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Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Fischer, Jan (referee) ; Zima, Jiří (advisor)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
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HPLC separation of chlorophenoxypropionic acid derivatives
Horová, Kateřina ; Kalíková, Květa (advisor) ; Šlechtová, Tereza (referee)
This Bachelor's thesis focuses on the separation of chlorophenoxypropionic acids and their derivatives by a high-performance liquid chromatography. The separations were performed in a reversed phase mode. These compounds are employed as herbicides, i.e. chemical substances to control unwanted plants, to kill weeds. The herbicides studied for the purposes of this thesis were 2-(4-chloro-2-methylphenoxy)propionic acid, 2-(2,4- dichlorophenoxy)propionic acid, 2-(2-chlorophenoxy)propionic acid, 2-(3- chlorophenoxy)propionic acid and 2-(4-chlorophenoxy)propionic acid. The study aimed at finding and optimizing chromatographic conditions for simultaneous separation of all five herbicides mentioned above. The analysis employed two types of columns, that is ZORBAX SB-C8 column and ZORBAX Eclipse XDB-C18 column whose level of polarity differ. As mobile phases, there were used acetonitrile/water, acetonitrile/formic acid, pH 2.1 and methanol/formic acid, pH 2.1 in various volume ratios. ZORBAX SB-C8 column, mobile phase methanol/formic acid (concentration of 0.365 mol/l, pH 2.1) 40/60 (v/v), temperature of 25řC, and flow rate of 1 ml/min delivered the most convenient separation conditions. Given these isocratic conditions, all the herbicides were baseline separated within 80 minutes. Keywords: HPLC,...
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Biochemical methods as tool for study of reproductive proteins
Postlerová, Pavla ; Zigo, Michal ; Pohlová, Alžběta ; Jonáková, Věra
Study of molecular mechanisms in reproduction is essential for the understanding of this outstanding process. Our lab studies proteins secreted by reproductive organs and sperm using various biochemical methods for a long time. We have expertise in protein extraction from spermatic cells using different approaches, and by kits for proteins from the sperm surface and distinct subcellular compartments. The proteins of reproductive organ fluids are separated by chromatographic methods, such as size exclusion chromatography, high-performance liquid chromatography with reverse phase (RP-HPLC) and affinity chromatography on matrices with various ligands. Proteins are subjected to SDS- or 2D-electrophoresis for their characterization and comparison of various extraction methods, different mammalian species, and sperm in different functional development. Electrophoretically separated proteins may be transferred onto nitrocellulose membrane (Western blot) for antibody detection or binding studies with lectin-labelled ligands (lectins, polysaccharides, zona pellucida glycoproteins). We use immunoprecipitation method with specific antibody for protein determination followed by the MALDI identification. Proteins are localized by immunofluorescent techniques on/in spermatic cells and tissue sections of reproductive organs. Isolation of proteins from reproductive tissues and fluids, and the antibody detection is crucial for the studying of reproductive protein origin.
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Comparison of HPLC a GC-MS method for pesticide determination in soil
Chalbia Václavíková, Alena ; Kočárek, Martin (advisor) ; Havlík, Jaroslav (referee)
Physical and chemical properties of pesticides may vary significantly. Pesticides can be acidic, neutral or alkaline. Some compounds containing phosphorus, other sulfur, nitrogen or halogens. These atoms can be important for the detection of pesticides. Some of the compounds are volatile, others on the contrary not evaporate, which is also one of the important properties for chromatography. The diversity of pesticides actually makes it impossible to create a universal method, which is very impractical in terms of quality and time determination. Because that pesticides are one of the most chemicals in most countries. In the food and drinking water are limits on pesticides in order to avoid negative impact on public health. For residues in soil or surface water limits are set. (Lutz et al., 2006)
The objective of this thesis is to evaluate the possibility of using two types of chromatographs with different detectors for the analysis of pesticide. Pendimethalin which was chosen for this work, will be analyzed usinga liquid chromatograph with UV detektor and gas chromatography with mass detector. Both this method will be compared as well two extraction methods (Soxhlet extraction and shaking), and two extraction agents (methanol and acetonitrile).
Another point of the work is to provethe hypothesis that, for the determination of pendimethalin in soil is by gas chromatography using a mass spectrometer in comparison with the high performance liquid chromatography time and more expensive, but will achieve a higher yield and a lower detection limit of the pesticide.
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Determination of different forms of casein in milk
Kaňková, Veronika ; Hejtmánková, Alena (advisor) ; Markéta, Markéta (referee)
Casein proteins are important escpecially for cheese making. In addition to technology and other factors, casein concentration in milk and relative representation of individual casein fractions influence cheese yield. Majority fractions are alfa-casein, beta-casein and kappa-casein. For the determination of proteins in the milk can be used electrophoretic techniques or near infra-red spektrometry. High performance liquid chromatography (HPLC) is going to be used. HPLC is widely used analytical method, which is based on differential affinity of the substances to the mobile and the stationary phase.
The thesis has introduced the method of determining the casein fractions by HPLC. The method was partially optimized using cow milk and calibrated to the standard solutions, which were purchased casein fractions derived from the bovine milk. Real samples of cow, sheep and goat milk were analyzed. The goat milk was available in several variants: Sanski goat milk and white shorthair goat from domestic or farm breeding. All milk samples were analyzed for casein and casein fractions proportions. Chromatograms show that the casein formula is different in cow, sheep and goat milk. Different concentrations of the casein fraction in the milk of various animal species have been statistically detected in almost all cases. The exception was the concentration of beta-casein in the milk of white shorthair goat from the domestic and the farm breeding and cow milk. In these types of milk there was no statistically significant difference in the concentration of beta-casein. Analysis of individual samples of white shorthair goat milk from the farm breeding shown that casein content in the milk of different animals reared under the same conditions may be different. Ratios of beta-casein to alfa-casein, beta-casein to kappa-casein and alfa-casein to kappa-casein were evaluated in all samples. Interspecific comparisons proved that ratios were statistically significantly different in all milks. In the milk of Sanski goat, there was found the stable ratio of beta-casein to alfa-casein during lactation. For all goat milk there were typical higher values of the ratio of beta-casein to kappa-casein. The ratio of alfa-casein to kappa-casein was highest in the sheep milk. Despite some shortcomings, it is possible to use the HPLC method possible for these purposes, but it is necessary to continue with its optimization.
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Determination of vitamin E in wheat different grain discoloration types
Veverková, Markéta ; Hejtmánková, Alena (advisor) ; Faměra, Oldřich (referee)
The diploma thesis deals with the determination of vitamin E in grains of wheat kernels with unusual coloring. In the theoretical part is mentioned botanical characterization of wheat, barley and tritordeum, vitamin E and its chemical and biological aspects and basics of chromatography with a focus on the high performance liquid chromatography (HPLC).
The analysis to quanify vitamin E was performed in the experimental part of the thesis. The analysis was conducted with samples of winter and spring wheat, spring barley and spring tritordeum from harvests of 2014 and 2015. These were varieties with unusual coloring of the grain. The evaluation was conducted by variety (winter wheat, spring wheat, spring barely, spring tritordeum) and by the color of the kernels (blue aleuron, purple pericarp, yellow pericarp). Subsection part of the thesis is dedicated to a quantification of vitamin E during long-term storage.
Based on the determination of total vitamin E amount in all analyzed varieties of cereal grains with a different color is not statistically significant difference in the values of the total amount of vitamin E. The difference between the content of vitamin E in the samples of the same varieties of different cereals harvest from a year 2014 and a year 2015 were not statistically significant. All varieties of wheat were quantified four vitamers: alpha-tocopherol, beta-tocopherol, alpha-tocotrienol and beta-tocotrienol. The amount of other vitamers was below the limit of detection. The total content of vitamin E and contents of individual vitamers coincide with the data given in the literature for wheat varieties with standard color of grain. Spring barley contained a slightly higher average levels of total vitamin E amount in comparison with varieties of spring and winter wheat. The total average amount of vitamin E in varieties of spring tritordeum was also slightly higher than in varieties of winter and spring wheat. From the long term storage point of view, it is clear that the total amount of vitamin E in both varieties is relatively stable and shows no clear trend in function of storage time.
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Biogenic amines in beer
Čiháková, Dagmar ; Orsák, Matyáš (advisor) ; Braný, Pavel (referee)
This thesis deals with the technological process of brewing beer, describes the raw materials needed for its production, and points out the useful and harmful substances contained in beer as biogenic amines (BA). Furthermore, there are described the issues of biogenic amines in food and primarily in beer, which is a histamine, putrescine, cadaverine, tyramine and tryptamine. In the practical section BA was determined in lager bottom-fermented beers from local microbreweries and large industrial breweries.
Beer is according to legislation considered as a safe food containing a variety of healthful nutrients such as B vitamins, proteins, carbohydrates, minerals, soluble fiber and polyphenolic merged, which have anticarcinogenic, antioxidant and antimicrobial effects. On the other hand, in beer we can find harmful substances such as alcohol, heavy metals, N-nitrosamines, aromatic hydrocarbons, polychlorinated biphenyls, nitrates and biogenic amines.
In the second part of the research are summarized the issues of BA in certain foods and beverages, their chemical structure, the way how they are created and their negative effects on the human body. BA are natural, biologically active substances that are essential for the human organism. Their excessive amount in beer is toxic for the human organism. Ethanol contained in the beer decreases the activity of the enzyme monoamine oxidase, and this leads to reduced degradation of BA. Intoxication of BA can cause headaches, vomiting, hypertension, allergic reactions, rashes and even loss of consciousness, therefore, should be the content of these substances monitored.
In the practical part of this theses the samples of bottom-fermented beers were analyzed. The first group of samples included unfiltred and unpsaterized beers from microbreweries. In the second group there were filtered and pasteurized beers from large breweries. HPLC determined BA in beer (histamine, putrescine, cadaverine, tyramine and tryptamine). The resulting values indicate that the domestic beers contain biogenic amines in very small concentrations, thus satisfy the legislative standarts. The results were also compared between the two groups of samples. These samples showed that the beer from microbreweries is not contaminated as originally was expected. It shows good technological processes in the manufacture of beer in such small devices.
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Analysis of Organic Acids in Wine
Cindrová, Kristina ; Orsák, Matyáš (advisor) ; Weitosch, Štěpán (referee)
Wine contains organic acids, which determine its final quality. Tartaric and malic acids are found in dominant concentrations. Also present are citric, lactic and succinic acids, and some volatile acids such as formic and acetic acid. The process of winemaking is associated with changes in the concentration of wine acids. The composition of acids in wine is also affected by the type, quality and ripeness of grapes, grape manufacture and wine production.
The aim of this study was to analyse the concentrations of tartaric, malic, citric, lactic, succinic, formic and acetic acid during the winemaking process in different press fractions of 8 varieties of white wines from the Vineyard centre Mělník - Chloumek and in 5 commercially purchased red wines, using HPLC with DAD detection, and to analyse the trend of changes in different phases of the winemaking process. The white wine press fractions were supplied following the wine press (A), settling of juice (B), in the phase of partially fermented juice (C) and during the maturation of young wine (D-G.). The samples were taken within 2-3 days. There were no red wine press fractions available from the vineyard. 5 bottles of different varieties of red wine were thus purchased from the shop and analysed. The GraphPad Prism programme was used to perform statistical analyses (ANOVA).
The hypothesis suggesting that tartaric acid would be the dominant acid was confirmed in 5 varieties of white wine and in all red wines.
The hypothesis suggesting a difference between red and white wines was also confirmed. There were significant differences in the concentration and composition of acids between young white wines and red wines.
The hypothesis that the concentration of all acids would increase was not confirmed. Tartaric acid showed the most linear trends of decrease, followed by malic acid. The trend of change in the concentrations of succinic, lactic, citric and formic acid increased in some varieties and it decreased in others.
The grape variety, weather during summer and autumn and the manufacturing processes all influence the acid composition in wine. These factors can explain the differences seen between different varieties of wine.
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Sója - funkční potravina
Zedníčková, Pavlína
This diploma thesis is about soybean as functional food. Functional food contain components with positive effect on human health. In soybean there are lot of these components and very valued are phytoestrogens. Phytoestrogens has estrogenic activity with positive effect in prevention of osteoporosis, breast and prostate cancer, cardiovascular disease and menopausal problems. In experimental part was measured level of isoflavones in different kinds of soy food. The method for separation was high performance liquid chromatography with mass spectrometry.
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