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Monitoring of arsenic forms in foodstuffs
Harkabusová, Veronika ; Hrstka, Miroslav (referee) ; Vitoulová, Eva (advisor)
The diploma thesis is dealing with monitoring of arsenic in foodstuffs. The aim of this thesis is the determination of arsenic in samples of fish and rice and the study of forms, in which arsenic occurs, using speciation analysis. Arsenic is known as a toxic element, but its measure of toxicity depends on the chemical form it occurs in. Arsenic is present in the environment naturally or it gets in the environment by human activities. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, detoxification and activation of this element in the natural environment and living systems. The field of arsenic speciation analysis has grown rapidly in recent years, because determination of the total element content is not sufficient in the case of arsenic. Speciation method was done using separation by high performance liquid chromatography and detection by atomic fluorescence spectrometry with hydride generation. Extractable arsenic was present in the form of nontoxic arsenobetaine in all analysed samples of fish. In samples of rice there was confirmed the presence of toxic inorganic species of arsenic, esspecially As (III), but their concentration was at low level.
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Reduction of polyatomic interferences in As and Se determination by ICP-MS
Vajnahij, Volodymyr ; Nováková, Eliška (advisor) ; Hraníček, Jakub (referee)
This bachelor thesis was focused on the eliminationof polyatomic interferences in the determination of As and Se using inductively coupled plasma mass spectrometry. For this purpose, the collision-reaction cell technique was employed. The collision-reaction cell was filled with either collision gas or collision-reaction gas, namely pure He and H2, at different flow rates.In the case of the determinationof arsenic,which is monoisotopic and therefore no isotope other than 75 As can be selected, one of the main polyatomic interferences is 40 Ar35 Cl+ , which has the same mass-to-charge ratio m/z = 75 as 75 As. In the case of selenium determination, there are isobaric interferences due to 40 Ar38 Ar+ , 40 Ar40 Ar+ and 38 Ar40 Ca+ affecting the measurement of 78 Se and 80 Se. When 78 Se was determined in the He mode with 5 ml ∙ min-1 , a 300-fold decrease in BEC was observed. At the same time, this collision gas flow rate is higher than the routinely used one and thus able to remove more polyatomic interferences caused by 40 Ar38 Ar+ and 38 Ar40 Ca+ , respectively.Aslight improvement in some parameters was also achieved by using the H2 mode, which is more effective in reducing polyatomic interferences in the determination of Se than the He mode. With the removal of argide interference, H2 reaction...
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Determination of selected heavy metals in samples of great tits feathers by inductively coupled plasma mass spectrometry
Adamová, Simona ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
EN As a result of human activity, a number of polluting substances are released into the environment. Heavy metals are one of the types of these contaminants. Their accumulation in the environment can have a negative impact on living organisms, including humans. For this reason, environment quality monitoring has become an important activity. Great tit (Parus major) can be a suitable bioindicator of the level of environmental contamination by heavy metals, which is acceptable mainly due to its abundance and occurrence in the vicinity of human settlements. This diploma thesis deals with the determination of six selected heavy metals in feather samples of these songbirds from several parts of the Czech Republic and other European countries. High pressure microwave mineralization in the presence of acids was used to prepare the samples. Selected heavy metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) technique, which is also suitable for ultratrace analysis due its very low limits of detection.
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Plant responses to combined arsenic and cadmium stress
Burešová, Andrea ; Mašková, Petra (advisor) ; Podlipná, Radka (referee)
Arsenic and cadmium are both non-essential, highly toxic and carcinogenic elements that often occur together in the environment. Given the frequent co-contamination of the environment, it is necessary to investigate both plant strategies for dealing with one metal(loid) and the mechanisms that lead to tolerance or, conversely, sensitivity in the presence of both elements. Simultaneous exposure to multiple toxic elements may lead to extensive plant damage, however it may also result in the increasing engagement and intensity of defence strategies. Contamination of the food chain through crops growing on contaminated soils is a major concern, one that poses a risk to both human and animal lives. The aim of this research field is to reduce accumulation and translocation to aboveground edible parts as much as possible, for example by understanding the mechanisms behind heavy metal accumulation and translocation, or by stabilising toxic elements in the soil, or by cleaning up contaminated soil. One method of clean-up is phytoremediation, which usually utilizes plants with high tolerance to toxic elements, called hyperaccumulators. The knowledge of how defence strategies and mechanisms are affected by the interaction of multiple elements is important for identifying plant species capable of activating...
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Study of road dust pollution using ICP mass spectrometry
Chalabala, Jan ; Komendová, Renata (referee) ; Vašinová Galiová, Michaela (advisor)
Nowadays, there are many studies focused on road dust as a matrix of interest because of its ability to accumulate contamination with contribution from road traffic. This master thesis is turned into study of road dust pollution from aglomeration of Ulaanbaatar, capital city of Mongolia. There are 113 samples devided on nine sets corresponding to major roads in Ulaanbaatar. Samples have been sieved on three size fractions and then decomposed by aqua regia. Middle size fraction 45–63 µm has been analyzed using ICP-MS mass spektrometry. For purposes of contamination assesment, analyzed elements have been devided into two groups: contaminants (Cr, Cu, Zn, Pb and As) and rare earth elements (REE). Measured contents for elements have been compared with values of geochemical backgroud. Firstly for each set of samples and secondly for each sampling point. For first group of elements (contaminants), antropogenic contamination have been found, especially in the centre of Ulaanbaatar. As a probable source of this contamination, road traffic for Cu, Zn and Pb and coal combustion for Pb a As, have been identified. For REE group hasn´t been found any antropogenic enrichment.
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Treatment of mine waters rich in arsenic
Řáhová, Jaroslava ; Drahota, Petr (advisor) ; Kindlová, Helena (referee)
Summary: This bachalor thesis deals with treatment of mine waters rich in arsenic. First part is an overview of decontamination methods used for elimination of arsenic from water. Emphasised parts are focused on arsenic adsorption on Fe-oxides and hydroxides, particles which may be formed in mine waters; as well as on ODAS treatment system, widely used for mine waters decontamination. The experimental part is a study of decontamination process at mine treatment plant waters in Kaňk, Kutná hora. Extremely high concentrations of arsenic (77,72 mg/L) are found in acid mine drainage from closed Turkaňk mine. Results of this thesis signifies incorporation of arsenic and other elements dissolved in mine water into secondary forming Fe-oxyhydroxides within decontamination process.
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Contribution to optimization of parameters of speciation analysis of As based on selective hydride generation in direct transfer mode and detection by atomic absorption spectrometry
Vyvadilová, Tereza ; Dědina, Jiří (advisor) ; Korunová, Vlasta (referee)
The presented thesis deals with optimization of parameters speciation analysis based on a selective hydride generation in a direct transfer mode of hydrides and on-line atomization in an atomic absorption spectrometer. In the first part of the thesis processes during generation were investigated. Important indicator of a reactions taking place in a generator is volume of hydrogen (created by decomposition of NaBH4) which is subsequently introduced to the atomizer. In this part of the thesis a new approach to determine a flow rate of hydrogen delivered to the atomizator was developed. An influence of relevant paremeters of the atomizers and atomic absorption spectrometers on basic analytical characteristics of arsenic determination based on hydride generation was performed in the second part. Three atomic absorption spectrometers were used and three sources of radiation were compared. The most important analytic characteristic was the limit of detection which is influenced by standard deviation of measurement values of blank samples and by sensitivity. The best values of the limit of detection were achieved with electrodeless discharge lamps. Key words: hydride generation, arsenic, speciation analysis, atomic absorption spectrometry
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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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Diel variations of selected elements in arsenic-rich stream at the Mokrsko
Nováková, Barbara ; Drahota, Petr (advisor) ; Skřivan, Petr (referee)
The filtration and ultrafiltration experiment was applied on the stream water at the Mokrsko gold deposit and the results revealed that most of the elements were in the dissolved form and the 0,45 or 0,1 m filters could be used. During two 24-h field experiments, water samples were collected at 1-h intervals in order to prove the diel changes in the concentration and speciation of several trace elements. The determination of sorption processes at the surface of or within the veneer of biofilm has been determined by collecting natural and artificial priphyton. The results showed regular diel changes of As, Sb and Mo with highest concentrations occurring after the moon and the lowest concentrations in the early morning. The dissolved concentrations of other elements are conservative or their values were closed to their detection limits. The diel cycles are caused by changes in adsorption/desorption equilibria induced by diel cycles of temperature. The samples of biofilm revealed increased concentrations of the elements under the study and their diel variation were significant (approximatelly 35-96%); however, biofilm-controlled diel cycles of dissolved concentrations have not been proved.
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