National Repository of Grey Literature 14 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
UV-photochemical generation of volatile species of tellurium and other transition metals
Jeníková, Eva
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...
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...
Electrochemical generation of tellurium and bismuth hydrides for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
Tellurium and bismuth are non-biogenous elements, which can be accumulated in human body. The aim of this work is focused on the determination of these elements by the electrochemical hydride generation with non-membrane electrolytic cell with quartz tube - atomic absorption spectrometry. The first step of the work was to optimize parameters for the continuous setup measurements and to obtain its figures of merit. After this, the arrangement with most suitable conditions for determination of these elements was converted to the flow injection setup (FIA) and all experimental parameters were again optimized and its figures of merit were obtained. The conditions of hydride generation were studied for platinum, lead and silver cathodes with hydrochloric and sulphuric acids and their sodium salts as electrolytes. The optimizations of the FIA setup were performed on platinum cathode in hydrochloric acid for bismuth and on lead cathode in sulphuric acid for tellurium. The limit of detection achieved for the generation of tellurium hydride was 1.1 ppm with a linear range up to 20 ppm; for the bismuth hydride the limit of detection was 9.5 ppm and limit of linearity 50 ppm. Keywords Bismuth, tellurium, electrochemical hydride generation, atomic absorption spectroscopy, flow injection analysis
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...
Determination of Te(IV) by photochemical generation of volatile compounds with atomic spectrometric detection
Ruxová, Helena ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This thesis deals with the development of a method suitable for determination Te(IV) by UV-photochemical generation of volatile compounds (UV-PVG) in liquid samples. Atomic absorption spectrometry (AAS) and atomic fluorescent spectrometry (AFS) were used as detection methods. The basis of the apparatus for UV-PVG was a mercury lamp wrapped by PTFE capillary. Firstly, the experimental parameters were optimized for both methods. The optimized parameters were the type, concentration, pH and flow rate of the reaction medium, the length of the PTFE reaction coil, carrier gas flow rate (argon), supportive gas flow rate (hydrogen) and atomization temperature. The figures of merit with both detection methods were determined and compared after the method was optimized. Detection limits achieved for these two detection methods were 6,0 µg dm-3 for AFS and 1,50 µg dm-3 for AAS. Performed interference study confirmed a significant effect of many cations of transition metals and hydride forming elements on tellurium determination. The influence of nitric acid in the sample was studied separately. The suitability of the method for tellurium determination was confirmed by using a spiked certified reference material.
Electrochemical generation of tellurium hydride for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Tellurium is non-biological element which is not common in the earth. It can be accumulated in a body and cause many health problems. In this work, tellurium is determined by the electrochemical hydride generation technique coupled with atomic absorption spectrometry with quartz tube atomizer. In the first part of this work, various relevant parameters of tellurium hydride generation were optimized to achieve high sensitivity. Under the optimal working parameters, calibration dependences and other basic characteristics were measured. Finally, the influence of oxygen added on the different places of set up was carried out. Optimized parameters were flow rate of the carrier gas, generation current, flow rate and concentration of electrolytes. Optimizations were measured for two different catholytes: hydrochloric and sulfuric acid, with similar results. In addition the calibration was measured with orthophosporic acid. Further experiments with oxygen were performed for sulfuric acid as the catholyte. Influence of oxygen on the baseline and the process of determination were performed, for both continuous and limited time addition.
Determination of Te(IV) by photochemical generation of volatile compounds with atomic spectrometric detection
Ruxová, Helena ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This thesis deals with the development of a method suitable for determination Te(IV) by UV-photochemical generation of volatile compounds (UV-PVG) in liquid samples. Atomic absorption spectrometry (AAS) and atomic fluorescent spectrometry (AFS) were used as detection methods. The basis of the apparatus for UV-PVG was a mercury lamp wrapped by PTFE capillary. Firstly, the experimental parameters were optimized for both methods. The optimized parameters were the type, concentration, pH and flow rate of the reaction medium, the length of the PTFE reaction coil, carrier gas flow rate (argon), supportive gas flow rate (hydrogen) and atomization temperature. The figures of merit with both detection methods were determined and compared after the method was optimized. Detection limits achieved for these two detection methods were 6,0 µg dm-3 for AFS and 1,50 µg dm-3 for AAS. Performed interference study confirmed a significant effect of many cations of transition metals and hydride forming elements on tellurium determination. The influence of nitric acid in the sample was studied separately. The suitability of the method for tellurium determination was confirmed by using a spiked certified reference material.
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...
Electrochemical generation of tellurium and bismuth hydrides for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
Tellurium and bismuth are non-biogenous elements, which can be accumulated in human body. The aim of this work is focused on the determination of these elements by the electrochemical hydride generation with non-membrane electrolytic cell with quartz tube - atomic absorption spectrometry. The first step of the work was to optimize parameters for the continuous setup measurements and to obtain its figures of merit. After this, the arrangement with most suitable conditions for determination of these elements was converted to the flow injection setup (FIA) and all experimental parameters were again optimized and its figures of merit were obtained. The conditions of hydride generation were studied for platinum, lead and silver cathodes with hydrochloric and sulphuric acids and their sodium salts as electrolytes. The optimizations of the FIA setup were performed on platinum cathode in hydrochloric acid for bismuth and on lead cathode in sulphuric acid for tellurium. The limit of detection achieved for the generation of tellurium hydride was 1.1 ppm with a linear range up to 20 ppm; for the bismuth hydride the limit of detection was 9.5 ppm and limit of linearity 50 ppm. Keywords Bismuth, tellurium, electrochemical hydride generation, atomic absorption spectroscopy, flow injection analysis
Electrochemical generation of tellurium hydride for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Tellurium is non-biological element which is not common in the earth. It can be accumulated in a body and cause many health problems. In this work, tellurium is determined by the electrochemical hydride generation technique coupled with atomic absorption spectrometry with quartz tube atomizer. In the first part of this work, various relevant parameters of tellurium hydride generation were optimized to achieve high sensitivity. Under the optimal working parameters, calibration dependences and other basic characteristics were measured. Finally, the influence of oxygen added on the different places of set up was carried out. Optimized parameters were flow rate of the carrier gas, generation current, flow rate and concentration of electrolytes. Optimizations were measured for two different catholytes: hydrochloric and sulfuric acid, with similar results. In addition the calibration was measured with orthophosporic acid. Further experiments with oxygen were performed for sulfuric acid as the catholyte. Influence of oxygen on the baseline and the process of determination were performed, for both continuous and limited time addition.

National Repository of Grey Literature : 14 records found   1 - 10next  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.