Stripping Voltammetry Research Articles

Simultaneous Electrochemical Detection of Cu2+ and Zn2+ in Pig Farm Wastewater.

In recent years, the rapid development of pig farming has led to a large quantity of heavy metal-polluted wastewater. Thus, it was desirable to develop a simple heavy metal detection method for fast monitoring of the wastewater from the pig farms. Therefore, there was an urgent need to develop a simple method for rapidly detecting heavy metal ions in pig farm wastewater. Herein, a simple electrochemical method for simultaneous detection of Cu2+ and Zn2+ was developed and applied to pig farm wastewater. With a glassy carbon electrode and anodic stripping voltammetry, simultaneous detection of Cu2+ and Zn2+ in water was achieved without the need for complicated electrode modification. Furthermore, it was found that the addition of Cd2+ can enhance the response current of the electrode to Zn2+, which increased the signal by eight times. After systematic optimization, the limit of detection (LOD) of 9.3 μg/L for Cu2+ and 45.3 μg/L for Zn2+ was obtained. Finally, it was successfully applied for the quantification of Cu2+ and Zn2+ with high accuracy in pig farm wastewater. This work provided a new and simple solution for fast monitoring of the wastewater from pig farms and demonstrated the potential of electrochemical measurement for application in modern animal husbandry.

Superior performance of N-doped carbon Nanoonions/Nafion based microfluidic electrochemical Cd2+ sensor when compared to Screen-Printed Carbon-Based electrode devices

The sensing of cadmium is important due to its highly toxic effects on various organs of humans and animals. Commonly employed are screen-printed carbon-based electrodes (SPCE) as suitable low-cost sensing platform. Microfluidic electrochemical sensor (μCS) can also be portable, highly sensitive, and low-cost but are up to now only seldom studied and applied. Here we demonstrate the superior performance of μCS over SPCE arrangements for sensing ultra-trace of Cd2+. Additionally, N-doped carbon nanoonions (N-CNOs) are introduced as sustainable non-metallic modifier and employed for both sensing arrangements. The study depicted that employing the modifier the electrochemically active surface area and the electron transfer rate in both arrangements is improved together with improve sensitivity. Both arrangements were compared using cyclic voltammetry and electrochemical impedance spectroscopy in [Fe(CN)6]3−/4−, and also square-wave anodic stripping voltammetry (SWASV) for Cd2+ sensing. The µCS arrangement clearly outperforms the SPCE arrangement in signal strength. For the final device (μCS modified with N-CNOs) a linear concentration range from 1.0 to 100 μg L−1 was achieved. The limit of detection and sensitivity resulted to 0.25 μg L−1 and 1.02 μA µg−1 L cm−2, respectively. Besides this excellent sensitivity combines with high stability, which was tested for 8 repetitive measurements with a single device resulting in high reproducibility. Additionally, this procedure was favorably employed for measurements of Cd2+ in different real samples, which demonstrated the excellent applicability of the device for the adsorption and detection of heavy metal ions.

An Electrochemical Strategy for Detection of Trace‐Level Binapacryl Using Square‐Wave Cathodic Stripping Voltammetry

AbstractBinapacryl is a fungicide and miticide from the dinitrophenol group and is used to control fungi and mites in agricultural areas. Since even trace amounts of pesticides can be highly toxic to humans and the environment, accurate and sensitive analytical methods are needed for their determination. Therefore, the electrochemical behavior of binapacryl fungicide on the glassy carbon electrode (GCE) was investigated using square wave cathodic stripping voltammetry (SWCSV) and cyclic voltammetry (CV). Some parameters such as accumulation potential, accumulation time, pulse amplitude, frequency, and step potential were optimized on GCE. From the plotted calibration graph, the linear operating range was found to be 0.16–6.20 μM (0.06–2.0 mg/L), and accordingly the limit of detection (LOD) and limit of quantification (LOQ) for the first and second peak were 0.060 μM/0.201 μM and 0.0627 μM/0.209 μM, respectively. The proposed method was applied for spiked tap water, apple juice and grape juice samples. An electroreduction mechanism has also been proposed for binapacryl with the participation of 2e−/2H+ via the nitro group of the molecule. Also, the selectivity of the method was demonstrated by investigating the interference effects of some pesticides on the determination of binapacryl.

Biochar from sugarcane bagasse: Synthesis, characterization, and application in an electrochemical sensor for copper (II) determination

Biochar (BC) is a carbonaceous material obtained from the thermal decomposition of organic matter under limited oxygen supply that plays an attractive role in waste management. In this study, biochar was prepared from sugarcane bagasse, using pyrolysis temperatures from 300 to 700 °C, and chemically activated with HNO3. Structural characterizations showed that degradation increased as pyrolysis temperature increased. Furthermore, a higher number of functional groups were observed for the materials produced under the lowest temperatures. Chemical activation resulted in oxidation and nitration of carbonaceous structure, increasing the number of functional groups on the materials. All materials were evaluated for the construction of electrochemical sensors towards Cu2+ ions voltammetric determination. The material produced at 400 °C pyrolysis temperature and activated (BCA400) provided the most intense response, which can be related to the presence of one of the highest numbers of surface groups, such as oxygen groups, on it. A method for Cu2+ determination was successfully developed based on differential pulse adsorptive stripping voltammetry (DPAdSV). A linear dynamic range (LDR) from 1.0 to 15.0 μmol L−1 was achieved, with limit of detection (LOD) of 0.36 μmol L−1, and limit of quantification (LOQ) of 1.09 μmol L−1. The method was also adequate in terms of accuracy and precision, as well as selective against most cationic species commonly found in tap water. The analyte was determined in tap water samples, in natura and spiked with the maximum concentration allowed by Brazilian legislation, and successful recovery values were obtained. Therefore, biochar from sugarcane bagasse, an environmentally-friendly material, was successfully used to construct an electrochemical sensor and determining an environmental and health interest analyte.

Electrochemical redox of arsenic (III) and Cu (II) mixtures with ultraflat Au(111) thin films in water

The ability to detect trace concentrations of arsenite, As (III), in real water solutions is impacted by co-contamination of other metals and co-occurring ions. The presence of copper (II) ions are the most likely co-contaminant in natural waters to interfere with electrochemical As (III) detection, due to the close oxidation potentials of Cu (II) and As (III). The use of well-oriented ultraflat Au(111) thin film electrodes provided increased peak separation and sensitivity for electrochemical deposition and oxidation of Cu (II) and As (III) in 0.5 M sulfuric acid compared to an Au wire electrode. However, mixtures of Cu (II) and As (III) altered the oxidation peak positions during both cyclic voltammetry (CV) and linear stripping voltammetry (LSV) analysis. Calibration curves using the standard additions method in trace concentrations were conducted for Cu, As, and Cu & As solutions. Sweeping the potential at 10 mV s−1 during CV in Cu & As mixtures resulted in a sequential deposition condition where a layer of Cu inhibited co-deposition of As to the electrode. In contrast, the rapid potential stepping of LSV to a potential where Cu and As reduction simultaneously occurs produced a peak profile different from Cu or As alone. A larger oxidation peak during LSV was also observed when both Cu and As were present. X-ray photoelectron spectroscopy indicates a Cu-As alloy is formed on the surface after LSV deposition.SYNOPSIS: Analysis of Cu (II), As (III) and Cu (II) & As (III) mixtures suggests that a Cu3As intermetallic phase is formed during LSV which impacts trace As detection even in trace Cu conditions. This has important implications for the ability to determine As concentrations near the MCL of 10 µg L−1 in natural water systems which may contain Cu (II) and other co-contaminants.

Highly sensitive and selective electrochemical monitoring of nickel in crude oil samples using cathodically pretreated-boron doped diamond electrode

Crude oil is a mixture of hydrocarbons found underground in liquid form and is a valuable fuel with a complex chemical structure. Crude oil is known to come from decaying plants and animals as a fossil product that emerged from the anaerobic process millions of years ago. In the formation of oil, it is accepted that crude oil has an organic origin, and most of the crude oil is found in sedimentary rocks, and the sediments have an organic and inorganic content.In this study, a voltammetric method was developed for the analysis of nickel, one of the metals with the highest density as a heavy metal in crude oil. In the developed voltammetric method, the boron-doped diamond electrode was activated in the cathodic direction at −3.0 V in 0.5 M H2SO4 media.As a result of this cathodic activation, nickel gave a very sensitive anodic signal around −0.15 V on the electrode surface. This anodic signal was determined to be linear in the range of 0.05–0.6 μM around −0.15 V in BR (pH 3.0) media by the anodic stripping voltammetry method. The limit of detection and the limit of quantification were determined to be 0.003 μM and 0.01 μM, respectively. The proposed method allowed the selective analysis of nickel in the crude oil sample without any separation and enrichment process.

Microelectrode Voltammetric Analysis of Low Concentrations of Se(IV) Ions in Environmental Waters.

The current research is an attempt to analyze on-site selenium(IV) ions in environmental water samples using an eco-friendly miniaturized sensor developed by deposition of a very thin amount of metallic bismuth in a solid Bi electrode tightly closed in miniaturized housing. Numerous experimental variables are optimized, including the composition of the supporting electrolyte and its pH, as well as activation and accumulation conditions. Under optimized measurement conditions, the method shows high sensitivity, permitting a very low limit of detection equal to 7 × 10-10 mol L-1 to be achieved in a short accumulation time of 50 s. The performance of this microsensor was investigated against numerous interference factors and its good anti-interference capability was demonstrated. A series of voltammetric experiments by differential pulse cathodic stripping voltammetry (DPCSV) were carried out and they proved that the miniaturized sensor is characterized by very good accuracy and precision as well as long-term stability. The solid bismuth microelectrode displays a good voltammetric response in the analysis of diverse samples with a complex matrix and demonstrates a good recovery rate.

Powerful Analytical Platform for Diazepam Determination in Pharmaceuticals and Alcoholic Drinks Based on Batch Injection Analysis Coupled with Adsorptive Stripping Voltammetry

The presented study focuses on the development and optimization of a powerful electroanalytical platform for the direct quantification of diazepam (DZP). This innovative approach integrates a batch injection analysis (BIA) system with a screen-printed electrode arrangement employing square-wave adsorptive stripping voltammetry (SWAdSV). The BIA-SWAdSV method underwent a comprehensive evaluation, wherein various experimental and instrumental parameters were systematically examined in detail. Beneficial analytical performance for detecting DZP was attained in Britton-Robinson buffer with pH 6.0, with an amplitude of 75 mV, a frequency of 10 Hz, a deposition potential of –1.2 V, a deposition time of 150 s, an injection volume of 75 μl, a dispensing rate of 7 μl s−1 and without stirring during the deposition step. Under these conditions, the proposed BIA-SWAdSV method demonstrated an adequately broad linear concentration range from 5 μM to 40 μM (R 2 = 0.997) with a micromolar limit of detection (2.0 μM) and a satisfactory precision (RSD = 5.0%). The practical applicability of the newly established and powerful analytical protocol was confirmed through the analysis of pharmaceuticals and a fortified samples of an alcoholic drink (rum) associated with potential criminal activities involving DZP abuse.

Sensitive determination of iodide at graphitic carbon nitride-chitosan composite modified screen-printed electrode in urine and salt using cathodic stripping voltammetry

Iodide is an important constituent in various biological processes; hence its determination is important. A simple voltammetric method has been investigated for iodide determination using disposable screen-printed electrode modified with graphitic carbon nitride-chitosan composite (gCN-Chit/SPE). The sensor presented excellent electrocatalytic response towards iodide sensing. The SEM analysis of the modified electrode showed a rough and sheet like morphology. The EDX analysis showed the high content of nitrogen elements in the composite layer of the modified electrode which is crucial for iodide ion sensing. Various parameters such as electrolyte concentration, deposition potential, deposition time etc. were optimized for iodide sensing. The use of low concentration of electrolyte favored the electro-oxidation of iodide. Under the suitable experimental conditions, the gCN-Chit/SPE exhibited good linear performance for iodide in the concentration range from 0.075 to 200 µM with a regression coefficient (R2) of 0.9946 and the limit of detection (LOD) of 0.01 µM. The electrode presented interference free effect for iodide in the presence of relatively high concentration of other substances. The sensor was applied to determine iodide in real samples such as urine, tap water and table salt. In real sample analysis good recoveries in percent was achieved using the developed electrode. Further, the composite layer at the electrode surface provided good mechanical stability and thus could be reused for several determinations. The results confirmed that the design electrochemical sensor could be successfully employed for real sample applications with highly sensitive iodide determination.

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.

Transition metal doped ZIF‐8 for the detection of the heavy metal Hg(II)

AbstractThe effects of heavy metals such as Hg(II) and Pb(II) on the human body are profound. Moreover, they pose significant concerns due to industrial development. Thus, the rapid and stable detection of heavy metal ions and related chemicals has emerged as an urgent issue. The application of Differential Pulse Stripping Voltammetry (DPSV) facilitated accurate and rapid detection of Hg2+ utilizing MOF materials and ZIF‐8 as detection agents. Pure ZIF‐8 served as the substrate material. Copper or nickel ions were individually introduced into the substrate material. This process resulted in the formation of bimetallic MOF materials. These materials were designated as CuZn and NiZn, respectively. Transition metal‐doped materials were used to modify the glassy carbon electrode (GCE), resulting in a substantial enhancement in the detection performance of Hg2+. The CuZn/GCE configuration demonstrated the most significant enhancement. When compared to a GCE modified with pure ZIF‐8, both sensitivity and the detection limit for free Hg2+ in the environment experienced increases of 450% and 64%, respectively. Stability and repeatability tests were conducted on the CuZn‐modified GCE. Results indicated that the electrode proved to be very stable and showed strong selectivity in the presence of interfering ions. The sensor modified with CuZn shows promising potential for monitoring trace Hg2+ levels.

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%.

In-situ deposition of gold nanoparticles on screen-printed carbon electrode for rapid determination of Hg2+ in water samples

Herein, an electrochemical sensor for Hg2+ detection using in-situ deposited gold nanoparticles modified screen-printed carbon electrode (SPCE) was developed. The gold nanoparticles and Hg were co-deposited on the electrode during the enrichment process. Scanning electron microscope (SEM) and Energy dispersive X-ray (EDX) spectrum prove the successful modification of gold nanoparticles. After modification, the active surface area of the electrode enlarged, the electron transfer ability enhanced, and the detection of Hg2+ became possible. After comprehensive optimization of experimental parameters, the proposed sensor can achieve rapid detection of trace Hg2+ in drinking water through differential pulse stripping voltammetry (DPSV). The limit of detection reaches 0.33 μg/L, the linear range is 0.5–80 μg/L. The test can be completed within 5 min. This sensor does not require extra electrode modification before detection, which can simplify experimental steps and improve detection efficiency, holding great promise for the on-site detection of Hg2+ in environmental and food samples.

Pyridine-assisted electrodeposition of Au(1 1 1)-dominant gold nanonetworks on glassy carbon electrode for anodic stripping voltammetry analysis of As(III), Se(IV) and Cu(II)

Gold nanonetworks with Au(111)-dominant facets (AuNNs(1 1 1)-D) modified glassy carbon electrode (GCE) was simply fabricated by electroreduction of Au(III) with the assistance of pyridine (Py). Cyclic voltammetry of Au(III)-Py complex exhibits two sequential cathodic peaks, reflecting the reduction of Au(III) to Au(I) intermediate and then to Au(0). The as-prepared AuNNs(111)-D/GCE was characterized by scanning electron microcopy, X-ray diffraction and electrochemistry methods, and the results showed that the gold crystalline spread out in a nanonetworks architecture with good distribution, high aspect-ratios, large roughness and 90 % Au(111) facets. The coordination effects of Py, the inferior affinity of Py on Au(111) facets and the sustained generation of Au(I) intermediate contributed to such gold nanoarchitecture. Differential pluse anodic stripping voltammetry analysis of As(III), Se(IV) and Cu(II) was performed on the AuNNs(1 1 1)-D/GCE with high performance. Sensitivity values of 16.9 µA μM−1 (As(III)), 9.51 µA μM−1 (Se(IV)), 6.09 µA μM−1 (Cu(II)), as well as limit of detection values of 0.67 nM (As(III)), 1.1 nM (Se(IV)), 0.53 nM (Cu(II)) were obtained (S/N = 3), respectively. The AuNNs(111)-D/GCE was used for As(III), Se(IV) and Cu(II) determination in real drinkable water samples with satisfied results.

A simple and reliable electrochemical method employing an unmodified boron-doped diamond electrode for the determination of triclocarban

Since the advent of the COVID-19 pandemic, triclocarban-containing cleaning products have been increasingly consumed. As triclocarban is an emerging compound, it is necessary to develop new sensors for its monitoring. So, a simple and reliable electroanalytical method for the determination of triclocarban using an unmodified boron-doped diamond electrode was developed. The application of a cathodic pretreatment (−2.0 V, 30 min, 0.5 mol L−1 H2SO4) on the electrode surface provided higher current intensities and lower resistance to charge transfer in contrast to the non-treated surface. On the diamond electrode surface, the triclocarban showed an irreversible behavior with two oxidation peaks at +1.10 and +1.40 V vs. Ag/AgCl, KCl(sat). The hypothesis for removing hydrogens of both amide groups of the triclocarban structure was supported by computational methodology which also explained the broadened oxidation peaks and the distance between them. The calibration curve for triclocarban, obtained by using differential pulse voltammetry in a supporting electrolyte composed of McIlvaine buffer (pH 3.0) and ethanol (80:20 v/v), covered a concentration range of 1.0 to 50 μmol L−1, and it exhibited a detection limit of 0.31 μmol L−1 under optimized experimental conditions. Using an accumulation time of 120 s at open circuit potential, a calibration curve by differential pulse adsorptive stripping voltammetry was constructed in a range of 0.05 to 20 µmol L−1 of triclocarban, with a detection limit of 18 nmol L−1. Triclocarban quantification assays were carried out on samples of antibacterial soaps and river water, and data were recorded with acceptable precision and accuracy.

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.

A highly sensitive electrochemical sensing probe incorporating classical Berthelot's reaction and glassy carbon electrode for measuring ultra-trace levels of ammonia/ NH4+ in water

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

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.

A Novel Thin-Layer Flow Cell Sensor System Based on BDD Electrode for Heavy Metal Ion Detection.

An electrochemical sensor based on a thin-layer flow cell and a boron-doped diamond (BDD) working electrode was fabricated for heavy metal ions determination using anodic stripping voltammetry. Furthermore, a fluidic automatic detection system was developed. With the wide potential window of the BDD electrode, Zn2+ with high negative stripping potential was detected by this system. Due to the thin-layer and fluidic structure of the sensor system, the electrodepositon efficiency for heavy metal ions were improved without using conventional stirring devices. With a short deposition time of 60 s, the system consumed only 0.75 mL reagent per test. A linear relationship for Zn2+ determination was displayed ranging from 10 μg/L to 150 μg/L with a sensitivity of 0.1218 μA·L·μg-1 and a detection limit of 2.1 μg/L. A high repeatability was indicated from the relative standard deviation of 1.60% for 30 repeated current responses of zinc solution. The system was applied to determine Zn2+ in real water samples by using the standard addition method with the recoveries ranging from 92% to 118%. The system was also used for the simultaneous detection of Zn2+, Cd2+, and Pb2+. The detection results indicate its potential application in on-site monitoring for mutiple heavy metal ions.

An innovative aluminium foil electrode modified with Al nanoparticles and EDTA for lead detection in biological samples

This study presents a novel Aluminium foil-based electrode characterized by its affordability, flexibility, and ease of modification with carboxylic moiety-containing organic molecules. Upon foil modification with Aluminium nanoparticles and EDTA (AlNP-EDTA/AlE), the modified electrode exhibits remarkable activity in the oxidation of lead at potentials around −0.4 V. The lead signal is derived from the oxidation of lead deposited on the electrode surface using anodic stripping voltammetry (ASV). The addition of EDTA to AlNP/AlE increased the anodic peak current of lead by more than 500 %. The surface characterization of the electrode was performed by scanning electron microscopy (SEM) and infrared spectroscopy (IR), while its electroactive properties were evaluated by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Optimal operating parameters include pH 2.1, square-wave voltammetry (SWV) with an accumulation time of 60 s and an accumulation potential of −0.8 V. A low detection limit of 0.20 µmol/L and a relative standard deviation (RSD) of 3.0 % were achieved using five different electrodes. The effectiveness of AlNP-EDTA/AlE was further demonstrated with consistent results in biological samples spiked with Pb.