Publikace vydané Univerzitou Pardubice / Published by the University of Pardubice
Stálý URI pro tuto komunituhttps://hdl.handle.net/10195/37631
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Článek Otevřený přístup peer-reviewedpublished Gadolinium of anthropogenic origin in food crops(University of Pardubice, 2022) Josefová, Dominika; Mišíková, Frederika; Krejčová, Anna; Patočka, Jan; Adam, MartinThe study is focused on the monitoring of rare earth elements (REE) in food crops with particular interest paid to the evaluation of gadolinium of anthropogenic origin. Macroscopic fungi were used as they are culinary processed and being also a good indicator of environmental pollution. In total, 46 dried mushroom samples originating from the Czech Republic and Slovakia were analysed. When using microwave decomposition of samples and the elemental analysis of Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, Y, Yb using inductively coupled plasma mass spectrometry (ICP-MS), the respective analytical procedure was optimised and validated. The study also included the calculation of the gadolinium anomaly in the processed samples, as well as the calculation of the amount of anthropogenic gadolinium. In the case of the gadolinium monitored, the minimum value found was 1.41 μg kg−1; the maximum being 361 μg kg−1, and the average 33.7 μg kg−1. The contribution of gadolinium of the anthropogenic origin ranged from 0.77 to 270 g kg−1.Článek Otevřený přístup peer-reviewedpublished Advances in perovskite doping – SrTiO3 with cobalt ions(University of Pardubice, 2022) Fejk, Jiří; Dohnalová, Žaneta; Honcová, Pavla; Adam, MartinThis paper supports the point of research on doping of inorganic materials – in this case, pigments – with various elements. Compounds on the basis of SrTiO3 with individually substituted titanium positions for the cobalt ions have been prepared by the solid-state reaction boosted by the prior-to-made mechanoactivation. Calcination temperature and the molar ratio of reactants were varied in order to study their effect on the pigment synthesis. Powdered materials were characterised in terms of thermal behaviour and the phase composition. Particle size distribution and application possibilities in ceramic glaze and organic binder along with colour properties were subsequently determined for selected samples. The prepared set of pigments SrTi1–xCoxO3 (x = 0.1–0.9) differed in characteristics according to a diverse range of substitution and conditions of the synthesis.Článek Otevřený přístup peer-reviewedpublished HILIC-MS analysis of common artificial sweeteners in food and beverages(University of Pardubice, 2021) Klikarová, Jitka; Štěpánová, Hana; Šimorová, Lenka; Česlová, Lenka; Fischer, Jan; Adam, MartinThe five most common artificial sweeteners were analysed in various samples of food and beverages and other products using hydrophilic-interaction liquid chromatography coupled with mass spectrometry. The optimised method employed Hypersil Gold HILIC analytical column combined with a binary mobile phase of 50 mmol/L ammonium acetate in water (pH 5; A)/acetonitrile (B) operating at a gradient program of 90–65 % B for 10 min. The individual sweeteners were quantified by the calibration curve method and the data obtained compared with the data declared on the packaging.Článek Otevřený přístup peer-reviewedpublished Multi-elemental analysis of wine samples using ICP-OES and ICP-MS methods. Anthropogenic gadolinium in wine(University of Pardubice, 2021) Mišíková, Frederika; Patočka, Jan; Krejčová, Anna; Adam, MartinThe study presented in this article has been focused on developing a method for elemental analysis of wine samples. A wide sample set of 200 wines contained white, rosé and red still wines; the wine vintages being 2013, 2014, 2015, 2016, 2017 and 2019. Samples were taken from wine festivals in Pardubice and Hradec Králové and private wineries in the Czech Republic. The analysis was performed using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS); the determined elements being As, Ba, Ca, Cd, Ce, Co, Cu, Dy, Er, Eu, Fe, Gd, Ho, K, La, Lu, Mg, Mn, Na, Nd, Ni, P, Pb, Pr, S, Sm, Sr, Tb, Tm, Y, Yb, and Zn. The data obtained were processed statistically and the Sr/Ba, Sr/Ca and Sr/Mg ratios were determined as potential indicators for the identification and classification of the wine origin. The existence of the so-called gadolinium anomaly for selected wine samples was investigated as evidence of the presence of anthropogenic gadolinium.Článek Otevřený přístup peer-reviewedpublished Preparation and reactions of diazonium salts. II. Reactions of ArN2+(Univerzita Pardubice, 1995) Štěrba, VojeslavArenediazonium slats can react with nucleophiles in three ways: (1) The substitution of diazonium group by nucleophile, (2) the substitution of a substituent at ortho or para position by a nucleophile, (3) the addition of a nucleophile to the diazonium group producing the corresponding diazo compound Ar-N=N-Nu od a five- or six-membered ring if the nucleophile is presented by an ortho-standing substituent with regard to the diazonium group.Článek Otevřený přístup peer-reviewedpublished Bestimmung der Temperaturabhängigkeit der Dichte von Rapsöl und Rapsöl-Methylester (Biodiesel) unter Anwendung der Methode der Volumen-ausdehnung(Univerzita Pardubice, 1995) Skopal, František; Komers, KarelSimple methods and apparatus for determination of the density of liquids at variable temperatures were developed. Their correct function was demonstrated by the comparison of the literature and experimental data for ethanol. The temperature dependences of the density of crude rape seed oil and of rape seed oil-ethyl ester (bio-diesel) were measured in the interval of 15–70 °C. The precision of the method described is better than ± 0.5 mg cm−3 at the temperature tolerance ± 0.1 °C.Článek Otevřený přístup peer-reviewedpublished Kinetic analysis of non-isothermal calorimetric data(Univerzita Pardubice, 1996) Málek, JiříA simple and reliable method of kinetic analysis of non-isothermal calorimetric data has been developed. This method allows to find appropriate model characterizing the kinetics of the process studied as well as to calculate reliable kinetic parameters. The application of this method is demonstrated for three different processes: (i) Curing reaction of an epoxy resin (ii) Crystallization kinetics of a chalcogenide glass (iii) Crystallization kinetics of zirconia gel The reliability of calculated kinetic parameters is tested by comparing calculated and experimental isothermal kinetic data. It is shown that a very good prediction of isothermal behavior can be obtained. Such modelling can be very useful for preparation of materials with defined properties.Článek Otevřený přístup peer-reviewedpublished On the compositional trend of photodarkening GexSe1-x(Univerzita Pardubice, 1996) Vindourek, Antonín; Tichý, Ladislav; Švejka, RadimGlassy GexSe1-x samples were prepared from 5N purity elements. The expansion coefficient (αp) and optical transmission of virgin and illuminated samples (halogen lamp at room temperature) have been studied. The extreme values of photodarkening are shifted into Se-rich region, somewhere close to x = 0.2. All the dependences (relative changes of Urbach edge slope, atomic volume (Vm) and expansion coefficient (αp) in the temperature range from 40 to 80 °C versus atomic fraction of Ge) indicate an extreme around x ≈ 0.2 in the region of the Philips threshold, where the mean coordination number of pseudoatom is: 〈CN〉 = 2.4.Článek Otevřený přístup peer-reviewedpublished Biosensors based on carbon paste electrodes using immobilized dehydrogenase enzymes. An overview and trends(Univerzita Pardubice, 1997) Lobo-Castañón, Maria Jesus; Alvarez-Crespo, Suzana L.; Alvarez-Gonzalez, Maria Isabel; Saidman, Silvana B.; Miranda-Ordieres, Arturo José; Tunon-Blanco, PaulinoAmperometric biosensors based on two different NADH catalytic systems are presented. Common to both types is the design strategy which consists in the direct mixing of the NAD' -dependent dehydrogenase enzymes and other modifying molecules with the carbon paste combined with physical barriers like dialysis membranes or conducting polymers. One type is based on the use of a redox mediator (the phenothiazine dye Toluidine Blue O) to make possible the electrocatalytic oxidation of the enzymatically produced NADH at potentials close to 0 V. The second type is based on the use of the electrochemically generated conducting polymers poly(o-aminophenol) (PAP) and poly(ophenylenediamine) (PPD), which allow not only the immobilization of enzyme and cofactor at the electrode surface but also the amperometric detection of NADH at potentials as low as 0 V without other immobilized electron transfer mediators. An ethanol biosensor based on the first catalytic system and ethanol, lactate and glutamate sensors based on the second one are presented.Článek Otevřený přístup peer-reviewedpublished Voltammetric determination of titanium, vanadium, and molybdenum using a carbon paste electrode modified with cetyltrimethylammonium bromide(Univerzita Pardubice, 1997) Stadlober, Monika; Kalcher, Kurt; Raber, GeorgMethods for the voltammetric determination of titanium, vanadium, and molybdenum using a carbon paste electrode modified in situ with cetyltrimethylammonium bromide (CTAB) are described. Titanium and vanadium are preconcentrated at the electrode surface via their anionic oxalate complexes from acidic solution at −1.2 and −0.9 V vs. the saturated calomel electrode. The accumulation process is due to in situ formation of an ion-exchanger at the electrode surface by adsorption of the surfactant, and to formation of ion-pairs or micellar congregates, since the concentration of CTAB is higher than the critical micellar concentration (CMC). Simultaneously during accumulation, titanium(IV)- and vanadium(V)-oxalates are reduced to their tri- and tetravalent states. The preconcentration of molybdenum(VI) was performed by adsorption and of ion-pairs of cetyltrimethylammonium and Mo(VI)-oxalates at a potential of −0.4 V. Molybdenum(VI)-oxalate is reduced to a mixed-valence compound of Mo(VI) and (V). Linear dependence of current on concentration exists in the ranges of 10 to 250 µg l−1 for titanium, 5 to 200 µg l−1 for vanadium, and 5 to 500 µg l−1 for molybdenum, when applying a preconcentration time of 1 min. The limit of detection (calculated as 3σ) is 0.1 µg l−1 Ti, 0.07 µg l−1 V, and 0.04 µg l−1 Mo with a deposition time of 10 min. The method presented in this report shows that CTAB is a suitable agent for modification of CPEs giving good reproducibility of results.