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HG-AAS with atomization in a dielectric barrier plasma discharge: method optimization and analytical applications
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
The aim of this diploma thesis was to optimize in detail atomization conditions for antimony hydride in a novel plasma atomizer based on a dielectric barrier discharge (DBD) with atomic absorption spetrometric detection. Argon was found as the best DBD discharge gas employing a flow rate of 50 ml min-1 Ar while the DBD power was optimized at 30 W. Analytical figures of merit including interference study of As, Se and Bi have been subsequently investigated and the results compared to those found in an externally heated quartz tube atomizer (QTA). The limit of detection reached in DBD (0.15 ng ml-1 Sb) is comparable to that observed in QTA (0.14 ng ml-1 Sb). Finally, possibility of stibane preconcentration in a DBD atomizer was studied. Preconcentration efficiency of 102 ± 6 % was found under optimized conditions.
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A novel AAS atomizer based on a dielectric barrier plasma discharge
Novák, Petr ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
Atomization of arsine in a novel hydride atomizer for atomic absorption spectrometry (HG-AAS) was thoroughly optimized. This plasma atomizer is based on a dielectric barrier discharge (DBD). Sensitivity and detection limit reached 0.48 s ng-1 As and 0.16 ng ml-1 As, respectively, under optimum atomization conditions (Ar discharge using a flow rate of 60 ml min-1 Ar, DBD power 17 W). Analytical figures of merit reached in DBD are comparable to those found in an externally heated quartz tube multiatomizer (MMQTA) that was chosen as a model of conventional approach to hydride atomization in HG-AAS. An extent of interferences (Se, Sb, Bi) during As determination was investigated comparing both MMQTA and DBD atomizers. The later one was found to be more resistant towards interferences. A simple preconcentration of As in a DBD atomizer was reached after oxygen introduction into the Ar plasma in the DBD resulting in analyte retention in the atomizer followed by its volatilization once the oxygen flow is switched off. Preconcentration efficiency of 100 % was reached and detection limit improvement by a factor of ten was achieved (0.01 ng ml-1 As, preconcentration period 300 s).
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Mineralogical analysis of historical paintings
Čermáková, Zdeňka ; Hradil, David (advisor) ; Kanický, Viktor (referee) ; Artioli, Gilberto (referee)
Historical painted works of art have a very complex inner structure. The period painting technique led to the execution of a ground layer followed by several layers of underpainting and a top paint layer, over which a layer of glaze has been applied to increase the resistance to external wear. Each of these colour layers is composed of a dye or a pigment (or their mixture) bound by organic binder. Throughout the history, pigments were commonly prepared from minerals, either extracted from natural deposits or created artificially. In these heterogeneous layers containing both inorganic and organic components, undesirable degradation changes either driven by processes taking place directly in the colour layer or influenced by external agents may occur. Mineralogical approach, which focuses primarily on the structure of studied pigments, helps in the clarification of the occurring processes, in the determination of conditions leading to degradation as well as in the identification of original/degradation phases. Furthermore, it can be profitably applied in the micro- analysis of mineral pigments present in tiny micro-samples obtained from works of art, contributes to the artwork's provenance/authorship studies and the determination of regional provenance of the employed mineral pigments. This Ph.D....
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Elemental and isotopic study of differentiated meteorites and implications for the origin and evolution of their parent bodies
Halodová, Patricie ; Košler, Jan (advisor) ; Řanda, Zdeněk (referee) ; Kanický, Viktor (referee)
ELEMENTAL AND ISOTOPIC STUDY OF DIFFERENTIATED METEORITES AND IMPLICATIONS FOR THE ORIGIN AND EVOLUTION OF THEIR PARENT BODIES Iron meteorites are differentiated meteorites composed largely of Fe-Ni alloys. The metallic phase of many iron meteorites shows a texture called the Widmanstätten pattern, which develops as a two-phase intergrowth of kamacite (α-bcc, ferrite) and taenite (γ-fcc, austenite), and forms by nucleation and growth of kamacite from taenite during slow cooling of the parent body. Selected iron meteorites - octahedrites of different structural and chemical groups (Canyon Diablo, Toluca, Bohumilitz, Horh Uul, Alt Biela, Nelson County, Gibeon and Joe Wright Mountain) were studied with intention to evaluate the scale and extent of Fe isotopic heterogeneities in iron meteorites and to find the possible link between the isotopic variations and thermal histories of the respective meteorite parent bodies. The Fe isotopic compositions of kamacite and taenite in the studied meteorites, obtained by three independent analytical techniques with different spatial resolution capabilities (laser ablation and solution MC ICP-MS and SIMS) show significant variations of up to ~4.5‰ in δ56 Fe. The taenite is isotopically heavier compared to kamacite in all studied meteorites. There is no correlation...
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Contributions to Volatile Compound Generation of Arsenic, Silver and Gold by Tetrahydroborate Reaction for Atomic Absorption Spectrometry
Musil, Stanislav ; Rychlovský, Petr (advisor) ; Kanický, Viktor (referee) ; Spěváčková, Věra (referee)
(EN) The presented dissertation thesis summarizes the results contained in five original research papers that were published in prestigious international scientific journals in the field of analytical chemistry and atomic spectrometry. It is devoted to the method of generation of volatile compounds using a tetrahydroborate reaction and detection in a quartz multiatomizer by atomic absorption spectrometry. The thesis can be divided into two thematic parts - speciation analysis of arsenic based on hydride generation technique with collection and separation in a cryogenic trap and generation of volatile species of transition metals. In the first thematic part pre-reduction of pentavalent inorganic and methylated arsenicals has been studied. A simple setup for on-line pre-reduction employing thioglycolic acid as a fast pre-reductant has been developed, connected with a current hydride generator and applied/verified to oxidation state specific arsenic speciation analysis of human urine samples. In the same method the possibility of drying the gaseous phase from water vapor has been investigated to avoid incidental blocking the cryogenic trap by frozen water and to decrease fluctuations of signal baseline. Pronounced losses of methylated species have been discovered on Nafion tube dryer currently used in...
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Use and limitations of laser ablation ICP-MS in geoscience applications
Míková, Jitka ; Košler, Jan (advisor) ; Kanický, Viktor (referee) ; Anczkiewicz, Robert (referee)
This dissertation contributes to applications of laser ablation plasma source mass spectrometry (LA ICP-MS) in Earth sciences. The primary goal of the thesis is to address some of the fundamental processes related to laser ablation of solid samples that result in decoupling of elements during laser ablation ICP-MS analysis. Better understanding of mechanisms that cause the elemental fractionation and matrix effects is necessary before the accuracy and precision of laser ablation ICP-MS analyses can be improved. The chemical and phase compositions of particles produced by laser ablation (266 nm Nd:YAG) of silicate NIST glasses and zircon were studied by SIMS and HR-TEM techniques with a particular focus on Pb/U fractionation. This is of great importance in geology as the Pb/U elemental fractionation hampered the precision and accuracy of the measured accessory mineral ages. The data suggest that chemical composition and mineralogy of particles produced at the ablation site during laser ablation differs from the original sample and varies with their size. This can result in elemental fractionation (non-stochiometric sampling) in material delivered to the ICP-MS for quantitative analysis. Evidence of the element fractionation is preserved in chemically zoned ejecta deposited around the ablation pit....
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Formulation the Methodology for Analysis the Seismic Response of the Piping Systems with Viscose Dampers
Chlud, Michal ; Salajka, Vlastislav (referee) ; Kanický, Viktor (referee) ; Malenovský, Eduard (advisor)
Viscous dampers are widely used to ensure seismic resistance of pipelines and equipment in nuclear power plants. Damping characteristics of these dampers are nonlinearly frequency dependent and thus causing complications in computational modelling of seismic response. Engineers commonly use two ways to deal with this nonlinearity: The first option is to consider damper by means of “snubber”. This is essentially linear spring element that is active for dynamic load and does not resist static loads. Snubber behaviour during seismic event is described by a equivalent stiffness (sometimes called pseudostiffness). The equivalent stiffness could be defined by the iterative calculations of piping natural frequencies and mode shapes taking into account seismic excitation. However, in complicated structures such as the main circulation loop of nuclear power plant the iterative calculation is difficult and could bring significant inaccuracies. On the other hand, the benefit of such modelling is a possibility to apply the commonly used linear response spectrum method for a solution. The second option is to describe damping characteristics using suitable rheological model. The seismic response is than determined by direct integration of the equations of motion. The behaviour of dampers is described exactly enough but the calculation and post-processing, especially nodal stresses time-histories, are time consuming. The goal of this work was to find a methodology for determining the seismic response of complex pipe systems with viscous dampers. Methodology allows a sufficiently accurate determination of the seismic response of piping systems and also allows obtaining of the results in effective time. The procedure is as follows. Firstly, specialized piping program (AutoPIPE) is used for the development of computational model. Next step is to determine a static response of structure and its verification with experimental measurements, if possible. Using script in Python language a computational model is converted from AutoPIPE into general finite element model in ANSYS system. Four-parameter Maxwell rheological model is used to describe behaviour of viscous dampers. Seismic load is represented by synthetic accelerograms. Newmark algorithm of direct integration of the equation of motion is used to obtain seismic response (only reactions and displacements in nodes of interest are necessary). Than is the equivalent stiffness is than gained from displacements and reactions as median value of their ratios. Received stiffness are subsequently transferred to AutoPIPE program where the seismic solution is performed using response spectra method. Finally, the dynamic response is combined with the static response and stress assessment according standards is done. The created methodology was applied in the seismic resistance calculation of the main circulation piping and piping of pressurizer in nuclear power plants type VVER 440 and type VVER 1000.
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Preconcentration Techniques for Determination of Uranium Using the Modified Sorbents.
Moos, Martin ; Řehůřková, Irena (referee) ; Kanický, Viktor (referee) ; Kráčmar, Stanislav (referee) ; Sommer, Lumír (advisor)
The work has been focused on the preconcentration techniques for determination of uranium on the modified sorbent, with the final use of ICP-OES and ICP-MS. First ICP-OES at a wavelength of 385.958 nm was used for determination of uranium. Parameters were optimized and the effect of mineral acids (HCl, HNO3), tensides (Septonex, Ajatin) and organic reagents like (4-(2-pyridylazo)resorcinol, ammonium pyrrolidinedithiocarbamate, 8-hydroxyquinoline-5-sulphonic acid and 1,2-dihydroxyanthraquinone-3-sulphonic acid) was observed. For ICP-MS an isotope 238U was chosen. As an internal standard 209Bi (200 ?g•l-1) was used. Modified silica gel was used (Silicagel tethered with C18, C8 alkyls and phenyl) and two types of Amberlite XAD 4 and XAD 16 for the preconcentration of uranium (VI). Commercially produced Amberlite was modified as follows: Drying at 100 °C (24 hours), milled, minced sorbent was selected and fractionated to particles size ranging from 0.32 to 0.63 ?m and finally activated in methanol. The deionised water and Septonex (5•10-3 mol•l-1) at pH 8 were used for Amberlite conditioning. The optimal sorption of uranium (VI) proceeded at pH 8 in the presence of 4-(2-pyridylazo)resorcinol or ammonium pyrrolidinedithiocarbamate with Amberlite XAD-16 moreover with 1,2-dihydroxyanthraquinone-3-sulphonic acid. All organic reagents have mass concentration five time larger than uranium . For the elution of uranium the mixture of 1 mol•l-1 HNO3 with acetone (ratio of 1:1) was used. Acetone was evaporated and the final analysis performed using ICP-OES. The preconcentration of uranium (VI) using Silicagel-C18 conditioning was performed with ethanol, deionised water and Zephyraminu (5•10-4 mol•l-1) at pH 8. For the Silica-C8 and Silicagel-Phenyl the same conditioning procedure without zephyramin was used. Silica-C18 had the highest sorption efficiency with 1,2-dihydroxyanthraquinone-3-sulphonic acid, Silicagel-C8 with ammonium pyrrolidinedithiocarbamate and Silicagel-Phenyl with 8-hydroxyquinoline-5-sulfonic acid, all organic reagents have mass concentration five time larger than uranium concentration. As an optimal elution mixture acetone and ethanol (ratio of 1:1) in the presence of 1 mol•l-1 HCl was evaluated. Acetone and ethanol was evaporated and the final analysis was performed using ICP-MS. Silicagel-C18 was evaluate as the most effective in the presence of zephyramin and 1,2-dihydroxyanthraquinone-3-sulphonic acid. Sorption was also tested in the presence of 20 ?g•l-1 microelements (Be, V, Co, Ni, Y, Pb, Th, Cd) and in the presence of a defined concentrations of K, Na, Ca, Mg, Al and Fe. Direct analysis of uranium was carried out on samples of water from the river Ploucnice and Turonian aquifers containing uranium, 3,5 and 19,3 ?g•l-1. Different type of water required preconcentration of uranium (VI) on Silica-C18 in the presence of 1,2-dihydroxyanthraquinone-3-sulphonic acid and zephyramin. The analysis results gave statistically satisfactory results, which were confirmed using standard addition of 20 ?g•l-1.
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Multicomponental Preconcentration of As, Sb, Se and Te on Modified Silica, Their Determination by ICP-AES (ICP-MS) and Application for Waters
Urbánková, Kristýna ; Řehůřková, Irena (referee) ; Kanický, Viktor (referee) ; Ventura, Karel (referee) ; Sommer, Lumír (advisor)
The determination of inorganic speciations of arsenic, antimony, selenium and tellurium in natural waters demands often separation and preconcentration. Solid phase extraction is a very effective method for these purposes. In this paper the separation and preconcentration of these microelements is realised on the basis of modified silica Separon SGX C18, SGX C8, SGX CN, SGX NH2, SGX Phenyl and strongly basic anion Exchanger SGX AX. The sorption was provided in the presence of cationic surfactants such as benzyldimethyl dodecylammonium bromide (Ajatin), benzyldimethyltetradecylammonium chloride (Zephyramine), 1-ethoxycarbonylpentadecyltrimetrhylammonium bromide (Septonex) and selected complexing agents 4-(2-pyridylazo)resorcinol (PAR), 8-hydroxyquinoline-5-sulphonic acide (8-HQS), 1,2-dihydroxybenzene (PYR), amonium 1-pyrrolidinecarbodithioate (APDC), sodium diethyldithiocarbamate (DTC) or thiourea(Thur). The interactions of the formed ion associate with the sorbent shows a complicated character which has not been cleared as yet. The previous conditioning of the sorbent plays an outstanding role. Thus, the sorption efficiency was studied in the presence and absence of surfactant and of selected organic complexing agents. Moreover, the influence of pH of the sorbed solution as well as the speed and the volume of the solution running through the sorbent and the type and volume of the eluent on the resulting sorption efficiency was evaluated. The sorption was successfully carried out from 50-1000 ml of solution which allows the 100 fold increase of the preconcentration factor and the determination of the microelements in g.l-1 instead of mg.l-1 by using the common ICP-AES. The influence of macroelements occurring in waters as well as B, Be, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sr, Ti, V and Zn in comparable concentrations involve less than 5% error. After the quantitative elution of microelements, the organic solvents were evaporated under IR lamps prior to the determination by ICP-AES and |ICP-MS. The conditions for the direct determination of arsenic, antimony, selenium and tellurium in g.l-1 with ICP-MS were also described in detail in the absence and presence of internal standards Ge and Bi. However, even in this case the preconcentration on silica in the presence of surfactant and selected organic complexants was also tested. When the sorption was followed from 500 ml a 50 fold enrichment factor is reached and the sensitivity for the microelements is improved. The direct determination and the sorption of microelements were applied on synthetic and real waters (dirinking, surface, mineral and sea waters). Instrumental and practical detection limits for various water samples were evaluated according to IUPAC. The results from 1000 ml solution of real waters after sorption on modified silica and the final determination of microelements with ICP-AES were compared with those from ICP-MS without sorption using the method of standards addition in the presence of suitable internal standards. By comparison of results for synthetic and real water samples the error of the determination of microelements was evaluated.
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Dynamic analysis of an in-line arranged cylindrical chimney
Harazim, Petr ; Kanický, Viktor (referee) ; Salajka, Vlastislav (advisor)
The diploma thesis deals with the response of a steel smokestack structure to wind loads. A detailed computational model implementing the finite element method was created in accordance with the available drawing documentation. The new smokestack was placed next to an existing one, thus it can be assumed that these two structures will affect each other. The thesis also elaborates on the problems of aerodynamic and aeroelastic stability of the earlier smokestack; in particular, the occurrence of vortex shedding in resonance with eigenfrequency of the structure, with the use of the program ANSYS CFX. The evaluation of the structure includes survey of the strength and deflections of the structure. The calculations are in accordance with valid ČSN EN norms.
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