Square Wave Anodic Stripping Voltammetry Research Articles (Page 1)

The detection and monitoring of mercury ions (Hg2+) in water have become increasingly critical due to their extreme toxicity, bioaccumulation potential, and regulatory significance under international frameworks such as the Minamata Convention. Persistent mercury contamination continues to affect water systems in both developed and developing nations, including India and the United Kingdom. As a step towards detecting mercury (Hg2+) in water samples, we have developed miniaturized point-of–analysis electrochemical sensor based on a new metal-free, thiadiazole (TDA) and triazine (Trz) linked porous organic polymer (TDA-Trz-POP). Unlike conventional sensors that rely on metal-based recognition elements, our heteroatom-rich POP enables highly selective Hg²⁺ capture via synergistic sulphur and nitrogen coordination. The resulting sensors exhibit a lower limit-of-detection (LoD) as 1.5 nM (≈ 0.4 ppb, below the WHO Limit of 6 ppb) and a Linear range of 5–100 nM (1.4 to 27 ppb). The selective and sensitive detection of Hg2+ attributed to the nitrogen- and sulphur-rich surface functionalities of the TDA-Trz-POP-modified electrode, with the underlying binding mechanism is discussed in detail. Using square wave anodic stripping voltammetry (SWASV), we demonstrate real-sample applicability in water, offering a robust, low-cost, and scalable solution for on-site mercury detection in groundwater. The present work is among the first demonstrations of a metal-free porous organic polymer (POP) integrated into SPEs for point-of-analysis mercury sensing with huge potential for public health in developing nations.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-19241-x.

The reuse of materials for the development of high-performance electrochemical sensors is explored in this work. Specifically, bismuth (Bi) films were electrodeposited using Bi extracted by using an aqueous two-phase system (ATPS) from discarded fusible plugs (BiSn alloy), which are used as safety valves in gas cylinders. The ATPS is an environmentally friendly strategy for liquid-liquid extraction, and its suitability for obtaining purified Bi for use in electrochemistry is demonstrated. As a proof-of-concept, the bismuth film electrodes obtained from extracted Bi (BiATPS-FE) were applied for the simultaneous voltammetric determination of heavy metal species (Cd2+ and Pb2+). By applying square-wave anodic stripping voltammetry (SWASV), BiATPS-FE displayed a similar voltammetric response toward both the analytes compared to bismuth film electrodes prepared from standard Bi precursors (Bi-STD). Under optimized conditions, the BiATPS-FE sensor exhibited linear ranges of 0.50 to 7.0 μmol L-1 and 0.40 to 5.0 μmol L-1 for Cd2+ and Pb2+, respectively, with limits of detection of 0.044 μmol L-1 (Cd2+) and 0.019 μmol L-1 (Pb2+). The developed voltammetric method, adopting BiATPS-FE, was successfully applied to lake water and tea drink samples for the simultaneous determination of Cd2+ and Pb2+, with recovery percentages ranging from 93% to 100%. Furthermore, the proposed sensor (BiATPS-FE) showed good repeatability and reproducibility. The exciting analytical performance verified for the Bi-film electrodes emphasizes the feasibility of combining environmentally friendly materials recovery and electrochemical strategies to propose value-added electrochemical sensors.

In this study, Bi2O3/CeO2 nanocomposite was synthesized using serine, which played a dual role by promoting uniform particle morphology and aiding combustion during synthesis, resulting in a highly porous nanostructure. The produced nanocomposite was applied as a highly efficient modifier for screen-printed electrode (Bi2O3/CeO2/SPE), facilitating the simultaneous quantification of Pb(II) and Cd(II) using square wave anodic stripping voltammetry (SWASV). Compared to conventional sensors, the proposed electrode exhibited significantly enhanced electrochemical behavior, attributed to the synergistic structural and electrical properties of CeO₂ and Bi₂O₃ as well as an increased surface area. The sensor demonstrated a reliable response and effective peak separation at optimal parameters. The current signals exhibited linearity within the concentration range between 0.5 and 85µg/L for both ions, achieving the limit of detection (LOD) of 0.09µg/L for Pb(II) and 0.14µg/L for Cd(II). The Bi2O3/CeO2/SPE was effectively utilized to detect cadmium and lead ions in water and food samples, demonstrating high recovery values across different spiked samples, and the outcomes closely matched those obtained through standard ICP analysis.

The toxicity of metal ions, such as lead (Pb2+) and cadmium (Cd2+), has been a worldwide issue since the 1970s. For Pb2+ specifically, chronic exposure via drinking water can have lasting health effects. While inductively coupled plasma‐mass spectrometry (ICP‐MS) and atomic absorption spectroscopy (AAS) are the most common instruments used for the detection of Pb2+, electrochemical methods like square wave anodic stripping voltammetry (SWASV) have classically shown promise. However, the determination of metals in a real sample matrix typically requires pretreatment and/or extraction of the analyte from the sample itself. Cloud point extraction (CPE) is a sustainable technique that can be used as a solventless substitute for liquid–liquid or solid‐phase extraction. While typically coupled to AAS detection, the applicability of CPE to electroanalysis is still not well understood, nor fully optimized. In this work, CPE was used to isolate Pb2+ from water samples for analysis by SWASV with a bismuth‐coated glassy carbon (Bi‐GC) electrode. This is the first report coupling CPE to electroanalytical detection of trace metals in the absence of mercury (Hg). In addition, a back extraction (BE) step was incorporated to recover Pb2+ from the surfactant‐rich phase, which resulted in a more sensitive and accurate method. High extraction efficiency was achieved and theoretical limits of detection (LOD) of 2.6, 0.81, and 1.7 μgL−1 were obtained with deposition times (tdep) of 1, 2, and 3 min, respectively. The optimized CPE‐SWASV procedure for Pb2+ was selective; only manganese (Mn2+) was identified as an interferant. Measurements in more complex water samples were also completed. Overall, this innovative CPE‐SWASV approach offers a sensitive, cost‐effective, and sustainable alternative to Hg‐based electrochemical quantification of Pb2+.

Lead (Pb) and cadmium (Cd) ions have serious negative impacts on human health and the ecological environment due to toxicity, persistence and nonbiodegradability. Among various trace Pb and Cd ions detection technologies, electrochemical analysis is considered as one of the most promising methods. The deposition of Bi nanoparticles on delaminated Ti3C2Tx (DL-Ti3C2Tx) develops a sensor with good conductivity and performance. Square wave anodic stripping voltammetry (SWASV) technology was applied to simultaneously deposit Bi on DL-Ti3C2Tx/GCE and achieve the rapid detection of Pb and Cd ions. The Bi nanoparticles effectively improved the sensitivity of Bi/DL-Ti3C2Tx/GCE sensors to detect Pb and Cd ions. The preparation conditions of the Bi/DL-Ti3C2Tx/GCE were optimized, including DL-Ti3C2Tx droplet amount, solution pH, Bi3+ concentration, deposition time and deposition potential, to improve the detection ability. The Bi/DL-Ti3C2Tx/GCE sensor has detection limits of 1.73 and 1.06 μg/L for Pb and Cd ions, respectively (S/N > 3). This electrochemical sensor is easy, sensitive and selective to apply in actual water samples for trace Pb and Cd ions detection.

We combined Au nanoparticles with Copper-1,3,5-benzene dicarboxylate (Cu-BTC) to modify the glassy carbon electrode (GCE) for Sb determination in water by square wave anodic stripping voltammetry (SWASV). Sb(V) is reduced to Sb(III) by potassium iodide (KI) and ascorbic acid (AA), allowing Sb(V) determination by subtracting Sb(III) from total Sb. The sensor's selectivity and stability stem from Sb-Cu2+ interaction, Cu-BTC's 3D structure, electrocatalytic activity and conductivity of gold nanoparticles (AuNPs). The sensitivity and detection limit of Sb(III) were 0.38 μA/μg/L and 0.24 μg/L. The sensitivity and detection limit of Sb(V) were 0.32 μA/μg/L and 0.38 μg/L. The Au/Cu-BTC sensor showed good reproducibility and recoveries in natural waters, showing promise for the practical determination of Sb(III/V) species.

Considering the extremely high toxicity of lead (Pb), early detection of atmospheric Pb levels is paramount for the implementation of preventive measures, to contain sources of emission, to minimize both human and plant exposure and to prevent accumulation in the biosphere. This work demonstrates a wearable "on-plant" sensor for electrochemical Pb detection in atmospheric aerosol samples. The sensor is screen-printed onto a flexible self-adhesive vinyl-based matte substrate which enables its attachment on plant leaves. It features a bismuth/Nafion-coated carbon working electrode transducer covered with a polyvinyl alcohol (PVA) membrane which serves as a passive in-situ gas collection layer and as an electrolyte-containing matrix. The Pb collected at the interface between the sample in the gas phase and the acetate buffer solution (ABS) embedded within the PVA membrane is measured by square wave anodic stripping voltammetry (SWASV). Different steps of the fabrication process were optimized and the detection of on plant leaves was demonstrated. Simulation experiments were conducted with a Pb-containing aerosol sprayed on the leaves to evaluate the effect of various operational parameters such as long-term stability, spraying time, accumulation time, or sensor/leaf bending. The "on-plant" sensor allows remote near real-time monitoring of Pb levels as low as 50μgL-1 in ambient air using a portable miniaturized potentiostat, and can be expanded to other target metals, forming the basis of an early warning system for atmospheric heavy metals exposure.

Methylmercury (CH3Hg+), a lipophilic environmental pollutant, accumulates in fish, shellfish, and other organisms, posing significant risks to human health through the food chain. Developing a convenient and sensitive analytical method for CH3Hg+ detection is crucial for reducing costs and enhancing the efficiency of food safety testing. In this study, we prepared an octyl-modified silica isoporous membrane on the indium tin oxide (ITO) electrode (Octyl-SIM/ITO) via the electrochemical-assisted self-assembly (EASA) method using octyltrimethoxysilane (O-TES) as the functional organosilane. The Octyl-SIM/ITO electrode exhibits vertically-ordered nanochannels and strong hydrophobic affinity, enabling selective penetration and enrichment of weakly polar analytes. Utilizing square wave anodic stripping voltammetry (SWASV), the Octyl-SIM/ITO electrode demonstrates superior electrochemical response signals for CH3Hg+ detection, achieving a detection limit as low as 4 nM. This method allows for accurate and reproducible detection of CH3Hg+ in fish and oyster samples with minimal sample preparation, offering promising potential for portable in situ detection.

Excessive levels of heavy metal pollutants in the environment pose significant threats to human health and ecosystem stability. Consequently, the accurate and rapid detection of heavy metal ions is critically important. A AgNPs@CeO2/Nafion composite was prepared by dispersing nano-ceria (CeO2) in a Nafion solution and incorporating silver nanoparticles (AgNPs). The morphology, microstructure, and electrochemical properties of the modified electrode materials were systematically characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and cyclic voltammetry (CV). By leveraging the oxygen vacancies and high electron transfer efficiency of CeO2, the strong adsorption capacity of Nafion, and the superior conductivity of AgNPs, an AgNPs@CeO2/Nafion/GCE electrochemical sensor was developed. Under optimized conditions, trace Pb2+ in water was detected using square wave anodic stripping voltammetry (SWASV). The sensor demonstrated a linear response for Pb2+ within the concentration range of 1-100 μg·L-1, with a detection limit of 0.17 μg·L-1 (S/N = 3). When applied to real water samples, the method achieved recovery rates between 93.7% and 110.3%, validating its reliability and practical applicability.

A composite (N-rGO@ppy) of N-doped reduced graphene oxide (N-rGO) coated with polypyrrole (ppy) particles was successfully synthesized. The incorporation of N-rGO significantly mitigates the aggregation of ppy synthesized in situ, and the doped N atoms improve the conductivity of graphene oxide (GO), thereby enhancing N-rGO@ppy's redox properties. Firstly, a glassy carbon electrode (GCE) modified with N-rGO@ppy (N-rGO@ppy/GCE) was used in combination with a bismuth film and square-wave anodic stripping voltammetry (SWASV) for the simultaneous trace analysis of Pb2+ and Cd2+. N-rGO@ppy/GCE exhibited distinct stripping peaks for Pb2+ and Cd2+, with a linear range of 1 to 500 μg L-1. The limits of detection (LODs) were found to be 0.080 μg L-1 for Pb2+ and 0.029 μg L-1 for Cd2+, both of which are significantly below the standards set by the World Health Organization (WHO). Subsequently, the same electrochemical sensing strategy was adapted to a more portable screen-printed electrode (SPE) to accommodate the demand for in situ detection. The performance of N-rGO@ppy/SPE for analyzing Pb2+ and Cd2+ in actual samples, such as drinking water, milk, and honey, showed results consistent with those obtained from conventional graphite furnace atomic absorption spectrometry (GFAAS).

Heavy metals such as cadmium, lead, arsenic, mercury, and chromium are harmful to human health, even in a trace amount. Despite existing guidelines and regulations for handling these toxic substances, mortality cases among wild animals due to heavy metal poisoning continue to occur. To effectively investigate the sources of heavy metal contaminants in the environment, it is essential to establish real-time monitoring systems across affected areas. This paper presents the design and development of a potentiostat device (HMstat) with the capability to perform a square wave anodic stripping voltammetry (SWASV). The HMstat was realized using a two-board type potentiostat design, incorporating through-hole technology for the analog component and the myRIO platform for the digital component. Performance evaluations indicated that the HMstat is capable of performing the SWASV method. The results demonstrated that the HMstat achieved an accuracy of 99.014%, remained within the tolerance range of components used and surpassed the existing solution.

This paper shows the fabrication of a new environmentally friendly sensor, an activated glassy carbon electrode with an in situ deposited bismuth film (aGCE/BiF), to determine Cd(II) and Pb(II) at the nanotrace level. The electrochemical activation of the GCE surface was achieved in a solution of 0.1 M phosphate-buffered saline (PBS) of pH = 7 by performing five cyclic voltammetric scans in the range of -1.5-2.5 V at ν of 100 mV/s. The newly developed electrode provides several advantages, such as an increased electron active surface (compared to the glassy carbon electrode) and improved electron transfer kinetics. As a result, the new voltammetric procedure (square-wave anodic stripping voltammetry, SWASV) was established and optimized. With the SWASV method, the following calibration curves and low detection limits (LODs) were obtained for Cd(II) and Pb(II), respectively: 5-100 nM, 0.62 nM, 2-200 nM, and 0.18 nM. The newly prepared method was used to determine the amounts of Pb(II) and Cd(II) in the certified reference material, and the results agreed with the certified values. Moreover, the procedure was successfully applied to determine the Cd(II) and Pb(II) in river samples. The official and standard addition methods validated the measurement results.

This study explores the development of an advanced electrochemical sensor designed for the simultaneous detection of Cd2+, Pb2+, Cu2+, and Hg2+ ions. The sensor utilizes sol-gel-synthesized bismuth vanadate (BiVO4) nanospheres, which are integrated onto a glassy carbon electrode (GCE), and employs square wave anodic stripping voltammetry (SWASV) for electrochemical determination of heavy metal ions. The as-prepared sensor demonstrated exceptional analytical performance and offered a wide linear detection range from 0 μM to 110 μM, along with low detection limits of 2.75 μM for Cd2+, 2.32 μM for Pb2+, 2.72 μM for Cu2+, and 1.20 μM for Hg2+ ions. These characteristics made the sensor highly suitable for precise monitoring of heavy metal contamination in both environmental and industrial samples. Beyond their sensing capabilities, the BiVO4 nanospheres also exhibited significant antimicrobial activity against bacterial strains such as E. coli and S. aureus, as well as fungal strains like C. albicans and C. parapsilosis. This antimicrobial effect was attributed to the enhanced surface reactivity and the generation of reactive oxygen species (ROS), which disrupt microbial cellular functions. This dual-functional approach highlighted the substantial progress in both electrochemical sensing and antimicrobial applications. This research presents a strong platform for tackling urgent challenges in environmental monitoring and microbial control.

This study explores the potential of using magnetic biochar derived from sesame seed cake (PMBS) and enhanced with polyaniline (PANI) for the removal of heavy metals from aqueous solutions. The synthesized PMBS was comprehensively characterized and evaluated as an effective adsorbent for Hg2+ and Cu2+ removal. This study assessed various physicochemical properties, including surface morphology, porosity, specific surface area, chemical composition, valence states, and magnetic characteristics, of the composite to determine its efficacy in heavy metal removal from wastewater. The adsorption performance of the magnetic biochar was significantly enhanced via PANI doping. Furthermore, the easy magnetic recovery of PMBS from aqueous solutions after adsorption was successfully demonstrated using an external magnetic field. The adsorption kinetics of heavy metal ions on PMBS followed a pseudo-second-order model, while Langmuir isotherm analysis confirmed monolayer adsorption behavior. The maximum adsorption capacities for Hg2+ and Cu2+ were determined to be 141.89 and 124.78 mg g−1, respectively. The electrochemical measurements of square wave anodic stripping voltammetry (SWASV) were employed to determine residual metal ion concentrations after adsorption. Calibration curves were constructed by varying the concentration of each ion, both individually (with the other held constant) and simultaneously (with both ions present in the same solution), to evaluate the electrode's performance in mixed-ion systems. The PANI-modified PMBS biochar demonstrates significant potential for wastewater treatment and is suitable for a broader range of separation applications.

A new electrochemical sensor devoted to Hg(II) trace determination was developed by tailoring a hybrid organic/inorganic interface using diazonium salts and gold nanoparticles (AuNPs). The AuNPs were electrodeposited for the very first time onto glassy carbon (GC) electrodes functionalized by thick (ca. 4 nm) diazonium films. The thickness of the organic films was obtained using atomic force microscopy (AFM) in scratching mode, while the AuNPs were characterized by field emission gun scanning electron microscopy (FEG‐SEM). Each step of the functionalization process was studied by cyclic voltammetry using ferricyanide and ruthenium hexaammine as the redox probes. The as‐prepared electrode was used for Hg(II) trace detection through square wave anodic stripping voltammetry (SWASV). A linear response was observed in the 1.0–9.9 nmol·L−1 range using a preconcentration time of 300 s, yielding a normalized sensitivity of 0.03 μA·L·nmol−1·min−1. The limit of detection (LOD) was determined to be as low as 300 pmol·L−1. The effect of major interfering metal cations on the sensor’s response was also investigated. In addition, the hybrid organic/inorganic interface strongly enhanced the lifetime of the sensor, this latter being extended up to 4 weeks.

The monitoring of heavy metals in aquatic ecosystems is of critical importance due to the toxic effects that these elements can have on wildlife and the potential risks that they pose to human health. Rivers situated in close proximity to agricultural regions are particularly susceptible to contamination from a combination of natural and anthropogenic sources. The study of bioaccumulation is of great importance for the early detection of environmental stressors. The combination of electrochemical techniques, such as square-wave anodic stripping voltammetry (SWASV), with automated flow-batch systems represents an efficient and cost-effective approach for the detection of trace metals in environmental samples. This study examines the bioaccumulation of cadmium and lead in Cyprinus carpio, a bioindicator of contamination in the Colorado River, Argentina. The fish were exposed to sublethal metal concentrations for 24, 48, and 96 h. Metal quantification was conducted using a novel automatic flow-batch system with SWASV and a bismuth film electrode. To the best of our knowledge, this constitutes the first application of this methodology on aquatic bioindicators for the assessment of metal accumulation in a natural environment. The technique demonstrated enhanced sensitivity and selectivity for the detection of trace metals. The bioaccumulation results demonstrated an increase in cadmium and lead concentrations in fish liver tissue after 96 h, reaching 10.5 µg g−1 and 11.9 µg g−1, respectively. Validation with inductively coupled plasma–atomic emission spectrometry (ICP-AES) demonstrated a satisfactory correlation, confirming the reliability of the method. This novel electrochemical approach offers enhanced accuracy and efficiency, making it a promising tool for environmental monitoring. The results indicate that Colorado River water is within safe levels for aquatic life regarding these metals. However, continuous monitoring is recommended to detect changes in contamination levels and protect ecosystem health, especially during water crises and under climate change.

Heavy Metals (HM) are identified as critical environmental pollutants, characterized by their extreme toxicity, ability to accumulate in ecosystems, and lack of degradability. Mercury, in its ionic form, is one of the most toxic pollutants, posing severe risks to the immune system, nervous system, and cellular structures. The electrochemical method for detecting heavy metals has attracted considerable attention due to its ability to produce accurate results, perform analyses faster, and achieve higher sensitivity levels. The main goal of this study is to develop a carbon-based sensor, suitable for the determination of mercury Hg (II). Here, based on the advantages of graphene oxide and gold nanoparticles, we developed the carbon sensor modified with -rGO@Au. The obtained nanomaterial (rGo@Au) is fully characterized using Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray Spectroscopy (EDS). The Electrochemical characterization of the CPE/rGOAu sensor was performed via Cyclic Voltammetry (CV), and Square Wave Anodic Stripping voltammetry (SWASV) was used as a typical technique for the determination of Hg (II). The oxidation peak currents of Hg (II) were proportional to concentration in the range of 0.66-3.11 ppm with a limit of detection of 0.22 ppm. In pursuit of practical applications, the sensor underwent additional testing to measure Hg(II) concentration in water samples.

Enhancement of electrode surface hydrophilicity and selectivity with Nafion-PSS composite for trace heavy metal sensing in electrochemical sensors

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga3+) and indium (In3+) in water samples using square wave anodic stripping voltammetry (SWASV). The electrochemical modification of PGEs with rGO and bimetallic Bi/Hg films (ERGO-Bi/HgF-PGE) exhibited synergistic effects, enhancing the oxidation signals of Ga and In. Graphene oxide (GO) was accumulated onto PGEs and reduced through cyclic reduction. Key parameters influencing the electroanalytical performance, such as deposition potential, deposition time, and pH, were systematically optimized. The improved adsorption of Ga3+ and In3+ ions at the Bi/Hg films on the graphene-functionalized electrodes during the preconcentration step significantly enhanced sensitivity, achieving detection limits of 2.53 nmol L−1 for Ga3+ and 7.27 nmol L−1 for In3+. The preferential accumulation of each post-transition metal, used in transparent displays, to form fused alloys at Bi and Hg films, respectively, is highlighted. The sensor demonstrated effective quantification of Ga3+ and In3+ in tap water, with detection capabilities well below the USEPA guidelines. This study pioneers the use of bimetallic films to selectively and simultaneously detect the post-transition metals In3+ and Ga3+, highlighting the role of graphene functionalization in augmenting metal film accumulation on cost-effective graphite rods. Additionally, the combined synergistic effects of Bi/Hg and graphene functionalization have been explored for the first time, offering promising implications for environmental analysis and water quality monitoring.

Abstract This research aims to optimize the effectiveness of a glassy carbon electrode by coating it with bismuth nanoparticles in both sphere and rod forms. The modified electrode is intended for the simultaneous analysis of heavy metals: Zn(II), Cd(II), and Pb(II) by using square‐wave anodic stripping voltammetry (SWASV). The synthesis optimization of bismuth nanospheres and nanorods was studied. Analysis of the nanoparticles’ morphology and structure was conducted using a scanning electron microscope (SEM). Under optimal conditions, the synthesized nanobismuth spheres measured 137.0±3.43 nm, while the bismuth rods measured 5.18±1.36 nm. The optimal SWASV conditions for the proposed electrode in heavy metal analysis involved a deposition potential of −1.4 V for 240 seconds, a frequency of 25 Hz, an amplitude of 25 mV, and a step potential of 4 mV. The linearity ranges for Zn(II), Cd(II), and Pb(II) were 20–130 μg L−1, 10–60 μg L−1, and 6–54 μg L−1, respectively, with detection limits of 4.0 μg L−1 for Zn(II), 1.6 μg L−1 for Cd(II), and 1.6 μg L−1 for Pb(II). The results demonstrated satisfactory performance with high repeatability, good selectivity, and sensitivity. Additionally, the proposed electrode was utilized to simultaneously determine heavy metal concentrations in seawater.