Facile preparation of a DNA sensor for rapid herpes virus detection

In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from ? 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.     

Electrochemical oxidation of adenosine-5′-triphosphate on a chitosan–graphene composite modified carbon ionic liquid electrode and its determination

In this paper a new electrochemical method was proposed for the determination of adenosine-5′-triphosphate (ATP) based on a chitosan (CTS) and graphene (GR) composite film modified carbon ionic liquid electrode (CTS–GR/CILE). CILE was fabricated by using ionic liquid 1-butyl-3-methylimidazolium dihydrogen phosphate ([BMIM]H₂PO₄) as the binder, which was further modified by GR and CTS composite. The modified electrode exhibited an excellent electrocatalytic activity toward the oxidation of ATP with the increase of the oxidation peak current and the decrease of the oxidation peak potential. The electrochemical parameters of ATP on CTS–GR/CILE were calculated with the electron transfer coefficient (α) as 0.329, the electron transfer number (n) as 2.15, the apparent heterogeneous electron transfer rate constant (ks) as 3.705 × 10^? 5 s^? 1 and the surface coverage (Γ_T) as 9.33 × 10^? 10 mol cm^? 2. Under the optimal conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10^? 6 to 1.0 × 10^? 3 M with the detection limit of 0.311 μM (S/N = 3). The proposed electrode showed excellent reproducibility, stability, anti-interference ability and further successfully applied to the ATP injection sample detection.     

Synthesis,processing and characterization of calcia-stabilized zirconia solid electrolytes for oxygen sensing applications

Precursor powders of calcia-stabilized zirconia (CSZ) solid electrolytes have been synthesized by a sol–gel method. The phase evolution of the precursor powders after thermal treatments at different temperatures were analysized by X-ray diffraction technique. Disc-shaped sensor elements were fabricated via uniaxial pressing of the calcined powders and subsequently sintered at 1650 °C. Scanning electron microscopy (SEM) was used to analyze the microstructure of the sintered pellets. Platinum electrodes were applied to the sintered elements to produce potentiometric/electrochemical gas sensors. The electrical response of the gas sensors to oxygen and the complex impedance of the sensors in air were measured at various temperatures. Impedance analyses indicate that the sensor cell with 15 mol% CaO has much lower resistance (the sum of bulk and grain-boundary resistance) than the sensor cell with 22 mol% CaO. This is also reflected by the EMF responses of both sensor cells to various oxygen concentrations in the testing gas. The EMF deviation from the theoretical value of the CSZ sensor cell with 22 mol% CaO was larger than that of the CSZ sensor cell with 15 mol% CaO. The corrrelations between material compositions, microstructures of the sintered pellets and the electrical properties of the sensors are discussed.     

Determination of benzalkonium chloride preservative in pharmaceutical formulation of eye and ear drops using new potentiometric sensors

A novel approach for determination of low concentrations of the preservative, benzalkonium chloride (BCCl), in pharmaceutical formulation constitutes is presented. New chemically modified carbon paste electrodes (CMCPEs) are developed. The first is based on an ion-association of BCCl with phosphomolybdic acid (PMA) as the ion-exchanger (BC–PM) dissolved in the mixed plasticizers dibutyl phthalate (DBP) and dioctyl sebacate (DOS) encoded sensor A. In the other electrode, encoded sensor B, the plasticizers DBP and dioctyl phthalate (DOP) are more suitable solvent mediators for the paste. These electrodes exhibit a Nernstian slope of 58.2 ± 0.6 and 62.3 ± 0.7 mV/decade in concentration range 1.3 × 10^? 7–1.7 × 10^? 4 M and 2.5 × 10^? 7–1.7 × 10^? 4 M with the limit of detection of 1.0 × 10^? 7 M and 1.6 × 10^? 7 for sensors A and B, respectively. The sensors have short and stable response time 5–8 s, good reproducibility and can be used in pH range of 5.7–8.6. The present electrodes show good discrimination of BCCl from several inorganic, organic ions and some common drug excipients. These characteristics of the electrodes make them useful in successful determination of BCCl in its pharmaceutical preparations (eye and ear drops) and aqueous solutions. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay.     

Preparation and characterization of biocompatible carbon electrodes

Electron transfer in microbial fuel cell and biosensors could be facilitated through high conductive materials with enhanced active surface area and appropriate redox potential suited to microbial metabolism. In the first strategy based on bulk doping, graphite/epoxy composite electrode (GECE) bulk was modified with six types of metal ion which were prepared through a wet impregnation procedure. In the second strategy, immobilization of redox dye on carbon cloth and graphite sheet was carried out using N,N′-dicyclohexylcarbodiimide for surface modification. Crystallinity, morphology, surface chemistry and electrochemical properties of all modified electrodes were investigated. Influence of redox behavior of electrodes suited to microbial metabolism and conducive to biofilm formation have been examined. It was observed that the Fe³⁺ doped GECE surfaces exhibited significantly high biofilm formation of 1.10(±0.18) × 10⁷ CFU/cm² as compared to other dopants. The microbial growth on the carbon cloth electrode and carbon fiber reinforced plate were found to be less (2.6(±0.97) × 10⁴, 4.8(±1.8) × 10³ CFU/cm² respectively) compared to GECEs.     

Voltammetric sensor based on carbon paste electrode modified with molecular imprinted polymer for determination of sulfadiazine in milk and human serum

A new sensitive voltammetric sensor for determination of sulfadiazine is described. The developed sensor is based on carbon paste electrode modified with sulfadiazine imprinted polymer (MIP) as a recognition element. For comparison, a non-imprinted polymer (NIP) modified carbon paste electrode was prepared. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods were performed to study the binding event and electrochemical behavior of sulfadiazine at the modified carbon paste electrodes. The determination of sulfadiazine after its extraction onto the electrode surface was carried out by DPV at 0.92 V vs. Ag/AgCl owing to oxidation of sulfadiazine. Under the optimized operational conditions, the peak current obtained at the MIP modified carbon paste electrode was proportional to the sulfadiazine concentration within the range of 2.0 × 10^? 7–1.0 × 10^? 4 mol L^? 1 with a detection limit and sensitivity of 1.4 × 10^? 7 mol L^? 1 and 4.2 × 10⁵ μA L mol^? 1, respectively. The reproducibility of the developed sensor in terms of relative standard deviation was 2.6%. The sensor was successfully applied for determination of sulfadiazine in spiked cow milk and human serum samples with recovery values in the range of 96.7–100.9%.     

Multi-walled carbon nanotube modified carbon paste electrode as an electrochemical sensor for the determination of epinephrine in the presence of ascorbic acid and uric acid

A biocompatible electrochemical sensor for selective detection of epinephrine (EP) in the presence of 1000-fold excess of ascorbic acid (AA) and uric acid (UA) was fabricated by modifying the carbon paste electrode (CPE) with multi-walled carbon nanotubes (MWCNTs) using a casting method. The electro-catalytic activity of the modified electrode for the oxidation of EP was investigated. The current sensitivity of EP was enhanced to about five times upon modification. A very minimum amount of modifier was used for modification. The voltammetric response of EP was well resolved from the responses of AA and UA. The electrochemical impedance spectroscopic (EIS) studies reveal the least charge transfer resistance for the modified electrode. The AA peak that is completely resolved from that of EP at higher concentrations of AA and the inability of the sensor to give an electrochemical response for AA below a concentration of 3.0 × 10^? 4 M makes it a unique electrochemical sensor for the detection of EP which is 100% free from the interference of AA. Two linear dynamic ranges of 1.0 × 10^? 4–1.0 × 10^? 5 and 1.0 × 10^? 5–5.0 × 10^? 7 M with a detection limit of 2.9 × 10^? 8 M were observed for EP at modified electrode. The practical utility of this modified electrode was demonstrated by detecting EP in spiked human blood serum and EP injection. The modified electrode is highly reproducible and stable with anti fouling effects.     

In vitro human periodontal ligament-like tissue formation with porous poly-l-lactide matrix

This study aimed to establish an in vitro human periodontal ligament-like tissue (HPdLLT) by three-dimensional culturing of human periodontal ligament fibroblasts (HPdLFs) in a porous poly-l-lactide (PLLA) matrix modified hydrophilically with ammonia solution. After ammonia modification, the surface roughness and culture-medium-soaking-up ability of the PLLA matrix increased, whereas the contact angle of water drops decreased. The thickness, porosity, and pore size of the PLLA matrix were 400 ± 50 μm, 83.3%, and 75–150 μm, respectively. HPdLFs (1 × 10⁵ cells) were seeded on the modified PLLA matrix and centrifuged to facilitate seeding into its interior and cultured for 14 days. Scanning electron microscope (SEM) observation, proliferation assay, picrosirius-red staining, and real-time polymerase chain reaction (RT-PCR) for type-1 collagen (COL1), periodontal ligament associated protein-1 (PLAP-1), fibroblast growth factor-2 (FGF-2), and alkaline phosphatase (ALP) mRNA were conducted on days 1, 3, 7, and 14. HPdLFs were observed entirely from the surface to the rear side of the matrix. Cell proliferation analysis, SEM observation, and picrosirius-red staining showed both progressive growth of 3D-cultured HPdLFs and extracellular matrix maturation by the secretion of COL1 and type 3 collagen (COL3) from days 1 to 14. Expressions of COL1, PLAP-1, and FGF-2 mRNA suggested the formation of cellular components and supplementation of extracellular components. Expressions of ALP, COL1, and PLAP-1 mRNA suggested the osteogenic potential of the HPdLLT. The results indicated in vitro HPdLLT formation, and it could be used in future periodontal ligament tissue engineering to achieve optimal periodontal regeneration.     

Detection of anticancer drug tamoxifen using biosensor based on polyaniline probe modified with horseradish peroxidase

Amperometric biosensor based on horseradish peroxidase immobilized via glutaraldehyde on the polyaniline modified platinum electrode shows evidenced promising characteristics in detecting anticancer drug tamoxifen. The sensor was fabricated simply by adsorbing horseradish peroxidase enzyme on the electrode surface for which Cyclic Voltammetry was used to monitor the electro-catalytic reduction of tamoxifen under diffusion-adsorption controlled conditions. Fourier Transform Infrared Spectroscopy, Cyclic Voltammetry and Electrochemical Impedance Spectroscopic techniques are used to characterize the electrochemical interfacial properties of surface modified electrodes. The first-hand effort on modified biosensor within Platinum/Polyaniline/Horseradish peroxidase biosensor system has demonstrated excellent electro-analytical properties with biosensor sensitivity of 1.6 μA ng mL^? 1. The optimum limit of detection and limit of quantification are 0.07 ng mL^? 1 and 0.29 ng mL^? 1 respectively for the determination of anticancer drug tamoxifen. It is felt that the present study will help in improving our knowledge of cost-effective quantitative determination of tamoxifen in metabolized biological fluids and other pharmaceutical formulations.     

Characterization of copper manganite oxide-polypyrrole composite electrodes cathodically polarized in acidic medium

We have studied the electrochemical behaviour induced by polarization in sandwich-type composite electrodes with the structure GC/PPy/PPy(Ox)/PPy where GC stands for glassy carbon, PPy for polypyrrole and Ox for Cu_1.4Mn_1.6O₄ nanoparticles. The electrodes were polarized at ?0.45 V/SCE in 0.15 M KCl aqueous solution at pH 2.2 either saturated in Ar or O₂ at 25 °C. The changes occurring on these electrodes were studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (EXAFS and XANES) techniques. In previous work we have shown that when the oxide particles are incorporated into the PPy matrix the Cu⁺ present in the initial oxide suffers dismutation to give Cu²⁺ and metallic Cu. In this work we show that the polarized electrodes also reveal the presence of metallic Cu and Cu²⁺. The data also show that the oxide particles embedded in the polarized electrodes contain Mn³⁺ and Mn⁴⁺, although the Mn³⁺/Mn⁴⁺ ratio is different from that found in the fresh electrodes. The Cl 2p XPS data show that in the electrode polarized in O₂ there is an enhancement of the Cl covalent contribution that appears at 200.8 eV (which is already present in the fresh electrode although with a very small intensity). This result suggests that the oxygen reduction reaction leads to an increase of the OH^? concentration inside the composite electrode that explains the charge transport in PPy at negative potentials.     

Modified carbon paste electrodes for Cu(II) determination

A new Cu²⁺ carbon paste electrode (CPE) using 2,2′-(1E,1′E)-1,1′-(2,2′-azanediylbis (ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(ethan-1-yl-1-ylidene)diphenol (ADEZEDP) has been prepared. The influence of variables including sodium tetraphenylborate (NaTPB), ionophore, and amount of multiwalled carbon nanotubes (MWCNT), CdO nanowires, CdS nanoparticles and palladium nanoparticles loaded on ADEZEDP and Nujol on the electrodes response were studied and optimized. At optimum values of all variables, for each nanomaterial the electrode response was linear in concentration range of 1.0 × 10^? 8 to 1.0 × 10^? 1 mol L^? 1 for ADEZEDP with Nernstian slope. The good performance of electrode viz. Wide applicable pH range (2.0–5.0), fast response time (≈ 6 s), and adequate life time (3 months) indicate the utility of the proposed electrodes for evaluation of Cu²⁺ ion content in various situations. Finally, these electrodes have been successfully applied for the determination of Cu²⁺ ions content in various real samples. The selectivity of proposed electrode was evaluated by separation solution method and fixed interference method.     

Synthesis of magnetite nanoparticles by surfactant-free electrochemical method in an aqueous system

A simple surfactant-free electrochemical method is proposed for the preparation of magnetite nanoparticles using iron as the anode and plain water as the electrolyte. This study observed the effects of certain parameters on the formation of magnetite nanoparticles and their mechanism in the system, including the role of OH^? ions, the distance between electrodes and current density. We found that OH^? ions play an important role in the formation of magnetite nanoparticles. Particle size can be controlled by adjusting the current density and the distance between electrodes. Particle size increases by increasing the current density and by decreasing the distance between electrodes. Particle formation cannot be favored when the distance between electrodes is larger than a critical value. The magnetite nanoparticles produced by this method are nearly spherical with a mean size ranging from 10 to 30 nm depending on the experimental conditions. They exhibit ferromagnetic properties with a coercivity ranging from 140 to 295 Oe and a saturation magnetization ranging from 60 to 70 emu g^?1, which is lower than that of the corresponding bulk Fe₃O₄ (92 emu g^?1). This simple method appears to be promising as a synthetic route to producing magnetite nanoparticles.     

Study on the microstructure and electrochemical kinetic properties of MmNi4.50−xMnxCo0.45Al0.30 (0.25 ≤ x ≤ 0.45) hydrogen storage alloys

The phase structures, surface morphologies and electrochemical kinetic properties of MmNi_4.50?xMn_xCo_0.45Al_0.30 (Mm is the mischmetal, x = 0.25, 0.30, 0.35, 0.40 and 0.45) hydrogen storage alloys have been investigated in this paper. The X-ray diffraction (XRD) shows that all the alloys mainly consist of LaNi₅ phase with CaCu₅-type structure, which belongs to P6/mmm space group (central symmetry). Scanning electron microscopy (SEM) tests indicate that there are partial element segregations in the alloys. Meanwhile, energy dispersive spectrum (EDS) results display that the elements constituting Mm exist in the matrix phase in relatively larger proportion, while Mn, Al and Co tend to appear in precipitate phase. For the alloy with x = 0.35, the electrochemical performances, including discharge capacity, high-rate dischargeability (HRD) and cycling life, of the alloy electrode are better than that of other alloy electrodes. With the increase of Mn content, the exchange current density (I₀) of the alloy electrodes first increases and then decreases, the hydrogen diffusion coefficient (D) of alloy electrodes gradually decreases. There is a linear correlation between HRD at a discharge current density of 1500 mA/g and I₀.     

Possible mercury speciation in urine samples using potentiometric methods

The strong dependence of heavy metal toxicity on metal physical–chemical structure has directed the interest in the qualitative and quantitative measurement of metal species in different environments. Mercury is ubiquitous in the environment, and occurs in three oxidation states in several physical and chemical forms. Among these, Hg(II) can severely damage the kidneys and the gastrointestinal tract, and is generally a serious hazard to human health. Potentiometric sensors based on ion-selective electrodes provide a simple, highly selective, precise, and economical method for online Hg(II) concentration monitoring in a variety of environments. Due to their selectivity, neutral carrier-based potentiometric sensors are routinely used for measuring ions directly in complex biological and environmental samples, and therein, several Hg(II)-selective electrodes have been studied in literature. This work presents a Hg(II) ion-selective electrode that uses a 1,4,8,11-tetrathiacyclotetradecane derivative entrapped inside a membrane for the measurement of Hg(II) in urine samples. Alumina modified dimethyl sulfoxide (AMDMSO) was used to separate Hg(II) from matrices, a mechanism already suggested in literature explaining the unique uptake of Hg(II) ions by binding as neutral at pH values < 3.     

Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: Application for highly selective determination of sotalol using voltammetry

A magnetic nano‐composite of multiwall carbon nanotube, decorated with NiFe₂O₄ nanoparticles, was synthesized with citrate sol–gel method. The multiwall carbon nanotubes decorated with NiFe₂O₄ nanoparticles (NiFe₂O₄–MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5–1000 μmol L^? 1 sotalol with a detection limit of 0.09 μmol L^? 1. The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine.     

Sulphonamide-imprinted sol–gel materials as ionophores in potentiometric transduction

This work proposes different kind of solid-contact graphite-based electrodes for the selective determination of sulphonamides (SPHs) in pharmaceuticals, biological fluids and aquaculture waters. Sulfadiazine (SDZ) and sulfamethoxazole (SMX) were selected for this purpose for being the most representative compounds of this group. The template molecules were imprinted in sol–gel (ISG) and the resulting material was used as detecting element. This was made by employing it as either a sensing layer or an ionophore of PVC-based membranes and subsequent potentiometric transduction, a strategy never reported before. The corresponding non-imprinted sol–gel (NISG) membranes were used as blank. The effect of plasticizer and kind/charge of ionic lipophilic additive was also studied.The best performance in terms of slope, linearity ranges and signal reproducibility and repeatability was achieved by PVC membranes including a high dielectric constant plasticizer and 15 mg of ISG particles. The corresponding average slope was ?51.4 and ?52.4 mV/decade, linear responses were 9.0 × 10^?6 and 1.7 × 10^?5 M, and limits of detection were 0.74 and 1.3 μg/mL for SDZ and for SMX, respectively. Good selectivity with log Kpot < ?0.3 was observed for carbonate, chloride, fluoride, hydrogenocarbonate, nitrate, nitrite, phosphate, cyanide, sulfate, borate, persulphate, citrate, tartrate, salicylate, tetracycline, ciprofloxacin, sulphamerazine, sulphatiazole, dopamine, glucose, galactose, cysteine and creatinine. The best sensors were successfully applied to the analysis of real samples with relative errors ranging from ?6.8 to + 3.7%.     

Ho3+ carbon paste sensor based on multi-walled carbon nanotubes: Applied for determination of holmium content in biological and environmental samples

For the first time a novel multi-walled carbon nanotubes (MWCNTs) modified Ho³⁺ carbon paste sensor is introduced. The electrode with a composition containing 20% paraffin oil, 60% graphite powder, 15% N-(1-thia-2-ylmethylene)-1,3-benzothiazole-2-amine (TBA) as an ionophore, and 5% MWCNTs, exhibits a stable potential response to Ho³⁺ ions with a nice Nernstian behavior (19.3 ± 0.3 mV decade^? 1) in a wide dynamic linear concentration range of Ho³⁺ ions (1 × 10^? 8–1.0 × 10^? 2 M). In the absence of MWCNTs, sensitivity of the Ho³⁺ sensor was relatively poor. The proposed modified Ho³⁺ sensor shows very low detection limit (7.0 × 10^? 9 M) and a fast response time (13 s). It has a long life time (more than 2 months) and its response is independent of pH in the range of 3.8–7.5. In term of selectivity, Ho³⁺ sensor has a good selectivity over all lanthanide members and common alkali and alkaline earth metal ions. The Ho³⁺ sensor was applied for the determination of Ho³⁺ ion concentration in water, holmium alloys and synthetic human serum.     

Iodide selective membrane electrodes based on a Molybdenum–Salen as a neutral carrier

A new polymeric membrane electrode (PME) and a coated platinum disk electrode (CPtE) based on Schiff base complex of Mo(VI) as a suitable carrier for I^? ion were described. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrodes. The electrodes exhibited a Nernstian slope of 63.0 ± 0.5 (CPtE) and 60.3 ± 0.4 (PME) mV decade^? 1 in I^? ion over a wide concentration range from 7.9 × 10^? 7 to 1.0 × 10^? 1 M for CPtE and 9.1 × 10^? 6 to 1.0 × 10^? 1 M I^? for PME. The potentiometric response of the electrodes was independent of the pH of the test solution in the pH range 2.0–8.5 with a fast response time (< 10 s). The process of transfer of iodide across the membrane interface was investigated by use of the AC impedance technique. The proposed sensors were successfully applied to direct determination of iodide in samples containing interfering anions, waste water and as indicator electrodes in precipitation titrations.     

Fabrication and electrochemical behavior of vertically-aligned carbon nanotube electrodes covalently attached to p-type silicon via a thioester linkage

Vertically-aligned single-walled carbon nanotubes (SWCNTs) (VACNTs) are becoming increasingly recognized due to their fast electron transfer rates. However, the chemistry available for further functionalizing these electrodes is limited. Here we describe a new approach to the fabrication of VACNTs. SWCNTs were covalently attached to a p-type silicon (100) (Si) wafer surface using a thioester linkage in which the nanotubes were firstly acid treated and then, in the presence of a hydroxylated Si wafer surface, reacted with phosphorus pentasulfide (a mild electrophilic catalyst). The novel nanostructure was characterized using atomic force microscopy (AFM) showing vertical alignment with FTIR spectroscopy indicating pendant thiocarboxylic acid groups for further reaction. In addition, electrochemical properties using cyclic voltammetry indicate that the electrodes have excellent electrochemical properties with an electron transfer rate of 2.98 × 10^? 3 cm s^? 1.     

Reliable synthesis of bismuth nanoparticles for heavy metal detection

A reliable and facile pathway is described here for preparing high-quality bismuth nanoparticles. Combined with hydrothermal method and confined growing effect of polymer, bismuth nanoparticles with uniform size and shape were obtained with remarkable productivity. The nanoparticles is proved to be pure Rhombohedral structure Bi crystals with R-3m space group and the diameter of the nanoparticles is about 80 nm with a quite narrow particle size distribution. Those bismuth nanoparticles were predicted to grow from a rolling process by sheet-like Bi nanocrystal intermediates. The obtained bismuth nanoparticles were used to prepare modified electrode for the detection of Cd²⁺ and Pb²⁺ in water solution by stripping analysis. Compared with naked glassy carbon electrodes, the modified electrode showed two obvious responses at −0.85 V and −0.62 V, corresponding to the reduction process of Pb²⁺ and Cd²⁺ and this well-resolved stripping response can be observed when the concentration is as low as 10 μg/L, indicating potential application in electroanalysis for environmental inspection.