Digitální knihovnaUPCE
 

20 (2014) Scientific papers, Series A

Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/75412

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201422

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Nyní se zobrazuje 1 - 10 z 22
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Determination of trinitrotoluene at ex-situ prepared bismuth film electrode: An initial study
    (University of Pardubice, 2014) Sopha, Hanna; Švancara, Ivan
    A bismuth film electrode prepared ex-situ on a glassy carbon powder substrate (BiF-GCPE) was applied to the determination of trinitrotoluene (TNT) in combination with square-wave adsorptive stripping voltammetry. The electroanalytical performance of the BiF-GCPE was studied in Britton-Robinson buffers in the range of pH 4-9, revealing the most favourable stripping signals in mild alkaline solutions (pH 9.0). For calibration, linear responses could be obtained in the concentration range of 0.5-5.0 ppm TNT, when using a deposition time of 60 s (R2 = 0.9999), and within 0.1-1.5 ppm TNT after deposition for 120 s (R2 = 0.9983). The LOD (3F) was estimated to be about 7 ppb (for deposition time of 240 s), and the BiF-GCPE exhibited a very good repeatability (RSD = ±2.3 %; n = 10, ci = 0.5 ppm). Finally, possible determination of TNT in the presence of nitrobenzene was also shown.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Lipidomic analysis of porcine organs using hydrophilic interaction liquid chromatography and mass spectroscopy
    (University of Pardubice, 2014) Cífková, Eva; Holčapek, Michal; Lísa, Miroslav
    The identification and quantitation of all lipids in complex biological tissues is the first step towards the understanding how lipids function in a biological system and the elucidation of the mechanism of lipid-related diseases including obesity, atherosclerosis, cancer, cardiovascular diseases, etc. Our optimized nontargeted method using hydrophilic interaction liquid chromatography (HILIC) coupled to electrospray ionization mass spectrometry (ESI-MS) was used for the characterization of the lipidome, mainly glycerophospholipids and sphingolipids in porcine brain, heart, kidney, liver, lung, spinal cord, spleen and stomach. Individual lipid classes are quantified based on the peak integration of individual lipid classes separated in the HILIC mode multiplied by their response factors and correlated by sphingosylethanolamine (d17:1/12:0) as a single internal standard. Subsequently, relative abundances of deprotonated molecules [M-H]– in negativeion ESI mass spectra are used for determination of lipid species concentration inside individual classes. The approach using [M-H]– ions enables to obtain detailed information about phosphatidylethanolamines and their different forms of fatty acyl linkage on the glycerol skeleton (plasmalogens and ether analogs), phosphatidylinositols and hexosylceramides in studied organs. Our results provide important knowledge about lipid representations in vital porcine organs and can be applied for future metabolic studies on human to investigate serious lipid-related human disorders.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Utilization of hydrosilated silica-based stationary phases for separation of antioxidants
    (University of Pardubice, 2014) Soukup, Jan; Janás, Petr; Jandera, Pavel
    We studied the influence of mobile phase composition on the retention of phenolic acids and flavonoid compounds on five different hydrosilated silica-based stationary phases in buffered aqueous acetonitrile. Cogent UDC cholesterolTM, Cogent bidentate C18TM and Cogent Phenyl hydrideTM columns show significant dual reversed-phase/normal-phase retention behaviour, while Cogent Diamond hydrideTM and Cogent Silica-CTM columns provide very low retention in the reversed-phase mode. The effect of the aqueous acetate buffer concentration on retention factors of phenolic acids and flavonoid compounds over the full mobile phase composition range, including both aqueous normal-phase (ANP) and reversed-phase (RP) mechanisms, can be described by a four-parameter equation for dual-retention mechanism. At increasing temperature, the retention factors and peak widths decrease in the aqueous normal-phase range. In agreement with van’t Hoff model, linear ln k versus 1/T plots were observed, showing a single retention mechanism. From among the stationary phases tested, Cogent UDC cholesterolTM column has high temperature stability (up to 100 °C) and provides the most selective and efficient separations of flavones in the ANP mode and Cogent Diamond hydrideTM is the most selective and effective for separation of phenolic acids.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Modification reactions applicable to polymeric monolithic columns. A review
    (University of Pardubice, 2014) Currivan, Sinéad; Jandera, Pavel
    Organic monolithic columns can be prepared from co-polymerizations of functional monomer and a cross-linker, resulting in a desired surface functionality. They can also be prepared to form a generic polymer monolith, in which the functionality can be altered by using a number of post-polymerization modifications. The reactions used to convert surface functionality include reaction chemistry, thermal or photo-initiated polymerization reactions, or the addition of nano-architectures, such as nano-particles or nano-tubes. This review article aims to highlight the available options in the modification of polymeric monolithic columns prepared by thermal or UV initiated polymerizations.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Relative quantitation of phosphatidylcholines with interfered masses of protonated and sodiated molecules by matrix-assisted laser desorption/ionization mass spectroscopy
    (University of Pardubice, 2014) Chagovets, Vitaliy; Holčapek, Michal; Lísa, Miroslav
    This work presents a computational method for deconvolution of interfered peaks of protonated and sodiated phosphatidylcholines (PCs) to solve the problem of relative quantitation of these PCs. The method is based on the fact that adducts of PCs with proton and sodium ion give unique characteristic peaks in tandem mass spectra. The intensities of these peaks were used to find out contribution of protonated and sodiated PCs to the formation of interfered peak in full-scan mass spectrum and, further, to correlate peak intensities that correspond to PCs in fullscan mass spectrum with PC’s concentrations. The model was calibrated on synthesized PCs and verified for applicability in the range of Na+ ion concentrations from trace to physiological one.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Carbon paste ion-selective electrode for ion-pair formation-based potentiometric titrations of anionic surfactants
    (University of Pardubice, 2014) Mikysek, Tomáš; Vytřas, Karel
    In this contribution, a new carbon paste ion-selective electrode was introduced for ion-pair formation-based potentiometric titrations of anionic surfactants. In the electrode, an extract of hexadecylpyridinium dodecylsulfate in o-nitrophenyl octyl ether was used as both the binder and the electroactive ion-exchanger. Concerning titrants, three cationic compounds were examined: hexadecylpyridinium chloride (CPC), (diisobutylphenoxyethoxyethyl)-dimethyl-benzylammonium chloride (Hyamine 1622, HYA) and 1,3-didecyl-2-methylimid-azolium chloride (Tegotrant A100, TGT). The last one gave potentiometric titration curves with the highest potential breaks (210-260 mV), followed with CPC (90-140 mV) and HYA (40-60 mV). Despite this, the practical use of TGT in control laboratories should economically be considered impossible for its too high price on market. According to the authors’ meaning, the use of CPC as a titrant seems to be the best compromise as the steepness of the corresponding titration breaks is sufficient and its price is acceptable as well.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Sensitive voltammetric method for determination of chemotherapeutic drug methotrexate using liquid mercury free silver solid amalgam electrode
    (University of Pardubice, 2014) Bandžuchová, Lenka; Šelešovská, Renáta; Chýlková, Jaromíra
    Voltammetric behaviour of a wide-spread used chemotherapeutic drug methotrexate (MTX) was investigated on a polished silver solid amalgam electrode (p-AgSAE) employing various voltammetric methods like cyclic voltammetry, direct current voltammetry and differential pulse voltammetry. It was found that MTX provided two reduction and one oxidation peak in an acidic medium, and the positively situated reduction signal (Ep = –340 mV), due its favorable analytical properties, was studied more in detail. 0.05 mol l–1 acetate buffer of pH 5 was selected as an optimum medium for monitoring of the MTX reduction on p-AgSAE. Operating parameters of differential pulse voltammetry were optimized and proposed voltammetric method provided high repeatability (relative standard deviation of 11 repeated measurements at concentration level of methotrexate of 1×10–7 mol l–1 equaled to 1.7 %), linear concentration range from 5×10–10 to 3×10–6 mol l–1 and low limit of detection (LD = 1.5×10–10 mol l–1). The applicability of proposed method was verified by analysis of real sample of chemotherapeutic preparation.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Quality evaluation of monoclonal antibodies suitable for immunomagnetic purification of native tau protein
    (University of Pardubice, 2014) Jankovičová, Barbora; Hromádková, Lenka; Kupčík, Rudolf; Kašparová, Jitka; Řípová, Daniela; Bílková, Zuzana
    Tau protein plays a crucial role in the neuronal cytoskeleton stabilization. Under the pathological conditions, it can be abnormally phosphorylated which leads to the aggregation and formation of neurofibrillary tangles representing pathological hallmark of Alzheimer’s disease (AD). For its association with neurodegenerative diseases, tau protein is intensively studied in various diagnostic and therapeutic applications. Since there is no standard of tau protein involving essential post-translational modifications, it is often necessary to purify it directly from cerebrospinal fluid (CSF) or blood of healthy or AD clinical signs exhibiting organism. The immunomagnetic purification based on the isolation of the target protein using a specific antibody bound to a magnetic carrier is the most effective tool for this purpose. High quality antibodies are the main prerequisite of successful purification, but many commercial antibodies do not comply with the challenging requirements for the immunosorbent preparation. In this work, we compared four different anti-tau monoclonal antibodies currently available on the market (clones HT7, BT2, 8F10, 7E5). The evaluation criteria were set along the intended use for the preparation of specific magnetic immunosorbent subsequently applicable for the native tau protein purification. We evaluated the characteristics declared by producers as specificity, purity and homogeneity. We also tested the binding affinity and IgG stability during the covalent immobilization to the surface of magnetic microparticles and during the immunoprecipitation of intact tau protein or tryptic tau fragments. The results are summarized and discussed here.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Study of compositional changes of (Ag-)Sb-S thin films after Ar+ ion laser irradiation by means of micro X-ray fluorescence
    (University of Pardubice, 2014) Gutwirth, Jan; Bezdička, Petr; Wágner, Tomáš; Frumar, Miloslav
    Thin amorphous films from (Ag-)Sb-S system were prepared as potential candidates for new phase-change memory films. Amorphous (Ag-)Sb-S thin films were deposited by thermal evaporation (TE) of Sb33S67 bulk sample followed by optically induced diffusion and dissolution (OIDD) of thermally evaporated Ag thin films. The phase-change recording process was realized via photocrystallization experiments done by Ar+ ion dot laser exposures of prepared films. Morphology of the laser exposed dots was observed by transmission optical microscopy while micro X-ray diffraction (:-XRD) was utilized for determination of crystallinity of the exposed dots. Laser induced changes were quantified by local measurement of optical transmission in dependence on laser exposure time. Compositional changes are determined via micro-X-Ray Fluorescence (:-XRF). The results prove crystallization of laser exposed thin film. Kinetic of this process is described in terms of transmittance change, evolution of X-Ray diffractograms and changes observable by optical microscopy. Moreover, the results do not indicate any significant chemical change in the case of stoichiometric Sb2S3 after laser irradiation while certain migration of silver takes place in sulfur rich Sb-S films doped by Ag.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Ball milling: A top down facile approach to synthesize AgInSe2 nanostructures
    (University of Pardubice, 2014) Pathak, Dinesh; Wágner, Tomáš; Šubrt, Jan; KupčíK, Jaroslav
    A quantum dot solar cell is an emerging field in solar cell research that uses quantum dots as the photovoltaic material. Quantum dots have band gaps that are tunable across a wide range of energy levels by changing the quantum dot size. The embedment of different sized dots within absorbing layer encourages harnessing of the maximum spectrum energy. Also other effects like very high surface to volume ratio, Quantum Transport make them attractive for future devices. For an attempt of AIS quantum dots (QDs), AIS nanoparticles with tetragonally distorted phase were prepared by mechanically alloying the synthesized bulk AIS powder at room temperature in a planetary ball mill under Ar. Nanoparticles are formed with range -10 nm in size. These ball-milled nanoparticles contain different shapes, and the Rietveld analysis of X-ray powder diffraction data reveals their detailed structural features. High resolution transmission electron microscope (HRTEM) images also detect the presence of the tetragonal phase in ball-milled samples. Peak Broadening (FWHM), which is the main characteristics of decrease in size, is observed. XRD data reveals the downscaling of crystallite from 103 nm to 7 nm, also tetragonally distorted structure of the system was not disturbed by milling. The DSC study also reveals the phase evolution and crystallization kinetics. Bulk samples show endo melting peak at 134 °C and 220 °C. Cooling-crystallization complexity of the peak/peaks signifies crystallization from melt was heterogeneous nucleation and crystallization from multiple types of centers. Unlike this, milled samples show two crystallization effects at approx. 135 °C and 380 °C. Optical properties were investigated to find band edges, and suggest it around 1.3 eV which is encouraging for photovoltaic applications.