Square-wave Voltammetry Analysis Research Articles

Study of graphene incorporation into ZnO-PVA nanocomposites modified electrode for sensitive detection of cadmium

The presence of heavy metals often causes significant health risks, particularly cadmium, which is known for its high toxicity. In this study, a glassy carbon electrode was successfully modified by incorporating ZnO-PVA-Graphene nanocomposite, leveraging the excellent electrical properties and electron mobility of the material. Comprehensive material analysis, including XRD, confirmed that ZnO maintained its hexagonal wurtzite crystal structure despite the addition of graphene. Moreover, FESEM analysis showed that increasing graphene concentration led to a reduction in ZnO particle size by 85, 68, and 52 nm, respectively, accompanied by a decrease in band gap energy, as verified by UV–Vis measurements. Photoluminescence tests were also conducted and the result showed a noticeable blue shift in ZnO-PVA-Graphene nanocomposites compared to ZnO-PVA, specifically in the near band-edge (NBE) UV emission within the 374–379 nm wavelength range. Through I–V characterization, the optimal graphene concentration for cadmium detection was identified as 1.5 wt% in ZnO-PVA-Graphene nanocomposites, showing an approximate ohmic response. Meanwhile, square-wave voltammetry analysis of cadmium concentrations ranging from 0 to 80 ppm produced a coefficient of determination of 0.98926 and a Limit of Detection (LOD) of 9.88 ppm. These results showed the significant potential of ZnO-PVA-Graphene nanocomposites as a promising material for further development as an effective electrode modifier, enhancing the sensitivity of detection systems.

Green electromembrane extraction of morphine by sodium alginate-g-polyacrylamide/agarose interpenetrating polymer network as a membrane

The isolation and pre-concentration of drugs from complex biological matrices prior to analysis remains a significant challenge. This study introduces a novel method for the extraction and determination of morphine from biological fluids utilizing a sodium alginate-g-polyacrylamide/agarose hydrogel electromembrane (EME) coupled with square wave voltammetry (SWV) at a glassy carbon electrode. This innovative approach eliminates the need for organic solvents, promoting a greener analytical methodology. The EME process involves the application of a direct current potential across the hydrogel membrane, facilitating the transport of charged morphine molecules from a donor solution (pH 7.0) to an acceptor solution (pH 3.0) under optimized conditions. Following extraction (70 V, 25 min), the acceptor solution is subjected to SWV analysis in a phosphate buffer solution (pH 6.0). This approach successfully extracts morphine, a highly polar compound (log P = 0.43), without requiring ion-pairing or carrier reagents. The method exhibits impressive limits of detection (LOD) and quantification (LOQ) of 0.036 μg/mL and 0.109 μg/mL, respectively. This work demonstrates the potential of the sodium alginate-g-polyacrylamide/agarose hydrogel EME coupled with SWV for the sensitive determination of morphine in urine and wastewater samples.

Square wave voltammetry based electrochemical determination of affinity of cholesterol triethylene glycol modified DNA-aptamers for protoporphyrin IX

Recent advancement in molecular medicine has seen applications of advanced biotechnology tools such as aptamer technology in therapeutics and diagnostics. Aptamer technology has witnessed various approaches including “Click-Chemistry” towards modifying aptamer structure to improve its potentials, but limited studies have reported the influence of such alteration on aptamer's specificity and affinity for their targets. Here, we utilized square wave voltammetry (SWV) electrochemical sensing based on heme to show the effects of cholesterol-triethylene-glycol (COL-TEG) modification of protoporphyrin-IX DNA-aptamers (OKA_24 and OKA_26) on their affinity for heme. Binding was evaluated by immobilizing 5 μM of heme onto cysteamine-glutaraldehyde-coated gold-electrode to construct electrochemical biosensor. Sensing of native/modified-aptamer was achieved by incubating their varying concentrations (9.76 nM - 10 μM) with heme-coated gold-electrode in HKSCM buffer pH 5, for 15 min. Chloroquine (2.5 μM) and non-binding HPIX-aptamer (2.5 μM) served as controls. Ferrocene was the redox solution used for SWV analysis. Protoporphyrin-IX DNA-aptamers specificity for heme was not tarnish by lipid conjugation. Selective binding of 2.5 μM of COL-TEG-OKA_24 and COL-TEG-OKA_26 to heme induced peak-current reduction by 30.68% and 24% respectively. Incubation of OKA_24 and OKA_26 aptamers produced resistance to current flow through the heme-coated gold-electrode by 23.21% and 14.4 8% respectively. Affinity SWV reveals that cholesterol conjugation decreases the affinity of COL-TEG-OKA_24 (KD = 4 7.13 ± 3.767 nM) and COL-TEG-OKA_24 (KD = 84.6 ± 8.7 nM) by 3- fold. There is a need to check the impact of such alteration on inhibition of heme to hemozoin polymerization, a process mediated by Plasmodium falciparum.

Voltammetric analysis of luminescent markers in gunshot residues.

Currently, SEM-EDS is used to detect gunshot residue (GSR) from the presence of Ba, Pb, and Sb in the sample. However, the development of new nontoxic ammunition (NTA) has prevented conventional metals from being found. In this work, we aim to determine the presence of an inorganic luminescent chemical marker based on rare earth in gunshot residues using the technique of squarewave voltammetry (SWV). After firing, the luminescent complex [(Eu2 Zr)(btc)3 (Hbtc)0.5 .6H2 O], which is used as a chemical marker, can be detected under a UV lamp. An aqueous solution with 0.1mol L-1 KCl as supporting electrolyte can be easily collected on carbon paste electrode surfaces for SWV analysis A=100 mV, f=10Hz, and step potential of 5mV are required. The luminescent marker incorporated into the carbon paste electrode showed two anodic peak currents in the region of 0.4V (vs Ag/AgCl) and at 0.75 V (vs Ag/AgCl) and also a cathodic one in 0.4V (vs Ag/AgCl). SEM-EDS was able to analyze the same voltammetric results for conventional and nontoxic ammunition containing the luminescent marker. Therefore, voltammetry and SEM-EDS are valid for detecting the new residue marker in GSR. Despite this, the electrochemical method is still more advantageous because of its low cost and lack of expensive equipment and supplies in forensic laboratories.

Direct electrochemical determination of methotrexate using functionalized carbon nanotube paste electrode as biosensor for in-vitro analysis of urine and dilute serum samples

Chemotherapy is a widely used effective method for the treatment of cancer in humans. Severity of dose levels and treatment duration necessitate frequent continuous monitoring of active drug concentration in human serum and urine. Development of an electrochemical biosensor for direct determination of methotrexate (MTX), a chemotherapy agent, from physiological fluids has been investigated. Functionalized multi-walled carbon nanotube paste electrodes (f-CNTPE) have been fabricated for simple, cost-effective and reusable electrochemical sensors. Scanning electron microscopy studies revealed that the fabricated electrode surface is comprised of nano-streaks of independent segregated CNTs with high porosity. Cyclic voltammetric analysis showed that f-CNTPE had an enhanced electrocatalytic activity with sensitivity as much as three times and less over potentials by 70 mV compared with a conventional carbon paste electrode. Under optimized experimental parameters, differential pulse voltammograms (DPVs) exhibited a gradual increase in peak current with concentration, and the plot of peak current against MTX concentration was linear in the range of 0.4–5.5 μM. Square-wave voltammetry analysis of methotrexate exhibited a linear determination range from 0.01 to 1.5 μM, and the low-detection-limit was 2.9 × 10−9 M. Steady-state current–time analysis mimic to hydrodynamic flow-cell experiments demonstrated a low-detection-limit of 10 nM (S/N ratio ~8) and an analysis time of mere 10 s. Selective determination of MTX at micromolar concentrations in the presence of a mixture of possible electroactive interferents, ascorbic acid, dopamine, etc. (1.5 μM each) is successfully demonstrated. The electrochemical biosensor allows the detection of MTX in-vitro directly from pharmaceutical drug, human serum and undiluted urine samples at very low concentration limits of as low as 5.0 × 10−7 M with recovery error limits of 4.5% at maximum.

Selective Determination of Levodopa in the Presence of Vitamin B6. Theophylline and Guaifenesin Using a Glassy Carbon Electrode Modified with a Composite of Hematoxylin and Graphene/ZnO

An electrode has been developed based on using a composite of hematoxylin/graphene/ZnO nanocomposite to modify a glassy carbon electrode (GCE). The electrode (HGGCE) was tested and found to be applicable for the voltammetric analysis of levodopa in the presence of vitamin B6, theophylline and guaifenesin using a 0.1 M phosphate buffer solution (PBS) pH 7 as the solvent. The HGGCE was used as the working electrode in cyclic voltammetry (CV) and square wave voltammetry (SWV) studies on the electrochemical behavior of levodopa at its surface. The results showed a dramatic enhancement in the oxidation current of levodopa and a shift in its oxidation potential towards more negative potentials as opposed to identical tests using bare GCE as the working electrode. The studies showed that the increase in the oxidation current has two linear profiles in two concentration ranges of 0.05 - 90.0 and 90.0 - 1000.0 μM. The detection limit of SWV analysis using the modified electrode was determined to be 0.03 μM (S/N = 3). Further advantages of the methods based on HGGCE include the simple modification procedure of the electrode, as well as its excellent sensitivity and reproducibility. The modified electrode was eventually found to be applicable to the determination of mixtures of levodopa, vitamin B6, theophylline and guaifenesin in real samples.

Tetrathiafulvalene aids in the atomic spectroscopic determination of total mercury

The determination of mercury simultaneously with other elements via inductively coupled plasma-mass spectrometry (ICP-MS) in airborne particulate matter (PM2.5) is still challenging due to the lack of accuracy for the low level mercury concentrations as a result of its volatility and tendency to adhere to the walls of the sample introduction system. This study investigated the effect of existing (gold and methionine) and new (lithium tetrathiafulvalene carboxylate (LiCTTF)) preservation agents in order to improve the determination of trace mercury in PM2.5 samples. Statistical analysis revealed that a concentration of 10 μg mL−1 of LiCTTF was sufficient to obtain highly accurate results with t values of 0.1044–1.1239 which are considerably less than the critical t value of 1.8 and apparent recoveries of 85–100%. An evaluation of the method revealed a spiked mercury recovery of 91% and a detection limit of 0.05 ng mL−1. The method was tested for the determination of trace metals in PM2.5 from atmospheric samples and led to the detection of low elemental concentrations in Singapore's atmosphere. The mechanism for the interaction of mercury with LiCTTF and tetrathiafulvalene (TTF) was studied by conducting in situ electrochemical studies. Cyclic voltammetry and square-wave voltammetry analyses of mercury, and mercury in presence of LiCTTF and TTF revealed complexation between the metal and sulfur-containing compounds.

Electrochemical reduction of sulfite based on gold nanoparticles/silsesquioxane-modified electrode

This paper reports the synthesis and characterization of the water-soluble form of 3-n-propyl(4-methylpyridinium) silsesquioxane chloride (Si4Pic+Cl−), which showed potential for application as a stabilizing agent for gold nanoparticles (AuNP). Dispersed and stable suspensions of nanoparticles, with an average diameter of 45nm, were obtained. Carbon paste electrodes modified with gold nanoparticles and Si4Pic+Cl− were constructed and applied in the detection and quantification of sulfite in acidic medium. Under these conditions, sulfur is in the electroactive form (sulfur dioxide) with a typical reduction peak at ca. −0.35V (vs. SCE). Considering the voltammetric signal for sulfite, the electrode modified with AuNP (CPE/Au-Si4Pic+Cl−) showed an electrocatalytic effect of ca. −0.20V compared to the bare electrode. In the square-wave voltammetry analysis, under optimized experimental conditions, the reduction peak increased with an increasing concentration of sulfite in the range of 2.54 to 48.6mgL−1. The calculated LOD and LOQ values for sulfite were 0.88 and 2.68mgL−1, respectively. The proposed method was successfully applied to white wine and coconut water samples, and no matrix effects were noted. Validation was performed through a comparison with results obtained by iodimetric titration. In recovery tests, the percentage recovery varied from 98 to 103% (n=3).

Electrochemical technique for detecting the formation of uranium-containing precipitates in molten fluorides

The electrochemical behavior of U(IV) in molten LiF–NaF–KF (46.5:11.5:42mol) (FLINAK) eutectic salt was studied by cyclic voltammetry and square-wave voltammetry analyses. The reduction of U(IV) proceeded in two steps: reduction of initial U(IV) to U(III), followed by three-electron reduction of U(III) to U metal. Both reactions were reversible and controlled by ion diffusion at a scan rate of 0.02–0.3Vs−1. A linear relationship between the reduction current density of U(III)/U(0) and the concentration of U(IV) was also established within 0.01–0.084molkg−1. When different concentrations of Li2O were added to the FLINAK–UF4 system, the peak current density of U(III)/U(0) was depleted because of the formation of UO2 precipitates. The apparent solubility product (Ksp) of UO2 in FLINAK–UF4–Li2O melts was approximately 4.75×10−6 mol3/kg3, which can be used to evaluate the allowable amount of dissolved oxide ions in uranium-based fluorides.

Mercury meniscus on solid silver amalgam electrode as a sensitive electrochemical sensor for tetrachlorvinphos

The in-house prepared mercury meniscus modified solid silver amalgam electrode (m-AgSAE) was successfully applied for the detection of organophosphate pesticide tetrachlorvinphos in pH 7 buffer solution. The electrochemical performance of m-AgSAE for the reduction of tetrachlorvinphos was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV), respectively. The surface morphology of solid silver electrode (AgE), as-amalgamated solid silver amalgam electrode (AgSAE), and polished solid silver amalgam electrode (p-AgSAE) was examined by field emission scanning electron microscopy (FESEM). Among the applied techniques, DPV and SWV analysis showed a remarkable increase in the reduction peak current and provided a simple, fast, and sensitive method for the determination of tetrachlorvinphos. The electrochemical impedance spectroscopy (EIS) was used to correlate the electrocatalytic activity of AgSAE, p-AgSAE and m-AgSAE with their interfacial charge transport capabilities. Under the optimized experimental conditions, the DPV and SWV responses were linear over the 1–9μM and 10–50μM concentration ranges with a detection limit of 0.06μM for DPV and 0.04 for SWV. The estimation of tetrachlorvinphos in the ground and waste water samples with the proposed method was in good agreement with that of the added amount. The proposed electrochemical method not only extends the application of non-toxic m-AgSAE, but also offers new possibilities for fast and sensitive analysis of tetrachlorvinphos and its structural analogs in environmental samples.

Adsorptive Square Wave Voltammetric Determination of Acyclovir and Its Application in a Pharmacokinetic Study Using a Novel Sensor of β-Cyclodextrin Modified Pencil Graphite Electrode

Abstract An electrochemical sensor for acyclovir (ACV) based on polymerization of β-cyclodextrin (β-CD) on electrochemically pretreated pencil graphite electrode (PGE) was built for the first time. A synergistic effect of β-CD was used to construct this sensor for quantification of this important drug. Scanning electron microscope (SEM) images show that polymer of β-CD has been successfully modified on the electrode. Square wave voltammetry (SWV) exhibited two linear dynamic ranges of 5 × 10−8 to 6 × 10−7 M and 1 × 10−6 to 9 × 10−6 M of ACV for its oxidation and the detection limit was found to be as low as 7.59 × 10−9 M of ACV. The parameters affecting ACV oxidation were investigated. The prepared electrodes showed good fabrication reproducibility. The analytical applications of the prepared electrodes were tested by using ACV dosage forms and human urine as a real sample. The SWV analysis has been successfully applied to pharmacokinetic studies of ACV in health human volunteers after oral administration of a single dose of Zovirax suspension (400 mg/5 mL).

Electrochemical behaviors of Dy(III) and its co-reduction with Al(III) in molten LiCl-KCl salts

In this work, the electrochemical behaviors of Dy(III) and its co-reduction with Al(III) on an inert tungsten electrode was investigated in LiCl-KCl molten salts at the temperature of 773K by using cyclic voltammetry (CV), chronopotentiometry (CP) and square wave voltammetry (SWV) techniques. The results showed that the reduction of Dy(III) ions in LiCl-KCl salts is a reversible diffusion controlled process through a one-step reaction: Dy(III)+3e− ↔ Dy(0). The diffusion coefficient of Dy(III) ions was calculated by both the CV and CP methods. Furthermore, the co-reduction of Al(III) and Dy(III) ions on the inert tungsten electrode allows Dy(III) ions to be reduced at a more positive potential through forming Al-Dy alloys. The concentration ratio of Al(III) cations to Dy(III) cations has a large impact on the formation of Al-Dy alloys. In a Dy(III) ion rich system, three signals attributed to the formation of Al-Dy intermetallic compounds were observed in CV and SWV analyses, while only two signals corresponding to Al-Dy intermetallic compounds were observed in the Dy(III) ion poor system. Potentiostatic and galvanostatic electrolyses performed on an aluminum electrode identified the co-reduction by the formation of one (Al3Dy) and two Al-Dy alloys (Al3Dy, AlDy), respectively. Finally, the electrolysis products were characterized by the Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) analyses.

Copper-doped titanium dioxide nanoparticles as dual-functional labels for fabrication of electrochemical immunosensors

Constructions of versatile electroactive labels are key issues in the development of electrochemical immunosensors. In this study, copper-doped titanium dioxide nanoparticle (Cu@TiO2) was synthesized and used as labels for fabrication of sandwich-type electrochemical immunosensors on glassy carbon electrode (GCE). Due to the presence of copper ions, Cu@TiO2 shows a strong response current when coupled to an electrode. The prepared nanocomposite also shows high electrocatalytic activity towards reduction of hydrogen peroxide (H2O2). The dual functionality of Cu@TiO2 enables the fabrication of immunosensor using different detection modes, that is, square wave voltammetry (SWV) or chronoamperometry (CA). While Cu@TiO2 was used as labels of secondary antibodies (Ab2), carboxyl functionalized graphene oxide (CFGO) was used as electrode materials to immobilize primary antibodies (Ab1). Using human immunoglobulin G (IgG) as a model analyte, the immunosensor shows high sensitivity, acceptable stability and good reproducibility for both detection modes. Under optimal conditions, a linear range from 0.1pg/mL to 100ng/mL with a detection limit of 0.052pg/mL was obtained for SWV analysis. For CA analysis, a wider linear range from 0.01pg/mL to 100ng/mL and a lower detection limit of 0.0043pg/mL were obtained. The proposed metal ion-based enzyme-free and noble metal-free immunosensor may have promising applications in clinical diagnoses and many other fields.

A new consumable anode material of titanium oxycarbonitride for the USTB titanium process

A single phase titanium oxycarbonitride TiC0.25O0.25N0.5 was prepared by sintering a homogenous mixture of TiO, TiC and TiN with a molar ratio of 1 : 1 : 2 by spark plasma sintering (SPS) at 1873 K. TiO0.25C0.25N0.5 was then used as the consumable anode for the USTB titanium process and the anode dissolution process was investigated by electrochemical methods. The results showed that TiO0.25C0.25N0.5 was electrochemically dissolved into Ti(2+) in the NaCl-KCl melts as determined by square-wave voltammetry analysis and simultaneously CO as well as N2 evolved in the anode as detected by mass spectroscopy. And TiO0.25C0.25N0.5 has exhibited a similar electron transfer resistance as TiC0.5O0.5 and TiN as measured by electrochemical impedance spectroscopy (EIS) analysis. By galvanostatic electrolysis, the cathode products were proved to be pure titanium powders. The results indicated that TiO0.25C0.25N0.5 is a suitable consumable anode for the USTB titanium process.

Reversible Phenol Oxidation and Reduction in the Structurally Well-Defined 2-Mercaptophenol-α3C Protein

2-Mercaptophenol-α₃C serves as a biomimetic model for enzymes that use tyrosine residues in redox catalysis and multistep electron transfer. This model protein was tailored for electrochemical studies of phenol oxidation and reduction with specific emphasis on the redox-driven protonic reactions occurring at the phenol oxygen. This protein contains a covalently modified 2-mercaptophenol-cysteine residue. The radical site and the phenol compound were specifically chosen to bury the phenol OH group inside the protein. A solution nuclear magnetic resonance structural analysis (i) demonstrates that the synthetic 2-mercaptophenol-α₃C model protein behaves structurally as a natural protein, (ii) confirms the design of the radical site, (iii) reveals that the ligated phenol forms an interhelical hydrogen bond to glutamate 13 (phenol oxygen-carboxyl oxygen distance of 3.2 ± 0.5 Å), and (iv) suggests a proton-transfer pathway from the buried phenol OH (average solvent accessible surface area of 3 ± 5%) via glutamate 13 (average solvent accessible surface area of the carboxyl oxygens of 37 ± 18%) to the bulk solvent. A square-wave voltammetry analysis of 2-mercaptophenol-α₃C further demonstrates that (v) the phenol oxidation-reduction cycle is reversible, (vi) formal phenol reduction potentials can be obtained, and (vii) the phenol-O(•) state is long-lived with an estimated lifetime of ≥180 millisecond. These properties make 2-mercaptophenol-α₃C a unique system for characterizing phenol-based proton-coupled electron transfer in a low-dielectric and structured protein environment.

The use of a gold electrode for the determination of amphetamine derivatives and application to their analysis in human urine

The catalytic abilities of gold electrode were tested for the quantitative determination of amphetamine (A) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) standards by their oxidation using cyclic voltammetry (CV). The value of the oxidative currents of A and MDMA standards at 0.80 V vs. SCE in 0.05 M NaHCO3 at the scan rate of 50 mV/s is linear function of concentration in range of 110.9-258.9 mM and 38.7-229.2 mM, respectively. Square wave voltammetry (SWV) revealed linear increase of current with concentration of MDMA (range 30.9-91.6 mM) and thus quantitative determination of amphetamine derivates. SWV analysis is successfully performed in spiked urine samples as well. A and MDMA in the presence of sucrose and as a content in illegally produced tablets were also analyzed. The voltammetric determination of A and MDMA derivatives using CV and SWV at gold electrode is a rapid, selective and simple procedure and its accuracy was confirmed with reference method, high performance liquid chromatography (HPLC). The spiked urine samples analysis offers additional possibility for the rapid detection of A and MDMA in human urine.

Magnetic electrochemical immunoassays with quantum dot labels for detection of phosphorylated acetylcholinesterase in plasma.

A new magnetic electrochemical immunoassay has been developed as a tool for biomonitoring exposures to organophosphate (OP) compounds, e.g., insecticides and chemical nerve agents, by directly detecting organophosphorylated acetylcholinesterase (OP-AChE). This immunoassay uniquely incorporates highly efficient magnetic separation with ultrasensitive square wave voltammetry (SWV) analysis with quantum dots (QDs) as labels. A pair of antibodies was used to achieve the specific recognition of OP-AChE that was prepared with paraoxon as an OP model agent. Antiphosphoserine polyclonal antibodies were anchored on amorphous magnetic particles preferably chosen to capture OP-AChE from the sample matrixes by binding their phosphoserine moieties that were exposed through unfolding the protein adducts. This was validated by electrochemical examinations and enzyme-linked immunosorbent assays. Furthermore, antihuman AChE monoclonal antibodies were labeled with cadmium-source QDs to selectively recognize the captured OP-AChE, as characterized by transmission electron microscopy. The subsequent electrochemical SWV analysis of the cadmium component released by acid from the coupled QDs was conducted on disposable screen-printed electrodes. Experimental results indicated that the SWV-based immunoassays could yield a linear response over a broad concentration range of 0.3-300 ng/mL OP-AChE in human plasma with a detection limit of 0.15 ng/mL. Such a novel electrochemical immunoassay holds great promise as a simple, selective, sensitive, and field-deployable tool for the effective biomonitoring and diagnosis of potential exposures to nerve agents and pesticides.

Experimental and theoretical study of DNA oxidation

AbstractThe electrochemical oxidation of DNA and bases at a glassy carbon electrode were investigated using cyclic and square-wave voltammetry analysis. The predicted oxidative potentials for DNA and bases using DFT method (B3LYP) are in agreement with the experimental ones.The DNA oxidation ascribes to N-protonated guanine and adenine. The calculated oxidative peaks indicate that the initial potential of DNA oxidation is around 0.432V for N-protonated guanine and 0.368V (vs.hydrogen standard electrode) at pH 7.00, and DNA as well as bases in acidity solution are more stable than those in alkalescent solution.

Bioelectrochemical Magnetic Immunosensing of Trichloropyridinol: A Potential Insecticide Biomarker

AbstractA fast, simple and sensitive bioelectrochemical magnetic immunosensing method is developed to monitor a potential insecticide biomarker, trichloropyridinol (TCP), in environmental sample. A magnet/glassy carbon (MGC) working electrode was used to accumulate immunocomplex associated magnetic beads and separate free and unbound reagents after liquid phase competitive immunoreaction among TCP antibody coated magnetic beads, TCP analyte and horseradish peroxidase (HRP) labeled TCP. The activity of HRP tracers was monitored by square‐wave voltammetry (SWV) by scanning electrocactive enzymatic product in the presence of 3,3′,5,5′‐tetramethylbenzidine dihydrochloride and hydrogen peroxide (TMB‐H2O2) substrate solution. The electrochemical signal of enzymatic product was greatly enhanced by dual accumulation events: magnetic accumulation of enzyme tracers bound magnetic beads and constant potential accumulation of enzymatic product. The voltammetric characteristics of substrate and enzymatic product were investigated, and the parameters of SWV analysis and immunoassay were optimized. Under the optimal conditions the immunosensor was used to measure as low as 5 ng L−1 (ppt) TCP, which is 50‐fold lower than the value indicated by the manufacture of the TCP RaPID Assay kit (0.25 μg/L, colorimetric detection). The performance of the developed immunosensing system was successfully evaluated with river water samples spiked with TCP, indicating this convenient and sensitive technique offers great promise for decentralized environmental application. This technique could be readily used for detection of other environmental contaminants by developing specific antibodies against the contaminants and are expected to open new opportunities for environmental monitoring and public health.