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UV-photochemical generation of volatile selenium compounds for ultratrace analysis by AAS
Rybínová, Marcela ; Rychlovský, Petr (advisor) ; Komárek, Josef (referee) ; Šíma, Jan (referee)
This thesis deals with the study of UV-photochemical generation of volatile compounds (UV-PVG) in connection with atomic absorption spectrometry (AAS). Selenium (Se(IV)) was selected as a model analyte and many experiments were carried out to expand the current sum of knowledge of the topic. The study was commenced by assembling the UV-PVG apparatus in the continuous flow mode. The detection method used was AAS with externally heated quartz furnace atomizer. The focus of the first step of the study was on the construction of the volatile compounds generator (UV-photoreactor) with emphasis on the material used; tubes made of teflon or quartz of different diameters were tested. The construction of the apparatus was followed by optimization of the reaction conditions (the type and concentration of the photochemical agent and other agents, which increase the analytical signal; the carrier gas and the auxiliary hydrogen gas flow rate; the sample flow rate). Eventually, the analytical figures of merit of the selenium determination using the proposed method were found. The results showed that teflon reaction tubes are a good competitor to those made of quartz. The accuracy of the method has been successfully verified by analysis of certified reference material and its applicability has been further tested...
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Contributions to Volatile Compound Generation of Arsenic, Silver and Gold by Tetrahydroborate Reaction for Atomic Absorption Spectrometry
Musil, Stanislav ; Rychlovský, Petr (advisor) ; Kanický, Viktor (referee) ; Spěváčková, Věra (referee)
(EN) The presented dissertation thesis summarizes the results contained in five original research papers that were published in prestigious international scientific journals in the field of analytical chemistry and atomic spectrometry. It is devoted to the method of generation of volatile compounds using a tetrahydroborate reaction and detection in a quartz multiatomizer by atomic absorption spectrometry. The thesis can be divided into two thematic parts - speciation analysis of arsenic based on hydride generation technique with collection and separation in a cryogenic trap and generation of volatile species of transition metals. In the first thematic part pre-reduction of pentavalent inorganic and methylated arsenicals has been studied. A simple setup for on-line pre-reduction employing thioglycolic acid as a fast pre-reductant has been developed, connected with a current hydride generator and applied/verified to oxidation state specific arsenic speciation analysis of human urine samples. In the same method the possibility of drying the gaseous phase from water vapor has been investigated to avoid incidental blocking the cryogenic trap by frozen water and to decrease fluctuations of signal baseline. Pronounced losses of methylated species have been discovered on Nafion tube dryer currently used in...
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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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Study of the interaction of hazardous metal – microplastic
Sinčáková, Lenka ; Řezáčová, Veronika (referee) ; Doležalová Weissmannová, Helena (advisor)
Mikroplasty, široko zastúpené vo vodnom prostredí, slúžia ako vektor širokej škály kontaminantov, vrátane ťažkých kovov. Táto práca sa zaoberá adsorpciou piatich ťažkých kovov (Pb, Hg, Zn, Cu and Cd) na polyetylén tereftalát (PET), rozšírený polutant riek a morí. Pokiaľ ide o vplyv veľkosti mikroplastov na proces adsorpcie, nebol zistený jasný trend. Salinita prostredia má značný vplyv na adsorpčný proces s pozorovateľným poklesom adsorbovaných množstiev v prostredí s vysokou iónovou silou. Analyzované ťažké kovy boli zoradené vzostupne podľa ich schopnosti adsorpcie na PET nasledovne: Hg
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Determination of mercury in selected fish species and in fish products
Kroupová, Kateřina ; Ing.Tomáš Gregor, Ph.D. (referee) ; Diviš, Pavel (advisor)
Theoretical part of the master thesis deals with the occurrence of different mercury species in the environment and describes analytical methods used for determination of mercury in biological samples. In practical part of the master thesis mercury concentration in 14 samples of selected fish and fish product was determined using single purpose absorption spectrometer AMA 254. Measured results were statistically processed and consulted with EU legislative norm.
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Study of organs of mice in inhalation experiments
Vrlíková, Lucie ; Diviš, Pavel (referee) ; Dočekal, Bohumil (advisor)
The diploma thesis is devoted to study potential risks for living organisms resulting from inhalation of nanoparticles of chosen heavy metals. The main aim of this work is the investigation of organs from experimental white mice after their guided inhalation of lead nanoparticles. The samples of liver and lungs from these animals are taken in time periods during the inhalation experiments and processed by specific methods for their evaluation. After pressurized microwave assisted decomposition of selected samples of mice organs in high purity concentrated nitric acid the content of lead is determined by atomic absorption spectrometry with electrothermal atomization. Furthermore, the changes are monitored using the microscopy of histological slides stained with hematoxylin-eosin. The results of both approaches are evaluated and compared within the frame of this work.
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Corrosion degradation of magnesium alloys in SBF solutions
Ročňáková, Ivana ; Horynová, Miroslava (referee) ; Doležalová Weissmannová, Helena (advisor)
Nowadays, magnesium alloys are used in many sectors of human activity, particularly in the aerospace and automotive industries, due to a combination of good mechanical properties and low density of magnesium. Recently, however, the attention is paid to the possibility of using magnesium alloys in the medical field, mainly due to the chemical properties of magnesium. The diploma thesis is focused on evaluating of the corrosion behavior of AZ31alloy and AZ61 alloys in SBF solutions that are solutions simulating body fluids. The alloys were subjected to immersion test in Hank’s solutions for time span from 24 to 1008 hours. The corrosion process was evaluated based on several factors: alloy composition, time and pH changes. The thesis also describes in detail the methodology for establishing magnesium and zinc by method of flame absorption spektrometry (F AAS). The determination of aluminum was carried out by atomic absorption spectrometry with electrothermal atomization (ET AAS).
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Determination of lead in lung and brain samples of experimental mice after the inhalation of nanoparticles
Demydenko, Yana ; Zlámalová Gargošová, Helena (referee) ; Vašinová Galiová, Michaela (advisor)
Lead is a heavy toxic metal whose nanoparticles are present in the air due to combustion processes. Data on the safe concentration of lead nanoparticles for human health have not been sufficiently investigated. Previous studies in experimental mice have shown that inhalation of lead nanoparticles first damages lungs and kidneys, then liver, spleen and brain. With prolonged exposure, lead accumulates in the teeth and bones. This bachelor thesis is focused on monitoring of the lead content in lung and brain samples of experimental mice after different periods of nanoparticle inhalation. The aim of this bachelor thesis was to develop an analytical method for the determination of lead in biological samples using atomic absorption spectrometry with electrothermal atomization (ET-AAS). In this work, a decomposition method for mineralization of the biological matrix in a microwave mineralizer was proposed, and a procedure for the determination of lead using ET-AAS was further developed. The determination of lead at 217 nm using the NH4H2PO4/Mg(NO3)2 matrix modifier was verified by analysis of certified reference materials. Analysis of organ samples from experimental mice confirmed the detoxification mechanism in exposed individuals with a dependence on the time since the end of inhalation of lead nanoparticles.
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