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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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Production, Characterization and Utilization of the Biomass from Various Sources
Gojkovic, Živan ; Vávrová, Milada (referee) ; Čertík, Milan (referee) ; Márová, Ivana (advisor)
Úprava biomasy je jedním z nejdůležitějších problémů v moderních přírodních vědách, protože je základní kategorií týkající se zemědělství, potravinářství, ekologie, zpracování odpadu a biotechnologie. Ať už živočišného, rostlinného nebo mikrobiálního původu, biomasa představuje obrovský zdroj surovin jako potravin, čistých chemikálií, bioaktivních molekul atd., jejichž izolace, charakterizace a formulace může vést k zajímavým novým produktům určeným pro lidskou spotřebu, nebo jako nový materiál v biomedicíně. Předložená studie byla zaměřena na výzkum dvou druhů biomasy - kuřecí kůže jako zdroje kolagenu t a biomasy mikrořasy Chlorella sorokiniana obohacené selenomethioninem (SeMet). V první části práce byl z kuřecí kůže izolován, identifikován a charakterizován kolagen typu I. Molekulární vlastnosti kuřecího kolagenu byly analyzovány a srovnány s jinými kolageny z živočišných kůží. Pro molekulární charakterizaci kolagenu byla použita viskosimetrie a ultrazvuková spektroskopie. Ultrazvukovou spektroskopií bylo zjištěno, že disagregace a zkapalňování hovězího kolagenu začíná při teplotě 40 °C, zatímco u kuřecího kolagenu začíná až při 50 °C. Viskosimetrie dále potvrdila vyšší tepelnou stabilitu kolagenu z kuřecí kůže, jeho denaturační teplota byla 50 °C, což je rovněž o deset stupňů více než u hovězího kolagenu. Kuřecí kolagen obsahuje dvakrát vyšší množství lysinu, což poskytuje tepelnou stabilitu kolagenu. Na základě získaných výsledků lze říci, že vzhledem ke své vysoké tepelné stabilitě a vhodnému aminokyselinovému složení, kuřecí kůže může být použita jako alternativní zdroj kolagenu typu I s aplikacemi v potravinářském průmyslu a biomedicíně. Druhá část práce byla zaměřena na obohacení biomasy zelené mikrořasy C. sorokiniana selenomethioninem. Experimentální část byla provedena v Laboratoři biotechnologie řas na Univerzitě Huelva ve Španělsku. Cílem první části experimentů bylo studovat vliv selenu na životaschopnost řas, morfologii buněk a akumulaci SeMet v biomase mikrořasy kultivované v dávkových kulturách. Subletální koncentrace Se v živném médiu, 40 mgL-1 (212 M), snížila rychlost růstu o 25 % ve srovnání s kontrolní kulturou. Hodnota EC50 45 mgL-1 (238,2 M) byla stanovena pro selenan. Ultrastrukturální studie ukazovaly na strukturální změny chloroplastu (granulární stroma, redukce thylakoid). Elektroforéza proteinů z biomasy mikrořasy ukazuje, že Se ovlivňuje expresi genu enzymu Rubisco. C. sorokiniana byla schopna akumulovat až 140 mgkg-1 SeMet během 120 h kultivace. Další část experimentální práce byla zaměřena na obohacování biomasy mikrořasy C. sorokiniana selenomethioninem během kontinuální kultivace s použitím 2,2 L bioreaktoru v kultivačním médiu s přídavkem koncentrace selenu v rozmezí od 5 do 50 mgL-1. C. sorokiniana rostla stejně ve všech testovaných koncentracích selenu kromě koncentrace 50 mgL1, která byla již po krátké době kultivace letální. Během kontinuální kultivace se 40 mgL-1 selenu, bylo získáno maximálně 246 gL-1 selenomethioninu denně. Výsledky ukazují, že kultivace v dávkových kulturách a dlouhodobá kontinuální kultivace mikrořasy C. sorokiniana pro získaní biomasy obohacené SeMet je možná pečlivým výběrem podmínek kultivace a subletálních koncentrací selenu v živném médiu.
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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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Optimization of antibacterial properties of polymer-phosphate bone fillers
Grézlová, Veronika ; Michlovská, Lenka (referee) ; Vojtová, Lucy (advisor)
Tato diplomová práce je zaměřená na přípravu polymer-fosfátových kostních cementů. Cílem je optimalizovat antibakteriální vlastnosti daného cementu přídavkem selenových nanočástic (SeNPs). V teoretické části práce je popsána charakteristika kosti, vlastnosti fosforečnanu vápenatého (TCP) a jeho polymorfů, použití kostního cementu a antibakteriálních nanočástic v medicíně. Experimentální část se věnuje přípravě vzorků, popisu metod a vyhodnocení vlivu SeNPs na vytvrzování kostního cementu, morfologii, krystalinitu, mechanické, reologické a antibakteriální vlastnosti. Výsledkem je zvýšení injektovatelnosti cementu a zrychlení jeho vytvrzování včetně pozitivního vlivu na mechanické vlastnosti. Antibakteriální vlastnosti vzorků byly testovány použitím diskové i diluční metody, což vedlo k pozitivnímu inhibičnímu účinku SeNP na grampozitivních bakteriích (G+), zejména Staphylococcus aureus a methicillin rezistentní Staphylococcus aureus. Kvantitativní uvolňování SeNP z modifikovaného kostního polymer-fosfátového cementu umožňuje jeho použití jako antibakteriální kostní výplně (například pro léčbu zánětu kostí).
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Speciation analysis of selenium in selenized yeast
Motlová, Tereza ; Vitoulová, Eva (referee) ; Diviš, Pavel (advisor)
The aim of the theses was determination of selenium species in yeast Saccharomyces cerevisiae cultivated in medium with added inorganic form of selenium (Sodium Selenite). Concentrations of Sodium Selenite in cultivation medium were 0,1; 1; 10 and 100 mg.l-1. Cultivation was undertaken in fermenting tub for period of 72 hours. Cultivated yeasts were extracted by use of enzymes and subsequently the species of selenium in particular parts of yeasts were determined. In order to determine selenium species, the method of high-performance liquid chromatography in combination with atomic fluorescent spectrometer and technique of hydride generation was used. Having analysed different fractions of the yeasts Saccharomyces cerevisiae it was ascertained that during cultivation the sorption of selenium occurred in form of Se4+ in cell membranes while in cytoplasm no inorganic forms of selenium were found. Furthermore, it was stated that yeasts Saccharomyces cerevisiae are able to metabolically change inorganic forms of selenium to organic forms (selenomethionine), while these forms are present in cytoplasm and they are likely to be bound to proteinic structures of cell membranes. An increase of concentration of Se4+ in cell membranes could be observed as a result of increasing concentration of Sodium Selenite in cultivation medium. In proteinic structures the concentration of organic selenium forms increased only to concentration 10 mg.l-1 of Sodium Selenite in cultivation medium.
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Vliv selenu a vitamínu E na kvalitu masa vykrmovaných býků
Navrátilová, Eliška
A control and an experimental group of bulls were set up for the experiment. The bulls were fed the same total mixed ration. The experimental group had this total mixed ration by the addition of vitamin E and selenium. The whole experiment lasted for 90 days. The bulls were weighed at monthly intervals. At the end of the experiment, the bulls were slaughtered at the slaughterhouse. Samples were taken from the muscle, which were wrapped and stored in a refrigerator. Individual analyses were conducted for a total of 4 weeks, from week 0 to week 4 of maturation. Analysis for selenium content and sensory properties of the meat was carried out at the beginning and at the end of maturation. The result showed that the addition of selenium and vitamin E to the total mixed ration did not affect weight and gain. The selenium content in the meat of the experimental group was higher and increased during maturation, while that of the control group was lower and gradually decreased. As the selenium content of the meat increased, the sensory parameters evaluated also improved, whereas the results of the control group were similar at weeks 1 and 4 of maturation.
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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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Photocatalysed Se Volatile Species Generation
Remperová, Natália ; Nováková, Eliška (advisor) ; Musil, Stanislav (referee)
Vapour generation techniques introduce the sample in the gas phase into the atomic absorption spectrometry detector. These generation techniques help to overcome the limitations of liquid sample introduction and allow to determine trace elements in different matrices. UV-photochemical generation is one of the techniques used for the generation of volatile species. Less harmful chemicals, minimisation of waste, more affordable analysis, or improved limits of detection are only a few benefits that this technique brings to the sample introduction techniques for spectrometric detectors in analytical chemistry. Selenium is one of the most studied elements by vapour generation techniques. However, a study of catalysed UV-photochemical generation of Se volatile species coupled with atomic absorption spectrometry detection and reliable determination of generation efficiency has not been published so far. The aim of this master project is to develop a method for the photochemical generation of Se volatile species from Se(IV) and Se(VI). Different photocatalysts are tested for the generation and their elemental composition, structure and size are investigated. First, the apparatus was assembled based on the information in the published literature and previous experiences of the researchers from our group....
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Toxicita selenových nanočástic v živočišném organismu
Hledíková, Jana
The aim of this study was to verify the toxicity of selenium nanoparticles in an animal organism. Wistar albino rats were divided into five groups. Four groups of rats were fed a monodiet with added SeNP at doses of 0,5; 1,5; 3,0 and 5,0 mg Se/kg per feed dose. The experiment lasted 28 days. During this, the weight of the animals was measured every 7 days (0, 7, 14, 21, 28). After putting to death the animals at the end of the experiment, some blood parameters and histopathology of selected tissues were determined. Total antioxidant capacity (TAC), glutathione peroxidase (GPx), superoxide dismutase (SOD), alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glucose, total protein and albumin were diagnosed in the blood. Blood and liver selenium levels were analyzed and liver function tests were performed. Histopathological evaluation of liver and intestinal tissue was performed. The weight gain of the rats did not show differences between the tested groups. Compared to the control group, the selenium content in the blood and liver increased in the tested groups. However, selenium content in the liver did not increase in the test groups in a dose-dependend manner. No differences in TAC and ALP and AST aktivity were found. A significant reduction in ALT aktivity was observed in the test groups compared to the control group. SOD aktivity was reduced in the SeNP test group with 5 mg Se/kg compared to all other groups. GPx aktivity had a slightly increasing trend depending on the dose of SeNP, but without a significant (p <0,05) effect. Histopathological examination revealed damage to the hepatic parenchyma and intestinal epithelium that was dose-dependend on SeNP. From this study, it can be concluded that short-term supplementation of SeNP may be safe and beneficial, for example in selenium deficiency or for therapeutic purposes.
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