National Repository of Grey Literature 101 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Monitoring process contaminants in coffee roasting using LC-MS
Ilyushchenkova, Alexandra ; Juglová, Zuzana (referee) ; Diviš, Pavel (advisor)
The bachelor thesis focuses on monitoring changes in the concentration of process contaminants during coffee roasting using liquid chromatography with mass detection. Green coffee was roasted at 220 °C for 14 minutes with two-minute intervals. Samples for analysis were taken from 10. by 24. minutes of roasting. Practical monitoring of the acrylamide’s formation during coffee roasting was not carried out, since it was not possible to detect acrylamide in coffee using a mass detector, even after its derivatization with thiosalicylic acid. The relevant data were taken from other scientific articles, which reported a linear increase in concentration with the roasting time up to the maximum value and a subsequent exponential decrease at the end of roasting. By monitoring 5-hydroxymethylfurfural, it was found that during roasting, this substance is gradually formed in coffee due to the decomposition of carbohydrates, however, with increasing roasting time, the degradation of this substance occurs quite quickly. The concentration of 5-hydroxymethylfurfural was also determined in coffee samples purchased in the trade network. Concentrations of 5-hydroxymethylfurfural in these samples ranged from 0,3 to 0,38 mg/kg, which are corresponded to those reported in other expert studies.
Optimization of concentration determination of degrdation products of uracil via LC-MS
Kavale, Gustav ; Ševčík, Jan (advisor) ; Míšek, Jiří (referee)
In the Czech Republic, tens of thousands of oncology patients undergo treatment based on fluoropyrimidines every year. Many of these patients suffer from negative side effects that can even have a fatal impact. Currently, the best described factor in the cause of the toxicity of fluoropyrimidines is the activity of the pyrimidine catabolism enzyme - dihydropyrimidine dehydrogenase. Due to the high frequency of pathogenic mutations in the dihydropyrimidine dehydrogenase gene, the extreme risk of toxicity affects hundreds of patients in the Czech Republic every year. For this reason, the "European Medical Agency" has issued a recommendation to carry out investigations for the possible occurrence of toxic effects before starting treatment. One of the diagnostic options for determining sensitivity to fluorouracil is metabolomic analysis, based on the quantification of degradation products of uracil metabolism in plasma using liquid chromatography with mass spectrometry. The goal of this work is to perform basic optimization of mass spectrometer parameters for quantification of selected degradation products of uracil metabolism. Keywords: Uracil, Fluoruracil, Liquid Chromatography, Mass Spectrometry
Phytochemical studies of potential phytopharmaceuticals using separation methods
Dulendarova, Elizabeta Hristiyanova ; Jenčo, Jaroslav (advisor) ; Křoustková, Jana (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department: Department of Pharmacognosy and Pharmaceutical Botany Candidate: Elizabeta Hristiyanova Dulendarova Supervisor: RNDr. Jaroslav Jenčo, Ph.D. Title of dissertation thesis: Phytochemical Studies of Potential Phytopharmaceuticals using Separation Methods The main aim of this diploma thesis was the identification of main alkaloidal components from the fraction of Papaver rhoeas L. (family Papaveraceae) alkaloidal extract - fraction PR-12-23. The introduction to the theoretical part summarizes alkaloids found in Papaver rhoeas L. and describes the separation methods used in the isolation process at the department of Phamacognosy and Pharmaceutical botany. Two main compounds within the extract were identified and separated based on HPTLC, HPLC-MS, and GC-MS chromatographic separation methods. For the subsequent fractions, the HPLC method development, optimization, and scaling up from analytical to preparative scale was done. After identification with the help of analytical HPLC and GC, the compounds were separated into fractions, isolated using preparative HPLC, and identified using NMR. The purified isolates were tested for anti-butyrylcholinesterase and cytotoxic biological activity, linked to AD and cancer, respectively. The first...
Analysis of drugs in the earthworms using the QuEChERS method
Navrkalová, Jitka ; Kučerík, Jiří (referee) ; Mravcová, Ludmila (advisor)
The content of this Bachelor‘s thesis is an analysis of pharmaceuticals in earthworms using the QuECHERS method followed by the LC-MS/MS analysis. The theoretical part focuses on the specific groups of used drugs, their properties and applications. Furthermore, it focuses on the occurrence of drugs in the environment from their input to the negative consequences including the impact on earthworms. The theoretical part also discusses the QuEChERS method and liquid chromatography with mass spectrometry. At first in the experimental part, the QuEChERS method (concretely parameters like organic solvent, aqueous phase composition, amount of EDTA, purification method) was optimized for the extraction of 31 drugs from earthworms analytically completed by LC MS/MS. This optimized and validated method is subsequently applied to the extraction of drugs from earthworms from the performed experiments. The experiments focus on the effect of drug concentration in soil and the presence of biochar on the uptake of different drugs by earthworms.
Qualitative analysis of selected glycosphingolipids subclasses isolated from human blood plasma using HILIC-ESI-MS/MS
ŠIKLOVÁ, Michaela
This bachelor thesis deals with the qualitative analysis of selected subclasses of glycosphingolipids isolated from human blood plasma using hydrophilic interaction liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HILIC-ESI-MS/MS). Glycosphingolipids are ubiquitous and structurally very diverse components of cell membranes involved in many cellular functions. It has been shown that changes in the structures of glycosphingolipids and their distinct expression can pose a key factor in the development of numerous diseases and different types of cancer.The theoretical part of this thesis is dedicated to a summary of fundamental knowledge about glycosphingolipids, their biosynthesis, classification, biological functions and their association with various types of diseases and cancers. Furthermore, methods of isolation, purification and analytical possibilities for the determination of glycosphingolipids in biological samples are described here.In the experimental part, blood samples were taken and processed together with the preparation of the necessary solutions, plasma samples, and standards. Moreover, a test analysis, optimization of mobile phase gradient and comparison of the most frequently used extraction methods according to Folch, Bligh and Dyer, Matyash, and Alshehry alongside fractionation of lipid extract is described in this part. An integral part of the experimental section was the identification and structural characterization of glycosphingolipids within selected subclasses, including the generation of GSL profiles in human blood plasma. In conclusion, the results of the work and answers to the stated research questions are summarized, including the evaluation of possible improvements in this field.
Stanovení kofeinu a jeho metabolitů pomocí HPLC/MS
Caffeine is probably the most frequently ingested drug in the world. A lot of people consume caffeine every day in beverages like coffee, tea and soft drinks. In human body caffeine is enzymatically transformed to a lot of metabolites and the first metabolic reactions lead to theophylline, theobromine and 1,7-dimethylxanthine. Consequently, caffeine and its metabolites can be found in human urine or plasma. This thesis deals with the development, optimization and validation of an analytical method for the determination of caffeine ant its metabolites by HPLC/MS. The composition of the mobile phase and settings of mass spectrometry detector were optimized. These steps led to the separation of analytes and to the achievement of stable and intense signal of the detector. An appropriate concentration range for each analyte according to the FDA rules was found. The method was used for the quantification of urinary content of caffeine, and its three metabolites.
Použití kapalinové chromatografie v analýze vzorků životního prostředí
This work deals with the use of HPLC method in the analysis of environmental samples. Cigarette butts are one of the most common garbage in nature. These cigarette butts may contain high amounts of polycyclic aromatic hydrocarbons (PAHs) and many other toxic and chemical compounds, which may contaminate the environment. One of the aims of this work was to optimize extraction process of 16 priority PAHs from freshly smoked cigarette butts and the HPLC/FLD analytical method and consequently to determine their contents in collected samples. The second part of the work is devoted to the introduction of a method suitable for the quantitative evaluation of metformin loss in 100% aqueous samples. The method will be further used for the analysis of standard solutions in the monitoring and evaluation of possible photochemical reactions of metformin.

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