National Repository of Grey Literature 28 records found  previous11 - 20next  jump to record: Search took 0.00 seconds. 
UV-photochemical generation of volatile species of tellurium and other transition metals
Jeníková, Eva ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee) ; Kanický, Viktor (referee)
This dissertation thesis is focused on UV-photochemical generation of volatile species of tellurium, ruthenium, rhenium and iridium coupled to methods of atomic spectrometry. In the first part, attention was paid to the optimization of parameters of UV-photochemical generation of volatile tellurium species and its application for speciation analysis of Te(IV) and Te(VI) in water samples. UV-photochemical generation was carried out in a UV-photoreactor, which consisted of a low-pressure mercury lamp wrapped with a polytetrafluoroethylene reaction coil that served as a reactor. Atomic absorption spectrometry with a continuum source of radiation and high resolution and atomization in a miniature diffusion flame were used to optimize the conditions of generation, which included the composition of the reaction medium, irradiation time and the addition of transition metals as modifiers. In order to achieve a higher sensitivity of determination, the generator was coupled to a triple quadrupole inductively coupled plasma mass spectrometer. Since efficient UV-photochemical generation of volatile species was achieved only from Te(IV), with no response from Te(VI), the feasibility of this technique for simple "non-chromatographic" speciation analysis was tested and a method for determination of Te(IV) and...
Determination of selected heavy metals in samples of great tits feathers by inductively coupled plasma mass spectrometry
Adamová, Simona ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
EN As a result of human activity, a number of polluting substances are released into the environment. Heavy metals are one of the types of these contaminants. Their accumulation in the environment can have a negative impact on living organisms, including humans. For this reason, environment quality monitoring has become an important activity. Great tit (Parus major) can be a suitable bioindicator of the level of environmental contamination by heavy metals, which is acceptable mainly due to its abundance and occurrence in the vicinity of human settlements. This diploma thesis deals with the determination of six selected heavy metals in feather samples of these songbirds from several parts of the Czech Republic and other European countries. High pressure microwave mineralization in the presence of acids was used to prepare the samples. Selected heavy metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) technique, which is also suitable for ultratrace analysis due its very low limits of detection.
Determination of lead and zinc in great tits blood
Greguš, Viktor ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
EN Determination of heavy metals in urban living passerine birds organism has been considered as suitable method for monitoring pollution of human enviroment which these elements can cause. This study deals with determination of zinc and lead in dried great tits blood samples using inductively coupled plasma-mass spectrometry technique. Dried blood samples were weighed, solubilized in nitric acid and hydrogen peroxide and microwavelly digested. Calibration standards for determined elements were prepared and basic analytical characteristics of the measurement were determined. Matrix interference was examined by measuring the recovery of element determination presented as a ratio of the slope of standard addition to the certified reference material of whole blood sample and the slope of external calibration.
Crystal chemistry of micas from České středohoří
Goll, Jan ; Skála, Roman (advisor) ; Ulrych, Jaromír (referee)
Six methods have been used to study micas from České středohoří mts.: X-ray difractometry (transmission and reflection), ICP MS, electron microprobe, Mössbauer spectroscopy and termogravimetry. The measurements of trace elements and REE's revealed very low tendency by normalization on chondrite reservoir and primitive mantle. Micas show high contents of TiO2 (9,47 wt.%) and BaO (up to 2,1 wt.%) in separated grains from rock. The micas classifications were determined by Tischendorf (2007) and Rieder (1998) as Fe-phlogopites. X-ray powder diffraction revealed cell dimensions and a common polytype 1M with space group C2/m. By Mössbauer spectroscopy have been studied the rates of Fe2+ /Fe3+ and they were 1,08 - 1,86 (except rock sample, which were 9:1). Termogravimetrical measurement until 1450řC revealed weight jump from 1120řC to 1270řC.
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...
Determination of lead and zinc in great tits blood
Greguš, Viktor ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
EN Determination of heavy metals in urban living passerine birds organism has been considered as suitable method for monitoring pollution of human enviroment which these elements can cause. This study deals with determination of zinc and lead in dried great tits blood samples using inductively coupled plasma-mass spectrometry technique. Dried blood samples were weighed, solubilized in nitric acid and hydrogen peroxide and microwavelly digested. Calibration standards for determined elements were prepared and basic analytical characteristics of the measurement were determined. Matrix interference was examined by measuring the recovery of element determination presented as a ratio of the slope of standard addition to the certified reference material of whole blood sample and the slope of external calibration.
Analysis of unstable complexes for study of enzymatic methylation of arsenic
Albrecht, Michal ; Petry-Podgórska, Inga (advisor) ; Červený, Václav (referee)
The main aim of this thesis was the development of conjugation of existing methods for analysis of arsenic-glutathione complexes (As-GS complexes) together with simple arsenic species (iAs, MMAs, DMAs) during simple run. The basic technique for analysis of As-GS complexes was the HPLC-ICP-MS method with a reverse phase separation column (C18). The separation problem of simple species has been overcome by extending of system by postcolumn hydride generation with cryotrapping system (HG-CT). The resulting HPLC/HG-CT-ICP-MS system provides a complex analysis of all the above-mentioned analytes. According to the currently available resources, it is an innovative system, where for the first time all the simple arsenic species (iAs, MMAs, DMAs) and the As-GS complexes were separated. Under the given conditions, the detection limit for the As-GS complexes of 1.9 pg cm-3 in the RP-HPLC-ICP-MS system (a quantification limit of 6.5 pg cm-3 ) was achieved at a sensitivity of 468 CPS s pg-1 . The HG-CT-ICP-MS system provided a detection limit for iAs of 1.2 pg cm-3 at a sensitivity of 1121 CPS s pg-1 , for MMAs of 0.043 pg cm-3 at a sensitivity of 895 CPS s pg-1 and for DMAs of 0.076 pg.cm-3 at a sensitivity of 926 CPS s pg-1 . This method was applied to achieve another aim, studying the pathways of enzymatic...
Preconcentration of hydride forming elements in quartz trap in connection with ICP-MS
Kašpar, Miroslav ; Matoušek, Tomáš (advisor) ; Rychlovský, Petr (referee)
Charles Uviversity in Prague Faculty of Science Department of Analytical Chemistry Student: Miroslav Kašpar Supervisor: RNDr. Tomáš Matoušek, Ph.D. Name of Thesis: Preconcentration of hydride forming elements in quartz trap with ICP-MS detection The aim of this thesis are pilot experiments employing quartz trap (QT) for preconcentration of hydride forming elements and their subsequent detection by inductively coupled plasma mass spectrometry (HG-QT-ICP-MS). Arsenic and antimony were chosen as model analytes. Preconcentration efficiency on quartz surface was studied in a trap, which was integrated into an interface between spray chamber and plasma torch. We have identified a critical loss of analyte during transportation, instability of the plasma due to sudden change of gas composition, poor repeatability and very quick release of Sb from the trap resulting in difficult quantification of Sb signal. Despite the efforts to resolve these experimental problems, so far we were unable to achieve improvements in analytical parameters compared to standard analytical methods. Keywords: Preconcentration, quartz trap, mass spectrometry with inductively coupled plasma, hydride generation, arsenic, antimony

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