE showed high sensitivity (4.24 μA μg−1 L), satisfactory linear range (0.50 μg L−1–5.00 μg L−1 and 5.00 μg L−1–30.00 μg L−1), and low detection limit (LOD, 0.013 μg L−1). The prepared sensor was showed an excellent repeatability and selectivity, and successfully used for determination of the As(III) ion in ambient waters and apple juice samples.

Copper Adsorption by a Clay from Central Ivory Coast: Analysis by Differential Pulse Anodic Stripping Voltammetry

Heavy metals such as copper are not only a problem for air pollution: they are bio persistent, disrupt ecosystems, damage soils, surface waters, forests, and crops, and accumulate in the food chain. The aim was to propose effective methods for quantifying and decontaminating wastewater containing copper. In this study, the treatment of copper(II)-containing wastewater was carried out using clay, and the concentration of Cu2+ was monitored using the differential pulse anodic stripping voltammetry method. Physical characterization revealed the porous nature of our clay. Furthermore, the kinetic study of Cu2+ adsorption on clay is adapted to the pseudo-order 2 kinetic model, and the appropriate isotherm is that of Langmuir with an equilibrium time of 20 min. Cu2+ adsorption is maximal at pH = 6. The maximum monolayer adsorption capacity was found to be 66.54 mg/g.

Effect of electrophoretic deposition for selective detection of Pb2+ ions using nitrogen and sulphur-doped reduced graphene oxide

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+ ionsusing 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.

Electrochemical sensing of Pb2+, Cu2+, and Hg2+ by an aminoclay-based porous covalent organic polymer/ multi-walled carbon nanotubes modified glassy carbon electrode

We present a novel electrochemical sensor for the simultaneous detection of Lead (Pb2+), Copper (Cu2+), and Mercury (Hg2+) ions in seafood samples using differential pulse anodic stripping voltammetry (DPASV) technique. The sensor incorporates an aminoclay-based porous covalent organic polymer (AC-PCOP) derived from the polymerization of aminoclay and 1,3,5-benzenetricarboxylic acid (trimesic acid). To enhance conductivity, the AC-PCOP is combined with multi-walled carbon nanotubes (MWCNTs) and utilized for modifying the surface of the glassy carbon electrode (GCE). The AC-PCOP was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and infrared spectroscopy (IR). These analyses confirmed the presence of a hierarchical architecture in the AC-PCOP, which exhibited a spherical shape. The proposed modifier facilitates the deposition-stripping process and electron diffusion between electrolyte and heavy metal ions. Optimized conditions yielded limit of detections (LODs) of 0.0006, 0.0016, and 0.0003 nM, with linear ranges from 0.002 to 1000 nM, 0.005 to 1000 nM, and 0.001 to 1000 nM for Pb2+, Cu2+, and Hg2+, respectively. The sensor successfully measured these ions in seafood samples. Control experiments and validation were performed using cold vapor atomic absorption spectrometry (CVAAS) to determine the ions in the chosen food samples.

Development of pectin-based gel electrolyte for wireless electrochemical determination of cadmium and lead using smartphone

A portable device offering effortlessness, mobility, and affordability for real-time and on-site monitoring of heavy metals is currently in great demand to maintain environmental sustainability. Herein, a platform utilizing a biopolymeric gel-based electrolyte for the on-field simultaneous determination of Cd(II) and Pb(II) is described. Pectin, a natural polymer, was exploited as a chemical delivery medium on account of its biodegradability, environmental friendliness, and rapid dissolving characteristics. The gel electrolyte was prepared by having pectin dissolved in KCl mixed with Sb(III)–Bi(III) bimetallic alloy solution, and casted onto a paper substrate. An in situ bimetallic alloy and pre-mixed bismuth nanoparticles modified screen-printed graphene electrode (Sb–Bi/BiNP/SPGE) were employed to enhance the electrochemical signals of Cd(II) and Pb(II) for the differential pulse anodic stripping voltammetry (DPASV). It was demonstrated that the platform was capable of generating sharp and well-defined current signals, achieving the low detection limits of 50.98 ng mL−1 for Cd(II) and 40.80 ng mL−1 for Pb(II). The reproducibility, as indicated by the relative standard deviation, was found to be less than 10.4 % (n = 10) for the developed gel-based device when coupled with a wireless near field communication (NFC) potentiostat. Lastly, the obtained sensor was applied for quantification of Cd and Pb in potentially contaminated groundwater samples. The recoveries obtained were satisfactorily within the acceptable range. The newly designed platform exhibited several advantages, including small sample volume (μL), low-cost, no sample preparation requirements, and being environmentally friendly. The convenience of a portable device utilizing the proposed biopolymeric gel-based electrolyte for on-field analysis makes it highly appealing for various applications.

Adaptive Fabrication of Electrochemical Chips with a Paste-Dispensing 3D Printer.

Electrochemical (EC) detection is a powerful tool supporting simple, low-cost, and rapid analysis. Although screen printing is commonly used to mass fabricate disposable EC chips, its mask is relatively expensive. In this research, we demonstrated a method for fabricating three-electrode EC chips using 3D printing of relatively high-viscosity paste. The electrodes consisted of two layers, with carbon paste printed over silver/silver chloride paste, and the printed EC chips were baked at 70 °C for 1 h. Engineering challenges such as bulging of the tubing, clogging of the nozzle, dripping, and local accumulation of paste were solved by material selection for the tube and nozzle, and process optimization in 3D printing. The EC chips demonstrated good reversibility in redox reactions through cyclic voltammetry tests, and reliably detected heavy metal ions Pb(II) and Cd(II) in solutions using differential pulse anodic stripping voltammetry measurements. The results indicate that by optimizing the 3D printing of paste, EC chips can be obtained by maskless and flexible 3D printing techniques in lieu of screen printing.

Voltammetry determination of Cd(II) and Pb(II) at TiO2/reduced graphene oxide modified electrodes

AbstractIn this article, a TiO2/reduced graphene oxide (rGO) composite was synthesized from rGO and soluble titanium hydroxide‐peroxide complexes. The obtained materials were characterized by X‐ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption, Raman spectroscopy and energy dispersive X‐ray spectroscopy‐elementary mapping. The TiO2/rGO composite was used as an electrode modifier for developing an electrochemical sensor to simultaneous analysis of Cd(II) and Pb(II) by using differential pulse anodic stripping voltammetry (DP‐ASV). Under optimal conditions, the linear correlation between the stripping peak current and the metal ion concentration is good in the range of 5–100 ppb for both metals (R2 ≥ 0.998), and a low detection limit (3.17 ppb for Cd(II) and 2.42 ppb for Pb(II)) was obtained. The interference study revealed that some metal cations had little influence on the DP‐ASV signals of Cd(II) and Pb(II). In addition, the developed electrode exhibited satisfied reproducibility and repeatability. The TiO2/rGO‐modified electrode was tested toward the detection of Cd(II) and Pb(II) in river waters and the obtained exceptional recoveries and results were further associated with AAS results. This study indicates that the TiO2/rGO composite might be an alternative for practical applications in the electrochemical determination of heavy metal ions in aquatic solutions.

Synthesis, properties, and applications of all-solid-state reference electrode based on AgTi2(PO4)3

High-density AgTi2(PO4)3 as a solid electrolyte was synthesised by a high-temperature solid-state process. The optimal sintering temperature was determined to obtain the best structural and electrical performance. Based on the as-prepared AgTi2(PO4)3 fast-ion conductor, a new type of all-solid-state reference electrode was prepared, and its electrochemical properties, such as cyclic voltammetry curves and potentials at varying pH, were investigated. A pH sensor was designed by combining an AgTi2(PO4)3 reference electrode with an Ir/IrO2 pH electrode. This pH sensor exhibited a good linear response to pH values in aqueous solutions and simulated seawater samples. In addition, a metal ion sensor, comprising the as-fabricated solid-state reference electrode, a Pt counter electrode, and a glassy carbon working electrode, was employed to quantify Cu2+, Hg2+, and Pb2+ concentrations using differential-pulse anodic stripping voltammetry. The resulting peak currents correlated with the metal ion concentrations and exhibited a low detection limit, good linearity, and wide detection range, which is suitable for performing chemical analysis in harsh marine environments.

Electrocatalytic detection of Hg(II) using a platinum electrode modified with composite film of cobalt(II) phthalocyanine tetra-substituted with 1-(methoxymethyl)-benzotriazole groups and co-electropolymerized polypyrrole

The presence of mercury adversely affects the daily lives of humankind due to its acute toxicity and environmental persistence. Therefore, the development of cost-effective smart materials which can allow the real time, ultrasensitive and discriminatory monitoring of mercury concentrations in industrial and municipal water treatment plants is an imperative. It is foreseen that this proposed water quality assurance measure will be of utmost importance to identify the culprits for the wide prevalence of this heavy metal ion in the environment. Herein, a platinum electrode (Pt) was modified via the simultaneous electropolymerization of polypyrrole (PPy) and the co-electrodeposition of tetra-[4-((1H-benzotriazole)methoxy)phthalocyaninato]cobalt(II) (CoPc-Bzt, 2, (Btz = benzotriazole)). The complementary electrode modification processes were performed in a 1:1 (v: v) DMF: acetonitrile containing 1 M tetrabutylammonium hexafluorophosphate electrolyte solution over 20 cycles using cyclic voltammetry to afford the chemically modified electrode (CME), Pt|PPy/2. Differential pulse anodic stripping voltammetry (DPASV) was used to detect Hg(II) ions using the CME within a 10 µM to 100 µM linear range while calculated limits of detection and quantification (LOD and LOQ) were determined as 3.11 and 10.00 µM, respectively. The analytical performance of the CME rendered a statistically accepted percentage recovery (97.4%) whereas that of Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) is 112.3%.

Synthesis of AgNPs/MnO2/rGO composite materials with adsorption properties and their application in analysis of anti-inflammatory and antibiotic agents

In this article, AgNPs and MnO2 were successively synthesized on the Graphene oxide (GO) substrate using an in situ method. The AgNPs/MnO2/GO nanocomposite material was modified onto the surface of a glassy carbon electrode (GCE) and the material was electrochemically reduced on the electrode surface. The material obtained after reduction was called AgNPs/MnO2/rGO, which was confirmed by X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) to examine the chemical bonding and by scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS) to demonstrate the elemental characteristics of the material. In addition, X-ray photoelectron spectroscopy (XPS) analysis was performed to determine the elemental composition, chemical state, and electronic state of the elements on the surface of the material. The application of the reduced material was for the analysis of Piroxicam and Ofloxacin using the differential pulse anodic stripping voltammetry (DP-ASV) method. The investigation of pH and scan rate (v) indicated that the synthesized material had adsorption properties and was applied for the analysis of the anti-inflammatory drug Piroxicam and the antibiotic Ofloxacin.

Simultaneous effect of pH, deposition time, deposition potential, and step potential on the stripping peak current of lead and cadmium by response surface methodology

In this paper, a simple voltammetric method has been reported for the lead, and cadmium determination using platinum nanoflowers modified glassy carbon electrode (PtNFs/GCE). The effects of pH, deposition time, deposition potential, step potential were investigated on the stripping peak current of lead, and cadmium based on response surface methodology (RSM). The results of RSM analysis and analysis of variance (ANOVA) have shown that the experimental data could be well described by quadratic regression equations with determination coefficients (R2) of 0.935, and 0.972 for the stripping peak current of lead, and cadmium, respectively. Results of the statistical analysis showed that the fit of the model was good in all cases. The maximum stripping peak current of the lead, and cadmium of 5.54µA, and 2.81µA, respectively were obtained at the optimum levels of process variables (pH (4.72), deposition potential (-1.14V), deposition time (120s), step potential (7mV)). Testing the model to analyze lead, and cadmium on the PtNFs/GC electrode using differential pulse anodic stripping voltammetry (DPASV) and obtained with the stripping peak current of the lead, and cadmium of 5.43µA, and 2.75 µA, respectively.

Heavy metal sensing in plant and soil solutions using carbon fiber electrode

Analysis of trace level metals in environmental samples (e.g., soil, water, and plant samples) is important for assessing environmental quality and food safety. This paper reports a non-toxic, eco-friendly, and cost-effective sensing method, capable of in-situ detection of microgram per liter (µg/L) levels of heavy metal ions in plant and soil solutions using carbon fiber electrodes (CFEs) produced without using any microfabrication. The electrochemical behaviors of the CFEs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. As proof of principle, the CFEs were validated for sensing selected heavy metals in buffer solutions as well as in extracted plant and soil solutions using differential pulse anodic stripping voltammetry (DP-ASV). Experimental results confirm that the CFEs were able to simultaneously measure cadmium (Cd), lead (Pb), and mercury (Hg) with a detection limit of 2.10, 0.93, and 1.85 µg/L respectively in buffer solution, showcasing good selectivity and sensitivity. The ideal pH range for heavy metal detection was also extensively investigated and was found to be between pH 4.0 and pH 5.0. These findings lay a better foundation towards long-term and stable electrochemical analysis for plant and soil solution matrices.

Didactic experiment for voltametric determination the complexing capacity of natural waters

The titration method can be applied to determine the complexation capacity between metal ions and ligands in natural water samples. The process involves the incremental addition of the metal to the sample containing a specific ligand, resulting in a titration curve that reflects the formation of complexes. The change in the curves slope indicates the saturation of the complexation capacity. In this study, the copper (II) ion was used due to its stability with organic ligands. The titration curve was analyzed to determine the complexation capacity (CC) and conditional formation constant (K) of the complex. Different mathematical treatments are proposed for this analysis. In the described experiment, differential pulse anodic stripping voltammetry was used to determine the complexation capacity of humic substances in natural waters. Experimental parameters such as pH, supporting electrolyte concentration, and volume of additions were previously optimized for the voltammetry technique. The obtained data were processed and analyzed, resulting in titration curves and voltammograms. The analysis of the curves allowed for the calculation of the complexation capacity and conditional stability constant of the formed complex. The results demonstrate the feasibility of the method as a didactic experiment for the voltammetric determination of natural water complexation capacity.

Simultaneous electrochemical sensing of heavy metal ions (Zn2+, Cd2+, Pb2+, and Hg2+) in food samples using a covalent organic framework/carbon black modified glassy carbon electrode

In this study, for the first time, a selective electrochemical sensor by glassy carbon electrode (GCE) modified with the covalent organic framework (COF) and carbon black (CB) was introduced and applied to simultaneous sensing of Zn2+, Cd2+, Pb2+, and Hg2+ via differential pulse anodic stripping voltammetry (DPASV). The COF is supplied through a condensation reaction between melamine and trimesic acid. The COF and CB, which are used to modify the GCE surface, increase electrochemical activity. The linearity to determine ions was achieved as Zn2+: 0.009–1100 nM, Cd2+: 0.005–1100 nM, Pb2+: 0.003–1100 nM, and Hg2+: 0.001–1100 nM. Besides, the detection limits for Zn2+, Cd2+, Pb2+, and Hg2+ have obtained 0.003, 0.002, 0.001 and 0.0003 nM, respectively. The CB-COF/GCE was applied to simultaneously measure the ions in food samples. For validation, atomic absorption spectrometry (AAS) was applied to measure the amount of target metal ions as a standard method in real samples.

Bismuth Nanoparticles Modified Indium Tin Oxide-Coated with Polyethene Terephthalate Electrode Using Hydrothermal Method for Pb Detection

Heavy metal elements are elements with comparatively high density and are dangerous even in a minimal quantity as they can persist in the environment. The electrochemical sensor can play an essential role in detecting heavy metals. However, the electrochemical sensor has drawbacks, such as low sensitivity and a high detection limit. Bismuth nanoparticles (BiNPs) can improve the sensitivity and lower the detection limit of an electrochemical sensor by modifying the working electrode. In this study, BiNPs produced by the hydrothermal method were drop-casted on the indium-tin-oxide (ITO) coated with polyethene terephthalate (PET) film (BiNPs/ITO-PET). The effect of the hydrothermal reaction was studied by varying the hydrothermal reaction period (5, 6, 7, and 8 h). X-ray Diffraction (XRD) was used to characterize the phase presence, and the morphology of BiNPs was characterized using a transmission electron microscope (TEM). The BiNPs/ITO-PET electrode was subjected to electrochemical characterization using cyclic voltammetry (CV) and the detection of Pb(II) using differential pulse anodic stripping voltammetry (DPASV). The BiNPs/ITO-PET electrode showed good electrochemical performance in detecting Pb(II).