National Repository of Grey Literature 41 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
The use of electrochemical oxidation in abacavir degradation studies
Pražáková, Lucie ; Kubíčková, Anna (advisor) ; Kozlík, Petr (referee)
The focus of this bachelor's thesis is the electrochemical degradation of abacavir. Abacavir is the active pharmaceutical ingredient of the medicine for human immunodeficiency virus (HIV). It was developed an electrochemical method for the oxidation of abacavir, including its excipients found in Ziagen tablets given to patients. Abacavir at a concentration of 0,15 mg·cm-3 was oxidized electrochemically at a constant potential (1,15V) on a specially assembled three-electrode apparatus. Subsequently, the quantity and type of the resulting products were analysed by a previously optimized chromatography method. The oxidation was relatively fast. After 7 minutes about 20 % of abacavir was oxidized. Two oxidation products were formed and their structures were confirmed by mass spectrometry.
Comparison of Calibration Methods for Determination of Quinine in Beverages
Handlová, Zuzana ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
The aim of this bachelor thesis is to compare three calibration methods used for determination of quinine in beverages performed by two instrumental methods. As the calibration methods, calibration curve method, standard addition method and spike were chosen. As the instrumental methods, UV spectrometry and RP-HPLC with UV and fluorescence detection were chosen. The calibration methods were compared in terms of accuracy, precision, and time consumption. The instrumental methods were compared in terms of accuracy. Five different tonic waters were chosen as authentic samples. The most precise results were provided by the calibration curve method. In terms of accuracy it was not possible to determine the most accurate calibration method. Spike was the least time-consuming calibration method. HPLC was more accurate compared to spectrometry. Key words: analytical calibration, spectrometry, high performance liquid chromatography, quinine
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.
Use of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection for metabolomic analysis of Gloeophyllum trabeum fungus
Kuchler, Ondřej ; Sobotníková, Jana (advisor) ; Kozlík, Petr (referee)
Fungus Gloeophyllum trabeum (Agaricomytes: Gloeophyllates) is a brown rot wood-decay fungus which produces a vast spectrum of volatile secondary metabolites. Scientific publications state, that one of the metabolites produced by G. trabeum, can be the substance (3Z,6Z,8E)-dodecatrien-1-ol. This chemical substance is also the main component of trail-following pheromone of Rhinotermitidae termite family. In this diploma thesis, I was trying to verify whether various species of G. trabeum are in fact capable of producing the substance (3Z,6Z,8E)-dodecatrien-1-ol. I was also focusing on the effects of saccharides, present in nutrient solutions, on quantitative and qualitative change in composition of volatile secondary metabolites produced by G. trabeum. The saccharides I used for my research were - maltose, fructose, sucrose, xylose, and mannose. The analysis was made by using comprehensive two-dimensional gas chromatography separation technique with time-of-flight mass spectrometric detection (GC×GC-TOFMS). During my research I discovered that one of obtained species of G. trabeum can produce substance (3Z,6Z,8E)-dodecatrien-1-ol, but only under specific conditions. It is produced when cultivating on Petri dishes on agar - cellulose growth media. The measurement was further validated by...
Characterization of lipids with four ester bonds in vernix caseosa by HPLC / MS
Tomášková, Sabina ; Cvačka, Josef (advisor) ; Kozlík, Petr (referee)
Diploma thesis is devoted to the analysis of triacylglycerol estolides (TG-est) by HPLC/MS. These lipids contain four ester bonds. TG-est are part of some vegetable oils and in mammals function as a storage form of metabolically important fatty acid estolides. The aim of this thesis was to prove the existence of TG-est in vernix caseosa and explore the possibilities of analysis in this material. Standards of TG-est were studied with using high-resolution and tandem mass spectrometry. Was suggested and optimized HPLC method for TG-est in a reverse nonaqueous system with the use of column Kinetex C18 and gradient elution with acetonitrile and 2-propanol. This method was used for analysis vernix caseosa fraction, and it was shown that TG-est are present in the sample. Attempts to simplify the lipid sample before analysis HPLC/MS by TLC fractionation were not very successful.
Separation and identification of lipopeptides by chromatography and mass spectrometry
Pravdová, Adéla ; Cvačka, Josef (advisor) ; Kozlík, Petr (referee)
5 Abstract Protein lipidation occupies an important place in the post-translational modification group. It plays an important role in the processes of cell differentiation or synaptic transmission. Changes in the presence of lipidated proteins may in some cases indicate the appearance of human diseases such as Huntington's disease, schizophrenia, or cancer. For this reason, their analysis has become desirable, but also problematic due to its specific characteristics. This work is focused on the development of conditions for measurement of lipopeptides produced by cleavage of proteins containing lipomodification. Two separation procedures were tested, in which the aim of work was to enrich the lipopeptides and remove as many other molecules as possible from the samples. The first test method - phase interface separation, using water and chloroform, was able to concentrate the lipopeptides on the phase interface and separate some of the added unmodified peptides from the mixture. The second method of separation was a solid phase using a C18 stationary phase. As a more suitable solid phase extraction variant, elution with solutions containing acetonitrile with trifluoroacetic acid was chosen as compared to solutions containing isopropyl alcohol. With the modified elution procedure, it was possible to separate...

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