Electrochemical Behavior of Hydrogen Peroxide at a Glassy Carbon Electrode Modified with Nickel Hydroxide–Decorated Multiwalled Carbon Nanotubes

Abstract

The multiwalled carbon nanotube–nickel hydroxide composite film used to modify glassy carbon electrode was prepared and confirmed by transmission electron microscopy and cyclic voltammetry. The process and mechanism of film formation were discussed in detail. The electrode modified with the composite film exhibited good catalytic activity toward electrochemical oxidation of hydrogen peroxide in 0.1 mol/L sodium hydroxide solution. Various factors affecting the electrocatalytic activity of nickel hydroxide film were investigated. The anodic peak current increased with the increased concentration of hydrogen peroxide. The linear range for the determination of hydrogen peroxide was from 1.5 × 10^?6 mol/L to 2.5 × 10^?3 mol/L with the detection limit 6.1 × 10^?7 mol/L (S/N = 3). And the proposed method was applied to the determination of hydrogen peroxide in disinfector with higher sensitivity and lower detection limit.     

Determination of Formaldehyde with a Platinum–Palladium–Graphene Nanocomposite Glassy Carbon Electrode

The oxidation of formaldehyde on a platinum (Pt)–palladium (Pd)–graphene nanocomposite glassy carbon electrode prepared by chemical reduction was characterized in 0.5?M sulfuric acid. The surface and morphology of the catalyst were characterized by transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. Bimetallic Pt–Pd nanoparticles were uniformly dispersed on the graphene sheets. Energy-dispersed X-ray spectroscopy was used to characterize the metal composition of the nanocomposite. The electrocatalytical characteristics of the modified electrode were investigated by cyclic voltammetry. The results show that the electrode displayed high activity for the oxidation of formaldehyde in sulfuric acid with a linear relationship from 4.50?µM to 0.180?mM and a detection limit of 2.85?µM. The low detection limit, wide linear dynamic range, and high sensitivity of the modified electrode suggests further applications.     

Direct Electrochemical Oxidation of NADPH at a Low Potential on the Carbon Nanotube Modified Glassy Carbon Electrode

Introduction Because of its novel structural and electronic proper-ties, high chemical stability, and extremely high me-chanical strength and modulus,1 carbon nanotube (CNT), which has become a major subject of many experimen-tal and theoretical investigations, has a wide potential application from structural materials to nanoelectronic components2-12 since its initial discovery by Iijima13 in 1991 and the subsequent report about the synthesis of large quantities of CNT by Ebbesen and cowork…     

The Electrochemical Behavior and the Determination of Bavistin on Glassy Carbon Electrode

Bavistin(MBC)'isatypeofveryimportantbactericides.Theanalyticalmethodsofthispesticideincludingchromatography',polarography'havebeenreported,butthereisnoreportaboutthedetendnationwithvoltanuntryonglassycarbonelectrode.Inthispaper,westudiedthevoltanunetric(CV)propertiesandthedifferentialpulsestrippingvoltanunetry(DPSV)detendnationofMBConglassycarbonelectrode.TheinstrUmentusedinthisexperimentwastheBAS-l(X)AElectroanalyser.Aglassycarbonelectrodewasusedastheworkingelectrode,aconunercialAgjA…     

Electrochemical Determination of Dopamine Using a Graphene–Screen-Printed Carbon Electrode with Magnetic Solid-Phase Microextraction

A magnetically separable Fe₃O₄@Diaion HP-2MG composite was prepared using the coprecipitation method and the resulting magnetic Fe₃O₄@Diaion HP-2MG composites were used for the separation and preconcentration of trace amounts of dopamine. For the detection stage, square wave voltammetry on a disposable graphene–screen-printed carbon electrode was successfully used for the determination of dopamine. The graphene–screen-printed carbon electrode exhibited excellent electroanalytical performance for dopamine. The linear concentration range was from 0.8 to 80?µM and a detection limit of 50?nM for dopamine was obtained. In combination with the magnetic solid-phase extraction method, the sensor response was linearly proportional to the concentration of dopamine in the range of 0.01–6.0?µM with a correlation coefficient of approximately 0.9992. The detection limit of the sensor was found to be 5.0?nM by square wave voltammetry. The combined methodology was successfully applied to determine dopamine in urine samples with good recoveries ranging from 95 to 98%.     

Voltammetric Determination of L‐Dopa Using a Carbon Nanotubes‐Nafion Modified Glassy Carbon Electrode

Abstract

A method for determination of L‐dopa by the adsorption stripping voltammetry (ASV) using a multiwalled carbon nanotubes (MWNTs)–Nafion modified glassy carbon electrode (GMGCE) was proposed. This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed and the anodic peak potential is ca. 0.374V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of L‐dopa in samples. There is a good linear relationship between the peak current (i_p) and L‐dopa concentration in the range of 3.5×10^?7～1.5×10^?5 mol/L, with the limit of detection 5.0×10^?8 mol/L.     

Preparation of Platinum Implanted Glassy Carbon Electrode and Electro-oxidation of Formic Acid and Formaldehyde

Electrocatalytic oxidation of small organic molecules has attracted considerable at-tentionin system of fuel celll-4. In this research field, Parsons4 pointed out that the electrodeswhich were prepared from non-noble substrates modified by excellent dispersal noblemetal particles and which still exhibited better catalytic activity should be studied. Ionimplantation is a technique with unique advantage and has been used in manyelectrochemical research fieldss'6. The present study is an at-tempt…     

Fabrication of CeO2 Nanoparticle Modified Glassy Carbon Electrode for Ultrasensitive Determination of Trace Amounts of Uric Acid in Urine

The preparation of a glassy carbon electrode modified by CeO2 nanoparticles was described, which was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In pH 6.0 buffer, the CeO2 nanoparticle modified electrode （CeO2 NP/GC） gave an excellent electrocatalytic activity for the oxidation of uric acid （UA）. The catalytic current of UA versus its concentration had a good linear relation in the range of 2.0 × 10^-7-5.0 × 10^- 4 mol/L, with the correlation coefficient of 0.9986 and detection limit of 1.0 ×10^-7 mol/L. The modified electrode can be used for the determination of UA in urine, which can tolerate the interference of ascorbic acid up to 1000-fold. The method was simple, quick and sensitive.     

Anodic Oxidation of α‐Lipoic Acid at a Glassy Carbon Electrode and Its Determination in Dietary Supplements

Abstract

Direct electrochemistry of alpha‐lipoic acid (ALA) was performed at a glassy carbon electrode using cyclic, differential pulse and square wave voltammetry over a wide range of pH. The oxidation of ALA is an irreversible process, pH independent, and involves the charge transfer of one electron. The diffusion coefficient of ALA was calculated from the results obtained at pH 6.9 in 0.1 M phosphate buffer and was shown to be D ₀=1.1×10^?5 cm² s^?1. The limits of detection (LOD) and quantification (LOQ) calculated from the results obtained at this pH are 1.8 and 6.1 µM, respectively.

The lipoic acid content in two dietary supplements samples, a syrup containing ALA and capsules of ALA, has been determined directly at the glassy carbon electrode by differential pulse voltammetry using the standard addition method.     

Electrochemical Analysis of Mercury Using a Kryptofix Carbon‐Paste Electrode

Abstract

Successful applications of different analytical procedures to determine quantitatively mercury in aqueous media can be found in recent literature. Fundamentally it has made use of Cold Vapour Atomic Absorption Spectrometry (CV‐AAS), X‐Ray Fluorescence or UV Spectrophotometry, Inductively Coupled Plasma Atomic Emission Spectrometry (ICP‐AES), or Inductively Coupled Plasma Mass Spectrometry (ICP‐MS), which are the techniques commonly used for trace measurement of heavy metal in the laboratory. In this paper a new and alternative methodology to determine quantitatively mercury in aqueous media is reported. A kryptofix carbon‐paste electrode has been used to determine voltammetrically mercury. The detection limit for mercury was evaluated to be 0.12 µg/l.     

Multiwalled Carbon Nanotubes β-Cyclodextrin Modified Electrode for Electrochemical Determination of Bisphenol S in Water Samples

Russian Journal of Electrochemistry - A voltammetric sensor for the determination of bisphenol S (BPS) in aqueous samples was fabricated by immobilization of β-cyclodextrin/multiwalled carbon...     

Nafion‐Modified Glassy Carbon Electrode for Trace Determination of Indium

Abstract

A new method for determination of trace indium is proposed by the adsorption stripping voltammetry (ASV) using a Nafion‐modified glassy carbon electrode (NMGCE). This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed, and the anodic peak potential is ca. ?0.548 V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of indium in water samples. There is a good linear relationship between the peak current (i_p) and indium(III) concentration in the range of 1.0×10^?9–1.0×10^?7 mol/l, and the limit of detection is 7.5×10^?10 mol/l.     

Electrochemical Oxidation at a Glassy Carbon Electrode of the Anti‐Arrhythmia Drug Disopyramide

Abstract

A voltammetric study of the oxidation of disopyramide has been carried out using a glassy carbon electrode. The electrochemical oxidation of disopyramide was investigated by cyclic, differential pulse, and square wave voltammetry. The oxidation of disopyramide is an irreversible, diffusion‐controlled process. The diffusion coefficient of disopyramide was calculated in pH 7.0 phosphate buffer to be D _disopyramide=3.8×10^?6 cm² s^?1. The oxidation of disopyramide is also pH dependent and for electrolytes with pH between 4 and 7 occurs with the transfer of one electron and one proton. In alkaline electrolytes, two consecutive charge transfer reactions are observed: both oxidation reactions involve the transfer of two electrons but only the first also involves the transfer of two protons. Two procedures for the analytical determination of disopyramide in pH 7.0 phosphate buffer were developed and compared and a detection limit LOD=1.27 µM was obtained.     

Determination of Hydrogen Peroxide by Electrochemiluminescence Using a Chitosan–graphene Composite Film Doped Cadmium-Tellurium Quantum Dot Modified Glassy Carbon Electrode

Here is reported the novel determination of hydrogen peroxide by electrochemiluminescence using a chitosan–graphene composite film doped cadmium-tellurium quantum dot modified glassy carbon electrode. The cadmium-tellurium quantum dots were studied by absorption and fluorescence spectroscopy. Scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the structure morphology of the composite matrix. The electrochemiluminescence emission was linear with the concentration of hydrogen peroxide in the range of 3.5?×?10^?7 to 1.1?×?10^?5?M with a determination limit of 2.1?×?10^?7?M. Furthermore, the modified electrode showed excellent reproducibility and stability.     

Voltammetric Determination of Dopamine in Human Serum and Urine at a Glassy Carbon Electrode Modified by Cysteic Acid Based on Electrochemical Oxidation of L ‐cysteine

Abstract

The voltammetric behavior of dopamine was studied at a glassy carbon electrode modified by cysteic acid, based on electrochemical oxidation of L ‐cysteine. The modified electrode showed strong electrocatalytic activity towards dopamine and good selectivity. In a phosphate buffer solution (pH 7.4), the anodic peak current obtain from the differential pulse voltammetry of dopamine was linearly dependent on its concentration in the range of 5×10^?9 to 4.0×10^?6mol · L^?1, with a detection limit of 2×10^?9mol · L^?1. The low‐cost modified electrode had been applied to the determination of dopamine in human serum and urine samples with satisfactory results.     

Voltammetric Determination of Hydroquinone using β‐Cyclodextrin/Poly(N‐Acetylaniline)/Carbon Nanotube Composite Modified Glassy Carbon Electrode

Abstract

An electrochemical sensor for hydroquinone (HQ) using β‐cyclodextrin/poly(N‐acetylaniline)/carbon nanotube composite (β‐CD/PAA/MWNTs) modified glassy carbon electrode has been successfully developed. Based on the synergistic effect of MWNTs and conducting PAA polymer and the accumulation effect of β‐CD, the analytical response of the β‐CD/PAA/MWNTs film to the electrochemical behavior of HQ was better than that of a β‐CD/PAA film, a PAA/MWNTs film, a PAA film, or a bare glassy carbon (GC) electrode. Under the conditions chosen, the anodic currents increased linearly with HQ concentration from 1×10^?6 to 5×10^?3 mol l^?1 and the detection limit was 8×10^?7 mol l^?1. This electrochemical sensor showed excellent reproducibility, stability and recovery for the determination of HQ.     

Electrochemical Characterization of CoHP–Si Incorporated into a Carbon Paste Electrode

Reduction of dioxygen at a carbon paste electrode (CPE) modified with cobalt hematoporphyrin complex immobilized on silica gel (CoHP–Si) was studied by cyclic voltammetry and rotating disk electrode. In 0.5molL^–1 KCl solution, the supported complex showed significant catalytic activity towards four-electron reduction of O₂ to H₂O at a relatively high pH (5.4). The reduction of dioxygen proceeds at a more negative potential (–0.375V) than the redox reaction Co^III/Co^II (0.464V), indicating that the mechanism does not involve the complex as an electron transfer mediator. Catalytic activity of CoHP–Si towards reduction of H₂O₂ was tested, but no activity was observed.Received October 26, 2002; accepted March 10, 2003 Published online July 16, 2003     

Cyclic Voltammetry Determination of Epinephrine with a Nano—gold Modified Glassy Carbon Electrode in the Presence of High Concentration Ascorbic Acid

As we know, there are usually some problems in electrochemical analysis with bare electrode to detect neurotransmitters. One is low electron transfer rate and the other is interfering compounds, such as ascorbic acid. So some kinds of modified electrodes have been successfully employed to promote the efficiency of electrochemical analysis1-4, such as Nafion modified electrode5,6 and SAM modified electrode7. They can attract positively-charged neurotransmitters while repulse negatively-cha…     

Discrimination of Tea by the Electrochemical Determination of its Antioxidant Properties by a Polyaniline – DNA – Polyphenazine Dye Modified Glassy Carbon Electrode

Abstract

Voltammetric sensors have been developed on the bases of polyaniline and polymeric forms of methylene blue, methylene green, and neutral red obtained by multiple cycling of the potential. The integrity of the layers and expansion of the pH range of redox activity have been achieved by intermediate adsorption of native DNA that stabilized the oxidized polyaniline form. The formation of the coating layer was confirmed by electrochemical impedance spectroscopy and scanning electron microscopy. Model oxidants (ascorbic acid, hydroquinone, and quercetin) in the concentration range from 1?×?10^?6 to 1?×?10^?3 mol L^?1 influenced the measured redox peaks of polymeric dyes with standard deviations from 2.4 to 5.5%. The peak currents were used for classification of tea brands using principal component analysis and linear discrimination analysis. The average discrimination of the tea brands purchased on local market was approximately 100%. The assessment of antioxidant properties of tea infusions was in agreement with results obtained using a coulometric bromine titration.     

Gold Nanoparticle-based Layer-by-Layer Enhancement of DNA Hybridization Electrochemical Signal at Carbon Nanotube Modified Carbon Paste Electrode

Nanoporous materials have been widely applied to biosensor investigation. Recently, Guo et al. have investigated the mesoporous materials modified carbon paste electrode for rapid cTnI (cardiac troponin I) detection with enhanced sensitivity1-3. However, …