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Electrochemical Procedure (electrochemical + procedure)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Electroanalytical Approach to Evaluate Antioxidant Capacity in Honeys: Proposal of an Antioxidant Index

ELECTROANALYSIS, Issue 18 2006
Mónica Ávila
Abstract A novel electrochemical route to estimate the antioxidant capacity in honey samples is proposed just using flow injection analysis. The analytical strategy involved the selective oxidation of polyphenolic compounds using two different target potentials, +0.8 and +0.5,V, at two different pHs. An oxidation current obtained at the fixed potential was used as an analytical guide of the antioxidant activity of the target honeys. Chemometrics (correlation and principal component analysis, PCA) demonstrated the significance of the electrochemical protocol versus the traditional spectrophotometric ones in the evaluation of antioxidant capacity and revealed the role of detection potential as a screening variable. The proposed protocol is very simple and fast. However, the most relevant merit of the electrochemical procedure is its inherent versatility which allows the evaluation of the antioxidant activity under predesigned controlled oxidation conditions. In addition, since intercept was statistically zero, its corresponding antioxidant content using just a calibration factor is proposed thus simplifying the calibration-analysis process. As a result, an electrochemical antioxidant index (EAI) is proposed. [source]

Non-Covalent Aggregation of Discrete Metallo-Supramolecular Helicates into Higher Assemblies by Aromatic Pathways: Structural and Chemical Studies of New Aniline-Based Neutral Metal(II) Dihelicates

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2005
Miguel Vázquez
Abstract Neutral manganese(II), iron(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) complexes with an N -tosyl-substituted N4 -donor Schiff base containing a 4,4'-methylenedianiline residue as spacer [H2La: N,N' -bis(2-tosylaminobenzylidene)-4,4'-methylenedianiline], and the zinc(II) complex with an analogous ligand [H2Lb: N,N' -bis(2-tosylaminobenzylidene)-4,4'-oxodianiline] have been prepared by an electrochemical procedure. FAB and ESI mass spectra of the complexes show peaks due to species corresponding to a general formula [M2(La,b)2 + H]+, thereby suggesting their dinuclear nature. A detailed study of the crystal packing in the unit cell of the zinc(II) complex with H2La shows that the helicates aggregate to form discrete prismatic moieties containing three molecules held together by ,,, and ,,, interactions. Moreover, the ZnII neutral dihelicate with H2Lb forms a 3D network in the solid state due to intermolecular ,-stacking interactions. 1H NMR studies of the diamagnetic compounds reported herein have been performed. Finally, the ligand H2La and its ZnII and CdII complexes have been studied by spectrophotometric and spectrofluorimetric techniques in order to get a better understanding of the formation mechanisms of the complexes and of the nature of their fluorescence emission. Emission studies show that the ZnII and CdII dihelicates with H2La display a green fluorescence in acetonitrile solution (, = 473 nm, , = 0.03 and , = 476 nm, , = 0.01, respectively). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Detection of Nucleic Acids Using Enzyme-Catalyzed Template-Guided Deposition of Polyaniline,

ADVANCED MATERIALS, Issue 4 2007
Q. Gao
An electrochemical procedure for the detection of nucleic acids is realized by utilizing polyaniline as a signal generator for the transduction of nucleic acid hybridization events (see figure). The unique combination of enzymatic amplification and template-guided deposition can be used in conjunction with other detection techniques, and the sensitivity of the biosensor increases with increasing time. [source]

Voltammetric Sizing of a Sphere

CHEMPHYSCHEM, Issue 10 2006
Nicole Fietkau
Abstract The size of a glass sphere positioned in the center of a microdisk electrode is determined by using a simple electrochemical procedure and is confirmed, additionally, by a microscopical measurement of the sphere at the time of the electrochemical measurement. The cyclic voltammetric response of the naked electrode and of the electrode with the sphere positioned in its center is recorded over a wide range of scan rates (0.002,1.5 V,s,1). The size of the sphere is then determined by comparison of the experimental voltammogram with simulations for each individual scan rate. [source]

Voltammetric Sizing of Inert Particles

CHEMPHYSCHEM, Issue 7 2005
Trevor J. Davies
Abstract The average size of inert particles is determined using a simple electrochemical procedure. Alumina particles are deposited on an edge-plane graphite electrode, and a cyclic voltammogram is recorded. The scan rate employed varies between 0.2 and 2 V,s,1. At these scan rates the diffusion layer thickness is greater than the size of the alumina particles, minimizing the influence of the particles, height on the observed voltammetry. The average size of the particles is determined via comparison of the experimental voltammograms with simulations. [source]