EIS characterization of tantalum and niobium oxide films based on a modification of the point defect model

Electrochemical impedance spectroscopy (EIS) studies were performed to analyze the passive properties of tantalum and niobium oxides films potentiostatically formed in a 0.1 M KOH solution. The quantitative characterization of these passive materials was carried out through a transfer function previously developed by our research group, which is based on the point defect model (PDM) framework considering the formation of molecular hydrogen. According to the PDM prediction criteria, Ta₂O₅ and Nb₂O₅ films exhibited an inherent n-type semiconductor behavior, which was confirmed by the parameters obtained from the fit to the transfer function. The diffusion coefficients of the oxygen vacancies were 0.53 ± 0.14 × 10⁻¹⁶ and 2.18 ± 0.14 × 10⁻¹⁶ cm² s⁻¹, for Ta₂O₅ and Nb₂O₅, respectively. And a slight increase of the corresponding hydroxyl vacancies diffusion (2.73 ± 0.02 and 2.23 ± 0.65 × 10⁻¹⁶ cm² s⁻¹) was obtained, suggesting the favorable diffusion of these defects due to the alkaline conditions.     

Determination of trace vanadium(V) by adsorptive anodic stripping voltammetry on an acetylene black paste electrode in the presence of alizarin violet

A sensitive and simplified voltammetric method is developed for the determination of trace amounts of vanadium(V) by adsorptive anodic stripping voltammetry using an acetylene black (AB) paste electrode. The method is based on the preconcentration of the V(V)–alizarin violet (AV) complex at open circuit while stirring the solution for 90 s in 0.15 mol dm⁻³ hexamethylenetetraamine–hydrochloric acid buffer (pH 4.4), the adsorbed complex is then oxidized, producing a response with a peak potential of 564 mV when scanning linearly from 0 to 1000 mV. For voltammetric determination of V(V), the parameters influencing the peak current have been optimized. Under the selected conditions, the peak current and concentration of V(V) accorded with linear relationship in the range of 8.0 × 10⁻¹⁰ mol dm⁻³–1.0 × 10⁻⁷ mol dm⁻³ (c_AV = 2.0 × 10⁻⁶ mol dm⁻³) and 1.0 × 10⁻⁷ mol dm⁻³–8.0 × 10⁻⁶ mol dm⁻³ (c_AV = 2.0 × 10⁻⁵ mol dm⁻³), the detection limit (three times signal to noise) was estimated to be 6.0 × 10⁻¹⁰ mol dm⁻³ for 90 s accumulation. The relative standard deviation (RSD) is 1.9% and 2.3% for V(V) concentrations of 1.0 × 10⁻⁷ mol dm⁻³ and 1.0 × 10⁻⁸ mol dm⁻³ respectively. Finally, this proposed method was successfully applied to the determination of V(V) in natural water samples.     

Temperature-dependent polymerization shrinkage stress kinetics of resin-composites

Objectives

To determine temperature dependence of shrinkage stress kinetics for a set of resin composites formulated with dimethacrylate monomer matrices.

Methods

Six representative resin composites with a range of resin matrices were selected. Two of them were considered as low shrinking resin composites: Kalore and Venus Diamond. The shrinkage stress kinetics at 23 °C and 37 °C were measured continuously using a Bioman instrument for 60 min. Stress levels between materials were compared at two intervals: 2 min and 60 min. Specimen temperatures were controlled by a newly designed heating device. Stress measurements were monitored for 1 h, after irradiation for 40 s at 550 mW/cm² (energy density = 22 J/cm²). Three specimens (n = 3) were used at each temperature per material.

Results

Shrinkage stress at 23 °C ranged from 2.93 MPa to 4.71 MPa and from 3.57 MPa to 5.42 MPa for 2 min and 60 min after photo-activation, respectively. The lowest stress-rates were recorded for Kalore and Venus Diamond (0.34 MPa s⁻¹), whereas the highest was recorded for Filtek Supreme XTE (0.63 MPa s⁻¹). At 37 °C, shrinkage stress ranged from 3.27 MPa to 5.35 MPa and from 3.36 MPa to 5.49 MPa for 2 min and 60 min after photo-activation, respectively. Kalore had the lowest stress-rate (0.44 MPa s⁻¹), whereas Filtek Supreme XTE had the highest (0.85 MPa s⁻¹). Materials exhibited a higher stress at 37 °C than 23 °C except for Kalore and Venus Diamond. Positive correlations were found between shrinkage stress and stress-rate at 23 °C and 37 °C (r = 0.70 and 0.92, respectively).

Significance

Resin-composites polymerized at elevated temperature (37 °C) completed stress build up more rapidly than specimens held at 23 °C. Two composites exhibited atypical reduced stress magnitudes at the higher temperature.     

Electrocatalytic activity of thianthrene toward one-electron oxidation of guanosine and DNA in a non-aqueous medium

In this study, the electrochemical behavior of thianthrene (TH) and its application toward the electrocatalytic oxidation of guanosine (Gs) and DNA in a non-aqueous solution are investigated using different voltammetric techniques. Guanosine and DNA are adsorbed on the glassy carbon electrode (GCE) by applying a positive potential to the GCE. The rate constant of catalytic reaction between DNA and TH and also between Gs and TH were evaluated using chronoamperometry which gave rate constants of 2.41 × 10⁶ cm³ mol⁻¹ s⁻¹ and 2.68 (±0.19) × 10⁶ cm³ mol⁻¹ s⁻¹, respectively. Also the diffusion coefficient of TH was obtained using hydrodynamic voltammetry (3.17 × 10⁻⁵ cm² s⁻¹). Furthermore, using hydrodynamic voltammetry, a one-electron mechanism for oxidation of Gs is suggested.     

Electrochemical impedimetry of electrodeposited poly(propylene imine) dendrimer monolayer

Voltammetric and electrochemical impedance spectroscopic (EIS) studies of generation one poly(propylene imine) (G1 PPI) dendrimer as an electroactive and catalytic nanomaterials both in solution and as an electrode modifier based on a simple one step electrodeposition method is presented. The G1 PPI exhibited a reversible one electron redox behaviour at E^0′ ca 210 mV in phosphate buffer pH 7.2 with diffusion coefficient and Warburg coefficient of 7.5 × 10⁻¹⁰ cm² s⁻¹ and 8.87 × 10⁻⁴ Ω s^−1/2 respectively. Cyclic voltammetric electrodeposition of a monolayer of G1 PPI on glassy carbon electrode was carried out between −100 mV and 1100 mV for 10 cycles. The nanoelectrode was electroactive in PBS at E^0′ ca 220 mV. Kinetic profiles such as time constant (4.64 × 10⁻⁵ s rad⁻¹), exchange current (1.55 × 10⁻⁴ A) and heterogeneous rate constant (4.52 × 10⁻³ cm s⁻¹) obtained from EIS showed that the dendrimer layer catalysed the redox reaction of Fe^2+/3+ in [Fe(CN)₆]^3−/4− redox probe.     

Sorption of water, ethanol or ethanol/water solutions by light-cured dental dimethacrylate resins

Objectives

This work is concerned with the study of the sorption and desorption process of water, ethanol or ethanol/water solution 50% (v/v) or 75% (v/v) by the dental resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D₃MA.

Methods

A thin resin disc is placed in a bath of time to obtain the sorption curve m_t = f(t). Then the liquid is desorbed until a constant mass for the disc is reached and the desorption curve is recorded. These experimental curves help in the determination of the sorbed/desorbed liquid amount at equilibrium, the percentage of the extracted mass of unreacted monomer known as “solubility”, and the sorption/desorption diffusion coefficient which expresses correspondingly the rate of the liquid sorption/desorption.

Results

The highest liquid uptake by dental resins was 13.3 wt% ethanol for Bis-GMA-resin, 12.0 wt% ethanol for UDMA-resin, 10.10 wt% ethanol/water solution for TEGDMA-resin, 7.34 wt% ethanol for D₃MA-resin and 6.61 wt% ethanol for Bis-EMA-resin. The diffusion coefficient for all resins was higher in water than in ethanol/water solution or ethanol. Bis-GMA-resin showed the highest diffusion coefficient (11.01 × 10⁻⁸ cm² s⁻¹) followed by Bis-EMA-resin (7.43 × 10⁻⁸ cm² s⁻¹), UDMA-resin (6.88 × 10⁻⁸ cm² s⁻¹), D₃MA-resin (6.22 × 10⁻⁸ cm² s⁻¹) and finally by TEGDMA-resin (1.52 × 10⁻⁸ cm² s⁻¹).

Significance

All studied dental resins, except TEGDMA-resin, absorbed higher amount of pure ethanol than water or ethanol water solution. TEGDMA-resin absorbed higher amount of ethanol/water solution (50/50 or 75/25 (v/v)) than water or ethanol. For all studied dental resins the diffusion coefficient was higher in water than in ethanol/water solution or ethanol.     

Poly(N-methylaniline)/nickel modified carbon paste electrode as an efficient and cheep electrode for electrocatalytic oxidation of formaldehyde in alkaline medium

This research in finding a cheap and efficient catalyst for electrooxidation of formaldehyde give us an attempt to make and examine the behavior of poly(N-methylaniline)/nickel modified carbon paste electrode (Ni/P(NMA)/MCPE) in absence and presence of formaldehyde. This involves in situ electropolymerization of N-methylaniline at carbon paste electrode, which is following to the incorporation of Ni(II) to polymeric layer by immersion of modified electrode in 1.0 M nickel sulphate solution. The electrocatalytic oxidation of formaldehyde was studied by cyclic voltammetry and chronoamperometry methods. The effects of scan rate and formaldehyde concentration on the electrocatalytic oxidation of formaldehyde were also investigated at the surface of Ni/P(NMA)/MCPE. The diffusion coefficient (D = 14.1 × 10⁻⁵ cm² s⁻¹), and some kinetic parameters such as the transfer coefficient (α = 0.45) and also second-order rate constant (k = 8.96 × 10⁻⁴ cm³ mol⁻¹ s⁻¹) of formaldehyde were calculated.     

Development of a carbon nanotubes paste electrode modified with crosslinked chitosan for cadmium(II) and mercury(II) determination

A functionalized carbon nanotubes paste electrode modified with cross-linked chitosan for the determination of trace amounts of cadmium(II) and mercury(II) by linear anodic stripping voltammetry is described. Under optimal experimental conditions, the peak current was linear in the Cd(II) concentration range from 5.9 × 10⁻⁸ to 1.5 × 10⁻⁶ mol L⁻¹ with a detection limit of 9.8 × 10⁻⁹ mol L⁻¹ and, for Hg(II) from 6.7 × 10⁻⁹ to 8.3 × 10⁻⁸ mol L⁻¹with a detection limit of 2.4 × 10⁻⁹ mol L⁻¹. The proposed method was successfully applied for the determination of Hg(II) in natural and industrial wastewater samples, and Cd(II) in sediments, human urine, natural, and industrial wastewater samples.     

A differential pulse voltammetric method for simultaneous determination of ascorbic acid,dopamine, and uric acid using poly (3-(5-chloro-2-hydroxyphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid) film modified glassy carbon electrode

A stable modified glassy carbon electrode based on the poly 3-(5-chloro-2-hydroxyphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (CDDA) film was prepared by electrochemical polymerization technique to investigate its electrochemical behavior by cyclic voltammetry. The properties of the electrodeposited films, during preparation under different conditions, and their stability were examined. The homogeneous rate constant, k_s, for the electron transfer between CDDA and glassy carbon electrode was calculated as 5.25(±0.20) × 10² cm s⁻¹. The modified electrode showed electrocatalytic activity toward ascorbic acid (AA), dopamine (DA), and uric acid (UA) oxidation in a buffer solution (pH 4.0) with a diminution of their overpotential of about 0.12, 0.35, and 0.50 V for AA, DA, and UA, respectively. An increase could also be observed in their peak currents. The modified glassy carbon electrode was applied to the electrocatalytic oxidation of DA, AA, and UA, which resolved the overlapping of the anodic peaks of DA, AA, and UA into three well-defined voltammetric peaks in differential pulse voltammetry (DPV). This modified electrode was quite effective not only for detecting DA, AA, and UA, but also for simultaneous determination of these species in a mixture. The separation of the oxidation peak potentials for ascorbic acid–dopamine and dopamine–uric acid were about 0.16 V and 0.17 V, respectively. The final DPV peaks potential of AA, DA and UA were 0.28, 0.44, and 0.61 V, respectively. The calibration curves for DA, AA, and UA were linear for a wide range of concentrations of each species including 5.0–240 μmol L⁻¹ AA, 5.0–280 μmol L⁻¹ DA, and 0.1–18.0 μmol L⁻¹ UA. Detection limits of 1.43 μmol L⁻¹ AA, 0.29 μmol L⁻¹ DA and 0.016 μmol L⁻¹ UA were observed at pH 4. Interference studies showed that the modified electrode exhibits excellent selectivity toward AA, DA, and UA.     

Electroanalytical determination of sildenafil in Viagra tablets using screen-printed and conventional carbon paste electrodes

This work compares the electroactivity of a conventional carbon-paste electrodes and screen-printed carbon electrodes. Potentiometric sensors responsive to sildenafil citrate (SILC) drug (the active component of Viagra) are described, characterized, compared and used for drug assessment. The proposed carbon paste electrode is fully characterized in terms of plasticizer type, response time, life span, soaking time, titrant, pH and temperature. The electrodes exhibited linear response with a Nernstian slope of 58.20 ± 1 and 58.82 ± 0.5 mV decade⁻¹ for SILC in the concentration range from 1.0 × 10⁻⁷ to 1.0 × 10⁻² and 5.30 × 10⁻⁷ to 1.0 × 10⁻² mol L⁻¹ with good reproducibility for CPE and SPE, respectively. Both CPE and SPE could be used in the pH range 3.0–5.0 and the isothermal coefficient is found to be 0.98 and 0.85 mV/°C, respectively. The limit of detection was found to be 9.0 × 10⁻⁸ and 3.5 × 10⁻⁷ mol L⁻¹ for CPE and SPE, respectively. They were applied to potentiometric determination of SILC in pure state and pharmaceutical preparation under batch conditions. The CPE and SPE sensors display good selectivity for SILC drug over large number of inorganic cations, sugars and amino acids commonly used in drug formulations. The CPE and SPE show high selectivity for the drug under investigation. The results obtained using the fabricated CPE is compared with those obtained by SPE for spiked pharmaceutical samples.     

Electrochemistry of magnolol and interaction with DNA

The electrochemical behaviors of magnolol have been studied at glassy carbon electrode using cyclic voltammetry, linear sweep voltammetry and chronocoulometry. Moreover, its interaction with DNA was investigated in solution by electrochemical methods and ultraviolet–visible spectroscopy. The experiment results indicated that the electrochemical oxidation of magnolol was an irreversible process with one proton and one electron transfer. The electron transfer coefficient (α) was calculated to be 0.441 ± 0.001. At the scan rate from 100 mV/s to 450 mV/s, the electrode process was controlled by the adsorption step and at the range of 600–950 mV/s the electrochemical oxidation was diffusion controlled process. The corresponding electrochemical rate constant (k_s) was 0.0760 ± 0.0001 s⁻¹. Through chronocoulometry experiment, the diffusion coefficient (D) and the surface concentration (Γ) were obtained as (3.76 ± 0.01) × 10⁻⁷ cm²/s and (2.98 ± 0.01) × 10⁻¹⁰ mol/cm². In addition, the interaction of magnolol and DNA was ascribed to be electrostatic interaction and the calculated association constant (β) and Hill coefficient (m) were 1.14 × 10⁵ M⁻¹ and 0.973. At last a sensitive and convenient electrochemical method was proposed for the determination of magnolol.     

Effect of pH and temperature on carbon-supported manganese oxide oxygen reduction electrocatalysts

Manganese oxides nanoparticles were chemically deposited on a high area (ca. 300 m² g⁻¹) carbon black substrate to act as electrocatalysts for oxygen reduction. The morphology and chemistry of the carbon-supported MnO_x nanoparticles was characterised by Transmission Electron Microscopy), X-ray Diffraction, and chemical analysis. The oxygen reduction reaction (ORR) catalytic activity was studied in the 7–10 pH range using a rotating disk electrode (RDE). High activity towards oxygen reduction and very good stability in neutral and slightly basic solution were obtained. At low current densities, at 25 °C, MnO_x/C displayed a reaction order with respect to OH⁻ ions of −0.5 and Tafel slopes of −0.153 and −0.167 V dec⁻¹ at pH 7 and 10 respectively; showing that the ORR mechanism on MnO_x/C is unchanged in the 7–10 pH range. From the data, we propose that the first electrochemical step of the 4-electron ORR mechanism, in the 7–10 pH range, is the quasi equilibrium proton insertion process in MnO₂ yielding MnOOH (insoluble in neutral or slightly basic solution). The ORR activity of the MnO_x/C materials increased with increasing temperatures from 5 to 40 °C. The 2-electron pathway of oxygen reduction, yielding hydrogen peroxides as intermediates, may however be favoured over the 4-electron O₂ reduction at higher temperatures.     

Simultaneous determination of epinephrine and uric acid at a gold electrode modified by a 2-(2,3-dihydroxy phenyl)-1, 3-dithiane self-assembled monolayer

In the present paper, the use of a gold electrode modified by 2-(2,3-dihydroxy phenyl)-1,3-dithiane self-assembled monolayer (DPDSAM) for the determination of epinephrine (EP) and uric acid (UA) was described. Initially, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various scan rates. The apparent charge transfer rate constant, k_s, and transfer coefficient, α, were calculated. Next, the mediated oxidation of EP at the modified electrode was described. At the optimum pH of 8.0, the oxidation of EP occurs at a potential about 155 mV less positive than that of an unmodified gold electrode. The values of electron transfer coefficients (α = 0.356), catalytic rate constant (k = 1.624 × 10⁴ M⁻¹ s⁻¹) and diffusion coefficient (D = 1.04 × 10⁻⁶ cm² s⁻¹) were calculated for EP, using electrochemical approaches. Based on differential pulse voltammetry, the oxidation of EP exhibited a dynamic range between 0.7 and 500.0 μM and a detection limit (3σ) of 0.51 μM. Furthermore, simultaneous determination of EP and UA at the modified electrode was described. Finally, this method was used for the determination of EP in EP ampoule.     

Ionic liquid salt bridge based on N-alkyl-N-methylpyrrolidinium bis(pentafluoroethanesulfonyl)amide for low ionic strength aqueous solutions

The phase-boundary potential between the moderately hydrophobic ionic liquid and a low ionic strength aqueous solution is demonstrated to be stable and constant with the standard deviation of 0.4 mV down to 20 μmol kg⁻¹ HBr, LiBr, and KBr solutions, for three ionic liquids that consist of either N-methyl-N-octylpyrrolidinium, N-heptyl-N-methylpyrrolidinium, or N-hexyl-N-methylpyrrolidinium and a common anion species, bis(pentafluoroethanesulfonyl)amide. This stability is promising for accurate measurements of pH of low ionic strength samples and reliable estimates of single ion activities in general. The phase-boundary potential deviates from the value determined by the partition of the ionic liquid in further dilute aqueous solutions. The magnitude of the deviation ranges from 3 to 11 mV at 5 μmol kg⁻¹ MBr (M is H⁺, Li⁺, or K⁺). The solubility of these ionic liquids in water is 0.2 mmol dm⁻³ at most at 25 °C, which is another advantage of ionic liquid salt bridge in electroanalytical chemistry.     

Selective electrochemical sensing of calcium dobesilate based on an ordered mesoporous carbon-modified pyrolytic graphite electrode

Cyclic voltammetric investigation of calcium dobesilate (CD) in aqueous acid media was carried out by using an ordered mesoporous carbon-modified pyrolytic graphite electrode (OMC/PGE). A pair of well-defined redox peaks of CD was observed at the OMC/PGE, showing its good elelctrochemial response towards CD. The anodic current is linear with CD concentration in the range of 1.0 × 10⁻⁷–1.3 × 10⁻³ mol L⁻¹, with a detection limit of 4.0 × 10⁻⁸ mol L⁻¹. Meanwhile, the proposed electrode can avoid some interference coexisting with CD, such as uric acid, serotonin, and ascorbic acid. The proposed method can be potentially applied for selective electrochemical sensing of CD in physiological condition.     

Preparation of poly N,N-dimethylaniline/ferrocyanide film modified carbon paste electrode: Application to electrocatalytic oxidation of l-cysteine

Functionalized poly N,N-dimethylaniline film was prepared by adsorption of ferrocyanide onto the polymer forming at the surface of carbon paste electrode (CPE) in aqueous solution. The electrocatalytic ability of poly N,N-dimethylaniline/ferrocyanide film modified carbon paste electrode (PDMA/FMCPE) was demonstrated by oxidation of l-cysteine. Cyclic voltammetry and chronoamperometry techniques were used to investigate this ability. In the optimum pH (6.00), the electrocatalytic ability about 480 mV and the catalytic reaction rate constant, (k_h), can be seen 3.08 × 10³ M⁻¹ s⁻¹. The catalytic oxidation peak current determined by cyclic voltammetry method was linearly dependent on the l-cysteine concentration and the linearity range obtained was 8.00 × 10⁻⁵ –2.25 × 10⁻³ M. Detection limit of this method was determined as 6.17 × 10⁻⁵ M (2σ). At a fixed potential under hydrodynamic conditions (stirred solution), the calibration plot was linear over the l-cysteine concentration range 7.40 × 10⁻⁶ M–1.38 × 10⁻⁴ M. The detection limit of the method was 6.38 × 10⁻⁶ M (2σ).     

Electrochemical layer-by-layer modified imprinted sensor based on multi-walled carbon nanotubes and sol–gel materials for sensitive determination of thymidine

A novel electrochemical sol–gel imprinted sensor for sensitive and convenient determination of thymidine was developed. Thin film of molecularly imprinted sol–gel polymers with specific binding sites for thymidine was cast on carbon electrode by electrochemical deposition. Multi-walled carbon nanotubes (MWCNTs) were introduced for the enhancement of electronic transmission and sensitivity. The morphology and performance of the imprinted film was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV) and amperometric measurements (i–t) in detail. The results showed that the imprinted film exhibited high selectivity toward thymidine. The linear range is over the range from 2 to 22 μmol L⁻¹, and the linear regression equation for thymidine is I = 0.867C + 0.232 with the detection limit of 1.6 × 10⁻⁹ mol L⁻¹(S/N = 3). The imprinted sensor was successfully employed to detect thymidine in some zidovudine-tablet samples.     

Penetration of weakly acidic polyelectrolytes into PVC membrane containing quaternary ammonium salt for potentiometry both by ion exchange and by coextraction with proton

The ion exchange of anionic polyelectrolytes (APEs) on the PVC membrane containing tridodecylmethylammonium bromide as a carrier was analyzed by monitoring elution of the bromide from and penetration of APEs into the membrane. The equilibration time for exchange by APEs was around three times longer than that by a common anion of perchlorate. Heparin at 10⁻⁴ mol L⁻¹ and poly(vinyl sulfate) (PVS) at 10⁻² mol L⁻¹ could completely replace the bromide in the membrane, while polyacrylate (PA) at 10⁻² mol L⁻¹ could not. The chemical amount of the penetrated PVS was comparable to that of the eluted bromide, while that of PA was much larger than that of the eluted bromide and even the total amount of the carrier. PA penetrated into the organic phase within the membrane by coextraction with proton as well as by ion exchange, so as to avoid geometric restriction on multiple ion-pair formation.     

A gold nanoparticle-modified PVC/TTF-TCNQ composite amperometric biosensor for glucose determination

A comparison of the analytical performances of several enzyme biosensor designs, based on the use of different tailored gold nanoparticle-modified composite PVC/TTF-TCNQ electrodes, is discussed. The analytical characteristics of glucose calibration plots and kinetic parameters of the enzyme reaction were compared for the biosensors tested: Au_coll + GOx, GOx + Au_coll, Mixed GOx + Au_coll and PVC/TTF-TCNQ-Au_coll. The presence of this nanomaterial enhances the analytical performance with respect to the precursor biosensor without Au. The proposed biosensor can be applied in batch (response linear up to 2.0 mM, sensitivity of 45 ± 0.5 mA M⁻¹ with a limit of detection, s/n = 3, of 6.2 × 10⁻⁶ M) and in FIA systems (linear range between 0.1 and 8 mM, sensitivity of 3.67 ± 0.3 mA M⁻¹ with a limit of detection, s/n = 3, of 1.9 × 10⁻⁵ M).     

One-impedance for one-concentration impedimetry as an electrochemical method for determination of the trace zirconium ion

A new method is established for the electrochemical detection of zirconium ion (Zr(IV)) based on electrochemical impedance spectroscopy transduction method, and hydroxamated gold surface recognition system. The method successfully served for the detection of Zr(IV) with a wide dynamic range of 1.0 × 10⁻⁹ to 5.0 × 10⁻⁵ mol L⁻¹, and a detection limit in nmol L⁻¹ scale. Construction of the calibration curve by “one-impedance for one-concentration” method developed here helped us to save the experimental time by saving the data acquisition time by a factor of ∼20, and further, eliminating data approximation and parameter extraction times.