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Speciation analysis of arsenic based on volatile species generation and dielectric barrier discharge plasma atomization
Plecháč, Matěj ; Kratzer, Jan (advisor) ; Kaňa, Antonín (referee)
SPECIATION ANALYSIS OF ARSENIC BASED ON VOLATILE SPECIES GENERATION AND DIELECTRIC BARRIER DISCHARGE PLASMA ATOMIZATION Bc. Matěj Plecháč 2024 Abstract Volatile species generation (VSG) comprises a group of techniques based on analyte derivatization in order to form a volatile compound prior to spectrometric detection. Selective analyte conversion from liquid to gas phase results in enhanced analyte introduction efficiency, but also in matrix separation and reduced risk of interferences. Moreover, VSG step can be utilized during speciation analysis or analyte preconcentration. The most frequent atomizers of volatile species are externally heated quartz tubes (QTA). Dielectric barrier discharge (DBD) atomizers have proved to be alternative hydride atomizers to QTA. The significant difference in toxicity of various species of the same element leads to the urgent need to develop new strategies for speciation analysis. Various approaches to speciation analysis of toxicologically relevant arsenic species including inorganic iAsIII and iAsV , monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethylarsine oxide (TMAsO) by hydride generation atomic absorption spectrometry (HG-AAS) were investigated in this work. All these species can be converted to volatile compounds. i.e. arsane and its methylated...
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Atomic fluorescence spectrometry with volatile species generation - a sensitive tool for ultra-trace elemental analysis
Štádlerová, Barbora
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...
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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...
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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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Chemical generation of volatile mercury species for speciation analysis - method optimization and analytical applications
Migašová, Michaela ; Petry-Podgórska, Inga (advisor) ; Spěváčková, Věra (referee)
Experimental conditions have been optimized for volatile species generation (VSG) of four mercury species and their subsequent atomization with detection by atomic absorption spectrometry (AAS). The species investigated were mercury (+II), methylmercury (+I), ethylmercury (+I) and phenylmercury (+I). Flow injection construction of volatile species generator and externally heated quartz tube atomizer were employed. The optimized parameters were the concentration of hydrochloric acid and sodium borohydride, the length of the reaction coil, carrier gas flow rate, atomization temperature and the amount of oxygen present in the atomizer. Furthermore, the effect of the drying tube on the signal of Hg species as well as the applicability of tin chloride as an alternative reductant instead of sodium borohydride were studied. Calibration curves were measured and the basic analytical figures of merit were determined, under optimum experimental conditions, for all four mercury species investigated. Limits of detection for Hg species ranged from 0.12 to 0.25 ng cm-3 , while sensitivity reached ca 0.10 s ng-1 at atomization temperature of 500 řC. Experiments focused on atomization temperature optimization have revealed that volatile compounds generated from organic Hg species decompose significantly. Speciation...
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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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Generation of volatile species of copper for atomic absorption spectrometry
Šoukal, Jakub ; Musil, Stanislav (advisor) ; Rybínová, Marcela (referee)
This thesis deals with optimization of conditions of chemical generation of volatile species of copper for atomic absorption spectrometry. The volatile species of copper were generated in the flow arrangement in a special generator by the reaction of the acidified sample with the solution of sodium borohydride in the presence of reaction modifiers. A diffusion flame was used as the atomizer of volatile species of copper due to its high robustness. First, all the parameters affecting atomization in the diffusion flame were optimized (flow rates and composition of gases, observation height). In the next section, concentration of individual reagents for chemical generation of volatile species was optimized, especially the concentration of nitric acid, sodium borohydride and reaction modifiers. Triton X-100 and Antifoam B were chosen as the best combination of modifiers with respect to threefold increase in sensitivity, tailing of measured signals and because of long-term repeatability. There was not observed any significant positive effect on the sensitivity of measurement for other tested reaction modifiers. The limits of detection and quantification were 62 mg dm−3 and 208 mg dm−3 , respectively. The repeatability of this method for concentration 2,5 mg dm−3 was 2,4%. Key words copper, chemical...
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