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Preparation and characterization of polyaniline-coated stationary phases doped with silver
Pátereková, Viktória ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
The aim of this study is a preparation of polyaniline stationary phases doped with silver for application in HPLC. Various polyaniline coated stationary phases differing in the addition of AgNO3 were polymerized. Some of them were subjected to Ag sedimentation, in others AgNO3 was added after polymerization. Stationary phases were investigated by scanning electron microscopy, atomic absorption spectroscopy, Raman spectroscopy, and Fourier transformation infrared spectroscopy. Columns filled with prepared stationary phases were compared with silver-free polyaniline column by separating a mixture consisting of caffeine, theobromine and theophylline in three chromatographic modes (NP-pure ACN, HILIC-98/2 (v/v) ACN/water and RP-20/80 (v/v) ACN/water) at a flow rate of 5 µL/min with UV detection at 265 nm and also by separating a mixture of 2'-aminoacetophenone, 3'-aminoacetophenone and 4'-aminoacetophenone in the same chromatographic modes, at a flow rate of 5 µL/min except from RP mode where a flow rate of 10 µL/min was used to accelerate separation. Polyaniline-coated columns doped with silver showed different selectivity in the RP mode of the mixture of caffeine, theobromine and theophylline when compared to polyaniline-coated columns without the addition of silver. Further, the columns were tested for...
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Development of method for determining aminoacid loading in solid phase peptide synthesis
Mácha, Hynek ; Nesměrák, Karel (advisor) ; Křížek, Tomáš (referee)
A simple method has been developed to determine amino acid loading in solid phase peptide synthesis. The method is applicable for the most common type of synthesis, which use FMOC as protective group and piperidine as a deprotecting agent. Both products of deprotection reaction are separated by HPLC and determined using an UV detector; an internal standard is added. The method gives true values that have been verified by an independent method. The RSD is 1.52%. The method is more accurate than the published methods and allows the determination from the waste of synthesis. The employing of the internal standard eliminated the necessity of dilution accuracy or known volumes.
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Characterization of different bran species in terms of ferulic acid content
Nábělek, Jakub ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor’s thesis works with an alkaline extraction of a ferulic acid from different kinds of cereal bran. Another researched issue was extraction of nutritionally interesting elements extracted from bran and from hydrolysed waste. Those extracts has possible usage as a mineral fertilizer for plants. In the theoretical part, this thesis deals with problematice of cereals, composition and differences in a cereal grain depending on kinds of cereal and an enviromental conditions. Chemical composition of cereal materials, focused on phenolic acids are also described. Another part deals with theoretical background of methods for the extraction of phenolic acids from bran with description of advantages and disadvantages. Methods for alkaline hydrolysis and extraction of minerals from different kind of bran bran are described in experimental part of this work. Sodium hydroxide (0,5 M) was used for the hydrolysis of bran material. For the determination of the yields of ferulic acid, HPLC method with UV/VIS detection at wave-length 330 nm with usage of mobile phase mixture of methanol and 0,5 % solution of formic acid was used. Acidified deionized water was used for the extraction of nutritionally interesting elements from bran and also from the hydrolyzed material. For the determination of the elemental composition of extracts (Cu, Fe, Zn, Mn, P, Ca, K, Mg), ICP-OES method was used. It was found, that differences in wheat bran species in terms of yields of Ferulic acid are satistically important. The biggest yields of ferulic acid was obtained from the sample of spelt. The smallest yields of this acic was obtained from the sample of oat. Content of micro and macro-elements showed statistical important differences in different kinds of bran and their hydrolyzed waste. Most abundand elemets were obtained from rice bran and from spelts hydrolyzate. The smallest abundand elemens were obtaned from oat bran and hydrolyzate.
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Developement and optimization of the method for the extraction of ferulic acid from wheat bran
Hubačová, Klára ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
Bachelor thesis is considering usage of wheat bran for an extraction of ferulic acid. Wheat bran is a large-scale by-product of milling industry which is produced during milling of cereals (wheat) into flour. This low-cost product is usually used as a livestock feed. An initiative is raised for some other potential applications, because too large quantity produced every year can not be consumed just as a feed. There is a significant amount of phenolic acids from which ferulic acid is the most abundant one. It was found out after examination of structure of the wheat bran. This acid is connected with polysaccharides of a cell wall. The alkaline hydrolysis was used to disrupt a linkage between ferulic acid and polysaccharides. Then ethanol was added to precipitate the polysaccharides and the mixture was filtered. The filtrate contains ferulic acid which has great health benefits such as anti-inflammatory, antioxidant, anti-carcinogenic, antimicrobial effect etc. It plays an important role as an agent against UV radiation in the cosmetic products.
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Determination of organic acids in beer
Štáblová, Taťána ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
The topic of this bachelor’s thesis is determination of organic acids in Czech beers with protected geographical indication. There are described the main components for beer production and the production of malt and beer itself in the theoretical part. Part of this work is dedicated to analytical methods used in determination of organic acids. High–performance liquid chromatography and ion chromatography were used to determine the content of organic acids. The experimental part deals with sample preparation, calibration solutions and procedure of analysis. The obtained results of analyzed substances are summarized, discussed, and compared with results of analyses of foreign papers. Differences in content of organic acids in lager and draught beers were determined. Five lager beers and five draught beers were used for the analysis.
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Use of rare oils in cosmetics
Pilipenco, Alina ; Szotkowski, Martin (referee) ; Němcová, Andrea (advisor)
The purpose of this bachelor thesis was to research rare oils. The oils from selected plants (poppy, cannabis, thistle) is characterized by the content of active phenolic compounds, fatty acid composition, antioxidant and antimicrobial effects. First part of the thesis is a literary research on a given topic, which contains the following parts: the universal chemical composition of vegetable oils, the characteristics and effects of selected oils and the ways of their obtaining for cosmetic purposes. The experimental part is focused primarily on the basic analysis of selected oil components and the preparation of the shower oil based on the obtained results. In conclusion are presented an overview of all the properties of selected oils, their practical use and assessment of their application in cosmetics.
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The possibility of using of elderberry fruit pomace
Ondrušová, Pavlína ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This diploma thesis concerns the determination of anthocyanin pigments in the elderberry pomace (Sambucus nigra L). The theoretical part describes in general the plant specification, its chemical composition, botanical characteristics and the possibility of utilization of elderberry in food processing industry and in pharmacy. However, the main concern of this thesis are the anthocyanins. This part is closely focused on chemical structure and factors that have significant influence over their stability. There are briefly summarized the positive effects of these colourants and their use in the food industry. In the experimental part, the elderberry juice and the extracts from the rhizomes were prepared. Two different solvents, a 1: 1 water / ethanol mixture and a mixture of water and methanol in the same ratio were used as extractors. To identify and quantify the dyes in the prepared samples, a chromatographic separation system (HPLC) with a Kinetex EVO C18 column and isocratic elution of the combined mobile phases of water of acetonitrile and formic acid was developed. The analysis only took 12 minutes. Two major dyes cyanidin-3-glucoside and cyanidin-3-sambubioside were identified and quantified by HPLC. The largest amount of anthocyanins was obtained by extracting mixture methanol / water (594.6 ± 0.42 mg.100 g-1). The content of anthocyanin dyes in dry extracts and juice was also determined by the often-used pH-differential method. Both results were compared. The HPLC method provided very accurate results against the less demanding pH-differential assay method, which proved to be suitable for the indicative measurement of anthocyanin content in real samples.
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Influence of the filtration and pasterurization on content of selected vitamins in beer
Šimíčková, Adéla ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This master thesis focuses on the influence of the filtration and the pasteurization on the content of the selected vitamins in beer. Specifically, the vitamin B2, B3, B6, B9 and B12. The high performance liquid chromatography with diode array detector was used as a separation method for the vitamin content analysis. First this method was optimized and then validated. The data obtained by analyzing 28 beer samples were evaluated using a statistical method – the analysis of variance. This method provided parameters P, F and Fcrit which are important for the assessment of the statistically significant differences between the individual groups of beer . Based on these parameters, a significant effect of the filtration was observed for the vitamin B2 and B3. The filtration has reduced the amount of the vitamin B2 while it increased the concentration of the vitamin B3. The pasteurization had no significant effect on the vitamin content.
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Study of the authenticity of chocolate with different content of cocoa solids
Vanduchová, Petra ; Dvořák, Miloš (referee) ; Diviš, Pavel (advisor)
This master's thesis deals with authenticity of chocolate with different content of cocoa solids. The theoretical part describes the production of chocolate products and the issue of food authenticity. Experimental part of this thesis is focused on the determination of total cocoa solids in the selected samples. Different samples of chocolate containing 50–90 % of cocoa were grated to fine particles, that were subjected to extraction without previous chemical treatment. The methylxanthines theobromine and caffeine were detected by HPLC to determine the content of fat–free cocoa solids. Fat–free cocoa solids content were found in the range 19,7–43,1 g/100 g of dry matter and the content of total fat was determined by the gravimetric method and was found in the range 30,9–55,4 g/100 g. The results of this thesis prove that, the producers meet the legislative requirements and the declared values are corectly declared on the wrappers of the product.
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Study of the chemical processes during kombucha technology
Chludilová, Markéta ; Obruča, Stanislav (referee) ; Pořízka, Jaromír (advisor)
The kombucha drink is referred to as leavened tea with added sponge called a scobie. In this way, a low-alcohol beverage is obtained, which gains considerable popularity, especially due to the alleged beneficial properties for human health. The microbial composition of this beverage is very rich, consisting of bacteria and yeasts living in a beneficial symbiosis [11]. The microbial composition of the drink and its beneficial effects on human health are very closely related. This work deals with the analysis of the chemical composition of the commodity beverage, especially with regard to the content of major components such as organic acids, carbohydrates and ethanol. These analytes are among the most common and most profoundly found substances in the carbohydrate beverage and are very closely related to the microbial composition of the scoby itself [3]. Combo beverage samples were supplied by RebornFood, one of which is the commercial production of this drink on the Czech market. At the same time, this company bases itself on purely natural fermentation of beverages, and therefore it is not particularly involved in the production process. The results of this diploma work point to the effect of the scoby used and the associated occurrence of analytes in the beverage, as well as the production process associated with the formation of analytes, which is described in several articles. It is expected that this work will provide information both on the production conditions and on the chemical properties of the beverage related to the condition of the scoby, which will be used further, both for RebornFood and the material used to solve the technical problems of this beverage production.
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