Application of the Potentiometric Stripping Analysis with Constant Current for the Determination of Lithium Ions Using a Spinel-Type Manganese (IV) Oxide-Modified Carbon Paste Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Determination of Analgesics (Dipyrone and Acetaminophen) in Pharmaceutical Preparations by Cyclic Voltammetry at a Copper(II) Hexacyanoferrate(III) Modified Carbon Paste Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical investigation of the dimeric oxo-bridged ruthenium complex in aqueous solution and its incorporation within a cation-exchange polymeric film on the electrode surface for electrocatalytic activity of hydrogen peroxide oxidation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Voltammetric performance and application of a sensor for sodium ions constructed with layered birnessite-type manganese oxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An electrochemical sensor for dipyrone determination based on nickel-salen film modified electrode

An amperometric dipyrone sensor based on a polymeric nickel-salen (salen = N,N'-ethylenebis(salicydeneiminato)) film coated platinum electrode was developed. The sensor was constructed by electropolymerization of nickel-salen complex at a platinum electrode in acetonitrile/tetrabuthylamonium perchlorate by cyclic voltammetry. After cycling the modified electrode in a 0.50 mol L-1 KCl solution, the estimated surface concentration was found to be equal to 1.29 x 10(-9) mol cm(-2). This is a typical behavior of an electrode surface immobilized with a redox couple that can usually be considered as a reversible single-electron reduction/oxidation of the nickel(II)/nickel(III) couple. A plot of the anodic current versus the dipyrone concentration for chronoamperometry (potential fixed = +0.50 V) at the sensor was linear in the 4.7 x 10(-6) to 1.1 x 10(-4) mol L-1 concentration range and the concentration limit was 1.2 x 10(-6) mol L-1. The proposed electrode is useful for the quality control and routine analysis of dipyrone in pharmaceutical formulations.

Enzymeless Hydrogen Peroxide Sensor Based on Mn-containing Conducting Metallopolymer

The [(Mn4O5)-O-IV(terpy)(4)(H2O)(2)](6+) complex, show great potential for electrode modification by electropolymerization using cyclic voltammetry. The voltammetric behavior both in and after electropolymerization process were also discussed, where the best condition of electropolymerization was observed for low scan rate and 50 potential cycles. A study in glass electrode for better characterization of polymer was also performed. Electrocatalytic process by metal centers of the conducting polymer in H2O2 presence with an increase of anodic current at 0.85 V vs. SCE can be observed. The sensor showed great response from 9.9 x 10(-5) to 6.4 x 10(-4) mol L-1 concentration range with a detection limit of 8.8 x 10(-5) mol L-1, where the electrocatalytic mechanism was based on oxidation of H2O2 to H2O with consequently reduction of Mn-IV to Mn-III. After, the Mn-III ions are oxidized electrochemically to Mn-IV ions. (C) 2012 Elsevier Ltd .... Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.

Carbon fiber microelectrodes for adsorptive stripping analysis of trace nucleic acids

Carbon fiber ultramicroelectrodes are shown to be suitable for adsorptive stripping potentiometric measurements of trace DNA and RNA. The origin of the carbon fiber has a profound effect upon its suitability for trace analysis of nucleic acids, with the 'Aesar' materials performing most favorably. The resulting ultramicroelectrodes offer effective adsorptive accumulation of DNA and RNA from unstirred microliter-volume solutions, and are shown to be useful in adsorptive stripping transfer experiments. The influence of the surface pretreatment and accumulation conditions is described, along with the analytical-performance characteristics. The detection limits are 6, 15 and 40 mu g/l tRNA, ssDNA and dsDNA, respectively (5 min accumulation). (C) 1998 Elsevier B.V. S.A.

Caffeine Determination at a Carbon Fiber Ultramicroelectrodes by Fast-Scan Cyclic Voltammetry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of N-Acetylcysteine by Cyclic Voltammetry Using Modified Carbon Paste Electrode with Copper Nitroprusside Adsorbed on the 3-Aminopropylsilica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A spectroelectrochemical study of the inhibition of the electrode process on copper by 2-mercaptobenzothiazole in ethanolic solutions

The effect of 2-mercaptobenzothiazole (MBT) on the corrosion of copper in ethanol-water mixture with 0.01 mol dm(-3) HClO4 was investigated by linear sweep voltammetry and surface enhanced Raman scattering spectroscopy. The linear sweep voltammetry for the copper electrode in the presence of MBT shows one anodic process associated with the oxidation of MBT, which leads to the formation of a film on the electrode. This film inhibits the anodic copper dissolution and cathodic hydrogen evolution reaction. SERS studies indicated that MBT oxidizes and forms polymeric complexes involving copper ions and the ionized form of thiol. (C) 1997 Elsevier B.V. Ltd.

Compositional and structural changes at the anodic surface of thermally poled soda-lime float glass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Utilization of electrochemical impedance spectroscopy for monitoring bornite (CU5FeS4) oxidation by Acidithiobacillus ferrooxidans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of citrate ions on the electrochemical behaviour of low-carbon steel in borate buffer solutions

The electrochemical behaviour of cold-rolled low carbon steel was studied on both active and passive potential regions in borate buffer solutions with and without the addition of sodium citrate (NaCit). In the active region anodic charges increased significantly and RCT values decreased with citrate, due to the formation of soluble complexes. In the passive potential region the film formed at +0.4 V in borate buffer solution with and without 0.010 M NaCit is probably enriched by Fe3O4 oxide, while films formed at +0.8 V are probably enriched by gamma-Fe2O3. The equivalent circuit [R-s(R(CT)Q)] fitted all experimental impedance data. (C) 2003 Elsevier Ltd. All rights reserved.

Electrochemical studies of copper-aluminum-silver alloys in 0.5 M H2SO4

The electrochemical behavior in 0.5 M H2SO4 at 25 degreesC of a Cu-Al(9.3 wt%)-Ag(4.7 wt%) alloy submitted to different heat treatments and an annealed Cu- Al(9.7 wt%)-Ag(34.2 wt%) were studied by means of open circuit potential (E-mix) measurements, potentiodynamic polarizations and cyclic voltammetry. SEM and EDX microanalysis were used to examine the changes caused by the electrochemical perturbations. The steady state potentials observed for the studied samples were correlated in terms of the phases present in the alloys surface. The resulting E/I potentiodynamic profiles were explained in terms of the potentiodynamic behavior of pure copper and pure silver. The presence of aluminum decreased the extent of copper oxidation. In the apparent Tafel potential region, two anodic Tafel slopes were obtained: 40 mV dec(-1) in the low potential region and 130 mV dec(-1) in the high potential region, which were related with the electrochemical processes involving copper oxidation. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Effect of hydrogen charging on the stability of SAE 10B22 steel surface in alkaline solutions

The influence of hydrogen charging into a quenched and tempered boron steel membrane electrode (SAE 10B22) was studied using borate buffer (pH 8.4) and NaOH solutions (pH 12.7), with or without the addition of 0.01 M EDTA. At the hydrogen input side, hydrogen charging influenced cyclic voltammograms increasing the anodic charge of iron(II) hydroxide formation, and decreasing the donor density of passive films. These results suggest that the hydrogen ingress caused instability of metallic surface, increasing the surface area activity. (C) 2005 Elsevier Ltd. All rights reserved.