Number of found documents: 244
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Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA
Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
2016 - English
2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic effects. A differential pulse voltammetric method at a glassy carbon electrode (GCE) was developed for sensitive determination of 2-NF. Under the optimum conditions found, a linear calibration dependence was obtained in the concentration range of 2 x 10(-7) - 1 x 10(-5) mol L-1, with the limit of quantification of 2 x 10 mol L-1. The practical applicability of this method was verified on the direct determination of 2-NF in a model sample of sand. Moreover, the mutual interaction between 2-NF and DNA was investigated using an electrochemical DNA biosensor (DNA-modified GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and square-wave voltammetry were employed in this study, confirming the formation of a 2-NF-DNA complex.\n Keywords: DNA biosensors; DNA interaction; glassy carbon electrode Available at various institutes of the ASCR
Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA

2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic ...

Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2016

THE PHOTOCATALYTIC ABATEMENT OF NOX IMISSIONS USING COMMERCIAL FUNCTIONAL COATING WITH POROUS MORPHOLOGY
Žouželka, Radek
2016 - English
Titanium dioxide is the most important photocatalysts used for purifying applications. It was the purpose of this study to investigate the photocatalytic activity of commercial Protectam FN (R) containing TiO2 nanoparticles towards NO and NO2. Experiments on concrete as a support for photocatalyst were carried out in two types of reactors with laminar and turbulent flow under ´´real world setting´´ conditions of temperature, relative humidity, irradiation and pollutant concentrations. The results showed that photocatalytic process significantly reduced both nitrogen oxides in the air. The decrease in the total concentration of nitrogen oxides on contact with the photocatalytic surface reached 20-50 %, i.e. at a concentration of 100 ppb the decrease in NO and NO2 was 20-50 ppb. The nitrogen oxides were oxidized up to their highest oxidation state, nitric acid ( or nitrates) and undesirable nitrous acid was not formed at all. The experimental study conducted showed that the photocatalytic oxidation on the surface of the photocatalytic Protectam FN (R) coating is an effective method for the removal of nitrogen oxides from contaminated air. Keywords: TiO2; NOx; imissions; photocatalysis; air purification Available at various institutes of the ASCR
THE PHOTOCATALYTIC ABATEMENT OF NOX IMISSIONS USING COMMERCIAL FUNCTIONAL COATING WITH POROUS MORPHOLOGY

Titanium dioxide is the most important photocatalysts used for purifying applications. It was the purpose of this study to investigate the photocatalytic activity of commercial Protectam FN (R) ...

Žouželka, Radek
Ústav fyzikální chemie J. Heyrovského, 2016

Possibilities of Hollow Fiber Microextraction and Voltammetric Detection of Homovanillic acid
Hrdlička, V.; Barek, J.; Navrátil, Tomáš
2016 - English
The contribution deals with hollow fiber liquid phase microextraction (HF-LPME) of homovanillic acid (HVA) and its subsequent voltammetric detection. In HF-LPME, HVA is extracted from acidic sample through thin supported liquid membrane into basic aqueous acceptor solution. Since common electrode materials such as gold, platinum or glassy carbon are only able to detect HVA under acidic or neutral conditions, a new method was developed, utilizing silica gel modified carbon paste electrode (CPE). Reached limit of detection in a 10 μL drop of the HVA extract of pH 13 was 1·10-5 mol L-1. Keywords: Hollow-fibers; Liquid phase microextraction; voltammetry Available at various institutes of the ASCR
Possibilities of Hollow Fiber Microextraction and Voltammetric Detection of Homovanillic acid

The contribution deals with hollow fiber liquid phase microextraction (HF-LPME) of homovanillic acid (HVA) and its subsequent voltammetric detection. In HF-LPME, HVA is extracted from acidic sample ...

Hrdlička, V.; Barek, J.; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2016

Oxidation of Bioflavonoids in Respect to their Chemical Structure
Sokolová, Romana; Ramešová, Šárka; Kocábová, Jana; Degano, I.
2016 - English
The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of bioflavonoids resulted in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESI-MS/MS and HPLC-DAD. Keywords: oxidation; flavonoids; voltammetry Available at various institutes of the ASCR
Oxidation of Bioflavonoids in Respect to their Chemical Structure

The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of ...

Sokolová, Romana; Ramešová, Šárka; Kocábová, Jana; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2016

Voltammetric Behavior of Explosive Potassium Salt of 2,4-Dinitrobenzofuroxan\non Electrodes with Mercury Surface
Šelešovská, R.; Sokolová, Romana; Matyáš, R.; Janíková, L.
2016 - English
Voltammetric behavior of potassium salt of 2,4-dinitrobenzofuroxan (KDNBF) has been\nfirstly studied using hanging mercury drop electrode (HMDE) and silver solid amalgam\nelectrode (AgSAE). Cyclic voltammetry was applied for the measurements of dependences on\npH and scan rate required for the elucidation of the ongoing electrode reactions and\ndifferential pulse voltammetry served for the development of sensitive method for KDNBF\ndetermination. Keywords: Potassium salt of 2,4-dinitrobenofuroxan; Hanging mercury drop electrode; voltammetry Available at various institutes of the ASCR
Voltammetric Behavior of Explosive Potassium Salt of 2,4-Dinitrobenzofuroxan\non Electrodes with Mercury Surface

Voltammetric behavior of potassium salt of 2,4-dinitrobenzofuroxan (KDNBF) has been\nfirstly studied using hanging mercury drop electrode (HMDE) and silver solid amalgam\nelectrode (AgSAE). Cyclic ...

Šelešovská, R.; Sokolová, Romana; Matyáš, R.; Janíková, L.
Ústav fyzikální chemie J. Heyrovského, 2016

Effect of substrate hydrophobicity on the electrocatalytic behaviour of phthalocyanine
Klusáčková, Monika; Janda, Pavel; Tarábková, Hana
2016 - English
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. Keywords: atomic force microscopy; cyclic voltammetry; electrocatalysis Available at various institutes of the ASCR
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 ...

Klusáčková, Monika; Janda, Pavel; Tarábková, Hana
Ústav fyzikální chemie J. Heyrovského, 2016

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 - English
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 moll−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. Keywords: Screen-printed carbon electrodes; Differential pulse voltammetry; Homovanillic acid Available at various institutes of the ASCR
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, ...

Makrlíková, A.; Ktena, A.; Fischer, J.; Navrátil, Tomáš; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2016

Mercury and its Future in the Czech Republic
Navrátil, Tomáš; Vytopilová, M.; Vlčková, Š.; Mrázová, K.; Zakharov, S.; Honsová, Š.; Pelclová, D.
2016 - English
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. Keywords: mercury; toxicity odf mercury; Homovanillic acid; Ministry of Environment of the Czech Republic Available at various institutes of the ASCR
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 ...

Navrátil, Tomáš; Vytopilová, M.; Vlčková, Š.; Mrázová, K.; Zakharov, S.; Honsová, Š.; Pelclová, D.
Ústav fyzikální chemie J. Heyrovského, 2016

Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
Ramešová, Šárka; Sokolová, Romana; Degano, I.
2016 - English
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. Keywords: flavonoids; electrochemistry; oxidation mechanism Available at various institutes of the ASCR
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 ...

Ramešová, Šárka; Sokolová, Romana; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2016

Poly(Methylene Blue) Modified Carbon-based Electrodes for Electrochemical Detection of Hydrogen Sulfide
Zlámalová, Magda; Janda, Pavel; Nesměrák, K.
2016 - English
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. Keywords: CFE; HOPG; electropolymerization Available at various institutes of the ASCR
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 ...

Zlámalová, Magda; Janda, Pavel; Nesměrák, K.
Ústav fyzikální chemie J. Heyrovského, 2016

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