|
|
Examination of caesium concentration trends in extracts from cement blocks simulating radioactive waste
Straka, Marek ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
Cement is widely used as a solidification material of low and intermediate level radioactive waste containing caesium before shallow land burial. The aim of this thesis was to extract caesium out of 17 cement samples with 6 different cement binder compositions, by extraction with deionized water, then determine the amount of caesium in the extracts and look for trends in the extract Cs concentrations with various extraction duration. Cement samples, with stable caesium nuclide, were used to simulate retention of caesium in immobilized radioactive waste. Ten extractions from each sample in total were made with time ranging from 2 to 1032 hours. Atomic absorption spectrometry with flame atomization, using acetylene as fuel and air as oxidant, was used for caesium determination. This method was optimized and the addition of KCl serving as ionization buffer for better results was explored and compared. Keywords Atomic absorption spectrometry, flame atomization, caesium, extraction,
|
|
|
Interferences in determination of antimony by electrochemical generation of volatile compounds and atomic fluorescence spectrometry
Kostúrová, Dominika ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
Antimony is a highly toxic element that enters the environment through natural processes and human activities as well. It is necessary to determine its ultra-trace amounts in various materials such as water, soil and biological samples. Due to the heterogeneity of sample matrices, the determination of antimony is problematic because of frequent interactions. The aim of this work was to investigate the effects of various interferents on the determination of antimony by electrochemical generation of volatile compounds and atomic fluorescence spectrometry. In total, 18 interference dependencies were measured in the determination of Sb(III) and Sb(V). The following ions were selected for the interference study: SO4 2- , Cl- , NO3 - , NO2 - , Fe3+ , Fe2+ , As3+ , Se4+ and Bi3+ . The As3+ ion had the most interesting course of all the interferents and could be used as a suitable additive to increase the sensitivity of antimony determination.
|
|
|
Development of HPLC separation of astaxanthin, β-carotene and lutein
Hrubcová, Kateřina ; Nováková, Eliška (advisor) ; Kozlík, Petr (referee)
This bachelor's thesis deals with the development of a method for the separation of carotenoid pigments, especially astaxanthin, β-carotene and lutein, produced by the microscopic green alga Tetracystis pulchra. The work compares published methods for the separation of carotenoid pigments and attempts to optimize a method suitable for the analysis of pigment extracts from Tetracystis pulchra cells. Optimized conditions for HPLC-DAD separation of carotenoid pigments were as follows: mobile phase A - ACN/MeOH/0,05M Tris-HCl buffer (pH = 8,0): 94/2/4, mobile phase B - MeOH/EtOAc: 68/32 under gradient elution, flow rate 0,25 ml min˗1 , column temperature 28 řC. The column used was Kinetex C18 (100 × 2,1 mm, 2,6 µm), injection volume was 20 µl and UV detection was performed at 470 nm. Total analysis time was 23 minutes. Key words: HPLC, astaxanthin, β-carotene, lutein
|
|
|
Photochemical vapor generation of rhenium with a detection by inductively coupled plasma mass spectrometry
Hašlová, Karolína ; Musil, Stanislav (advisor) ; Nováková, Eliška (referee)
This bachelor thesis deals with an optimization of the conditions of photochemical vapor generation of rhenium with detection by inductively coupled plasma mass spectrometry. Photochemical vapor generation was realized using an ultraviolet irradiation in a high-efficiency photochemical reactor with an inner reaction channel from a formic acid based medium in presence of reaction modifiers. Optimizations of parameters affecting the generation efficiency was implemented step by step - reaction medium flow rate (irradiation time), formic acid concentration, addition of acetic acid and reaction modifiers (transition metals) and carrier gas flow rate. The addition of an appropriate combination of reaction modifiers - cadmium(II) and iron(II) ions, had a key impact on photochemical generation of volatile species of Re and led to more than 40-fold increase in generation efficiency. A further (2-fold) increase in generation efficiency was achieved by wrapping the high-efficiency photochemical reactor with an aluminum foil, probably due to more efficient irradiation of the sample in the generator. The limit of detection and quantification were determined as 0.24 ng dm-3 and 0.80 ng dm-3 Re, respectively. The repeatability of the method 100 ng dm-3 Re was 4.8%. Key words photochemical vapor generation,...
|
|
|
Determination of selected metals in tea samples and bag materials
Hlávka, Jan ; Nováková, Eliška (advisor) ; Hraníček, Jakub (referee)
This bachelor thesis is dealing with determination of antimony in materials modern pyramid-shape tea bags. Possible presence of antimony in these materials, e.g. polyethylene terephthalate (PET) or mixed materials, is caused by using it like catalyst in production of polyethylene terphthalete. The goal of this bachelor thesis is the verification of hypothesis, that antimony is present in materials of pyramide tea bags and that it is released to consumed drink, if higher concentration of antimony is present, and that it could pose a health risk to the consumer. At the same time, I studied if tea leaves are contaminated by other toxic elements, from which some can result from intesive agricultural production. They can be used as pesticides or be presnet in industrial fertilizers. In this thesis I examined the content of As, Cd, Cu, Sb and Zn in tea leaves sold in pyramide bags. These pyramide bags were purchased in local supermarkets and shops. The content of Sb in bags was determined too. The applied method included the decomposition of samples in a microwave decomposition device and analysis of the composition of the resulting solution by the ICP-MS method. Determined contents of the investigated elements were expressed like content of element in the sample in dry mass and the results were compared...
|
|
|
Generation of zinc volatile species for determination by atomic spectrometry
Dlouhá, Kateřina ; Nováková, Eliška (advisor) ; Kratzer, Jan (referee)
This diploma thesis deals with the determination of zinc by volatile species generation with detection by atomic absorption or fluorescence spectrometry. Volatile zinc species are generated using hydrochloric acid and sodium borohydride stabilized with sodium hydroxide. Conditions influencing the generation and atomization of volatile species were optimized, namely hydrochloric acid concentration, sodium borohydride concentration, sodium hydroxide concentration, hydrochloric acid flow rate, sample loop volume, reaction coil volume, frit porosity in a gas-liquid separator, argon and hydrogen flow rates, and last, the temperature to which the quartz atomizer is heated. Under the optimal conditions, the detection limit of 33 μg·l−1 and the limit of determination of 110 μg·l−1 were reached. It was found that the addition of various reagents (especially 8-hydroxyquinoline) can increase the generation efficiency. With the addition of 1 % (m/V) 8-hydroxyquinoline to the standard/sample the limit of detection was 4 μg·l−1 and the limit of quantification was 12 μg·l−1 . Using an atomic fluorescence spectrophotometer as the detector, the standard reference material was analyzed and good match with the certified concentration value was found, the certified zinc concentration value in the reference material is...
|
|
|
Job satisfaction of teaching staff at primary and secondary schools in the Vysočina region
Nováková, Eliška ; Tureckiová, Michaela (advisor) ; Šafránková, Jana Marie (referee)
The diploma thesis deals with the job satisfaction of pedagogical employees working in elementary and high schools in the Vysočina Region. The main goal of the thesis is to ascertain how are the pedagogical employees in the elementary and high schools of the Vysočina District overall satisfied with individual aspects of the selected outside factors of job satisfaction. The next goal of the thesis is to compare job satisfaction of pedagogical employees in the individual aspects of the selected outside factors. In the theoretical part, the thesis is focused on the theories of job satisfactions and the relationship between job satisfaction and work performance. Furthermore, the thesis deals with selected outside factors, which influence job satisfaction. The investigation is carried out in the selected elementary and high schools in the Vysočina Region. To obtain the necessary data, a non-standardized questionnaire of job satisfaction was created, which was then filled in by 149 teachers of both elementary and high schools in the Vysočina Region. The statistical compilation of the data showed, that the teachers of the selected elementary and high schools of the Vysočina Region are satisfied in their job. On the other hand, the research confirmed differences in the degree of satisfaction based of the...
|
|
|
UV-photochemical generation of volatile compounds of selenium and tellurium
Nováková, Eliška
The presented thesis deals with UV-photochemical generation of volatile compounds of Se and Te from various species. The aim of the project was to expand the current state of knowledge by the application of photocatalytic reduction of higher oxidation states of Se and Te for the speciation analysis based on UV-photochemical generation of volatile compounds. The first step of the study was the assembly of the apparatus for the photocatalysed UV-photochemical generation of volatile compounds. The material of reactor and the whole experimental set-up were based on literature survey and previous research done in our research group. Experiments were directed towards finding the optimum conditions for generation of volatile compounds of selected model elements Se and Te. Se was studied as the element most commonly determined by the UV-photochemical generation of volatile compounds. Conversely, Te was selected as a model analyte representing elements forming less stable volatile compounds. The second part was the application of the optimised method of photocatalysed UV- photochemical generation of volatile Se compound to the determination of Se in water matrices, liquid certified reference materials and also samples of dietary supplements. TiO2/UV-photochemical generation was also successfully modified to...
|
|
|
The pragmatic competency of students of Japanese - speech act of refusal
Nováková, Eliška ; Kanasugi, Petra (advisor) ; Tirala, Martin (referee)
(in English): This thesis focuses on pragmatic competence of Czech students of Japanese, specifically on the speech act of refusal. The aim is to find out how students differ in comparison to native speakers of Japanese. Another aim is to compare Japanese students based on the length of their stay in Japan, their Japanese proficiency, and the textbook used at the beginner level. The theoretical part describes pragmatic competence, politeness theory, the speech act of refusal and its specifics in Japanese. The practical part focuses at the analysis of refusals from the Discourse Completion Task (DCT) using semantic formulas. Usage of these formulas by native speakers and student are then compared. Found differences from the native speakers are further examined among students according to Japanese proficiency, length of their stay in Japan and textbook used at the begginer level. Finally, the results are summarized.
|
|
| |
guest ::
RSS feed.