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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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Transport properties of dextran-based hydrogel systems
Vyroubal, David ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focused on study of transport properties of dextran-based hydrogel systems. The aim of this work is to determine their ability to absorb and release substances. Nile red was used as a probe to examine the transport properties of these systems. All hydrogels were prepared by the so-called wet way. At first stock solutions of dextran and surfactants were prepared and subsequently mixed to form a hydrogel. Nile red was dissolved in the surfactant stock solution and colored gels were formed upon mixing with dextran stock solution. Several types of gels were thus formed which differ in the concentration of the surfactant and nile red used. Supernatants were spectrophotometrically measured at various time intervals. For study of transport properties in multiple surroundings, the original supernatant was replaced after hydrogel preparation with a surfactant solution or physiological saline solution.
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Optical determination of the state of charge of vanadium flow battery cells
Šacl, Vojtěch ; Chladil, Ladislav (referee) ; Novák, Vítězslav (advisor)
The investigated subject for this diploma thesis is getting know properties of the vanadium redox battery (VRB), especially electrolyte. Specialization is applied to the state of charge of this cell and its measurements using the optical methods. Upon different state of charge is changed oxidation number of vanadium and resultant color of the electrolyte. Using spectrofotometry method that characteristic property is undergone measurement. The basic thing was learning to handle a measurement system. The first practical measurement was executed on example foils. Upon measurement of vanadium cell there was obtained the values of absorbation, which they were used for determination of state of charge.
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Determination of surfactants in waste waters
Švec, Pavel ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
Surfactants belong to surface-active compounds that have ability to restrain the surface tension; this ability is exploited to eliminate impurities. This study is focused on determination of surfactants in waste water to which these compounds can be transported from various cleaning and washing articles. In theoretical part are listed basic classifications of surfactants, their properties and requests of Czech legislative for their content in waste water. Furthermore here are described chosen analytical procedures for determination of anion-active, cation-active and non-ionic surfactants in waste water. The conclusion of the work is evaluation of measured results of surfactants concentration in inflow and outflow of waste water from waste-treatment plant in University of Veterinary and Pharmaceutical Sciences Brno and waste water from neutralizating station in FCH BUT. To determination of anionic surfactants were used two methods, arbitration method with usage of methylene blue and mobile analytics method which is based on chemical reaction between target compound and chemical agent. This reaction leads to formation of coloured compound able to spectrofotometric determination.
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Coproduction of polyhydroxyalkanoates and violacein employing members of the genus Janthinobacterium
Uhrová, Kateřina ; Mravec, Filip (referee) ; Obruča, Stanislav (advisor)
This bachelor's thesis deals with the study of appropriate conditions for the cultivation of bacteria of selected genera Janthinobacterium, specifically strains CCM 160 and CCM 1888 and the genus Iodobacter fluviatilis strain CCM 3308 from the Czech collection of microorganisms. The most suitable conditions for bacterial growth were investigated. The aim was to identify ideal production medium, cultivation volume, temperature and conditions in the form of submerged and static cultivation. At the same time, one of the strains used was chosed, which appeared to be the best producer of metabolites. Production of the purple pigment violacein and polyhydroxyalkanoates (PHA) was observed during the cultivations. Violacein was extracted using methanol and the concentration of the produced violacein content was measured using UV/VIS spectrophotometry. The PHA content was determined using gas chromatography. The obtained data were compared with each other and it was determined whether the production of both metabolites is mutally affected. Furthermore, cultivation on a solid carrier was carried out, which proved more effective in the production of violacein than in a liquid medium. This type of cultivation could in the future lead to the commercial production of violacein, which has a number of positive properties. The 16S rRNA and phaC genes were detected using the multiplex PCR method.
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Sensory analysis as a means to increased transparency of analytical methods used in practical chemistry education
Kocichová, Kristýna ; Rusek, Martin (advisor) ; Kolář, Karel (referee)
The theoretical part of the thesis is focused on the description of sensory analysis, its history, basic methods, principles, and procedures in the analysis of solutions. It specializes in three basic tastes: salty, sour and bitter. It then focuses on explaining the basic analytical methods whose applications can be found in practical chemistry teaching, in particular an introduction to the principles of conductometry, spectrophotometry and potentiometry. It then addresses the issues of science teaching, language and the difficulty to learn these sciences. The aim of this bachelor thesis was an attempt to increase the transparency of analytical methods in practical chemistry teaching through sensory analysis methods. Building on previous work addressing this issue, further experimental activities were designed and piloted. These activities give the possibility to increase first of all the interest and motivation of the students in chemistry, then to lead the students to think on their own, to find new solutions, to be able to work with the instruments within the analytical methods and to verify and compare the results of the measurements. The activities have been validated on chemistry teacher education students and are included in the practical part divided into sensory and instrumental parts. The...
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Water quality analysis using colorimetry
Kovaldová, Eliška ; Zumberg, Inna (referee) ; Čmiel, Vratislav (advisor)
This bachelor's thesis deals with the analysis of water quality using colorimetry. Part of the work is an introduction to the physical and chemical parameters of water, as well as optical methods, which include photometry, spectrophotometry and colorimetry, and an introduction to regression analysis. These methods and analysis are followed by a practical part by measuring pH, nitrate and water hardness using a spectrophotometer and an AS7262 visible light sensor with a SparkFun development board. At the end of the work there is a comparison of absorption spectra, calibration curves and linear regression parameters of both methods.
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Processing of sauerkraut juice to enhance its stability and consumer acceptance
Kohoutová, Lenka ; Mikulíková, Renata (referee) ; Hoová, Julie (advisor)
This diploma thesis focuses on the development possibilities of fruit and vegetable juices containing sauerkraut juice, the characterization of their nutritional and sensory qualities and their stability, as well as the potential for enriching selected juices with probiotic culture of Lactobacillus plantarum. The best combinations of various juice mixtures were selected based on sensory analysis and were stored for 30 days at 8 °C. Changes in selected parameters were monitored during the storage. Antioxidant activity, total flavonoids and polyphenols content and content of total water-soluble and reducing saccharides were determined by spectrophotometric methods. HPLC was used for lactic and L-ascorbic acid determination, flow cytometry was used for probiotic cell content determination, culture test was used to observe viability of cells, pH was monitored. Contents of antioxidant activity and of total polyphenols content did not drastically change during the storage. Major changes were observed in total and reducing sugar content and total flavonoids content. It was observed that probiotic viability was preserved for 14 days, decrease occurred afterwards. In order to achieve as high content of probiotics as possible, it would be advisable to store probiotically enriched juices for maximum of 14–19 days at temperature of 8 °C. The highest viability was observed in JHM sample (containing apple, pear, carrot and sauerkraut juice in the same ratio). Even through viability of probiotic cells was determined as low, these presented functional beverages remain nutritionally, visually and taste-wise interesting products, which can help popularize the consumption of non-traditional local foods.
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Antioxidative parameters of fruit model product.
KRATOCHVÍLOVÁ, Lenka
The content of the main components (anthocyanins, quercetin, chlorogenic acid, L-ascorbic acid, rutin, total polyphenols) was determined in the syrup of elderberries (Sambucus nigra L.) by spectrophotometry or high-performanceliquid chromatography. Furthermore, the antioxidant activity of this syrup was determined using three methods: ABTS, FRAP, and DPPH. The measurement results were statistically processed and compared using correlation analysis, specifically using the Pearson correlation coefficient. It was found that the prepared product contains 2160 mg/kg anthocyanins, 201 mg/kg rutin, 26 mg/kg chlorogenic acid and 679 mg/l polyphenols. No free quercetin was found. The content of L-ascorbic acid in the original elderberries was relatively low and therefore for study purposes, the syrup was enriched with this substance in the amount of 0.5% (w/w) to study the connection of its content with other substances. It is clear from the statistical processing that the concentration of chlorogenic acid correlates with the antioxidant activity measured by the FRAP method and the concentration of polyphenols to the antioxidant activity measured by the DPPH method.
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