National Repository of Grey Literature 38 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Trapping of volatile cadmium species on gold surfaces for atomic absorption spectrometry
Sagapova, Linda ; Svoboda, Milan ; Matoušek, Tomáš ; Kratzer, Jan
Simple preconcentration step was developed for cadmium determination after chemical vapor generation prior to atomic absorption spectrometric detection. Chemical vapor generation of cadmium was performed in the presence of Cr3+/KCN as modifiers.
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...
Speciation analysis of arsenic-glutathione complexes by ion-pairing HPLC-ICP-MS
Zušťáková, Veronika ; Matoušek, Tomáš (advisor) ; Červený, Václav (referee)
The thesis has focused on the separation of arsenic-glutathione species using ion-pairing high performance liquid chromatography with detection by inductively coupled plasma mass spectrometry. Species were separated on chromatographic column Prodigy ODS (3) using an aqueous mobile phase containing 4.7mM tetrabutylammonium hydroxide (TBAH), 2mM malonic acid and 4% methanol at pH 5.85 in the isocratic mode. Simple arsenic species - arsenite (iAsIII), arsenate (iAsV) monomethylarsenic acid (MAsIII), monomethylarsenous acid (MAsV), dimethylarsenic acid (DMAsIII) and dimethylarsenous acid (DMAsV), which served as arsenic standards to determine retention times, were successfully separated under these conditions. Arsenic-glutathione complexes As(GS)3, MAs(GS)2 and DMAs (GS) were not successfully separated. These complexes provided peaks of simple arsenic species. Peak broadening was observed in the first analysis of As(GS)3 and MAs(GS)2 complexes, which disappeared in subsequent analyses. This broadening probably represents a residual of glutathion complex which disintegrated to single species. Powered by TCPDF (www.tcpdf.org)
Generation of volatile species of palladium for atomic absorption spectrometry
Vyhnanovský, Jaromír ; Musil, Stanislav (advisor) ; Matoušek, Tomáš (referee)
This thesis deals with optimization of the conditions for chemical generation of volatile species of palladium in combination with atomic absorption spectrometry. The volatile species of palladium were generated in a flow injection system by the reaction of an acidified sample with the solution of sodium borohydride in the presence of reaction modifiers. A diffusion flame atomizer was used due to its high robustness. In the first part of this thesis the optimization of parameters affecting the atomization in the diffusion flame was carried out (flow rates and composition of gases, observation height). In the second part, concentrations of individual reagents used (nitric acid, sodium borohydride, Triton X-100, Antifoam B, sodium diethyldithiocarbamate) were optimized. The positive effect of the reaction modifiers was demonstrated, especially that of sodium diethyldithiocarbamate, which lead to a tenfold increase in the sensitivity. The limits of detection and limits of quantification for the wavelength 244,8 nm were 0,25 mg dm-3 and 0,67 mg dm-3, respectively. The repeatability for this method for the concentration 5 mg dm-3 was 2,8 %. Key words: palladium, chemical generation of volatile species, atomic absorption spectrometry
Free Analyte Atom Distribution, Reactions and Analyte Reatomization in Quartz Tube Hydride Atomizers for Atomic Absorption Spectrometry
Matoušek, Tomáš
Free Analyte Atom Distribution, Reactions and Analyte Reatomization in Quartz Tube Hydride Atomizers for Atomic Absorption Spectrometry Abstract of Dissertation Tomáš Matoušek The Dissertation presents summary of studies of processes taking place in quartz tube hydride atomizers for atomic absorption spectrometry. Spatially resolved measurements of free atoms of hydride forming elements within the quartz tube atomizers (QTA) have been introduced. Both the cross-sectional [1] and the longitudinal [2,3] free atom distribution has been thoroughly investigated, bringing valuable information concerning the nature of the processes taking place within QTA. From the practical point of view, no effects arising from an inhomogeneous free atom distribution are to be expected in the most common externally heated atomizer. The role of the tube surface in the decay of the free analyte atoms has been demonstrated. Strong evidence has been obtained on analyte reactions within the QTA, leading to the formation of polyatomic analyte particles enhancing the free atom decay. These reactions are responsible for calibration graph curvature or even roll-over. It should be noted that the existence of such particles was not directly proven here, e.g., by using non-specific absorption or light scattering. On the other hand,...
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

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