National Repository of Grey Literature 46 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Photochemical generation of volatile species of rhodium as an efficient sample introduction technique for inductively coupled plasma mass spectrometry
Hašlová, Karolína ; Musil, Stanislav (advisor) ; Nováková, Eliška (referee)
This master's thesis is focused on development of a new analytical method based on photochemical generation of volatile species (PCVG) of rhodium as an efficient sample introduction technique for inductively coupled plasma mass spectrometry. At first, the conditions affecting the PCVG efficiency were optimized, namely carrier gas flow rate, irradiation time, composition of the reaction medium as well as the impact of transition metal ions as potential sensitizers was examined. The combination of Cu2+ and Co2+ was found optimal, enhancing the PCVG efficiency more than 60-fold. Additionally, a serious effect of the residence time of volatile species in the reaction medium, after exiting the irradiated part of the photoreactor, was found. The PCVG efficiency was doubled by modifying the output part of the photoreactor and another two-fold increase in the PCVG efficiency was achieved using the addition of nitrate anions to the reaction medium. Under chosen optimal conditions, the limit of detection and quantification were 13 pg dm-3 (3σ, n = 11) and 42 pg dm-3 (10σ, n = 11), respectively, and the PCVG efficiency was determined to be 13.5 ± 0.1%. The repeatability (n = 10) at 20 ng dm-3 was 2.9%. These experiments were followed by a study of interferences commonly occurring in the PCVG methods (chloride...
Atomic fluorescence spectrometry with volatile species generation - a sensitive tool for ultra-trace elemental analysis
Štádlerová, Barbora ; Musil, Stanislav (advisor) ; Spěváčková, Věra (referee) ; Dočekalová, Hana (referee)
This thesis encompasses a development of innovative methodologies based on atomic fluorescence spectrometry, offering precise and sensitive determination of ultra-trace elements, such as bismuth, cadmium, and nickel. The common denominator of all parts of this work is the use of a research-grade non-dispersive atomic fluorescence spectrometer (AFS). First part of this work is dedicated to the development of a highly sensitive methodology for bismuth determination based on hydride generation (HG) coupled with AFS. Bismuthane was generated by the reaction with NaBH4 in HCl medium in a flow injection arrangement and directed by a stream of carrier argon and hydrogen to an atomizer. A detailed optimization of the optical path of the spectrometer (electrodeless discharge lamp, lenses and interference filter) and atomization parameters in two flame atomizers - miniature diffusion flame (MDF) and flame-in-gas-shield atomizer (FIGS) - was performed. An excellent repeatability and extremely low limits of detection were achieved, namely 1.8 ng L−1 with the MDF and 0.9 ng L−1 with the FIGS. Subsequently, a photochemical vapour generation (PVG) of bismuth was coupled to AFS, employing a flow injection arrangement of the generator, a standard mercury low-pressure UV lamp and a coiled Teflon reactor. A flow rate...
Photocatalysed Se Volatile Species Generation
Remperová, Natália ; Nováková, Eliška (advisor) ; Musil, Stanislav (referee)
Vapour generation techniques introduce the sample in the gas phase into the atomic absorption spectrometry detector. These generation techniques help to overcome the limitations of liquid sample introduction and allow to determine trace elements in different matrices. UV-photochemical generation is one of the techniques used for the generation of volatile species. Less harmful chemicals, minimisation of waste, more affordable analysis, or improved limits of detection are only a few benefits that this technique brings to the sample introduction techniques for spectrometric detectors in analytical chemistry. Selenium is one of the most studied elements by vapour generation techniques. However, a study of catalysed UV-photochemical generation of Se volatile species coupled with atomic absorption spectrometry detection and reliable determination of generation efficiency has not been published so far. The aim of this master project is to develop a method for the photochemical generation of Se volatile species from Se(IV) and Se(VI). Different photocatalysts are tested for the generation and their elemental composition, structure and size are investigated. First, the apparatus was assembled based on the information in the published literature and previous experiences of the researchers from our group....
Volatile species generation – an efficient sample introduction technique for ICP-MS
Musil, Stanislav
Various techniques of volatile species generation, the ways of coupling to ICP-MS and recent results of our laboratory in the field of photochemical vapor generation of transition metals were presented in this lecture.
Determination of cadmium by chemical vapour generation coupled with atomic fluorescence spectrometry
Štádlerová, Barbora ; Sagapova, Linda ; Musil, Stanislav
Development of a methodology for determination of cadmium based on chemical vapour generation coupled with atomic fluorescence spectrometry.
Chemical vapor generation of cadmium for analytical atomic spectrometry
Sagapova, Linda ; Kodríková, Barbora ; Svoboda, Milan ; Musil, Stanislav ; Kratzer, Jan
Chemical vapor generation of cadmium volatile compounds was optimized in order to determine trace Cd concentrations by atomic absorption spectrometry (AAS). Several reaction modifiers based on inorganic salts and complexes of CrIII+, CoII+, TiIII+, TiIV+ were tested to improve analytical performance and generation efficiency.
GC-MS identification of photochemically generated volatile species of tungsten
Vyhnanovský, Jaromír ; Forczek, Sándor ; Musil, Stanislav
The presentation focused on the identification of volatile products of photochemical vapor generation of tungsten by GC-MS.
Possibilities of electrochemical generation of volatile compound of gold
Průša, Libor ; Hraníček, Jakub (advisor) ; Musil, Stanislav (referee)
The possibilities of electrochemical generation of gold volatile compound have been studied in this work. All experiments have been employed in electrochemical continuous flow generation. The previous aim of this work was to investigate if it is possible to generate the volatile form of gold using electrochemical generation of volatile compounds. Lead, platinum and alloy of lead and tin were used as cathode materials. Consequently, optimizations of experimental conditions were carried out. The optimized experimental conditions were: carrier gas flow rate, flow rate of electrolytes, electric current used for electrochemical generation, influence of the different types of gas-liquid separator, atomizer temperature. The calibration and other characteristics were found. At the conclusion, effect of oxygen on the signal intensity was studied. Key words Electrochemical generation of volatile compound atomic absorption spectrometry quartz tube atomizer flow-through electrolytic cell volatile compound gold
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...
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

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