National Repository of Grey Literature 59 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Development of a novel method for nucleotide pool analysis in bacterial cells
Zborníková, Eva ; Rejman, Dominik (advisor) ; Pacáková, Věra (referee) ; Kozlík, Petr (referee)
(EN) This thesis deals with the determination of nucleotides in bacterial cells. Nucleotides play crucial role in most of the metabolic pathway. Determining their concentrations could give us important clues about the influence of internal and external conditions on the bacterial metabolism. Previously published papers dealing with the analysis of nucleotides and other intracellular metabolites can be divided into two groups according to the analytical approach: a) metabolomic approach and b) targeted approach dealing with narrow group of target analytes. In the case a) most authors use the state-of-the-art LC-MS/MS technique, whereas in the case b) robust UV detection coupled mainly to IP-LC is widely used. The aim of this study was to combine both approaches to obtain a method for routine analysis that would take advantages of mass detection, such as sensitivity and selectivity, while avoiding the need of demanding optimization of MS/MS transitions and expert service. The main purpose of the newly developed HILIC-MS method is its universal applicability in most biological and biochemical laboratories.
Separation of polar pharmaceutically active compounds by multimodal chromatography with UV and MS detection.
Grybinik, Sofiya ; Bosáková, Zuzana (advisor) ; Pacáková, Věra (referee)
This thesis is focused on the analysis of pharmaceutically active ingredients with use of mixed-mode liquid chromatogrpahy on columns Acclaim mixed-mode WAX-1, Acclaim mixed-mode WCX-1 and Acclaim mixed-mode HILIC-1. For the purpose 16 analytes were chosen with acidic, basic or neutral properties. All the analytes are of great use in pharmaceutical industry thus their efficient separation plays a very important role. Mixed-mode chromatography is becoming an increasingly popular method for the analysis of diverse compounds thanks to its mechanism based on the combination of two and more interaction modes (hydrophilic interaction, ion-exchange and reversed-phase mechanism). This HPLC technique can be useful for the analysis of the compounds which are poorly soluble in mobile phase while using reversed-phase techniques for charged and polar compounds. Considering the above mentioned facts the application of mixed-mode stantionary phase can be especially beneficial for the development of new drugs which may have various physical and chemical properties. In this work 16 analytes were analysed under different conditions. The data obtained from the measurements was used to construct the plots depicting relationship between the retention factors of analytes and organic compound content, buffer...
Determination of proteinogenic amino acids by high-performance separation techniques
Hodek, Ondřej ; Křížek, Tomáš (advisor) ; Pacáková, Věra (referee) ; Tůma, Petr (referee)
(EN) Proteinogenic amino acids are key components of living organisms. Thus, the latest metabolomics research has focused on developing fast and sensitive methods for the determination of amino acids. In this context, this thesis contains two studies describing development of high-performance separation techniques for the quantification of amino acids. In the first study, a capillary electrophoresis method was developed for the determination of free amino acids in tobacco plants, particularly focusing on optimizing the extraction of amino acids from solid plant materials. The extraction procedure was optimized using design of experiments (DoE) to obtain the highest possible extraction yield of amino acids. Factors such as volume and concentration of the extraction solvent (hydrochloric acid) were assessed as the most significant. Subsequently, the optimal values of these factors were determined using response surface methodology (RSM). Lastly, proteinogenic amino acids were quantified using capillary electrophoresis with contactless conductivity detection and calibration with internal standard, which improved the precision of the method. The second study aimed at developing a supercritical fluid chromatography method for the determination of free proteinogenic amino acids in human plasma. The most...
Polymeric nanofibrous carriers for local application of hydrophobic drugs - studying of the drug release profiles by HPLC
Hampejsová, Zuzana ; Bosáková, Zuzana (advisor) ; Pacáková, Věra (referee) ; Marie Tlusťáková, Marie (referee)
Immunosupresive and cytostatic drugs have many serious side effects which are dose dependent. Local application of drugs prolongs and increases the concentration of drug in the target place and, therefore, may reduce their serious side effects. Polymeric fiber carrier could be used as drug delivery system for local application. Polylactide (PLA) micro/nanofibers containing hydrophobic drugs (immunosupresive drug cyclosporine A and cytostatic drug paclitaxel) were prepared to study this potential medicinal application. Poly(ethylene)glycols (PEG) of various molecular weight (6, 20 and 35 kDa) were incorporated to the structure of fibers to improve compatibility of PLA-drug system and influence the release profiles of hydrophobic drugs. For the systematic development of these materials, it is important to describe the context of the preparation of nanofibers, their morphology and drug release profiles. Therefore, HPLC methods with tandem mass spectrometric or UV detection were optimized and validated to determinate the influence of composition of nanofibers on release kinetics of drugs to different medium (phosphate buffer, hydrogels). The nanofibers with added PEG released significantly higher amounts of drugs and prolonged the release time, compared to the fibers containing only drugs. A multiple...
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš ; Křížek, Tomáš (advisor) ; Pacáková, Věra (referee) ; Srbek, Jan (referee)
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
Utilization of mass spectrometry for analysis of biologically active compounds
Kaliba, David ; Jelínek, Ivan (advisor) ; Pacáková, Věra (referee) ; Smrček, Stanislav (referee)
This PhD thesis provides a commented set of four publications. These publications are focused on capillary electrophoresis, liquid chromatography, and UV/Vis spectrometry used to study complexes of rhenium with aromatic ligands. The methods of mass spectrometry with soft ionization techniques, 1 H and 13 C nuclear magnetic resonance, and infrared spectrometry were used for structural characterization of the individual complexes. The complexes were synthetized in reactions of the rhenium precursor tetrabutylammonium tetrachlorooxorhenate with the corresponding ligand under both aerobic and anaerobic conditions. In the course of the research, it was revealed that the prepared complexes (with Re in the oxidation number +V and +VI) are unstable and their oxidation numbers change to another more stable form (Re+VII ). Sub-projects which were successfully implemented during the research were as follows:  Design and successful realization of the process of synthesis of selected rhenium complexes with aromatic ligands 1,2-dihydroxybenzene, 1,2,3-trihydroxybenzene, and 2,3-dihydroxynaphthalene in reactions with and without air access, and their structural characterization by ESI-MS, APPI- MS, LDI-MS, ESI-MS/MS, NMR, and IR.  ESI-MS SRM and UV/Vis time studies of the behaviour of primary rhenium complexes...
Analysis of biologically active substances by modern separation methods
Bierhanzl, Václav Matěj ; Čabala, Radomír (advisor) ; Pacáková, Věra (referee) ; Sýkora, David (referee)
The thesis is dedicated to the phospholipids and their polar headgroups analysis by gas chromatography, capillary electrophoresis and mass spectrometry. Phospholipids are the most important polar lipids and they are classified into phospholipid classes according to their phosphorylated groups. Phospholipids can be found in cell membranes and the changes in their ratio are monitored to research the impact of external conditions on cells. Actually thin layer chromatography is still used for phospholipid class ratio analyses. It is not suitable for microbiological research due to its time demandingness. The presented compendium of papers engaged in phospholipid classification is targeted on Bacillus subtilis strain, which produces potential antibiotics with detergent effect - surfactin. Published methods can be used for research of optimal conditions for producing microbe cultivation. Because non-polar parts of the phospholipid molecule (fatty acids) can affect the analysis methods on spliced polar headgroups have to be designed. Capillary electrophoresis and gas chromatography methods were developed and the latter one was further optimized for simultaneous analysis with fatty acids. Additional part deals with an alternative approach which consists in direct injection on mass spectrometer of intact...
Hybridly stabilized arc as a tool for biomass gasification and the degradation of water-soluble organic compounds
Hlína, Michal ; Pacáková, Věra (advisor) ; Jelínek, Ivan (referee) ; Pekárek, Stanislav (referee)
(EN) A plasma torch (the source of plasma) with Gerdien arc was utilized as the source of energy in a reactor for gasification of biomass and for the degradation of organic compounds dissolved in water circling around the arc where the dissolved compounds are exposed to an intensive ultraviolet radiation. Thermal plasmas have electrons, ions and neutrals in thermal equilibrium and are quite often characterized by higher pressures and temperatures than nonthermal plasmas. Therefore, thermal plasmas generally carry a huge amount of energy which can be employed for heating and subsequent gasification of various types of materials. Thermal plasma gasification reactors are operated at higher temperatures than conventional reactors which results in a very good composition with a high percentage of hydrogen and carbon monoxide in produced synthetic gas. Spruce sawdust and spruce pellets were gasified at feeding rates up to 60 kg/h. Oxidizing media such as water, carbon dioxide, oxygen or their mixtures had to be added to the reactor during experiments to avoid the formation of solid carbon. The compositions of produced gas significantly corresponded to calculated compositions and the produced gas was of high quality - hydrogen content approximately 45 % vol., carbon monoxide approximately 48 % vol., a...

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