Polyaniline-ZnO−NiO Nanocomposite Based Non-enzymatic Electrochemical Sensor for Malathion Detection

An electrochemical sensor based on polyaniline-ZnO−NiO (PANI-ZnO−NiO) nanocomposite was developed for the non-enzymatic detection of malathion. The structure, surface morphology, and optical properties of the as-prepared nanocomposite were studied by XRD, FTIR, SEM, and UV-Vis spectroscopy. The electrochemical behavior of the nanocomposite based sensor was first evaluated through cyclic voltammetry (CV). Under optimum conditions, differential pulse voltammetry (DPV) was further utilized for malathion detection, which proved the PANI-ZnO−NiO/GCE electrode as an effective electrochemical sensor. The developed electrochemical sensor showed a low detection limit of 1.0×10⁻⁸ M with a wider linear range of 10 to 70 nM for malathion.     

Sensitive Hydrazine Electrochemical Biosensor Based on a Porous Chitosan–Carbon Nanofiber Nanocomposite Modified Electrode

A novel electrochemically-based biosensor was developed for the determination of hydrazine by modifying a glassy carbon electrode with an aqueous dispersion of carboxylic group-functionalized carbon nanofiber/chitosan solution, and then absorbing hemoglobin on the surface of chitosan-carbon nanofibers. Nafion was used to coat the hemoglobin membrane. The interactions of hemoglobin and the nafion/chitosan-carbon nanofibers were investigated by ultraviolet-visible absorption, infrared, and circular dichroism spectroscopies. The results indicated that the native structure of hemoglobin was retained post-immobilization. The circular dichroism results showed that the α-helical structure of hemoglobin was preserved though a small change was observed in the presence of the nafion/chitosan-carbon nanofibers. The modified nanofibers were further characterized by scanning electron microscopy, electron impendence spectroscopy, and cyclic voltammetry. The electrocatalytic mechanism of hemoglobin to the oxidation of hydrazine was investigated and an irreversible diffusion-controlled electrode process was obtained. The electron transfer rate constant (k_s), transfer coefficient (α), and Michaelis–Menten constant (K_m) were also evaluated. The peak current of the catalytic oxidation was linear with hydrazine concentration from 3.722 × 10^?5 to 1.601 × 10^?3 molar with a correlation coefficient of 0.995. The detection limit was estimated to be 2.7 micromoles per liter. The sensitivity, stability, and reproducibility of the nafion/hemoglobin/chitosan-carbon nanofiber/glassy carbon electrode for the oxidation of hydrazine were also investigated.     

Electrochemical Detection of Nitrite Based on Reaction with 2,3‐Diaminonaphthalene

Abstract

A voltammetric method for the determination of trace amounts of nitrite is proposed. In acidic solution, 2,3‐diaminonaphtalene (DAN) reacts with nitrite to form the 1‐N‐naphtotriazole. At the end of this reaction, the unreacted DAN was measured at a carbon paste electrode by using differential pulse voltammetry. Different parameters, such as pH of the medium, effect of the reaction time, and the effect of DAN concentration on the percentage of signal decrease, have been optimised. Detection limit of 0.2 µmol L^?1 was achieved. Results were improved by using bath injection analysis technique which permit 120 analysis per hour. Nitrites were determined in the real samples. The results have been compared with those obtained by spectrophotometric method based on the Griess reaction, and they are satisfactory. The method developed can be applied for rapid detection and monitoring trace of nitrite for field measurements because the instrumentation required is portable.     

Electrochemical Determination of Epinephrine with a Pyrolytic Graphite Electrode in the Presence of Ascorbic Acid and Dopamine

Epinephrine (EP) is one of the most important neurotransmitters in mammalian central nervous systems, existing in the nervous tissue and body fluid in the form of large organic cations, and controlling the nervous system in the series of biological perfor…     

Electrochemical Oxidation of Hydrazines at a 4-Pyridyl Hydroquinone Modified Electrode

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Sensitive Electrochemical Detection of Thiabendazole in Fruits Using Ag−MoS2 Electrode

Herein, Ag nanoparticles (NPs) modified MoS₂ (Ag−MoS₂) was applied to the surface of glassy carbon (GC) to produce a robust electrochemical sensor for the detection of thiabendazole, a common antifungal in the post-harvesting of fruits. Cyclic voltammetry studies confirmed thiabendazole exhibited an irreversible, diffusion-controlled process on Ag−MoS₂ with a two-fold increase in peak current than the pristine MoS_2. A square wave voltammetry was used for the detection of TBZ. The developed sensor exhibited a linear range between 1–10 μM with LOD down to 0.1 μM (S/N>3). Analysis of TBZ in mango and banana matrices gave a recovery of 91.6–100.4 % indicating the suitability of the sensor for food safety monitoring.     

An Enzyme Electrode Based on the Covalently Binding of Horseradish Peroxidase to a Self-assembling Monolayer Modified Gold Electrode

Tledetenhinationofl1ydrogenperoxideisofprachcalimportanceinchemical,biologi-cal,clinical,andmanyotllerfields.EnZylneelectrodeshavebeenutilizedasil1esensorforhydrogenperoxideduetoitssensitivity,reliability,andoPerahonalsimplicityl-ll.Manymethodshavebeenusedtoiminobilizehorseradishperoxidasegu)onelec-trodessucl1asadsorphononpretreatedcarbonorgupl1iteeIectrode'-',cross-liIthingwithpolymer"'andmikingwih1gnplhteoilPaste"',t.Inil1epresentwork,developmentofanefficienthydrogenperoxidesensorwasenvisa…     

Electrochemical Study on the Behavior of Methimazole with the Modified Au–C–GCE Electrode

Russian Journal of Electrochemistry - Au/XC-72 nanoparticles prepared via microwave-assisted polyol processes were used as the active materials for methimazole detection. The Au/XC-72 modified...     

Abnormal IR Spectra of CO Adsorbed on the Surface of Glass Carbon Electrode Modified with Polypyrrole Film with Platinum Microparticles

Recentiy,inCorPOhoonOfPtorPdInic~clesintocondUedngpolyInfilmsmededonthee1eCtrodechwasstudied.ThemalledelnddsedexCellenteleCtr~cactivitiesintheOkidationOfsInallOrgbocmolecules[l-3].ItwasreportedthattheglaSs~GC)electrthemalledwithapotwrrOleop)filmwithPtndcrOPanides(Pt/PWGCelectrode)shedaconsiderabfyhighereleCtrOCatalyticactivitythanthaOfthebarPtelectrodefortheOaldationOfmethanol[3].ItiswellknownthadurngtheOkidationOfmethanol,COcanbeProdUedandposonthePtanode,leading'tothedeceasei…     

Studies on Electrochemical Behavior of Bleomycin and Its Interaction with DNA at a Co／GC Ion Implantation Modified Electrode

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Voltammetric Study and Detection of Methane on Nickel Hydroxide–Modified Nickel Electrode

Abstract

The nickel hydroxide–modified nickel (NMN) electrode was prepared by cyclic voltammetry. The modified electrode exhibited better catalytic effect toward electrochemical oxidation of methane in 1.0 mol · L^?1 NaOH solution. The catalytic activation of nickel hydroxide on the nickel electrode surface was investigated in different supporting electrolyte solutions by the cyclic voltammetry method in detail, and the related electrochemical oxidation of methane at the NMN electrode was first proposed by amperometric i‐t curve method under the experiment conditions. The results indicated that in the 1.0 mol · L^?1 NaOH solution, the anodic peak current increased with the increased concentration of methane.     

Electrochemical Modified Electrodes Based on Metal‐Salen Complexes

Abstract

A general view of the electroanalytical applications of metal‐salen complexes is discussed in this review. The family of Schiff bases derived from ethylenediamine and ortho‐phenolic aldehydes (N,N′‐ethylenebis(salicylideneiminato)—salen) and their complexes of various transition metals, such as Al, Ce, Co, Cu, Cr, Fe, Ga, Hg, Mn, Mo, Ni, and V have been used in many fields of chemical research for a wide range of applications such as catalysts for the oxygenation of organic molecules, epoxidation of alkenes, oxidation of hydrocarbons and many other catalyzed reactions; as electrocatalyst for novel sensors development; and mimicking the catalytic functions of enzymes. A brief history of the synthesis and reactivity of metal‐salen complexes will be presented. The potentialities and possibilities of metal‐Salen complexes modified electrodes in the development of electrochemical sensors as well as other types of sensors, their construction and methods of fabrication, and the potential application of these modified electrodes will be illustrated and discussed.     

Study on Lead Dioxide Modified Electrode and Its Application in Detection of Phenols

IntroductionOflate,thereisagreatinterestintheimprovementofleaddioxideasananodematerialforelectrosynthesis,ozonegenerationandwastewatertreatmentowingtoitshighelectri calconductivity ,largeoxygenoverpotentialandchemicalin ertness.1 5PbO2 canbeobtainedasanodicdepositsfromsolu tionsofthelow valenceions,basicstudiesontheseelec trodesaremainlyconfinedtothenucleationgrowthprocessofleaddioxidecrystallites ,ormodifiedbyothercationsinordertoimproveitsproperties.6 However,itselectrocatalyticactivi tydepe…     

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…     

Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode

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Spillover on a Platinum Electrode Modified by MWNTs

The spillover phenomenon is observed on the platinum (Pt) disk electrode modified by multi-wall carbon nanotubes (MWNTs). The rate of the spillover of oxygen-containing species produced on Pt surface to and from MWNTs is fast. However for hydrogen-adatoms, the spillover is very weak. The selective spillover on the Pt/MWNTs electrode may provide a novel way to design catalysts.     

Novel Electrochemical Sensor for Sunset Yellow Based on a Platinum Wire–Coated Electrode

Abstract

In this research, the construction and general performance characteristics of a sunset yellow sensor based on sunset yellow–cetyl pyridinum (SY-CPY) ion pair as an ion exchanger were described. A coated platinum wire electrode (CPE) was prepared and compared with coated graphite (CGE) and membrane electrode (PME). The CPE exhibited a rapid and Nernstian response (?29.77 ± 0.2 mV decade^?1) to SY concentration range from 3.16 × 10^?7 to 3.16 × 10^?3 mol dm^?3 within pH 4.5–9.5. Interfering effects of some foreign substances were reported. The optimized matrix was successfully applied to the determination of SY in artificial mixtures and commercial soft drinks. The results showed good agreements with the determination made by use of high-performance liquid chromatography.     

Immobilization of Horseradish Peroxidase on a Biocompatible Titania Layer–Modified Gold Electrode for the Detection of Hydrogen Peroxide

Abstract

A procedure for fabricating an enzyme electrode has been described based on the effective immobilization of horseradish peroxidase to an ultrathin titania layer–modified self‐assembled gold electrode. The resulting electrode exhibits excellent electrocatalytical activity to hydrogen peroxide in the presence of hydroquinone as a mediator. The analytical conditions were studied in detail by using an amperometric method. Under the optimized conditions, a detection limit of 7.1×10^?7 mol l^?1 and a linear response to hydrogen peroxide that ranged from 1×10^?6 mol l^?1 to 7.6×10^?4 mol l^?1 were obtained. The reproducibility and stability were examined with satisfactory results.     

Electrochemical Studies of Pirarubicin and Its Interaction with DNA at a Co／GC Ion Implantation Modified Electrode

IntroductionIon implantation is a new material surfacemodification technique.It has been also applied tostudying the electrochemical behaviors of organicdrugs and biological materials as well as their de-terminations. This method offers good stability,reproductivity and catalytic activity[1] .Pirarubicin( THP) is an active highly effective and new antitu-moral anthracycline antibiotic,which has gainedwidespread clinical use in the chemotherapeutictreatment of a variety of human cancers.The d…