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Effect of substrate hydrophobicity on the electrocatalytic behaviour of phthalocyanine
Klusáčková, Monika; Janda, Pavel; Tarábková, Hana
2016 - anglický
In this work, the electrocatalytic activity of pyridinoporphyrazine mediator deposited on two substrates with different hydrophobicity has been presented. We focused on hydrophobic highly oriented pyrolytic graphite (HOPG) as well as hydrophilic annealed gold electrode (Au111). The immobilization of mediator has been carried out spontaneous adsorption from aqueous solution on electrode surfaces. The different hydrophobicity surface resulted in change the electrocatalytic activities of mediator to hydrogen in aqueous solution. For this purpose, electrochemical, in situ spectroelectrochemical, and ex situ microscopically characterizations have been performed. The detailed comparison of surface morphology, surface coverage, surface roughness parameters, thickness of deposited layers of mediator, and pH solution has been studied.
Klíčová slova:
atomic force microscopy; cyclic voltammetry; electrocatalysis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Effect of substrate hydrophobicity on the electrocatalytic behaviour of phthalocyanine
In this work, the electrocatalytic activity of pyridinoporphyrazine mediator deposited on two substrates with different hydrophobicity has been presented. We focused on hydrophobic highly oriented ...
Electrochemical Methods for Determination of Three Tumor Biomarkers for Neuroblastoma: Homovanillic Acid, Vanillylmandelic Acid, and 5-Hydroxyindoleacetic Acid
Makrlíková, A.; Ktena, A.; Fischer, J.; Navrátil, Tomáš; Vyskočil, V.
2016 - anglický
Tumor biomarkers – homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid – have been determined at a screen-printed carbon electrode in small volume samples. For all measurements, Britton-Robinson buffer (0.04 moll−1, pH 3.0) was used as an optimum medium for all three analytes. Dependences of the peak current on the concentration were linear for all compounds, with the limits of quantification 0.8 μmol∙l–1 for homovanillic acid, 0.2 μmol∙l–1 for vanillylmandelic acid, and 0.2 μmol∙l–1 for 5-hydroxyindoleacetic acid. Depending on the results of the measurements, the future experiments should be performed in human urine.
Klíčová slova:
Screen-printed carbon electrodes; Differential pulse voltammetry; Homovanillic acid
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Electrochemical Methods for Determination of Three Tumor Biomarkers for Neuroblastoma: Homovanillic Acid, Vanillylmandelic Acid, and 5-Hydroxyindoleacetic Acid
Tumor biomarkers – homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid – have been determined at a screen-printed carbon electrode in small volume samples. For all measurements, ...
Mercury and its Future in the Czech Republic
Navrátil, Tomáš; Vytopilová, M.; Vlčková, Š.; Mrázová, K.; Zakharov, S.; Honsová, Š.; Pelclová, D.
2016 - anglický
Toxicity of mercury has been discussed for many years by specialists as well as by laymen. Legislative tools connected with measures and conditions concerning the trade, manufacture, use and interim storage of mercury, mercury compounds, mixtures, mercury-added products and the management of mercury waste are currently being prepared. Some suggestions and prepared measurements are mentioned and discussed in this contribution. Of course, it is necessary to differentiate among various forms of it, i.e., metallic form, vapors, amalgams, soluble and insoluble inorganic and organic compounds.
Klíčová slova:
mercury; toxicity odf mercury; Homovanillic acid; Ministry of Environment of the Czech Republic
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Mercury and its Future in the Czech Republic
Toxicity of mercury has been discussed for many years by specialists as well as by laymen. Legislative tools connected with measures and conditions concerning the trade, manufacture, use and interim ...
Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
Ramešová, Šárka; Sokolová, Romana; Degano, I.
2016 - anglický
The natural flavonoid rhamnetin (2-(3,4-dihydroxyfenyl)-3,5-dihydroxy-7-methoxychromen-4-one) is important bioactive compound. Rhamnetin was studied in aqueous solution by electrochemical methods. The oxidation mechanism proceeds in sequential steps, which correspond to the hydroxyl oxidation of groups in the three aromatic rings. The study is based on in situ spectroelectrochemistry and identification of products by HPLC-DAD and HPLC–ESI MS/MS.
Klíčová slova:
flavonoids; electrochemistry; oxidation mechanism
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
The natural flavonoid rhamnetin (2-(3,4-dihydroxyfenyl)-3,5-dihydroxy-7-methoxychromen-4-one) is important bioactive compound. Rhamnetin was studied in aqueous solution by electrochemical methods. The ...
Poly(Methylene Blue) Modified Carbon-based Electrodes for Electrochemical Detection of Hydrogen Sulfide
Zlámalová, Magda; Janda, Pavel; Nesměrák, K.
2016 - anglický
A comparative electrochemical study has been carried out of the electropolymerization of phenothiazine derivative, methylene blue (MB). Electrochemical properties of resulting electrocatalytically active methylene blue polymer (pMB) have been studied on three various carbon-based substrates: basal plane of highly oriented pyrolytic graphite (HOPG), pencil-graphite electrode (PGE) and carbon fibre micro electrode (CFE). Electrodes modified with the polymer (HOPG/pMB, PGE/pMB and CFE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing dissolved monomeric methylene blue. Electrocatalytic activity of three developed electrode systems towards hydrogen sulphide has been compared. Developed electrodes have been further investigated as potential sensors for sulfhydryl-containing compounds.
Klíčová slova:
CFE; HOPG; electropolymerization
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Poly(Methylene Blue) Modified Carbon-based Electrodes for Electrochemical Detection of Hydrogen Sulfide
A comparative electrochemical study has been carried out of the electropolymerization of phenothiazine derivative, methylene blue (MB). Electrochemical properties of resulting electrocatalytically ...
Poly(methylene blue) modified carbon based electrodes for the determination of sulfhydryl-containing compounds
Zlámalová, Magda; Janda, Pavel; Nesměrák, K.
2016 - anglický
This research presents the study of electrochemical polymerization of phenothiazine derivative, methylene blue (MB). Electrochemical pro perties and analytical application of resulting electrocatalytically active poly(methylene blue) (pMB) have been investigated. Three various carbon-based substrates: basal plane of highly oriented pyro lytic graphite (HOPG), pencil graphite electrode (PGE) and carbon fibre micro electrode (CFE) have been used. Aforementioned electrodes modified with the polymer (HOPG/pMB, PGE/pMB and CFE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing dissolved monomeric methylene blue. Electrocatalytic activity of three developed electrode systems towards hydrogen sulphide has been compared. Developed electrodes have been further investigated as potential sensors for sulfhydryl-containing compounds.
Klíčová slova:
carbon-based electrodes; electropolymerization; hydrogen sulphide
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Poly(methylene blue) modified carbon based electrodes for the determination of sulfhydryl-containing compounds
This research presents the study of electrochemical polymerization of phenothiazine derivative, methylene blue (MB). Electrochemical pro perties and analytical application of resulting ...
Role of Intramolecular Electron Interactions in Cathodic Reduction of Three Isomeric Benzenedialdehydes in Non-aqueous Media – a (Spectro)Electrochemical Study
Kantnerová, Kristýna; Klíma, Jiří; Ludvík, Jiří
2016 - anglický
This contribution is focused on cathodic reduction of three isomeric benzenedialdehydes – orthophthalaldehyde (OPA), isophthalaldehyde (IPA) and terephthalaldehyde (TPA) – in non-aqueous acetonitrile and dimethylformamide. Although their electrochemical behavior in aqueous solutions has been published several times, their investigation in organic aprotic solvents is lacking. Using DC-polarography, cyclic voltammetry, preparative electrolyses, coulometry and UV/Vis spectroelectro-chemistry their reduction was described and in the case of OPA and TPA, stable radical anions were characterized by EPR spectroscopy. The role of intramolecular electron interactions in their cathodic reduction is discussed.
Klíčová slova:
Orthophthalaldehyde; OPA; IPA
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Role of Intramolecular Electron Interactions in Cathodic Reduction of Three Isomeric Benzenedialdehydes in Non-aqueous Media – a (Spectro)Electrochemical Study
This contribution is focused on cathodic reduction of three isomeric benzenedialdehydes – orthophthalaldehyde (OPA), isophthalaldehyde (IPA) and terephthalaldehyde (TPA) – in non-aqueous acetonitrile ...
Electrochemical Impedence Spectroscopy and Steady-State Voltammetry at the Micro- between Two Immiscible Electrolyte Solution
Silver, Barry Richard; Holub, Karel; Mareček, Vladimír
2016 - anglický
The kinetic data of simple tetraethylammonium ion transfer across the water/1,2-DCE interface obtained by electrochemical impedance spectroscopy and steady-state voltammetry are compared. It is shown that the geometry of the microcapillary tip region is of critical importance to obtain reliable kinetic data. Quasi-reversible behavior of the ion transfer reaction, corresponding to an apparent standard rate constant of about 0.2 cm s-1, is observed with both experimental methods.\n
Klíčová slova:
liquid-liquid interface; ion transport; AC impedance
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Electrochemical Impedence Spectroscopy and Steady-State Voltammetry at the Micro- between Two Immiscible Electrolyte Solution
The kinetic data of simple tetraethylammonium ion transfer across the water/1,2-DCE interface obtained by electrochemical impedance spectroscopy and steady-state voltammetry are compared. It is shown ...
Study of 2-Nitrofluorene Interaction with DNA at a Glassy Carbon Electrode
Skalová, Štěpánka; Stávková, K.; Vyskočil, V.; Barek, J.
2016 - anglický
2-Nitrofluorene (2-NF) is a nitrated polycyclic aromatic hydrocarbon (NPAH) which occurs as the environmental pollutant. It is a potential carcinogen and mutagen. Interaction of deoxyribonucleic acid (DNA) with 2-NF was monitored using an electrochemical DNA biosensor prepared from a glassy carbon electrode (GCE) and low-molecular-weight DNA by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square-wave voltammetry (SWV).\nThere were no damaging interactions observed between DNA and 2-NF using EIS. However, CV shows intercalation of this substance into the DNA structure to form the complex 2-NF–DNA. Intercalation was also observed by SWV, confirming intercalation to reduce the number of electroactive sites and thus reducing the peak heights of adenosine and guanosine.
Klíčová slova:
DNA biosensor; glassy carbon electrode; voltammetry
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Study of 2-Nitrofluorene Interaction with DNA at a Glassy Carbon Electrode
2-Nitrofluorene (2-NF) is a nitrated polycyclic aromatic hydrocarbon (NPAH) which occurs as the environmental pollutant. It is a potential carcinogen and mutagen. Interaction of deoxyribonucleic acid ...
Structural, Redox and Spectrometric Characterization of Energetic Material FOX-7 (2,2-dinitroethene-1,1-diamine) in Solution
Šimková, Ludmila; Ludvík, Jiří
2016 - anglický
The investigation of energetic materials, especially organic nitro-amino-derivatives, always has attracted attention of physical chemists. However, published articles demonstrate lack of systematic study of molecules based on aliphatic backbones, rather than aromatic structures. This work represents the first systematic electrochemical and spectrometric characterization of 2,2-dinitroethene-1,1-diamine (FOX-7) in aqueous and aprotic solvent. Based on the results obtained from combination of electrochemistry with spectrometric methods, the actual structure of FOX-7 in various media was revealed, its reducibility described and radical intermediates as well as products were intercepted, isolated and characterized.
Klíčová slova:
FOX-7; 2,2-dinitroethene-1,1-diamine; structure
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Structural, Redox and Spectrometric Characterization of Energetic Material FOX-7 (2,2-dinitroethene-1,1-diamine) in Solution
The investigation of energetic materials, especially organic nitro-amino-derivatives, always has attracted attention of physical chemists. However, published articles demonstrate lack of systematic ...
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