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Methods for Elemental Speciation of Arsenic Compounds.
Navrátilová, Jana ; Jarošová, Alžběta (referee) ; Golian,, Jozef (referee) ; Šimko, Peter (advisor)
Speciační analýza arsenu v různých matricích s využitím HPLC/ICPMS byla předmětem této práce. Toxicita arsenu závisí na oxidačním stavu a formě, ve které je přítomen. Znalost zastoupení specií arsenu je nutná k hodnocení toxicity a biodostupnosti. Obecně, anorganické specie jsou více toxické než organické. V práci byla studována degradace arsenocukrů v mořských řasách za simulovaných přirodních podmínek. Původní arsenocukry byly transformovány na arseničnan a kyselinu dimethylarseničnou. Arsen vstupuje do rostlin z půdy a vody a následně může vstoupit do potravního řetězce. S ohledem na tuto skutečnost byla speciační analýza provedena u vybraných vzorcích rýže, zakoupených v české obchodní síti. Stanovený celkový obsah arsenu se pohyboval v rozmezí 36.06 µg/kg - 218.11 µg/kg a hlavními speciemi byla kyselina dimethylarseničná a anorganický arsen (54-78%). Mořské ryby a tuky obsahují významnou část arsenu ve formě zvané arsenolipidy. Část práce byla zaměřena na analýzu arsenolipidů u máslové ryby (Lepidocybium flavobrunnrum) s celkovým obsahem arsenu 1.8 mg/kg a 22% celkového arsenu bylo vyextrahováno pomocí hexanu, což potvrzuje lipofilni charakter těchto sloučenin. Hlavní specií stanovenou ve vodném extraktu byl arsenobetain, představující 89%.
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Investigation of Miniature Devices for Collection of Hydride Forming Elements in Atomic Spectrometry Methods
Krejčí, Pavel ; Čelechovská, Olga (referee) ; Janoš, Pavel (referee) ; Otruba, Vítězslav (referee) ; Dočekal, Bohumil (advisor)
Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
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Study of Generation, Trapping and Atomization of Hydride Forming Elements for Atomic Spectrometry
Furdíková, Zuzana ; Sommer, Lumír (referee) ; Čelechovská, Olga (referee) ; Řehůřková, Irena (referee) ; Dočekalová, Hana (advisor)
Interference effects of co-generated hydrides of arsenic, antimony, bismuth and selenium on trapping behavior of selenium or antimony hydrides (analytes) within iridium modified, transversely heated graphite tube atomizer (THGA) was investigated. A twin-channel hydride generation system was used for independent separate generation and introduction of analyte and interferent hydrides, i.e. in simultaneous and/or sequential analyte-interferent and interferent-analyte mode of operation. Influence of the analyte and modifier mass, interferent amount, trapping temperature and composition of the gaseous phase was studied. A simple approach for elimination of mutual interference effects by modification of the gaseous phase with oxygen in substoichiometric ratio to chemically generated hydrogen is proposed and suppression of these interference effects is demonstrated. A hypothesis on mechanism of trapping and mutual interference effects is drawn.
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Multicomponental Preconcentration of As, Sb, Se and Te on Modified Silica, Their Determination by ICP-AES (ICP-MS) and Application for Waters
Urbánková, Kristýna ; Řehůřková, Irena (referee) ; Kanický, Viktor (referee) ; Ventura, Karel (referee) ; Sommer, Lumír (advisor)
The determination of inorganic speciations of arsenic, antimony, selenium and tellurium in natural waters demands often separation and preconcentration. Solid phase extraction is a very effective method for these purposes. In this paper the separation and preconcentration of these microelements is realised on the basis of modified silica Separon SGX C18, SGX C8, SGX CN, SGX NH2, SGX Phenyl and strongly basic anion Exchanger SGX AX. The sorption was provided in the presence of cationic surfactants such as benzyldimethyl dodecylammonium bromide (Ajatin), benzyldimethyltetradecylammonium chloride (Zephyramine), 1-ethoxycarbonylpentadecyltrimetrhylammonium bromide (Septonex) and selected complexing agents 4-(2-pyridylazo)resorcinol (PAR), 8-hydroxyquinoline-5-sulphonic acide (8-HQS), 1,2-dihydroxybenzene (PYR), amonium 1-pyrrolidinecarbodithioate (APDC), sodium diethyldithiocarbamate (DTC) or thiourea(Thur). The interactions of the formed ion associate with the sorbent shows a complicated character which has not been cleared as yet. The previous conditioning of the sorbent plays an outstanding role. Thus, the sorption efficiency was studied in the presence and absence of surfactant and of selected organic complexing agents. Moreover, the influence of pH of the sorbed solution as well as the speed and the volume of the solution running through the sorbent and the type and volume of the eluent on the resulting sorption efficiency was evaluated. The sorption was successfully carried out from 50-1000 ml of solution which allows the 100 fold increase of the preconcentration factor and the determination of the microelements in g.l-1 instead of mg.l-1 by using the common ICP-AES. The influence of macroelements occurring in waters as well as B, Be, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sr, Ti, V and Zn in comparable concentrations involve less than 5% error. After the quantitative elution of microelements, the organic solvents were evaporated under IR lamps prior to the determination by ICP-AES and |ICP-MS. The conditions for the direct determination of arsenic, antimony, selenium and tellurium in g.l-1 with ICP-MS were also described in detail in the absence and presence of internal standards Ge and Bi. However, even in this case the preconcentration on silica in the presence of surfactant and selected organic complexants was also tested. When the sorption was followed from 500 ml a 50 fold enrichment factor is reached and the sensitivity for the microelements is improved. The direct determination and the sorption of microelements were applied on synthetic and real waters (dirinking, surface, mineral and sea waters). Instrumental and practical detection limits for various water samples were evaluated according to IUPAC. The results from 1000 ml solution of real waters after sorption on modified silica and the final determination of microelements with ICP-AES were compared with those from ICP-MS without sorption using the method of standards addition in the presence of suitable internal standards. By comparison of results for synthetic and real water samples the error of the determination of microelements was evaluated.
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Evaluation of water quality in water treatment plant Mokošín
Vosáhlo, Jan ; Vybíralová, Pavla (referee) ; Biela, Renata (advisor)
The theme of this thesis is " Evaluation of water quality in water treatment plant Mokošín". The source of water supply are 4 artesian wells. The paper first describes the supply area and water treatment plant with individua water treatment technologies. In the practical section there is the specification of contaminating elements required to be separated at the water treatment plant. Since it is an underground source of water, there is an increased amount of iron and manganese. Increased attention is given to arsenic, which occurs in two water sources in recent years. There are also offered the possibilities of removing arsenic at water treatment plant and two filter materials tested in the laboratory. Monitoring of water quality takes place always in resources and after treatment in the time period of five years, the arsenic values are reported for ten years.
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Preparation of geopolymeric binders for toxic metals inhibition
Jevická, Lucie ; Kalina, Lukáš (referee) ; Šoukal, František (advisor)
This thesis deals with preparation of geopolymeric binders for inhibition of toxic elements, especially arsenic. It studies influence of content progress of different phases in prepared binders on leachability of As during the setting. The aim of this study is to determine the type of inhibition or the cause of leachability of As in prepared binders respectively. Fly ash from high-temperature coal combustion, slag, cement kiln dust and sodium hydroxide solution were used for experimental works. FT-IR, TG-DTA, XRD analyses after different hydration times were used. The leachates were analyzed by ICP-MS. Calorimetric measurements of tested mixtures fresh pastes were implemented to learn about setting process. Hardened binder specimens were tested for bending and compressive strength.
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Representation of selected elements in human hair
Jochimová, Eva ; Janoušková, Eva (referee) ; Zemanová, Jana (advisor)
Hair is an excellent matrix for monitoring trace elements and minerals in the body. To long-term changes in concentration of elements in the body are reflected in their value in her hair, so the assessment of the organism from the mineral analysis of hair is a very suitable method. This method is widely used in toxicological testing and forensics. This work deals with the analysis of Mg, K, Fe, Zn, Mn, Se, As, Cd and Pb in 100 samples by ICP-MS. It is a male hair samples with the age range 19 – 74 years. Analysis of hair revealed that concentrations of individual elements are moving in a narrow range of values. Values of older age category are in some case significantly deflective.
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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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Specific substances in drinking water sources
Konečný, Jiří ; Kučera, Tomáš (referee) ; Biela, Renata (advisor)
In this bachelor thesis I dealt with specific substances which occures in sources of drinking water and pollutes quality of water. Especially its heavy metal, sulfur compounds, nitrogen, phosphorus and other. In this thesis I deal with possibilities about remove of these substances by using various methods, especially absorption on filter materials. These thesis is focused on using absorption on suitable materials for reduction of concentration arsenic and cadmium in drinking water. In first part I‘ve characterized subtances which occures in the water and outlined a way to remove them. Second part is focused on laboratory observation to efficiency of removing arsenic and cadmium on sorption materials.
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