National Repository of Grey Literature 164 records found  beginprevious152 - 161next  jump to record: Search took 0.00 seconds. 
Microdetermination of cobalt by methods of molecular and atomic absorption spectrometry
Charuza, Martin ; Řezáčová, Veronika (referee) ; Sommer, Lumír (advisor)
This diploma thesis is focused on microdetermination of cobalt by UV-VIS spectrophotometry with organic agents and comparison with atomic absorption spectrometry. In the first part properties, occurance and importance of cobalt in the environment are desribed, complete with as a part of vitamine B12. Attention is also given to cobalt compounds, especially in the oxidative states +II and +III. Methods of preconcentration and preparation cobalt determination in real samples are adduced. In this thesis are described some optical analytical methods with accept on spectrophotometric agents for determination of cobalt. The experimental part of this thesis icludes optimalization of the spectrophotometric determination of cobalt with choosen organic agents 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol and optimalization of atomic absorption spectrometry for cobalt determination. All of real samples of water (surface, underground, mineral and waste) were measured by both 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol via UV-VIS and via atomic absorption spectrometry. Results of determinations were compared. A sample of vitamine B12 was measured too by all techniques.
Bioavailability of metals species in water ecosystem
Tandler, Ágnes ; Řezáčová, Veronika (referee) ; Vávrová, Milada (advisor)
Koncentrace volných kovových iontů je často jen malou částí celkové koncentrace kovu v prostředí. Přes tento malý obsah, je ve většině případů koncentrace volných kovových iontů klíčovým faktorem při určování biodostupnosti a toxicity pro organizmus. Membránová technika Donnan se používá k měření koncentrace volných kovových iontů a v této diplomové práci je ověřena pro směsi kovů (Pb + Cu) při absenci a přítomnosti malých organických ligandů. Olovo a měď jsou environmentálně důležité kovy díky své toxicitě a rozdílným vazebným vlastnostem ve vztahu ke studovaným ligandům.
Characterization of the resin gels for mercury determination by DGT technique.
Finsterlová, Hana ; Řezáčová, Veronika (referee) ; Diviš, Pavel (advisor)
The aim of this thesis is testing of resin gels used in diffusive gradients in thin films technique (DGT) for determination of mercury in natural waters. The sorbets, chosen for preparation of resing gels were: Duolit GT- 73, Spheron- Thiol, and Chelex 100 and newly modified sorbent Iontosorb AV. At the beginning of work, the preparation procedure of all resing gels was optimized. After optimalization of preparation procedure the resin gels were tested in mercury model solutions. The recovery test and time dependence test were performed. When the basic tests were finished, they were followed by the tests of influence of natural ligand (humic acids and chlorides), and other parameters (above all pH and ionic strenght), on mercury determination by DGT technique.
critical Evaluation of metrhods for determination of Sulphates in waters
Havelková, Ludmila ; Řezáčová, Veronika (referee) ; Sommer, Lumír (advisor)
The aim of this work was the evaluation and method optimalization for determination of sulfates in aqueous solutions with application on different kinds of waters. For determination of sulfates were used two different procedures, turbidimetric and volumetric. In turbidimetric procedure was use optimized conditions applicable determination of sulfates in range from 0 – 20 mg.l-1. For stabilization of the colloid was use glycerine, himself sulfates sedimentation is discharged in BaSO4 form. By volumetric methods are used titration on the dithizone like indicator while using Pb(NO3)2 like volumetric reagent. Other indicator bromsulfonazo III, whitch are used for determination of sulfates by the help of volumetric solutions Ba(ClO4)2 and BaCl2. All volumetric determinations proceeded in acidic medium. During research of interferences ions on the individual titraction was detected substantial effect Ca2+, Mg2+ and Fe3+, which was needing divide off on the exchanger resin. Ions aforementioned don't interfere turbidimetric determination of sulfates.
New resin gels for application in DGT technique
Trávníčková, Jana ; Řezáčová, Veronika (referee) ; Dočekal, Bohumil (advisor)
Diffusive gradients in thin films technique (DGT) is a simple preconcetration method for in situ determination of labile metal ions in aquatic systems. It eliminates contamination problems associated with the sampling and transport into the laboratory. The DGT technique is based on a simple device that accumulates metal ions on a cation-exchange resin, immobilized in thin layer of hydrogel, after passage through the diffusion layer. The cation-exchanger, usually Chelex 100, is selective for binding free or weakly complexed metal ions in solution. This diploma thesis deals with the characterization of a new resin gel based on ion exchanger with anchored thiol-functional groups, Spheron-Thiol, for DGT technique. This new binding agent with a high selectivity for „heavy“ metal ions could provide more information on the labile metal species in water systems. The performance of DGT technique with utilization of Spheron-Thiol resin was investigated by the determination of Cd, Cu, Ni and Pb under laboratory conditions. Due to the strong adsorption of copper to the Spheron-Thiol, it is necessary to decompose the resin gel in nitric acid prior to the determination. New resin gel provides reliable information of trace metal concentrations within the pH range 6 – 8 typical for natural waters. The effect of competitive ligands, iminodiacetic and humic acids, on Cd, Cu, Ni a Pb sorption on Spheron-Thiol and Chelex 100 resin gels was determined.
Testing of modified Iontosorb resins for its use in diffusive gradient in thin films technique
Szkandera, Roman ; Řezáčová, Veronika (referee) ; Diviš, Pavel (advisor)
6-mercaptopurine was joined by diazotation and copulation reactions on Iontosorb AV. Presence of thiol groups in modified resin was showed by infrared spectrometry. Amount of thiol groups was determined by iodometric titration. Resin gel was preparated from modified resin and agarose and both of them were tested for mercury determination by DGT technique.
Determination of nitrates in vegetables by capillary izotachophoresis
Jančová, Nikola ; Zlámalová Gargošová, Helena (referee) ; Řezáčová, Veronika (advisor)
This bachelor thesis deals with determination of nitrates in vegetables employing the capillary isotachophoresis technique. The literature review is devoted to occurrence of nitrates in vegetables, their health risks, the influence of food processing onto nitrate content, commonly used methods of determination as well as the capillary isotachophoresis and its practical application. Experimental part focuses on the application of capillary isotachophoresis for determination of nitrate content in vegetables obtained from conventional agriculture and organic farming.
Nitrogen and its compounds in wastewater
Venská, Petra ; Skoumalová, Marta (referee) ; Řezáčová, Veronika (advisor)
The bachelor thesis summarizes the possible forms of nitrogen and nitrogen compounds in wastewater and ways of elimination of these compounds including physical/chemical processes and biological processes. The physical/chemical methods described in the thesis are air stripping, breakpoint chlorination, sorption and membrane separation. The biological processes include nitrification, denitrification, anoxic ammonium oxidation and SHARON, CANON and OLAND systems. The experimental part is devoted to quantifying nitrates, nitrites and ammonium in wastewater samples using mobile analytical methods.
Phosphorus and its compounds in the environment
Lefnerová, Marcela ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This bachelor´s thesis deal with problems of phosphorus in waters, mainly in garden pond. This thesis analyse phosphorus attributes, forms of occurrence and negative effect in excessive occurrence. Next part is concentrate on common methods for remove phosphorus from water and methods of determination in waters and soils. For thesis on important mainly chapter about mobile analyse. Last part deals directly with bathing ecological ponds and Union of founding and maintenance of green. This part occupy with goals this union and introduction of control of materials, mainly from point of view of volume of phosphorus infuse to pond water.
The occurence of Cadmium in environment
Bělohlávková Staffová, Petra ; Řezáčová, Veronika (referee) ; Sommer, Lumír (advisor)
Heavy metals, including cadmium, belong to the contaminants of the environment. With permanently increasing pollution, there is an increase of these metals in the water, in the air and in the soil, which are involved in the food chain and subsequently the food of human. Cadmium has received considerable attention for its toxicological properties. Similarly, monitoring of cadmium in the Czech Republic is relatively large. There is a legislative measure regarding not only the permitted level of cadmium in the air, in the water, in the soil, but also food and is also restricted its use in the industry. Further they developed methods of its determination. In this work was devoted to attention photometric determination and some electroanalytical methods, then spectrometric methods mainly atomic absorption spectrometry and atomic emission spectrometry, which is currently the most widely used.

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2 Řezáčová, Vendula
10 Řezáčová, Veronika
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