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Isolation and fractionation methods for determination of humic substances content in South Moravian lignite
Černý, Pavol ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis focuses on isolation and fractionation of humic substances (HS) from the natural matrix of lignite, which comes from southern Moravia from the mine Mír Mikulčice. In the theoretical part, it informs the reader about the issue, starting with information about lignite and HS. In this work, the standard procedure of isolation and fractionation of HS was used as according to the International Humic Substances Society (IHSS). The content of HS in the natural matrix of lignite was determined, and then isolated HS were subjected to physicochemical characterization – elemental analysis (EA), thermogravimetric analysis (TGA), UV/Vis spectrometry, infrared spectrometry with Fourier transformation (FTIR) and the acidity of humic acids (HA) was determined by potentiometric titration. EA was used to detemine the content of biogenic elements, moisture and ash content were determined by TGA. By using FTIR, various functional groups and building blocks that are present in supramolecules of HS were indentified and absorption coefficients EET/EBT, E2/E4, E2/E3 a E4/E6 were determined by UV/Vis spectrometry. Results represent good characterization of HS isolated from lignite and are in agreement with scientific literature.
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Determination of Paracetamol content in selected drugs using ATR-FTIR spectrometry
Waczulíková, Kristína ; Sedláček, Petr (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis deals with determination of paracetamol content in selected drugs by ATR-FTIR spectrometry and aims to design and optimize determination of paracetamol in dosage forms by a direct measurement of the sample, called ‘dry way’. Tablets of three drugs containing paracetamol have been studied. Wavelength ranges were determined from the measured FTIR spectra as regions where the absorptions of fillers (microcrystal cellulose, starch and magnesium stearate) were minimal. Absorption bands of paracetamol were selected at the wavenumbers of 1 503 cm-1 and 1 224 cm-1 in order to construct a calibration curve. The contents of paracetamol in the drug tablets were calculated using calibration curves obtained by the method of simple regression analysis. The lowest deviation from the amount of 500 mg paracetamol per tablet as reported by the manufacturer was from the calibration curve for paracetamol with microcrystalline cellulose. The determined amounts of paracetamol per tablet in the selected drugs lied within range 493.5–505.5 mg. These results point to the conclusion that the ATR-FTIR spectrometry method can be used for the quantitative determination of paracetamol in drugs using direct measurement, as deviations from the reference value of 500 mg did not exceed 1.5 % for cellulose and 3.85 % for magnesium stearate and therefore are within acceptable limits for the exploratory study.
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Use of Hofmeister series of ions for fractionation of soil humic acids
Kebabová, Mona ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The bachelor thesis deals with the study of the structure and behaviour of humic acids (HA) in the presence of salts of the Hofmeister series of ions. Haplic Luvisol and sodium humate extracted from it were characterized by elemental analysis (EA) and thermogravimetric analysis (TGA) to determine the percentage of elements and ash. Fourier Transform Infrared Spectroscopy (FT-IR) was used to determine the functional groups in the sample. UV-VIS was used to investigate the effect of the Hofmeister salts. From its results were calculated the absorption coefficients EET/EBZ, E2/E3, E2/E4 and E2/E6, and the specific absorbance values SUVA254 and SUVA280. Other methods like Dynamic Light Scattering (DLS) and fluorescence spectroscopy were used to better understand HA's structure. The main goal of this bachelor thesis was to find a simple experimental method based on which we would be able to study supramolecular associations of HK, which are preferentially linked to the formation of weak intra- and intermolecular interactions in aqueous solutions.
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Determination of content of selected nonsteroidal antiphlogistic – Ibuprofen in drugs using UV/Vis and FTIR spectrometry
Lindovský, Jiří ; Sovová, Šárka (referee) ; Enev, Vojtěch (advisor)
The main aim of bachelor thesis was to validate the content of the nonsteroidal antiphlodstic in drugs using spectrometric methods and subsequent comparison of results. Specifically, the thesis is focused on Ibuprofen, which is used mainly as analgesic and antipyretic. This substance was chosen for its significant ability of absorbing electromagnetic radiation in ultraviolet and infrared regions of spectra. For this purpose, various generics were selected and analyzed by molecular absorption spectrometry (UV/Vis) and infrared spectrometry with Fourier transform (FTIR). Very important factor influencing chemometric properties of the obtained results was optimalization of the spectrometric methods. After designing the working procedure, sample solutions were prepared from Ibuprofen-containing dosage forms using suitable solvent and these samples were analyzed spectrometrically. The content of Ibuprofen in individual samples was calculated from the measured UV/Vis and FTIR spectra using method of standard addition. The results show that infrared spectrometry seems to be more suitable method for determining the Ibuprofen content. Nevertheless, it should be noted that the choice of a suitable extractant is very important step in the determination. The information obtained from this bachlor’s thesis could be used in future routine inspections and monitoring of drugs.
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Study of biological activity of superabsorption polymers
Männlová, Adriana ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
This thesis is focused on the study of the biological activity of superabsorbent polymers for environmental and agricultural applications. Generally these hydrogels perform many functions in the soil, which is increasingly stressed by treatment with synthetic fertilizers and thus loses their natural properties, such as the uptake of moisture. Addressing these issues is now in superabsorbent polymers that can absorb and also retain a lot of water around the root system as long as possible. They can perform the function of carriers gradual release fertilizer. Based on the literature review was designed and conducted the study of biological activity in the soil model on corn sown. SAPs were prepared in the framework of contract research Faculty of Chemistry of the Technical University in Brno with the company Amagro Ltd. The content of the experiment, the superabsorbent polymer, observing effects on the growth of dent corn. He was also studied root system for absorption of nutrients. Further changes were observed rheological properties of prepared superabsorbent polymer, superabsorbent polymers since they provide a source of nutrients and help to retain moisture in the soil, it is necessary to know their viskoelstick properties even at temperatures below freezing. This work is based primarily on the use of great motivation superabsorbent polymers in agriculture and also in environmental protection.
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Stability of natural oils used in cosmetics and pharmaceuticals
Milerová, Helena ; Enev, Vojtěch (referee) ; Hurčíková, Andrea (advisor)
The bachelor's thesis deals with the issue of stability of selected plant oils used in the cosmetic industry. Six oils were subjected to analysis using differential scanning calorimetry (DSC), which determined the oxidation onset temperatures for all samples. The aim of the thesis is to evaluate the use of the DSC method for obtaining data on the thermo-oxidative stability of plant oils. For comparison, the samples were also measured using the Rancimat method, a commercially established procedure in which the samples were exposed to elevated temperature using air flow. The results yielded induction periods, which indicate the time until the sample starts to oxidize. After measuring the samples using both methods, the oils were ranked according to their oxidative stability from the most stable to the least stable. The resulting sequences from both methods were nearly identical. DSC has proven to be a suitable method for measuring the thermo-oxidative stability of plant oils.
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Effect of freeze-drying conditions on the hydrophobic interaction between native hyaluronan and fluorescent probe
Říha, Karel ; Venerová, Tereza (referee) ; Enev, Vojtěch (advisor)
The biopolymer native hyaluronan possesses the amphiphilic character of its molecule. Which means that it contains both a hydrophilic and a hydrophobic part. This character of the molecule favors interactions between hydrophobic ligands and hydrophobic parts of the chain, making hyaluronan one of the compounds potentially suitable as drug carrier systems. The aim of this bachelor thesis was to prepare a carrier system based on hyaluronan and model hydrophobic compounds (fluorescent probes). The fluorescent probe we used was pyrene. Furthermore, the work was focused on the study of lyophilization conditions, which would lead to the actual influence of hydrophobic interactions between the substances we used. The main techniques that served us to verify the effectiveness of lyophilization (in the sense of supporting the creation of a hydrophobic effect between individual hyaluronan chains) were: thermogravimetric analysis, fluorescence spectrometry, and last but not least, infrared spectroscopy with Fourier transformation.
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Program-controlled freeze drying for the preparation of the drug-delivery system based on polysaccharide and hydrophobic molecules
Dufková, Michaela ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
The lyophilization process favors the hydrophobic effect between the individual dextran chains. This hydrophobic effect allows hydrophobic drugs to settle and remain within the biopolymer. Due to hydrophobic effect, dextran can serve as a carrier for the distribution of hydrophobic drugs. The goal of this thesis was to prepare a carrier system based on native dextran using program-controlled freeze-drying. Hydrophobic drugs were modeled using the fluorescent probes pyrene and prodane. The effectiveness of promoting the hydrophobic effect was studied using infrared spectrometry, fluorescence spectrometry and scanning electron microscopy. Using ATR-FTIR spectrometry, a shift of the absorption band of thevalence vibration of the C–O bond in OH groups in alcohol was observed. Using fluorescence spectrometry, the emission polarity index was calculated for pyrene from the 1st and 3rd maximum fluorescence intensity, and for prodan, a shift of the maximum fluorescence intensity to lower wavelengths was observed. SEM images showed that during the lyophilization process, the dextran structure formed a dense network of fibers, indicating the presence of many sites with a higher content of hydrophobic domains. Positive results were obtained with these methods, which proved the positive effect of lyophilization on the formation of a hydrophobic effect between individual polysaccharide chains. The results may contribute to the development of carrier systems for hydrophobic drugs.
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Physicochemical characterization of soil humic substances isolated from modal brown soil
Churina, Iuliia ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
This bachelor thesis deals with the physicochemical characterization of soil humic substances isolated from brown earth modal based on the international IHSS procedure. Humic substances are organic compounds occurring in soil and have a significant influence on soil processes and properties. The aim of this work is to obtain detailed information on the physical and chemical properties of humic substances such as mean molecular weight (Mr), spectral characteristics, elemental composition and thermal stability. Soil humic substances samples were characterized by thermal techniques such as thermogravimetric (TGA) and elemental analysis (EA). Different instrumental methods such as UV/Vis spectrometry, infrared spectrometry and fluorescence spectrometry were used to analyze the samples. The results of this work can contribute to a better understanding of soil processes and properties, which can lead to improved agricultural production and environmental protection.
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Enzymatic Degradation of Biochar
Zmijová, Marie ; Enev, Vojtěch (referee) ; Kalina, Michal (advisor)
Human prosperity is inextricably linked to healthy soil. It turns out that the application of biochar improves soil properties and, as a result, also the growth and yield of plants. The presence and activity of soil biota contributes to soil quality, but it also excretes compounds that can degrade biochar. Experiments simulating the action of enzymes and root exudates were carried out in order to find out whether there are physico-chemical changes in biochar. Three biochars, which were chosen for this purpose were degraded using an H2O2 solution, simulating enzymatic action. Samples were subsequently analyzed using TGA, FTIR, SEM and contact angle measurement. It was found that the amount and type of degraded biochar matter depends on the parameters of its production. The amount of functional groups containing oxygen on the surface of biochar rises due to enzymatic oxidation and the surface’s hydrophobicity decreases as a result. An extraction test using citric acid, a root exudate representative, showed that the sample had been washed more effectively, leading to a higher proportion of organic matter in the biochars. In the obtained leachates, the amount of elements released from the biochar was monitored using ICP-OES. The initial washing led to the release of the largest amount of micro and macro elements, which caused a decrease in the pH value of the solution and an increase in conductivity. The pH value of the solution had a major influence on the amount of released multivalent elements (Ca, Mg). The combination of these changes that may occur in the soil system probably does not change the desired effect of biochar and its use may be beneficial in the long term.
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