National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Hydride generation of tellurium for atomic absorption spectrometry
Bufková, Kateřina ; Musil, Stanislav (advisor) ; Matoušek, Tomáš (referee)
This master's thesis deals with optimization of conditions of chemical hydride generation of tellurium and conditions of its atomization, specifically in three types of atomizers - in a diffusion flame (DF), in a heated multiple microflame quartz tube atomizer (MMQTA) and in a dielectric barrier discharge (DBD) atomizer. Tellurium hydride was generated in a flow injection arrangement and a high-resolution continuum source atomic absorption spectrometer was used for detection. As hydride generation can be only done from tetravalent species of tellurium, at first a simple procedure of pre-reduction of hexavalent species of tellurium by heating a standard in hydrochloric acid at 6 mol dm-3 was verified. Further, conditions of chemical generation were optimized with a goal to achieve as high generation efficiency as possible, namely, concentration of hydrochloric acid and sodium tetrahydroborate, volume of the reaction coil and a flow rate of carrier gas. Subsequently, conditions of atomization of tellurium hydride were examined with chosen optimal generation conditions. In the case of DF, it was an amount of hydrogen in the flame, a total flow rate of gases and observation height. In the case of MMQTA, temperature of the atomizer, a flow rate of carrier gas and a flow rate of air or oxygen needed for...
Hydride generation in connection with inductively coupled plasma mass spectrometry
Matoušek, Tomáš
An overview describing technique of volatile hydride generation in connection with inductively coupled plasma mass spectrometry including speciation analysis.
Speciation analysis of As and Hg in biological material
Petry-Podgórska, Inga ; Matoušek, Tomáš ; Migašová, M. ; Zemanová, Veronika ; Pavlík, Milan ; Pavlíková, D. ; Kratzer, Jan
This work was focused on an analysis of arsenic in selected plants and mercury in hair. A combination of HPLC and ICP-MS was used for analysis of biological tissues extracts. The\nspeciation analysis of low molecular arsenic and mercury species like inorganic iAs3+ and iAs5+, methylarsenic and dimethylarsenic forms was carried out with hydride generation (HG)\ntechnique, arsenic peptides and inorganic mercury (iHg2+) and its methylated form (MHg+) - with reverse phase (RP) chromatography and detected by ICP-MS.
Determination of arsenic species in seafood reference materials by ICP-MS with hydride generation and cryotrapping
Pokorná, Nikola ; Matoušek, Tomáš (advisor) ; Červený, Václav (referee)
The aim of this work was to determine chemical species of arsenic in sea originating certified reference materials. Measurements were done using method of hydride generation. Hydrides were preconcentrated in liquid nitrogen cooled tube and detected using inductively coupled plasma mass spectrometry. During the testing of the method, mutual conversion of arsenic species was observed for inorganic arsenic, monomethyl arsenic and dimethylarsenic. Further study revealed that with presence of matrix and hydrogen peroxide, demethylation occured only in hydride generation phase, not during extraction. Dissociation of hydrogen peroxide in extracts was verified using catalase. End of the demethylation process was proved using measurement with addition of arsenic species standards. The newly invented procedure was used to determine arsenic species in reference materials with sufficient accuracy. Final results are compatible with results from different method, and already published results as well. Key words: speciation analysis, arsenic, hydride generation, seafood, inductively coupled plasma mass spectrometry
Fate of smelter dusts in temperate and semi-arid soils
Ettler, V. ; Jarošíková, A. ; Mihaljevič, M. ; Kříbek, B. ; Veselovský, F. ; Penížek, V. ; Vaněk, A. ; Šráček, O. ; Matoušek, Tomáš ; Mapani, B. ; Kamona, F. ; Nyambe, I.
Our results indicate that, compared to semi-arid areas (where inorganic contaminants are rather immobile in soils despite their high concentrations), a higher potential risk exists in smelter-affected humid areas, where metal(loid) contaminants can be easily released by extensive weathering of particulates in the soil systems.
Determination of Inorganic Arsenic in Samples of Marine Origin
Marschner, Karel ; Matoušek, Tomáš ; Dědina, Jiří ; Musil, Stanislav
A fast screening method for determination of inorganic arsenic in marine samples was developed. This method is based on selective\nhydride generationanddetectionby inductively coupled plasmamass spectrometry. Using a high concentration of hydrochloric acid\ntogether with hydrogen peroxide for hydride generation leads to selective conversion of inorganic arsenic species into arsane. The\naccuracy of this method was verified by comparative analyse by high performance liquid chromatography coupled with hydride generationandatomic\nfluorescence detection.
Hydride generation in connection with inductively coupled plasma mass spectrometry
Matoušek, Tomáš
An overview describing technique of volatile hydride generation in connection with inductively coupled plasma mass spectrometry.
Speciation analysis of inorganic arsenic in seafood material
Pokorná, Nikola ; Matoušek, Tomáš (advisor) ; Musil, Stanislav (referee)
This thesis was focused on extraction of individual arsenic species from reference materials of fish protein DORM-3 and DORM-4. Extracts were then analyzed by a hydride generation method with detection by inductively coupled plasma mass spectrometry. Materials were extracted in two ways - in a microwave device and in a heating block. It was found that extraction with 2% nitric acid is not efficient. Extraction performed in 2% nitric acid with addition of hydrogen peroxide at various concentrations increased the extraction yield, but it caused conversion of arsenic species. This conversion would mean the overestimation of inorganic arsenic content.

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