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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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Atomization of volatile germanium species in hydride generation atomic absorption spectrometry
Slota, Alexandra ; Kratzer, Jan (advisor) ; Štádlerová, Barbora (referee)
The aim of this thesis was to optimize the atomization conditions of volatile Ge species for hydride generation atomic absorption spectrometry (HG-AAS). The selected species were inorganic germanium (iGe) and its methyl-substituted forms: monomethylgermanium (MMGe) and dimethylgermanium (DMGe). The atomizers for which optimizations were performed included diffusion flame (DF), multi-atomizer (MMQTA), dielectric barrier discharge (DBD) either with sinusoidal modulation of the high voltage source and glued electrodes (REF-SIN) or sputtered electrodes with rectangular high voltage waveform modulation (SE-SW), and finally atmospheric pressure glow discharge (APGD). Under optimal atomization conditions, the highest sensitivity, around 10 ms/ng, was found in DBD atomizers. The advantage of the SE-SW configuration, compared to the REF- SIN arrangement, is better peak shape and repeatability of the measurements. Atomizers such as DF and MMQTA provided mutually comparable sensitivity, which was about 5 times lower than in DBD. The APGD atomizer was the only atomizer studied in which the sensitivity was not comparavle among Ge species. The sensitivity for both methylated species was about half that for iGe (3.0 ms/ng). As part of the mechanistic study, high Ge deposition rates in all types of atomizers,...
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Information System Assessment and Proposal of ICT Modification
Krätzer, Jan ; Novák, Lukáš (referee) ; Koch, Miloš (advisor)
This diploma thesis is focused on the appraisal of the current state and the proposal for changes of the selected company Masaryk University that serves as a supporting element for the employees who deal with the actions of legally compulsory service. The appraisal of the current state of the information system is based on the analysis; the change proposals were sumbitted to the employees who are responsible for the operation and development of the information system.
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Information System Assessment and Proposal of ICT Modification
Krätzer, Jan ; Novák, Lukáš (referee) ; Koch, Miloš (advisor)
This bachelor thesis deals with the assessment of the current situation of the information system of the company and it also focuses on the proposal of changes of this system in order to provide users more comfortable and faster work by its usage. The assessment of information system is based on the analysis and consultations with the firm's employees. The result of the solution was accepted by the CEO and the changes were valued as very beneficial.
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Atomization of hydride forming elements in dielectric barrier plasma discharges
Baranová, Barbora ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
The aim of this diploma thesis was to optimize the atomization conditions of two hydride forming elements - bismuth and tellurium in dielectric barrier discharge (DBD) plasma atomizers using atomic absorption spectrometry (AAS) as a detector. Two types of electrode constructions of planar DBD atomizers were studied: glued and sputtered electrodes while two construction of high voltage power supply sources were investigated employing either a sinusoidal or square wave modulation of high voltage function. The effect of the gas phase dryer included in the apparatus upstream the atomizer was also investigated. A nafion membrane tube dryer was identified as the most effective one. Its efficiency was verified using optical emission spectrometry. With the nafion tube included in the apparatus, two main parameters of DBD atomizers were optimized: the voltage of the power supply source and argon flow rate, which served as a discharge gas. Using optimal conditions, analytical characteristics were determined for all atomizers used and these were subsequently compared with those achieved in an externally heated quartz (multi)atomizer (MM)QTA. In the case of bismuth, the optimal argon flow rate was determined to be 75 cm3 min-1 for all atomizers. The optimal value for the power supply source with sinusoidal...
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Modular design for in-atomizer preconcentration of hydride forming elements with AAS detection
Novák, Petr ; Kratzer, Jan (advisor) ; Korunová, Vlasta (referee)
Modular design of hydride trap-and-atomizer device for AAS is constructed and tested. Modular design enables to test different preconcentration surfaces easily. Efficient in- atomizer preconcentration allows to reach detection limits of hydride forming elements at ultratrace levels. Bismuth and arsenic were chosen as model analytes and their preconcentration efficiencies were quantified employing quartz and sapphire as preconcentration surfaces. The results reached in the modular design were compared to those found previously in the compact quartz trap-and-atomizer device. The performance of the modular design is fully comparable with that of compact trap-and-atomizer design. Modular design can thus be employed for testing of novel preconcentration surfaces.
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