Differential Pulse Anodic Stripping Voltammetry Research Articles

Ultra-thin silver nanowires’ synthesis in pore-confined space of mesoporous silica thin film

In the present work, we report a synthesis procedure for the preparation of vertically aligned mesoporous silica thin films containing long, nanometer-scale thin silver nanowires inside pores. The inter-channel nanowires had a fine crystalline structure and a diameter of no more than 2 nm. Despite the diameter being the edge of the theoretical possibility of synthesis, the nanowires were stable enough to be observed by transmission electron microscope and could be clearly observed. For the synthesis, we applied the idea of silica nanoreactors, and the procedure consists of two steps: fabrication of an initial organically-functionalized silica thin film containing silver ions distributed regularly inside vertically aligned pores and following thermal decomposition resulting in the decomposition of the organic anchoring groups and the formation of metallic crystalline nanowires from released silver atoms. Both the final nanocomposite and the initial material were studied by means of transition electron microscopy and electrochemical techniques: linear scan and differential pulse anodic stripping voltammetry. The crystallinity of silver nanowires inside silica mesopores was proved by electron diffraction. The spatial confinement realized by silica nanochannels facilitated the stabilization of relatively small and ultra-thin nanowires and the formation of a hexagonal P63/mmc silver crystalline structure instead of the more common Fm3m cubic.

Voltammetric sensing of Cd(II) at ZIF-8/GO modified electrode: Optimization and field measurements

In this work, a metal-organic framework/graphene oxide (MOF(ZIF-8)/GO) nanocomposite was utilized for the electroanalysis of trace level of Cd(II) after modification of a cheap graphite rod electrode (GRE). After closed circuit process on the modified electrode, the differential pulse anodic stripping voltammetry (DPASV) technique was used for measuring of Cd(II). In optimal conditions, the sensor showed a linear dependence of current with concentration range 0.1–30 ppb for Cd(II). Moreover, limit of detection 0.03 ppb were obtained. Besides good selectivity, the sensor also indicated good reproducibility (below 5%). Moreover, the sensor showed satisfactory sensing performance in river, dam and wastewater samples with recovery ranging from 97.2% to 102.4%. Additionally, possible interfering cations were examined, but no significant interference was found. For the detection of trace Cd(II) in real matrices, this sensor illustrated other good merits like high stability, rapidity and simplicity.

Microdroplet anodic stripping voltammetry at the in situ preparing antimony‐modified rotating disk electrode for determination of Cd(II) and Pb(II)

AbstractA simple electroanalytical method for Cd(II) and Pb(II) detection based on differential pulse anodic stripping voltammetry (DPSV) with in situ prepared antimony‐modified glassy carbon rotating disk electrode (in situ Sb‐GC‐RDE) was developed. The electrochemical detection was performed in a microdroplet (50 μL) of 0.01 M hydrochloric acid that is placed between the electrode surface (top) and a Parafilm®‐covered glass slide to maintain a hydrophobic surface (bottom). This method includes a preconcentration process using a membrane filter (MF). The target metal ions were complexed with 1‐(2‐pyridylazo)‐2‐naphthol (PAN) as a chelating agent, which was accumulated on the MF via filtration. The RDE microdroplet anodic stripping voltammetry was suitable for the elution and determination of metal ions accumulated on the MF. The in situ preparation of antimony‐modified electrode allows the use of common GC electrode with high performance. The detection limits for Cd(II) and Pb(II) were 1.4 and 1.1 μg/L, respectively. The proposed method was successfully used in natural water samples for the simultaneous determination of Cd(II) and Pb(II).

A novel electrochemical sensor based on sodium alginate‐decorated single‐walled carbon nanotubes for the direct electrocatalysis of heavy metals ions

AbstractIn recent years, the presence of heavy metal ions in food chains and water poses serious environmental and human health problems. Therefore, there has been a pressing need for fast simple, sensitive, and accurate methods for their detection. In this study a novel electrochemical sensor based on alginate sodium biopolymer decorating single‐walled carbon nanotubes was elaborated for the detection of trace level of heavy metal ions. Different brown algae were used to extract sodium alginate, with Cystoseira being the most common. Due to its high extraction yield and high mannuronate/guluronate (M/G) ratio, Compress a brown algae was chosen to disperse with single‐walled carbon nanotubes. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy were monitored to investigate each surface modification. Differential pulse anodic stripping voltammetry (DPASV) was used to follow the electrochemical heavy metal ions determination. Moreover, the performance of the optimized heavy metal ions sensor in terms of sensitivity, linear range, limit of detection, and reproducibility was investigated. The detection limits were found to be 0.1, 31, and 1 nM for Pb2+, Cd2+, and Cu2+, respectively. The results reported in this work showed good stability, high sensitivity, and appealing inter‐electrode repeatability. Finally, lead detection in tap water was carried out. The metrological performance of the present sensor makes it a good alternative for heavy metal ions detection.

Functionalization of Screen-Printed Electrodes with Grape Stalk Waste Extract-Assisted Synthesized Silver and Gold Nanoparticles: Perspectives of Electrocatalytically Enhanced Determination of Uranyl Ion and Other Heavy Metals Ions.

Recently, nanotechnology and nanoparticles (NPs) such as AgNPs and AuNPs have become important in analytical chemistry due to their great potential to improve the performance of electrochemical sensors. In this work, Ag and Au nanoparticles have been synthesized using a green route in which a grape stalk waste extract is used as a reducing agent to obtain metallic nanoparticles. These NPs were used to customize the surface of commercial screen-printed electrodes (SPCNFEs). The spin-coating method was used to modify commercial SPCNFEs under a nitrogen atmosphere. The resulting electrodes were used in a determination study of Cd(II), Pb(II), and U(VI) with differential pulse anodic stripping voltammetry (DPASV). The customized green AgNPs and AuNPs electrodes presented higher sensitivity and electroanalytical performance than the non-modified SPCNFE. The results showed that the best analytical parameters were obtained with the green, silver nanoparticle SPCNFEs, with a LOD of 0.12 μg L-1 for Pb(II), which is a lower value compared to the most restrictive regulation guidelines. Additionally, the U(VI) ion was successfully determined using the developed G-AgNPs-SPCNFE in spiked tap water, showing comparable results with the ICP-MS technique.

Electrochemical Determination of Vitamin B12 (Cyanocobalamin) using Mercury Nanodroplets Supported at Montmorillonite on a Carbon Paste Electrode (CPE)

A simple and effective electrochemical sensor for cobalt using mercury nanodroplets supported on montmorillonite (MMT) was developed. Physical analyses allowed the identification of crystalline structure, morphology, and presence of mercury structures in MMT-Hg2+ with nanometric dimensions between 3 and 11 nm. Electrochemical responses obtained by differential pulse anodic stripping voltammetry (DPASV) using carbon paste electrode modified with montmorillonite decorated with mercury nanodroplets (CPEM-MT-Hg) toward cobalt (II) provide a limit of detection (LOD) of 3.4 × 10−6 mol L−1, limit of quantification (LOQ) of 1.1 × 10−5 mol L−1, and a linear dynamic range (LDR) from 3.5 × 10−5 to 2.9 × 10−4 mol L−1. The developed method was applied to the determination of cobalt ions in a commercial vitamin B12 sample.

TiO2/Ni–NC Hybrid Derived from Ti3C2TX/NiMOF for Highly Sensitive Electrochemical Sensing of Mercury Ions

Mercury ions (Hg2+) pose serious threats to ecological environment and human health, which lead to the increasing demand for rapid and sensitive detection methods. Herein, an electrochemical sensor based on titanium dioxide/nickel nanoparticles-nitrogen doped carbon (TiO2/Ni–NC) modified glassy carbon electrode (GCE) was developed for the detection of Hg2+. A Ti3C2TX/NiMOF composite was synthesized by in situ growing NiMOF on the multilayered structure of Ti3C2TX. Through a facile pyrolysis treatment, TiO2/Ni–NC was derived from Ti3C2TX/NiMOF. N element doped carbon with a porous structure provided electron transfer channels for the electrochemical reaction and an ideal matrix for immobilizing catalytic sites. The TiO2 and Ni nanoparticles were homogeneously distributed on the carbon matrix, and they exhibited good catalytic activity toward the electrochemical reaction of Hg2+. The accumulation of Hg2+ was promoted due to the chelation with the doped N element. The differential pulse anodic stripping voltammetry (DPASV) method coupled with the TiO2/Ni–NC/GCE sensor was used to determine the concentration of Hg2+. Under the optimal conditions, our proposed method presented a wide detection range (1 nM to 10 μM) and a low detection limit (0.79 nM). The sensor provided a satisfactory recovery in real water sample analysis, demonstrating the feasibility for environmental monitoring applications.

Electrochemical Determination of Hg2+ on a Poly (Eriochrome Blue Black R) Modified Carbon Paste Electrode

In this work a new, simple, fast, and efficient electrochemical approach for the determination of inorganic mercury (Hg2+) using the differential pulse anodic stripping voltammetry (DPASV) technique was presented. This is achieved by modifying the surface of a carbon paste electrode by electropolymerization of Eriochrome blue black R. First, the behavior of Hg2+ on the modified electrode is studied by cyclic voltammetry and electrochemical impedance spectroscopy, to evaluate performance and understand the phenomena that take place on its surface. DPASV is then used to optimize the sensor in HClO4 medium. After optimization, a linear calibration graph was obtained in the concentration range of 1x10-9 to 9x10-9 mol.L-1 with correlation coefficient R2= 0.9975%, the limit of detection (LOD) and the limit of quantification (LOQ) obtained are respectively 3.23x10-10 mol.L-1 and 1.07x10-9 mol.L-1. The relative standard deviation (RSD) for 7 measurements is 3.07%, which proves that this sensor is reproducible. Finally, this method has been successfully applied in real samples of water and the results obtained are satisfactory because the recovery rates of Hg2+ vary from 99.2 to 100.1%.

Benzimidazole-modified polyaniline micro-shells for electrochemical detection of cadmium in aqueous solution

Benzimidazole-functionalized polyaniline (BMPANI) was synthesized by interfacial poly­merization technique and used for electrochemical sensing of cadmium ions in an aqueous solution. The material was characterized for its structural and morphological features using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The BMPANI has a micro-shell structure produced from the self-assembly of the monomer units in solution before the polymerization reaction. The material was trialed for cadmium ion sensing using a BMPANI-modified carbon paste electrode (BMPANI-CPE). Electrochemical techniques, i.e., cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV), were performed to assess the sensing characteristics of the material. Various electrode preparation parameters, i.e., deposition potential, pH of deposition solution, and thickness of the active layer, were optimized to achieve the highest level of sensitivity. The selectivity towards cadmium ions, interference from other ions, as well as stability and reusability of the BMPANI-CPE, were also examined and found to be satisfactory.

Development of a novel sensor based on Bi2O3 and carbonized UIO-66-NH2 nanocomposite for efficient detection of Pb(Ⅱ) ion in water environment

Development of an efficient monitoring technology for rapid detection of toxic Pb(Ⅱ) ion in water environments is extremely important. Here, a novel and highly sensitive sensor was prepared using one-step calcination technique, based on Bi2O3 nanoparticles and carbonized metal–organic framework (MOF) nanocomposite. Scanning electron microscopy, transmission electron microscopy, contact angle and X-ray photoelectron spectroscopy characterization methods were used to analyze the morphology and structure of the prepared materials. Based on the electrical double-layer capacitance theory and Raman spectroscopy, changes to the active sites of different modified materials were investigated. Besides, differential charge densities and adsorption energies of the different modified materials in Zr-O clusters were calculated using density functional theory (DFT). A Bi2O3 and carbonized UIO-66-NH2 (Bi2O3/C-UIO-66-NH2) -modified glassy carbon electrode was used to detect Pb(Ⅱ) by differential pulse anodic stripping voltammetry. Under optimal experimental parameters, the developed electrochemical sensor has a wide linear range (2–130 μg/L) and a low detection limit (0.05 μg/L). Meanwhile, the sensor has excellent stability, repeatability, and anti-interference properties and has been successfully applied to detect Pb(Ⅱ) in actual water samples. The results of this paper show that our developed sensor an efficient and rapid sensor technology for monitoring lead in water environment.

Highly Sensitive Simultaneous Stripping Voltametric Detection of Zn2+, Cd2+ and Hg2+ by Bismuth Codeposition Procedure with Graphdiyne−Modified Electrode

In this paper, graphdiyne (GDY)−modified glassy carbon electrode was prepared and further used for the sensitive and simultaneous detection of three target heavy metal ions of Zn2+, Cd2+ and Hg2+ by codeposition with Bi3+ in the mixture solution. GDY−modified electrodes exhibit a larger electrode area and abundant active sites, which is favorable for absorbing more metal ions. Bismuth has low toxicity and can form alloys with zinc, cadmium and mercury. Therefore, three kinds of heavy metal ions can be pre-concentrated with bismuth on the GDY−modified electrode surface, and the following stripping analysis results in high sensitivity and selectivity. By using differential pulse anodic stripping voltammetry, the detection ranges of Zn2+, Cd2+ and Hg2+ were from 2.0 to 100.0 μM with low detection limits of 0.255 μM, 0.367 μM and 0.796 μM, respectively. In addition, the sensor showed excellent repeatability, reproducibility, and stability, which was applied to sensitive analysis of river water samples with satisfactory results.

A Disposable Electrochemical Sensor for Lead Ion Detection Based on In Situ Polymerization of Conductive Polypyrrole Coating

Lead, a toxic heavy metal, is considered one of the most serious pollutants in the water environment, posing a grave threat to human health and the global ecosystem. In this work, a simple, fast and sensitive sensor strategy for detecting trace lead ions (Pb2+) in water was proposed. The disposable electrochemical sensor was fabricated with a screen-printed carbon electrode (SPCE), and the working electrode was modified in a single step with in situ polymerized phytic acid functionalized polypyrrole (PA-PPy). Differential pulse anodic stripping voltammetry (DPASV) was employed to realize the efficient detection of Pb2+ in the range of 10–600 nM with a low detection limit of 0.43 nM (S/N = 3). The PA-PPy@SPCE sensor exhibits good stability, repeatability and anti-interference performance, indicating a promising application for real sample detection, and satisfactory recoveries were obtained when detecting Pb2+ in real tap water samples. Furthermore, the rapid sensor strategy with in situ polymerization of phytic acid functionalized polypyrrole composite material enables large-scale Pb2+ sensor preparation.Graphical Abstract

Stripping voltammetry on palladized aluminum: A novel sensing platform for trace analysis of copper

In the present work, palladized aluminum as a new type of solid electrode has been applied for the determination of copper by differential pulse anodic stripping voltammetry (DPASV) technique. The proposed electrode was prepared rapidly by electroless deposition of metallic palladium on the aluminum surface and had good sensitivity and selectivity. The experimental variables such as electrode preparation conditions, type and concentration of supporting electrolyte, supporting electrolyte pH, preconcentration potential, preconcentration time, convection intensity, and scan rate of electrode potential were optimized. Under the optimum conditions, a linear calibration graph was achieved in the concentration range of 3–60 µM with a correlation coefficient of 0.999 and a detection limit of 2.8 µM. It was found that the proposed method was free from common interferences which were presented in the used real sample. The palladized aluminum electrode was used successfully to determine of copper content in nutritional supplement tablets, and suitable recovery results were obtained.

Sonochemical fabrication of gradient antibacterial materials based on Cu-Zn alloy.

At present research, we highlight ultrasonic treatment as a new way to create materials with a gradient change of chemical or physical properties. We demonstrate the possibility to fabricate novel materials with biocide activity based on simple and cheap Cu-Zn alloy. In this research, we propose a green preparative technique for the sonication of an alloy in an alkali solution. The method leads to a significant visual change and differentiation of particles into three different fractions. Due to the chemical micro gradients in media near the solid surface under intensive sonication, fast formation of specific functional groups occurs on the particles' surface. The particles were studied X-ray diffraction analysis (XRD) analysis, the field-emission scanning electron microscope (SEM) as well as electron backscatter diffraction (EBSD) mode, X-ray Photoelectron Spectroscopy (XPS), the differential pulse anodic stripping voltammetry (DPASV) technique. A strong correlation of both methods proves a redistribution of copper ions from Fraction I to Fraction III that influence for the antibacterial properties of the prepared material. The different biocidal activity was demonstrated for each separated Fraction that could be related to their different phase content and ability to release the different types of ions.

Electrochemical sensor based on amine- and thiol-modified multi-walled carbon nanotubes for sensitive and selective determination of uranyl ions in real water samples.

Novel selective and sensitive electrochemical sensors based on the modification of a carbon paste electrode (CPE) with novel amine- and thiol-functionalized multi-walled carbon nanotubes (MWCNT) have been developed for the detection and monitoring of uranyl ions in different real water samples. Multiwalled carbon nanotubes were grafted with 2-aminothiazole (AT/MWCNT) and melamine thiourea (MT/MWCNT) via an amidation reaction in the presence of dicyclohexyl carbodiimide (DCC) as a coupling agent. This modification for multiwalled carbon nanotubes has never been reported before. The amine and thiol groups were considered to be promising functional groups due to their high affinity toward coordination with uranyl ions. The modified multi-walled carbon nanotubes were characterized using different analytical techniques including FTIR, SEM, XPS, and elemental analysis. Subsequently, 10 wt% MT/MWCNT was mixed with 60 wt% graphite powder in the presence of 30 wt% paraffin oil to obtain a modified carbon paste electrode (MT/MWCNT/CPE). The electrochemical behavior and applications of the prepared sensors were examined using cyclic voltammetry, differential pulse anodic stripping voltammetry, and electrochemical impedance spectroscopy. The MT/MWCNT/CPE sensor exhibited a good linearity for UO22+ in the concentration range of 5.0 × 10-3 to 1.0 × 10-10 mol L-1 with low limits of detection (LOD = 2.1 × 10-11 mol L-1) and quantification (LOQ = 7 × 10-11 mol L-1). In addition, high precision (RSD = 2.7%), good reproducibility (RSD = 2.1%), and high stability (six weeks) were displayed. Finally, MT-MWCNT@CPE was successfully utilized to measure the uranyl ions in an actual water sample with excellent recoveries (97.8-99.3%). These results demonstrate that MT-MWCNT@CPE possesses appropriate accuracy and is appropriate for environmental applications.

Voltammetric investigations of functional dyspepsia drug acotiamide at pencil graphite electrode: An eco-friendly and cost effective stripping detection method

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.

Determination of clenbuterol with differential pulse anodic stripping voltammetry technique at tungsten disulfide-modified electrode

In the present work, tungsten disulfide was synthesised and characterised by using X-ray diffraction and scanning electron microscopy. This material was employed to modify a glassy-carbon electrode to analyse clenbuterol. The results show that tungsten disulfide displays electrocatalytic activity toward clenbuterol oxidation. The proposed technique is prospective for clenbuterol examination. The limit of detection and the linear range are 0.51 mM and 1–210 mM.

Electrochemical (bio)sensors based on carbon quantum dots, ionic liquid and gold nanoparticles for bisphenol A

Electrochemical (bio)sensors were developed for bisphenol A (BPA) determination. Screen printed carbon electrode (SPCE) was modified with ionic liquid 1- butyl-3-methylimidazolium tetrafluoroborate (IL), carbon quantum dots (CQD) and gold nanoparticles (AuNP) for the fabrication of the BPA sensor. Electrode surface composition was optimized for the deposition time of AuNP, amount of CQD and percentage of IL using the central composite design (CCD) method. The results of the CCD study indicated that maximum amperometric response was recorded when 9.8 μg CQD, 3% IL and 284 s AuNP deposition time were used in modification. Tyrosinase (Ty) was further modified on the AuNP/CQD−IL/SPCE to fabricate the biosensor. Analytical performance characteristics of the BPA sensor were investigated by differential pulse anodic adsorptive stripping voltammetry and the AuNP/CQD−IL/SPCE sensor exhibited a linear response to BPA in the range of 2.0 × 10−8 – 3.6 × 10−6 M with a detection limit of 1.1 × 10−8 M. Amperometric measurements showed that the linear dynamic range and detection limit of the Ty/AuNP/CQD−IL/SPCE were 2.0 × 10−8 – 4.0 × 10−6 M and 6.2 × 10−9 M, respectively. Analytical performance characteristics such as sensitivity, reproducibility and selectivity were investigated for the presented (bio)sensors. The analytical applicability of the (bio)sensors to the analysis of BPA in mineral water samples was also tested.

Highly efficient detection of Pb(II) ion in water by polypyrrole and metal-organic frame modify glassy carbon electrode

Since lead is teratogenic, carcinogenic and mutagenic, people pay increasing attention to lead contamination in water environment. In this work, a novel electrochemical sensor was developed to detect Pb(II) ion in water by PPy, MOFs and bismuth film (BF) modify GCE. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, contact angleanalyses, cyclic voltammetry and differential pulse anodic stripping voltammetry were used to characterize the BF-PPy/UIO-66-NH 2 /GCE surface, revealing the physical and electrochemical properties of the electrode. MOFs increased the specific surface area and adsorption site of the electrode. The PPy enhanced the conductivity of the composites materials. MOFs and PPy synergistically promoted the electrochemical performance of the electrode. The deposition potential, deposition time, solution pH and Bi (III) concentration were optimized to determine the optimal detection condition. The electrode has a wide linear range (0.5 to 10 μg/L) with a low detection limit (0.05 μg/L). This electrode also has good anti-interference, repeatability and stability. Besides, it has been successfully applied to the detection of actual water samples. The recovery rates ranged from 95.4 % to 102.8 % with a relative standard deviation (RSD) less than 4.40 %. Our results provide an insight on efficient and rapid detection of Pb(II) ions in water environment in the future. • MOFs and polypyrrole synergistically promoted the electrochemical performance. • The fabricated BF-PPy/UIO-66-NH 2 /GCE shows a low Pb(II) detection limit. • This sensor was applied to the detection of Pb(II) in tap water and groundwater.

Ultra-sensitive simultaneous electrochemical detection of Zn(II), Cd(II) and Pb(II) based on the bismuth and graphdiyne film modified electrode

In this paper, a new dendritic bismuth and graphdiyne (Bi/GDY) film was fabricated on the surface of glassy carbon electrode (GCE) with a facile casting and electrodeposition procedure, which possessed significantly large active area, binding strength on electrode interface and fast electron transfer ability. The modified electrode was acted as an ultra-sensitive electrochemical sensor for individually and simultaneously assay of Zn(II), Cd(II) and Pb(II) by using differential pulse anodic stripping voltammetry (DPASV). As a result, the ultra-low detection limits (0.115 nM of Zn(II), 0.171 nM of Cd(II) and 0.146 nM of Pb(II), S/N = 3) and a wide linear concentration range from 10.0 nM to 100.0 μM were obtained. The constructed sensor exhibited excellent repeatability, reproducibility, stability and could be used to sensitive detect real seawater sample. The analytical results of Bi/GDY/GCE was further verified via atomic absorption spectroscopy. Therefore, Bi/GDY-based electrochemical sensor possesses great potentials for advanced applications in environment, biomedicine and food fields.