Ruthenium Oxide Hexacyanoferrate Research Articles

Reduced Graphene Oxide/Ruthenium Oxide Hexacyanoferrate Nanocomposite for Electrochemical Determination of Ethanol in Commercial Samples

Reduced graphene oxide/ruthenium oxide hexacyanoferrate (rGO/RuOHCF) modified electrode showed synergic activity between the materials attested by the increase of electrochemical current and stability. The preparation of the nanocomposite was made by a simple two-step electrochemical approach. The material structure was characterized by spectroscopic techniques (Raman, infrared and energy-dispersive X-ray) as well as its morphology by scanning electron microscopy and compared to the analogously prepared reduced graphene oxide (rGO) and ruthenium oxide hexacyanoferrate (RuOHCF) thin films spectra and images. The results suggest that the improvement of the nanocomposite electrochemical activity is generated by the well-distributed RuOHCF nanometric particles over high-surfaced graphene sheets. Ethanol electrochemical oxidation in the rGO/RuOHCF modified electrode was performed in 0.1 mol L-1 NaCl (pH = 1.5) solution and it showed an anodic current peak starting at 0.9 V. Scan rate tests exhibited a diffusioncontrolled process not followed by any coupled chemical reaction. The determination of ethanol by amperometry coupled with batch injection analysis (BIA) system resulted in a wide linear range (20-400 mmol L-1) and good sensitivity (0.150 μA L mmol-1). The nanocomposite also showed application as an electrochemical sensor of ethanol in commercial samples mainly because of its easy preparation comparing to biosensors.

Ruthenium Oxide Hexacyanoferrate as an Effective Electrode Modifier for Amperometric Detection of Iodate and Hydrogen Peroxide

Ruthenium oxide hexacyanoferrate (RuOHCF) film was electrochemically deposited on to a glassy carbon (GC) surfaceusing consecutive cyclic voltammetry as a facile and green synthetic strategy. The electrochemical behaviour and electrocatalytic properties of the modified electrode Ru?HCF/GC were evaluated with regards to electroreduction of hydrogen peroxide and iodate in a strong acidic medium (pHs 1.0-2.0) by using different electrochemical techniques, including cyclic voltammetry and amperometry at a constant potential. Electrochemical studies indicated that Ru?HCF/GC possess a high catalytic activity in both studied reactions, fast response and good reproducibility of the current signal. The Ru?HCF/GC exhibits enhanced electrocatalytic behaviour compared with other modified electrodes reported before. The simple and reproducible procedure for electrode fabrication, the wide linear range, anti-interference performance and long-time stability of the Ru?HCF/GC make it a promising sensing material for practical quantitative determination of hydrogen peroxide and iodate. Remarkably, the reported modified.

Electrochemical synthesis of reduced graphene oxide/ruthenium oxide hexacyanoferrate nanocomposite film and its application for ranitidine detection

Abstract Here we describe a simple and rapid voltammetric fabrication of a novel nanocomposite modified glassy carbon electrode (GCE) based on reduced graphene oxide/ruthenium oxide hexacyanoferrate (rGO/RuOHCF). The performance of the electrode was tested for ranitidine (RTD) electrocatalytic oxidation. Characterization techniques confirmed an efficient electrochemical reduction of graphene oxide (GO) and the formation of ruthenium oxide hexacyanoferrate (RuOHCF) nanoparticles. The nanocomposite presented well distributed ~89 nm particles entrenched in wrinkled graphene sheets. The electrochemical behavior of RTD on the nanocomposite surface was examined by cyclic voltammetry, and its mass transport process was evaluated by scan rate test. The parameters of the amperometry with batch-injection analysis (BIA) system for RTD determination were optimized, and the calibration curve presented high linearity (R2 = 0.999) from 5.0 to 100.0 μmol L−1, good sensitivity of 0.216 μA L μmol−1, and a limit of detection (LD) of 274.4 nmol L−1. RTD from pharmacological samples was successfully determined, with approximately 95% of recovery.

Determination of Fe(III) in wine samples using a ruthenium oxide hexacyanoferrate modified microelectrode

The electrocatalytic reduction of Fe(III) was investigated using a carbon fibre microelectrode modified with a ruthenium oxide hexacyanoferrate film (RuOHCF/CFM). At surfaces containing this chemical modifier, Fe(III) is electrocatalytically reduced at 0.0V without interference from Fe(II), hence allowing the speciation of Fe(III). A linear relationship between the cathodic current and concentration of Fe(III) was obtained by amperometry in the range 10–210μmolL−1 with detection and quantification limits of 0.22 (S/N=3) and 0.74 (S/N=10)μmolL−1, respectively. The described amperometric method was successfully applied for the determination of Fe(III) in different wine samples.

Hydrogen peroxide monitoring in Fenton reaction by using a ruthenium oxide hexacyanoferrate/multiwalled carbon nanotubes modified electrode

A novel amperometric sensor based on the incorporation of ruthenium oxide hexacyanoferrate (RuOHCF) into multiwalled carbon nanotubes (MWCNTs) immobilized on a glassy carbon electrode is described. Cyclic voltammetry experiments indicated that the cathodic reduction of hydrogen peroxide at the RuOHCF/MWCNTs100/GC modified electrode is facilitated, occurring at 0.0V vs. Ag/AgCl/KCl(sat). Following the optimization of the experimental conditions, the proposed sensor presented excellent analytical properties for hydrogen peroxide determination, with a low limit of detection (4.7μmolL−1), a large dynamic concentration range (0.1–10mmolL−1) and a sensitivity of 1280μAmmol−1Lcm−2. The usefulness of the RuOHCF/MWCNTs100/GC electrochemical sensor was confirmed by monitoring the consumption of hydrogen peroxide during the degradation of phenol by the Fenton reaction.

Low-potential reduction of sulfite at a ruthenium-oxide hexacyanoferrate modified electrode

The low-potential reduction of sulfite at a ruthenium-oxide hexacyanoferrate (RuOHCF)-modified electrode is reported. A decrease (200mV) in the overpotential of the sulfite reduction reaction and a substantial current increase (compared to the bare glassy-carbon electrode) were verified. Evidence is found for a mass transport regime which includes a thin-layer diffusional process (sulfite species trapped within the RuOHCF film) responsible for the lowered reductive potential (rather than electrocatalytic properties of the film). The low-potential (−0.2V vs. Ag/AgCl/saturated KCl) amperometric detection of sulfite in 0.25molL−1 HCl was free of interferences from substances typically found in food samples.

Amperometric Detection of Ranitidine Using Glassy Carbon Modified with Ruthenium Oxide Hexacyanoferrate Adapted in a Flow Injection System

AbstractA simple analytical method for ranitidine quantification was developed based on the electrocatalytic oxidation of ranitidine on a glassy carbon electrode modified by electrochemical deposition of ruthenium oxide hexacyanoferrate. Under optimal experimental conditions, the peak current response increases linearly with a ranitidine concentration over the range of 1.25–7.50 µmol L−1. The detection limit of the method was estimated to be 25 nmol L−1. The proposed method improves the analytical parameters obtained by other electroanalytical methods for the quantification of this drug, and it was employed for quantification of ranitidine in 3 commercial samples, the results being in agreement with those obtained by the manufactures.

Studies on the Electrocatalytic Reduction of Hydrogen Peroxide on a Glassy Carbon Electrode Modified With a Ruthenium Oxide Hexacyanoferrate Film

Studies on the Electrocatalytic Reduction of Hydrogen Peroxide on a Glassy Carbon Electrode Modified With a Ruthenium Oxide Hexacyanoferrate Film

A selective sensor based on a glassy carbon electrode modified with carbon nanotubes and ruthenium oxide/hexacyanoferrate film for simultaneous determination of ascorbic acid, epinephrine and uric acid

The development of a highly selective sensor for voltammetric determination of ascorbic acid (AA), epinephrine (EP) and uric acid (UA) in the same solution has been achieved by a glassy carbon electrode modified with multi-walled carbon nanotubes and ruthenium oxide hexacyanoferrate film. The modified electrode showed effective catalytic activity toward the electro-oxidation of AA, EP and UA by separating their oxidation peak potentials and producing larger anodic peak currents than those at unmodified electrodes. The electron transfer efficiency and rate constant of the oxidation process were studied using electrochemical impedance spectroscopy. The electro-catalytic peak currents of differential pulse voltammograms increased linearly with AA, EP and UA concentrations in the ranges of 0.2–15.0 μM, 0.1–10.0 μM and 0.90–250 μM with a detection limit of 0.087, 0.052 and 0.599 μM, respectively. The modified electrode showed good sensitivity, selectivity and stability for the voltammetric determination of these important biological compounds. The modified electrode was satisfactorily used for simultaneous determination of AA, EP and UA in pharmaceutical and biological samples.

Flow injection amperometric determination of hydrogen peroxide in household commercial products with a ruthenium oxide hexacyanoferrate modified electrode

Hydrogen peroxide was determined in oral antiseptic and bleach samples using a flow-injection system with amperometric detection. A glassy carbon electrode modified by electrochemical deposition of ruthenium oxide hexacyanoferrate was used as working electrode and a homemade Ag/AgCl (saturated KCl) electrode and a platinum wire were used as reference and counter electrodes, respectively. The electrocatalytic reduction process allowed the determination of hydrogen peroxide at 0.0 V. A linear relationship between the cathodic peak current and concentration of hydrogen peroxide was obtained in the range 10–5000 μmol L−1 with detection and quantification limits of 1.7 (S/N = 3) and 5.9 (S/N = 10) μmol L−1, respectively. The repeatability of the method was evaluated using a 500 μmol L−1 hydrogen peroxide solution, the value obtained being 1.6% (n = 14). A sampling rate of 112 samples h−1 was achieved at optimised conditions. The method was employed for the quantification of hydrogen peroxide in two commercial samples and the results were in agreement with those obtained by using a recommended procedure.

Studies on the kinetics of ascorbate oxidation at a ruthenium oxide hexacyanoferrate modified electrode towards the detection at microenvironments

The electrocatalytic oxidation of ascorbate on a ruthenium oxide hexacyanoferrate (RuOHCF) glassy carbon (GC) modified electrode was investigated at pH 6.9 by using rotating disc electrode (RDE) voltammetry. The influence of the systematic variation of rotation rate, film thickness, ascorbate concentration and the electrode potential indicated that the rate of cross-chemical reaction between Ru(III) centres immobilized into the film and ascorbate controls the overall process. The kinetic regime may be classified as a S k″ mechanism and the second order rate constant for the surface electrocatalytic reaction was found to be 1.56 × 10 −3 mol −1 L 1 s −1 cm. A carbon fibre microelectrode modified with the RuOHCF film was successfully used as an amperometric sensor to monitor the ascorbate diffusion in a simulated microenvironment experiment.

Continuous monitoring of ascorbate transport through neuroblastoma cells with a ruthenium oxide hexacyanoferrate modified microelectrode

The uptake of ascorbate by neuroblastoma cells using a ruthenium oxide hexacyanoferrate (RuOHCF)-modified carbon fiber disc (CFD) microelectrode (r = 14.5 microm) was investigated. By use of the proposed electrochemical sensor the amperometric determination of ascorbate was performed at 0.0 V in minimum essential medium (MEM, pH = 7.2) with a limit of detection of 25 micromol L(-1). Under the optimum experimental conditions, no interference from MEM constituents and reduced glutathione (used to prevent the oxidation of ascorbate during the experiments) was noticed. The stability of the RuOHCF-modified electrode response was studied by measuring the sensitivity over an extended period of time (120 h), a decrease of around 10% being noticed at the end of the experiment. The rate of ascorbate uptake by control human neuroblastoma SH-SY5Y cells, and cells transfected with wild-type Cu,Zn-superoxide dismutase (SOD WT) or with a mutant typical of familial amyotrophic lateral sclerosis (SOD G93A), was in agreement with the level of oxidative stress in these cells. The usefulness of the RuOHCF-modified microelectrode for in vivo monitoring of ascorbate inside neuroblastoma cells was also demonstrated.

Preparation, characterization and electrocatalytic behavior of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate hybrid film-modified electrodes

Polynuclear mixed-valent hybrid films of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate (ZnO/ZnHCF-RuOHCF) have been deposited on electrode surfaces from H 2SO 4 solution containing Zn(NO 3) 2, RuCl 3 and K 3[Fe(CN) 6] by potentiodynamic cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide and ruthenium oxide hexacyanoferrate (RuOHCF) in the hybrid film. The effect of type of monovalent cations on the redox behavior of hybrid film was investigated. In pure supporting electrolyte, electrochemical responses of Ru II/III redox transition occurring at negative potential region resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF-RuOHCF hybrid film was investigated towards oxidation of epinephrine, dopamine and l-cysteine, and reduction of S 2O 8 2− and SO 5 2− as well as IO 3 − using cyclic voltammetry and rotating ring disc electrode (RRDE) techniques.

FIA determination of ascorbic acid at low potential using a ruthenium oxide hexacyanoferrate modified carbon electrode

The anodic oxidation of ascorbic acid on a ruthenium oxide hexacyanoferrate modified electrode was characterized by cyclic voltammetry. On this modified surface, the electrocatalytic process allows the determination of ascorbic acid to be performed at 0.0 V and pH 6.9 with a limit of detection of 2.2 μM in a flow injection configuration. Under this experimental condition, no interference from glucose, nitrite and uric acid was noticed. Lower detection limit values were obtained by measuring flow injection analysis (FIA) responses at 0.4 V (0.14 μM), but a concurrent loss of selectivity is expected at this more positive potential. Under optimal FIA operating conditions, the linear response of the method was extended up to 1 mM ascorbic acid. The repeatability of the method for injections of a 1.0 mM ascorbic acid solution was 2.0% ( n = 10). The usefulness of the method was demonstrated by an addition-recovery experiment with urine samples and the recovered values were in the 98–104% range.

Flow Injection Amperometric Detection of 2‘-Deoxyguanosine at a Ruthenium Oxide Hexacyanoferrate Modified Electrode

A ruthenium oxide hexacyanoferrate (RuOHCF) modified electrode was developed. Hydrodynamic voltammetry was employed to demonstrate the remarkable electrocatalytic activity toward the oxidation of 2'-deoxyguanosine. The RuOHCF modified electrode was used as amperometric detector for 2'-deoxyguanosine determination in a FIA apparatus. The influence of various experimental conditions was explored for optimum analytical performance, and at these experimental conditions, the method exhibited a linear response range to 2'-deoxyguanosine extending from 3.8 to 252 micromol L(-1) with detection limit of 94 nmol L(-1). Applications in DNA samples were examined, and the results for determination of 2'-deoxyguanosine were in good agreement with those obtained by HPLC analysis. Studies on the kinetics of the in vitro consumption of 2'-deoxyguanosine by acetaldehyde were also performed.

Electrocatalytic oxidation of deoxyguanosine on a glassy carbon electrode modified with a ruthenium oxide hexacyanoferrate film

The electrocatalytic oxidation of deoxyguanosine on a ruthenium hexacyanoferrate (RuOHCF) glassy carbon (GC) modified electrode was investigated in acid medium by using rotating disc electrode (RDE) voltammetry. Chronoamperometric experiments allowed information on the charge transport rate through the RuOHCF film and at a very short time window a diffusion-like behavior was observed with a D ct value of 2.7 × 10 −11 cm 2 s −1 for a film with Γ = 4.47 × 10 −9 mol cm −2. The influence of systematic variation of rotation rate, film thickness and the electrode potential indicates that the rate of cross-chemical reaction between Ru(IV) centers immobilized into the film and deoxyguanosine controls the overall electrodic process and the value of the rate constant was found to be 3.2 × 10 6 mol −1 L 1 s −1. The relatively high rate constant of the cross-reaction, the facile penetration of the substrate through the film and the fast transport of electrons suggest that the electrocatalytic process occurs throughout the film layer.