Study on poly(3,4-ethylenedioxythiophene) behaviour in the I−/I2 solution

The properties of poly(3,4-ethylenedioxythiophene) (PEDT) film have been studied in iodide solutions by cyclic voltammetry and stripping voltammetry methods. It has been shown that formation of charge-transfer complexes between iodine species and polymeric rings promotes storage of iodine on an electrode covered by PEDT film. Due to this behaviour the PEDT layer can be employed for electroanalysis of dilute (10⁻⁴–10⁻³ M) solutions of iodide salts by stripping voltammetry methods. The possibility of PEDT film application for zinc-iodide rechargeable batteries was also examined.     

The cathodic stripping voltammetric determination of traces of iodide with a hanging copper amalgam drop electrode

A hanging copper amalgam drop electrode (HCADE) is used for the determination of traces of iodide by cathodic stripping voltammetry. The cathodic stripping peak of copper(I) iodide from the HCADE is better defined than that of mercury(I) iodide from a hanging mercury drop electrode. Optimum conditions and interferences are reported. With a 3-min deposition time at ?0.1 V vs. SCE, the calibration plot is linear up to 2 × 10^?6 mol dm^?3 iodide. The detection limit for iodide with the HCADE under voltammetric conditions is 4 × 10^?8 mol dm^?3; this is lowered to 8 × 10^?9 mol dm^?3 by using the differential pulse stripping technique.     

利用碘离子增感效应和金电极导数阳极溶出法研究铜丶铅和镉的同时测定

A method of simultaneous determination of copper (II), lead (II) and cadmium (II) in sulphuric acid-iocide ion medium was established by derivative anodic stripping voltammetry (DASV) on the gold electrode. The peak theights of lead and cadmium were increased by enhancement effect of iodide ion and the peaks of bismuth and copper were well formed and completely resolved on gold electrode in the presence of iodide ion, therefore peak of copper is not affected by bismuth. The sensitivities for copper, lead and cadmium were very high and their peak potentials in the stripping voltammogram were +0.25, -0.2 and -0.27 volt, respectively. The dependence of peak height of these elemets on their concentrations was linear. The detection limits for copper, lead and cadmium were 0.2 0.2 and 0.05 ppb, respectively. We have further studied the electrode process by means of triangle cyclic voltammetry and proved that he electrode reaction of copper is reversible, and that the reversibility of electrode reactions of lead and cadmium is not good.     

Determination of heavy metals and iodide by stripping voltammetry in sodium chloride on mercury-graphite electrodes

The behavior of Cd(II), Pb(II), Cu(II), and I⁻ in the aqueous solutions of sodium chloride is studied by stripping voltammetry. A new version of using an indicator electrode from carbon glass ceramics modified with mercury for the consecutive stripping determination of Cd(II), Pb(II), Cu(II), and iodide is proposed. The mercury-graphite electrode was formed in the solution of a supporting electrolyte based on NH₄Cl, HCl, 0.05 M potassium tetraoxalate (KH₃C₄O₃ · 2H₂O), and 5 × 10⁻⁵ M mercury(II). At first, Cd(II), Pb(II), Cu(II), and then iodide were determined by anodic-cathodic stripping voltammetry after adding a sample solution (table salt, 10–100 mg/mL NaCl).     

Electroanalysis of the Anthelmintic Drug Bithionol at Edge Plane Pyrolytic Graphite Electrode

An electrochemical study of the anthelmintic drug bithionol using edge plane pyrolytic graphite electrode (EPPGE) is presented for the first time by applying different electrochemical techniques, such as cyclic voltammetry (CV), square‐wave voltammetry (SWV), square‐wave adsorptive stripping voltammetry (SWAdSV), and alternating current (AC) impedance spectroscopy. Mechanistic aspects of the electrode reaction were studied implying a quasireversible electrode reaction from an adsorbed state of the reactant, coupled with a follow‐up chemical reaction to a final electroinactive product. The overall mechanism appears totally irreversible under conditions of CV at moderate scan rate, while being quasireversible under conditions of the fast SWV. Furthermore, an optimisation of the analytical procedure for quantitative determination of bithionol was conducted by applying SWV in an adsorptive stripping mode. The calibration curve was constructed in the concentration range of 0.1–1.0 μmol L^?1 (R²=0.9984) with a sensitivity of 3.6 μA L μmol^?1 and LOD of 26.7 nmol L^?1. The simple and sensitive SWAdSV procedure was proved to be suitable for the analysis of spiked urine samples.     

甲基对硫磷在聚噻吩/纳米二氧化钛修饰玻碳电极上的电化学行为及其测定

用循环伏安法(CV)、线性扫描溶出伏安法(LSSV)研究了甲基对硫磷(MPT)在聚噻吩/纳米二氧化钛修饰玻碳电极(PTh-NTiO2/GCE)上的电化学行为.实验表明,该修饰电极能显著提高MPT的氧化还原峰电流,在B-R缓冲溶液(pH 5.72)中,于-0.662V( vs.SCE)处产生灵敏的不可逆还原峰,其峰电流与...     

A sensitive determination of dopamine in the presence of ascorbic acid using a nafion-coated clinoptilolite-modified carbon paste electrode

A selective dopamine determination using a nafion-coated clinoptilolite-modified carbon paste electrode in the presence of ascorbic acid was studied. Both cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV) were used for measurements of dopamine. To improve the selectivity of the clinoptilolite-modified carbon paste electrode in presence of a high concentration of ascorbic acid, the electrode surface was coated with nafion membrane. Experimental parameters affecting the determination of dopamine, including the clinoptilolite ratio, nafion membrane thickness, preconcentration time, preconcentration solution pH, stripping solution pH and interferences are discussed. The developed sensor has a wide linear range, a low detection limit, and good stability and reproducibility. The sensor offers a good alternative to existing analytical methods for dopamine, permits a relatively short analysis time, and is simple, selective and inexpensive.     

Determination of azinphos-ethyl insecticide by adsorptive stripping voltammetry on the hanging mercury-drop electrode

The electrochemical characteristics of azinphos-ethyl (APE) have been determined by means of electrochemical techniques such as cyclic voltammetry (CV) and adsorptive stripping voltammetry (ASV) at a hanging mercury drop electrode (HMDE) over a wide range of pH from 2.0 to 8.0. The cyclic voltammograms demonstrate the adsorption of this compound at the mercury electrode. A systematic study of the various operational parameters that affect the stripping response was carried out by differential pulse voltammetry (DPV). With a preconcentration potential of −0.6 V and a 60 s preconcentration time, the limit of detection was 5.42 × 10⁻⁹ M, and the relative standard deviation (n = 5) was 2.7 % at concentration level of 6.45 × 10⁻⁷ M APE. The degree of interference from diverse ions and some other pesticides on the differential pulse stripping signal for APE was evaluated. Finally, the method was applied to the determination of APM in spiked soil, tap water, and treated wastewater. The text was submitted by the author in English.     

Direct determination of brucine by square wave voltammetry on 4-amino-2-mercaptopyrimidine self-assembled monolayer gold electrode

4-Amino-2-mercaptopyrimidine self-assembled monolayer (AMP SAMs/Au) was prepared on a gold electrode. The AMP SAMs/Au was characterized by using attenuated total reflection-fourier transform infrared (ATR-FTIR) and A.C. Impedance. The electrochemical behavior of brucine on AMP SAMs/Au was studied by cyclic voltammetry (CV) and square wave adsorptive stripping voltammetry (SWASV). The modified electrode showed an excellent electrocatalytic activity for the redox of brucine. The catalytic current increased linearly with the concentration of brucine in the range of 4.0 x 10(-7) to 2.0 x 10(-4) mol l(-1) by square wave voltammetry response. The detection limit was 6.0 x 10(-8) mol l(-1).     

Electrodeposition of Se on carbon-supported Pt nanoparticles by cyclic voltammetry

Cyclic voltammetry (CV) is a powerful and popular electrochemical technique widely used to study the surface structure of materials through the electrochemical behaviors. Herein CV is utilized to study the electrochemical deposition of selenium (Se) on carbon black-supported Pt nanostructures. We synthesized carbon-loaded platinum nanoparticles (Pt/C) by microwave method and studied the electrochemical behavior of selenium on them. Through the experiment of changing the reverse potential, the corresponding relationship between the Se deposition peak and stripping peak was clarified and the deposition and stripping process of Se was proposed. Meanwhile, we synthesized cubic and octahedral nanocrystals of Pt, and used CV to study the Se deposition on these nanosctructures supported by carbon. It was found that the relative intensity of UPD peaks on Pt is different, as Pt_cube@C is dominated by (100) and Pt_oct@C electrode is dominated by (111) while Pt@C falls in between.

     

Voltammetric determination of <Emphasis Type="Italic">D</Emphasis>-penicillamine based on its homogeneous electrocatalytic oxidation with potassium iodide at the surface of glassy carbon electrode

The electrooxidation of D-penicillamine (D-PA) has been studied in the presence of potassium iodide in various buffered aqueous solutions (4.00 ≤ pH ≤ 9.00) at the surface of glassy carbon electrode using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. It has been found that under optimum pH (pH 5.00) in cyclic voltammetry, the electrooxidation of D-PA in the presence of potassium iodide as a homogeneous mediator occurred at a potential about 220 mV less positive than that in absence of potassium iodide at the surface of glassy carbon electrode. The homogeneous electrocatalytic oxidation current wave of D-penicillamine was linearly dependent on the D-PA concentration and a linear calibration curve was obtained in the ranges 3.0 × 10⁻⁵−1.5 × 10⁻³ M and 9.0 × 10⁻⁶−1.2 × 10⁻⁴ M of D-PA with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. The detection limits (2σ) were determined as 3.0 × 10⁻⁵ and 3.5 × 10⁻⁶ M with CV and DPV, respectively. This method was also used for voltammetric determination of D-PA in pharmaceutical preparation by standard addition method.     

Electrochemical Studies of Three Dimensional Graphene Foam as an Electrode Material

Graphene foam is one kind of network of three dimensional (3D) graphene, which inherits the properties of two dimensional graphene and overcomes the aggregation/stacking of graphene sheets. In this work, graphene foam has been characterized by scanning electron microscopy and Raman spectroscopy. A graphene foam electrode was evaluated as a new electrode material by cyclic voltammetry (CV) and used for the detection of trace level of Pb²⁺ by anodic stripping voltammetry (ASV). Under the optimized condition of deposition potential (‐1.2 V) and deposition time (2 min), the detection limit is estimated to be 40 nM for Pb²⁺ based on the 3σ method.     

Crystallic silver amalgam--a novel electrode material

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.     

Electrochemical Detection of Pb(II) by Glassy Carbon Electrode Modified with Amine-Functionalized Magnetite Nanoparticles

An amine-Fe₃O₄ modified glassy carbon (GC) electrode was constructed for detecting Pb(II) ions in wastewater. The electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Square wave anodic stripping voltammetry (SWASV) was used to detect the Pb(II), and the detection limit of Pb(II) was 0.15 µM. The sensitivity of the electrode to detect Pb(II) was about 10.07 µA/µM, with a correlation coefficient of 0.991, which was approximately 10 times bigger than that of a pure Fe₃O₄ modified electrode. The electrode also showed good selectivity and stability. This results indicated that the amine-magnetite material could have some potential applications in heavy metal ions detection in wastewater.     

Anodic stripping voltammetry and chronopotentiometry of copper at a rotating carbosital disk electrode

The use of a new carbon material — carbosital — for electrodes is reviewed. The behaviour of copper deposited on the carbosital electrode surface in anodic stripping voltammetry and chronopotentiometry is discussed. In anodic stripping voltammetry with a rotating carbosital disk electrode, the peak current and the number of coulombs involved in stripping copper are directly proportional to the square root of the electrode rotation rate during preelectroiysis; the peak current is directly proportional to the potential scan rate during stripping. For anodic stripping voltammetry and anodic stripping chronopotentiometry, linear calibration graphs are obtained in the range 1 X 10^-3–1 x 10^-6 M copper(II). The method is applicable to analysis of high-purity cadmium for copper.     

Preconcentration and voltammetric determination of palladium (II) at sodium humate modified carbon paste electrodes

A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II) was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (I_pa1 and L_pa2) were proportional to the Pd(II) concentration in the range of 4.7 × 10^–6 - 9.4 × 10^–8 M. The developed method was applied to the quantitative determination of palladium in real samples.     

A New and Cost Effective Approach for Simultaneous Voltammetric Analysis of two Related Benzimidazole Drugs and their Determination in Biological Fluids

A polymerized film of eriochrome black T (EBT) was prepared on the surface of pencil graphite electrode in alkaline solution by cyclic voltammetry. The redox response of the poly (EBT) film at the electrode appeared in a couple of redox peak in 0.1 M sodium hydroxide. The poly (EBT) film‐coated electrode exhibited excellent electrocatalytic activity towards the oxidation of rabeprazole sodium (RAB sodium) and domperidone (DOM) in Britton‐Robinson buffer (pH 4.0). The polymer film modified electrode conspicuously enhanced the redox currents of the cited mixture and could sensitively and separately determine them. Both cyclic voltammetry (CV) and square wave adsorptive stripping voltammetric (SWAdSV) methods were utilized to determine this mixture. The linearity of CV ranged from 4.1‐120 μM and 5.2‐90 μM for RAB sodium and DOM, respectively while SWAdSV was 7.5‐80×10⁻⁷M and 5–70×10⁻⁷M for RAB sodium and DOM, respectively. With good selectivity and sensitivity, the present method provides a simple method for selective detection of RAB sodium and DOM binary mixture in synthetic mixtures and biological fluids.     

Electrochemical study of breast cancer cells MCF-7 and its application in evaluating the effect of diosgenin.

The electrochemical behavior of breast cancer cells was studied on a graphite electrode by cyclic voltammetry (CV) and potentiometric stripping analysis (PSA). In both cases, only one oxidative peak at approximately +0.75 V was observed. The peak area in PSA was used to study the growth of the cells and the effect of diosgenin on MCF-7 cells. The results showed that diosgenin can effectively inhibit the viability and proliferation of the breast cancer cells.     

Flow-injection determination of iodide ion in nuclear emergency tablets, using boron-doped diamond thin film electrode

The electrochemical determination of iodide was studied at boron-doped diamond thin film electrodes (BDD) using cyclic voltammetry (CV) and flow-injection (FI) analysis, with amperometric detection. Cyclic voltammetry of iodide was conducted in a phosphate buffer pH 5. Experiments were performed using glassy carbon (GC) electrode as a comparison. Well-defined oxidation waves of the quasi-reversible cyclic voltammograms were observed at both electrodes. Voltammetric signal-to-background ratios (S/B) were comparable. However, the GC electrode gives much greater in the background current as usual. The potential sweep rate dependence exhibited that the peak current of iodide oxidation at 1 mM varied linearly (r² = 0.998) with the square root of the scan rate, from 0.01 to 0.30 V s⁻¹. This result indicates that the reaction is a diffusion-controlled process with negligible adsorption on BDD surface, at this iodide concentration. Results of the flow-injection analysis show a highly reproducible amperometric response. The linear working range was observed up to 200 μM (r² = 0.999). The detection limit, as low as 0.01 μM (3σ of blank), was obtained. This method was successfully applied for quantification of iodide contents in nuclear emergency tablets.     

Cadmium determination in phosphate fertiliser using a PAN-Nafion® modified glassy carbon electrode by stripping voltammetry

A simple method for the determination of trace cadmium (Cd) (II), using a disposable 1-(2-pyridylazo)-2-naphthol [PAN]-Nafion®-coated glassy carbon electrode, has been developed. The modified electrode exhibited a significant improvement on both sensitivity and selectivity for Cd (II) determination, compared with a bare glassy carbon electrode (GCE), a PAN-coated GCE (PAN-GCE), and a Nafion®-coated GCE (Nafion® GCE). Differential pulse anodic stripping voltammetry (DPASV) was performed, in 0.05?M potassium hydrogen phthalate (KHP) buffer medium, after Cd (II) ion accumulation. The Cd(II) ion accumulated on the PAN-Nafion® surface of the glassy carbon working electrode through the formation of a chemical complex at an open circuit. The modified GCE with Cd (II) complex was then transferred to a 0.1?M KI solution and subjected to an electrochemical stripping procedure. Cyclic voltammetry (CV) was employed to confirm the successful stepwise assembly procedure for the modified electrode. The structure of PAN-Nafion® on the surface-modified electrode was characterised by scanning electron microscopy (SEM). System variables were optimised to yield the most suitable conditions, including the pH and concentration of the accumulation medium, deposition potential, deposition time, and amount of coated PAN-Nafion®. The quantitative analysis of contaminated cadmium in phosphate fertiliser samples was performed. The results obtained from the proposed method agree well with those obtained by inductively coupled plasma-optical emission spectrophotometry (ICP-OES).