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Hollow-fibre Based Microextraction and Voltammetric Determination of Vanillylmandelic Acid
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš
2017 - English
New method of liquid/liquid/liquid hollow fibre based microextraction of vanillylmandelic acid coupled with voltammetric determination is being developed. Selected liquid membranes based on alcohols, aliphatic hydrocarbons and esters were tested. Highest enrichment factor of 2.52 after 30 minutes of extraction was obtained using propyl benzoate, RSD = 18.2 % (n=5). Mechanically and cathodically pretreated (-1000 mV vs. Ag/AgCl/3M KCl, 15 s) boron doped diamond electrode in a miniaturized arrangement was used for DPV determination. LOD = 1.2 micromol/l, RSD = 5.9% (n=10) for a 10 microl extract.
Keywords:
Hollow-fibres; Liquid phase microextraction; Voltammetry
Available at various institutes of the ASCR
Hollow-fibre Based Microextraction and Voltammetric Determination of Vanillylmandelic Acid
New method of liquid/liquid/liquid hollow fibre based microextraction of vanillylmandelic acid coupled with voltammetric determination is being developed. Selected liquid membranes based on alcohols, ...
Voltammetric Determination of Tumor Biomarkers using Flow Injection Analysis with Amperometric Detection
Němečková-Makrlíková, Anna; Matysik, F.-M.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2017 - English
Three tumor biomarkers (homovanillic acid, vanillylmandelic acid, and 5-hydroxyindole-3-acetic acid) have been determined by flow injection analysis with amperometric detection at screen-printed carbon electrodes in optimum medium of Britton-Robinson buffer (0.04 mol l(-1), pH = 2.0). Dependences of the peaks current on the concentration of biomarkers were linear in the tested concentration region from 0.05 to 100 mu mol l(-1), with the limits of detection of 0.065 mu mol l(-1) for homovanillic acid, 0.053 mu mol l(-1) for vanillylmandelic acid, and 0.033 mu mol l(-1) for 5-hydroxyindole-3-acetic acid (calculated from heights), and 0.024 mu mol l(-1) for homovanillic acid, 0.020 mu mol l(-1) for vanillylmandelic acid, and 0.012 mu mol l(-1) for 5-hydroxyindole-3-acetic acid (calculated fromareas), respectively.
Keywords:
vanillylmandelic acid; homovanillic-acid; urine; flow injection analysis; 5-hydroxyindole-3-acetic acid; homovanillic acid; vanillylmandelic acid; tumor biomarkers
Available at various institutes of the ASCR
Voltammetric Determination of Tumor Biomarkers using Flow Injection Analysis with Amperometric Detection
Three tumor biomarkers (homovanillic acid, vanillylmandelic acid, and 5-hydroxyindole-3-acetic acid) have been determined by flow injection analysis with amperometric detection at screen-printed ...
Long-Term Sustainability of Research Infrastructures
Hrušák, Jan; Harrison, A.; Lenoir, L.
2017 - English
The second volume of the ESFRI Scripta series is dedicated to\nthe outcomes of the ad hoc Working (WG) Group on Long-Term\nSustainability (LTS) of Research Infrastructures.\nThe LTS WG was created by ESFRI in 2016 to comprehensively respond\nto the Conclusions of the Competitiveness Council of the European\nUnion of 27th May 2016 that „underlines the importance of ensuring\nLong-Term Sustainability of Research Infrastructures and invites the\nCommission to prepare together with ESFRI and relevant stakeholders a\ntargeted action plan“.\nESFRI has previously developed its concept of lifecycle of the Research\nInfrastructures in the framework of the Roadmap evaluation exercise,\nand at all stages of the lifecycle different aspects of sustainability were\nidentified. The LTS WG has analysed the Long-Term Sustainability\nof Research Infrastructures from a broad perspective taking the\nESFRI viewpoint well beyond the mere economical analysis. Scientific\nexcellence is the condition sine qua non for sustainability throughout\nthe entire RI lifecycle, and its persistence is crucial in the long-term\noperational phase. Excellence in science and outstanding quality services\nto the users are imperative for the successful performance of each\nResearch Infrastructure, and they are addressed in the monitoring and\nreviewing processes by ESFRI.
Keywords:
sustainability; research infrastructures; ESFRI
Available in digital repository of the ASCR
Long-Term Sustainability of Research Infrastructures
The second volume of the ESFRI Scripta series is dedicated to\nthe outcomes of the ad hoc Working (WG) Group on Long-Term\nSustainability (LTS) of Research Infrastructures.\nThe LTS WG was created by ...
Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection
Makrlíková, Anna; Matysik, F.-M.; Navrátil, Tomáš; Barek, J.; Vyskočil, V.
2017 - English
Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 mol-l-1 , pH 2.0) was used as an optimum carrier solution.\nDependence of the peak current on the analyte concentration was linear in the whole tested\nconcentration range (from 0.5 to 100 mikromol-l-1) with limits of detection 0.033 mikromol-l-1 \n(calculated from peak heighst) and 0.012 mikromol-l-1 (calculated from peak areas).
Keywords:
Amperometric detection; Flow injection analysis; 5-Hydroxyindole-3-acetic acid
Available on request at various institutes of the ASCR
Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection
Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 ...
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Hromadová, Magdaléna; Kocábová, Jana; Kolivoška, Viliam; Pospíšil, Lubomír
2017 - English
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results show that the oxide growth kinetics depends on pH of the electrolyte\nsolution and the total amount of irreversibly formed oxide under the potentiodynamic\nconditions decreases with decreasing buffer pH in accord with thermodynamic considerations.\nCathodic current corresponding to hydrogen evolution reaction diminishes in the presence of\nanodically modified electrode compared to bare zirconium.
Keywords:
zirconium; oxide film; hydrogen evolution
Available on request at various institutes of the ASCR
Effect of pH on the Oxide Film Formation on a Pristine Zr Electrode
Effect of pH on the oxidation of zirconium metal was studied by cyclic voltammetry in\naqueous borate buffer solutions as a function of the potential scan rate and pH from 4.80 to\n9.17. The results ...
High resolution infrared spectroscopy as diagnostic tool for combustion and plasma chemistry
Zelinger, Zdeněk; Nevrlý, Václav; Grigorová, Eva; Bitala, P.; Dostál, Michal; Suchánek, Jan; Kubát, Pavel; Engst, Pavel; Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk
2017 - English
Monitoring of transient species within combustion experiments (laminar flames, shock-tubes, flow reactors, etc.) is still relatively challenging task especially if application of non-invasive, i.e. optical detection methods is required. High resolution infrared spectroscopy is based on observation of the fine rotation structure that accompanies vibration transitions and thus provides direct information essential to characterization of both molecular structure and reaction dynamics. Thanks to its outstanding advantage enabling unambiguous assignment of specific molecular system according to its spectral feature, it can serve as a helpful tool for exploring complex reaction mechanisms as well as chemical reactivity of individual species present in laboratory flames or plasmas.\nPrevious studies gaining new insights into combustion and plasma chemistry as well as our recent advances targeted towards application of high resolution infrared spectroscopy for species concentration measurement in laminar flames are summarized here below.
Keywords:
spectroscopy; plasma chemistry; infrared spectra
Available in digital repository of the ASCR
High resolution infrared spectroscopy as diagnostic tool for combustion and plasma chemistry
Monitoring of transient species within combustion experiments (laminar flames, shock-tubes, flow reactors, etc.) is still relatively challenging task especially if application of non-invasive, i.e. ...
Photocatalytic active coatings-environmental way to improve quality and durability of buildings
Sázavská, T.; Jakubičková, M.; Jirkovský, Jaromír; Šubrt, Jan; Peterka, F.
2017 - English
Transparent coatings of TiO2-SiO2 nanocomposite were developed to be applied on building facades in order to prevent growth of microorganisms and thus to improve urban building sustainability. Structure and texture characteristics of the prepared nanocomposites were determined by electron microscopy (SEM, TEM + EDS), their photocatalytic activity was quantified by testing self-cleaning ability and antimicrobial activity. The self-cleaning properties were evaluated according to the standard ISO method based on photocatalytic degradation of methylene blue. The TiO2-SiO2 nanocomposite coatings were applied on various types of substrates commonly used in building industry. The antimicrobial activity was mainly investigated for algae because these microorganisms are often responsible for facades ageing. According to the laboratory tests the prepared TiO2-SiO2 nanocomposites are highly efficient. This fact was already proved by first applications in real conditions. The transparent SiO2-TiO2 nanocomposites represent an ecological and noninvasive way how to keep nice appearance of buildings for a long time. It is due to their permanent photocatalytic activity causing self-cleaning and algicidal effects. Such coatings may significantly reduce ageing processes on facades of buildings that are caused by microbiological pollution and smog exhalations.
Keywords:
Photocatalysis; Photocatalytic algae degradation; Photocatalytic paint
Available at various institutes of the ASCR
Photocatalytic active coatings-environmental way to improve quality and durability of buildings
Transparent coatings of TiO2-SiO2 nanocomposite were developed to be applied on building facades in order to prevent growth of microorganisms and thus to improve urban building sustainability. ...
Wavelength modulation spectroscopy for multicomponent ana-lytics of biomass burning tracers
Dostál, Michal; Válek, V.; Suchánek, Jan; Kristlová, E.; Roupcová, P.; Zelinger, Zdeněk; Nevrlý, Václav; Bitala, P.; Vašinek, M.; Kubát, Pavel; Ferus, Martin; Civiš, Svatopluk
2017 - English
The potential of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for monitoring of several species produced by biomass burning is in focus of this work. The infrared spectra of selected molecules (HCOOH, C2H2, CH3CN, N2O, CH3OH, CH3COCH3) are measured in laboratory conditions and the selectivity and of this method is demonstrated.
Keywords:
spectroscopy; biomass burning tracers; TDLAS system
Available in digital repository of the ASCR
Wavelength modulation spectroscopy for multicomponent ana-lytics of biomass burning tracers
The potential of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for monitoring of several species produced by biomass burning is in focus of this work. The infrared spectra of selected molecules ...
Hydroxyl radical measurement in atmospheric pressure dimethyl ether-air laminar premixed flat flame using tunable diode laser absorption spectroscopy
Nevrlý, V.; Dostál, Michal; Bitala, P.; Zelinger, Zdeněk; Suchánek, Jan; Válek, V.; Klečka, V.; Kubát, Pavel; Engst, Pavel; Vašinek, M.; Wild, J.
2017 - English
Spectroscopic detection of hydroxyl (OH) radical and determination of its concentration in flames have an elusive history and considerable influence on combustion research. Electronic transitions in ultraviolet spectral region were extensively studied in this context and until recent time chemiluminescence or laser induced fluorescence of excited hydroxyl (OH*) radical is broadly used for absolute concentration and temperature measurement in flames.\nHowever, number densities of molecular species and population of relevant quantum levels in ground electronic state can be directly estimated from intensities of absorption lines observed by probing rovibrational transitions in infrared spectral region. Application of near-infrared tunable diode laser absorption spectroscopy (NIR-TDLAS) for the given purpose was demonstrated in an earlier work of Aizawa et al. [1]. Following his pioneering studies summarized in [2], we further explored feasibility of NIR-TDLAS (especially 2f-WMS technique) for monitoring minor species within combustion experiments particularly when dealing with dimethyl ether (DME) flames. Here we report our first results of NIR-TDLAS measurements focused on hydroxyl radical detection in laminar premixed flame burning DME-air mixture under fuel-lean conditions.
Keywords:
spectroscopy; tunable diode laser absorption spectroscopy; hydroxyl
Available in digital repository of the ASCR
Hydroxyl radical measurement in atmospheric pressure dimethyl ether-air laminar premixed flat flame using tunable diode laser absorption spectroscopy
Spectroscopic detection of hydroxyl (OH) radical and determination of its concentration in flames have an elusive history and considerable influence on combustion research. Electronic transitions in ...
Mystery of Ageing of „Zero-Valent Iron“ (ZVI)
Wouafo, M. T.; Donkeng Dazie, Joel; Tchatchueng, J. B.; Noubactep, Ch.; Ludvík, Jiří
2017 - English
So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and oxygen cannot be considered as pure Fe0 but as a mixture of its corrosion products.\nThe remediation process occurs on the surface of these iron particles, hence, the degree of\n„corrosion“ is crucial for the process itself. Therefore, investigation of „aging“ of ZVI is an\nimportant prerequisite for deeper understanding of its activity.\nIn this work, the first results of the systematic study of aging of iron metal powder are\npresented. The investigation was performed in batch conditions in aqueous buffered solutions\npH 4, 4.7, 5.5 and in the presence of air oxygen. Increasing and then decreasing concentration\nof the Fe2+ ion in the solution appeared to be the important marker of aging process.\nIn the second part of the work, removal of Zn2+ ions using ZVI was investigated.\nElectrochemical techniques, namely polarography and its differential pulse form (DPP) were\nused for permanent monitoring of the presence of Fe2+ and Zn2+ ions in the studied solution.\nChanging concentrations of both ions revealed that at pH 5.5 the optimum aging time of ZVI\nfor removal of Zn2+ from aqueous solution is 6 hours.
Keywords:
zero-valent iron; aging effect; zinc ion removal
Available on request at various institutes of the ASCR
Mystery of Ageing of „Zero-Valent Iron“ (ZVI)
So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and ...
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