National Repository of Grey Literature 115 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Elemental analysis of leaf and soil samples using the ICP-MS
Švecová, Pavla ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
EN Theaimofthisthesiswastodeterminethecontentofselectedelements,namelyarsenic,cadmium, copper, nickel, lead, calcium, and zinc in leaf and soil samples. The analysed samples were received from many locations in the Czech Republic and various European countries. Leaf samples were dried and digested in a microwave digestion system for the determination of thetotal content ofelements.Soil samples wereanalysed usinganextractionprocedurewithaquaregiaas the extractant according to ISO 11466. This method was also applied to certified reference materials to verify the usage of this procedure. The content of elements in leaf and soil samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Thecontentofelementsinleavesshowedawiderangeofvaluesforeachelement.Concentrations of elements ranged for calcium 0.98 to 16.6mg g-1 , nickel 0.16 to 10.20μg g-1 , copper 2.60 to 43.80 μg g- 1 , zinc 13.4 to 489 μg g-1 , arsenic 0.01 to 11.60 μg g-1 , cadmium < LOD to 7.02 μg g-1 , and lead 0.03 to 71.40μg g-1 , respectively. Generally, higher values of heavy metals were obtained for samples from areas with mining activities or from industrial zones. Recoveryofelementsintheusedcertifiedreferencematerialsshowedvaluesrangingfrom68.4% to 121%. Two types of reference materials were used, and the recovery...
Determination of active substances and possible degradation products in a historical sample of Algena from 1981
Bauerová, Markéta ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
The Algena tablet was an over-the-counter drug in the second half of the twentieth century in Czechoslovakia. Algena was mainly used against pain. The tablet contains four active substances: aminophenazone, aprobarbital, phenacetin, and caffeine. The aim of this thesis was to analyse the active substances in the Algena tablet from 1981,determinate theircontent,and possible degradation products.To complete these goals the RP-HPLC method with UV detection had to be involved and optimized.HPLC-MS was used to detect possible degradation products. Separation was performed on the XBridge® BEH C18 column (150×3.0 mm; 2.5 µm), binary elution was used. The first component of the mobile phase was0.1% aqueous solution of acetic acid and the second component was methanol. The determined contents of active substances (decelerated by the manufacturer) were: amino- phenazone 97.0%,aprobarbital89.2%, phenacetin 96.0% and caffeine 93.2%.Degradation products of the active substances were not detected by HPLC with MS detection. Key words: Algena, aminophenazone, aprobarbital, caffeine, degradation, phenacetin, RP-HPLC
Optimization of 5-fluorouracil determination by high-performance liquid chromatography
Durychová, Eva ; Křížek, Tomáš (advisor) ; Kozlík, Petr (referee)
This thesis is dedicated to the development of a method for the determination of 5-fluorouracil by high-performance liquid chromatography, which could be used for determination of its encapsulation efficiency by liposomes. First, separation of 1 mM standard of 5-fluorouracil was tested on several types of columns. Among tested columns belonged a C18 column, a C18 column with positive surface modification, a phenyl-hexyl column and several fluoride columns together with two HILIC columns. A mixture containing 10 mM CH3COONH4, pH = 4,5 and MeOH in the ratio of 98/2 was initially used as the mobile phase. The results showed, that 5-fluorouracil elutes on all columns too close to the dead time, where different impurities often elute. To avoid possible distortion of 5-fluorouracil signal by impurities potentially occurring in the real sample, several adjustments of chromatographic conditions were tested. The most effective solution was addition of 5 mM ion-pairing agent (namely tetrabutylammonium chloride hydrate) to the mobile phase, together with adjusting pH to 8,0 to support the ionization of the analyte. In the combination with mobile phase modified in this way, a phenyl-hexyl column with retention time 4,36 minutes reached the best result, therefore it was selected for the final determination of...
Determination of bile acids in bronchoalveolar lavage of patients after lung transplantation
Plášilová, Denisa ; Kozlík, Petr (advisor) ; Petr, Tomáš (referee)
Lung transplantation is a life-saving treatment for patients suffering from lung failure. However, the median survival of patients after this procedure is still low (6 years). The main reason is mainly due to chronic lung allograft dysfunction, which can lead to graft rejection. Gastroesophageal reflux has been identified as a major risk factor for this dysfunction (some studies also report duodenogastroesophageal reflux), which has been shown to worsen after lung transplantation. Markers of gastroesophageal reflux may include bilirubin, pepsinogen II (some studies report pepsin), pH and bile acids. In this study, all these markers were determined in a cohort of bronchoalveolar lavage samples and compared with each other and with clinical data that classify progressive deterioration of lung function after transplantation. After measuring the samples by LC-MS/MS, it was found that the total bile acid concentration measured by the enzymatic assay did not match the total bile acid concentration measured by liquid chromatography. The samples were subjected to hydrolysis and solvolysis to determine whether the disproportionation in the two methods was due to atypical conjugated or sulphated bile acids. Significant correlations were found between clinical data and bile acid concentrations and between...
Hydrophilic Interaction Liquid Chromatography in the Analysis of Intact Glycopeptides
Molnárová, Katarína ; Kozlík, Petr (advisor) ; Coufal, Pavel (referee) ; Cvačka, Josef (referee)
The analysis of glycoproteins represents a significant challenge in glycoproteomics, primarily due to the macro- and microheterogeneity of protein glycosylation. Hydrophilic interaction liquid chromatography (HILIC) is a convenient alternative to reversed-phase chromatography, commonly used in glycoproteomic analysis. This dissertation thesis discusses the potential of HILIC in glycoproteomic analysis, ranging from the separation of glycopeptides on polar stationary phases to the use of HILIC in sample preparation processes. First, the effect of acetonitrile concentration on glycopeptide precipitation was investigated, depending on the type of glycan attached. Subsequently, three commercially available stationary phases were tested: a column containing a silica gel modified with five hydroxyl groups, an amide stationary phase, and a zwitterionic stationary phase. Their efficiency in separating glycopeptide isomers, differing only in branching and/or linkage position, was compared. Further research was devoted to the separation of human immunoglobulin G glycopeptides using relatively new columns that have not yet been characterized in glycoproteomic analysis. These columns, provided by Advanced Chromatography Technologies, included unmodified silica gel (HILIC-A), aminopropyl- modified sorbent...
Development of mass spectrometric methods for structural analysis of fatty acids and estolides
Cudlman, Lukáš ; Cvačka, Josef (advisor) ; Kozlík, Petr (referee) ; Lísa, Miroslav (referee)
(EN) This doctoral thesis summarizes the use of modern mass spectrometric methods for the structural identification of fatty acids and triacylglycerol estolides (TG-EST) and their subsequent characterization in the lipidome of vernix caseosa, i.e., the biofilm covering the skin of the human fetus during the last trimester of in-utero development. Vernix caseosa has mainly antimicrobial properties and the ability to heal wounds and burns. The first part of the doctoral thesis focuses on the diversity of fatty acids in the lipidome of vernix caseosa. These acids form the structural subunits of complex lipids, such as the abundant triacylglycerols and wax esters. By studying fatty acids and their structural features, this thesis has provided valuable insights into the structural variability of the vernix caseosa lipidome. Without a full understanding of the structure of these key subunits, it would be impossible to complete the analysis of this lipidome in the future. In this thesis, fatty acids using high-performance liquid chromatography (HPLC) and modern mass spectrometry methods, namely ultraviolet photodissociation (UVPD) and ozone-induced dissociation (OzID), were characterized. The coupling of HPLC and mass spectrometry (HPLC-MS) provided unambiguous information on the positions and geometry of...
Separation of pharmaceutically active compounds by mixed-mode and chiral chromatography: interaction study
Fojtíková, Sofia ; Bosáková, Zuzana (advisor) ; Kozlík, Petr (referee) ; Fischer, Jan (referee)
During the drug development process, the pharmaceutical industry often relies on chromatographic techniques. High-performance liquid chromatography (HPLC) is among the most commonly used chromatographic techniques for these purposes, with reverse phase and HILIC being the most common choices. However, despite their popularity, these techniques have several drawbacks, such as the contribution of secondary interactions that arise from the nature of the carrier material, and limitations in terms of analyzing molecules with certain properties. In this sense, multimodal (also called mixed-mode) chromatography (MMC) appears to be a promising technique capable of addressing these challenges. The first part of the dissertation is focused on the comparison of the retention of structurally different molecules in different chromatographic systems using seven different multimodal stationary phases and the effort to elucidate the interaction mechanisms applied to the individual studied stationary phases. By observing the trends, obtained under different conditions for molecules with different physicochemical properties, it was at least partially achieved. Chiral chromatography is another key tool in the analysis of pharmaceuticals. Its main purpose in the development of medicinal products is to separate...
Determination of calcium, magnesium and phosphorus in selected types of animal bones
Škardová, Alice ; Hraníček, Jakub (advisor) ; Kozlík, Petr (referee)
This research focuses on the elemental analysis of selected elements (calcium, magnesium, and phosphorus) within the bones of various animal species, aiming to make comparative nutritional assessments. The obtained bone samples were subjected to mechanical grinding and then quantitatively weighed into collapsible cartridges. Using high-pressure microwave decomposition with the incorporation of nitric and hydrochloric acid, the samples were transformed into solution form, which was then appropriately diluted. The analysis of the liquid samples was carried out using a mass spectrometer with inductively coupled plasma. The observed composition for each sample was calculated using the calibration curve, accounting for both sample mass and dilution factors. All results obtained exceeded the detection limit for calcium 0.38 mg/l, magnesium 0.037 mg/l, and phosphorus 0.078 mg/l. The main finding of this research is the complete understanding of the elemental makeup present within the bones of distinct animal species.
Analysis of bilirubin's relevant photoproducts and their biological significance in the issue of neonatal jaundice
Křepelka, David ; Kozlík, Petr (advisor) ; Zelenka, Jaroslav (referee)
Neonatal jaundice occurs in almost 60% of full-term and 80% of premature babies, where a slightly increased concentration of bilirubin protects against oxidative stress just after birth. When a specific bilirubin level is exceeded in serum (usually above 340 µmol·l-1 ), bilirubin-could induce kernicterus. These negative states are prevented by blue-green light phototherapy (420-510 nm), which converts bilirubin into more polar photoproducts that are more easily excreted via bile and/or urine. Published data have shown that newborns with indicated phototherapy may develop clinical problems later in life (higher incidence of e.g. asthma, allergies, type 1 diabetes was observed at a later age). A possible reason for the occurrence of these diseases is the specific biological activity of photoproducts. This study aims to purify an unknown photoproduct (band P), formed after 8 hours of irradiation of a bilirubin solution with blue light, and to establish a quantitative analytical method for its measurement in relevant matrices. This product was isolated and separated by a thin layer and subsequent column flash chromatography. In the next part, an LC-MS/MS method was developed for quantification of band P. Finally, urine, plasma, and feces samples collected from 15 newborns before and after phototherapy...
Development of the UHPLC-PDA method to determine the active substances in the tablet Ataralgin
Chocová, Natálie ; Kozlík, Petr (advisor) ; Hraníček, Jakub (referee)
The Ataralgin tablet is an over-the-counter drug that helps against pain and elevated body temperature. The tablet contains three active substances - paracetamol, caffeine and guaifenesin. The aim of this thesis was to develop a rapid, effective, selective and simple UHPLC-PDA method suitable for the determination of active substances in the Ataralgin tablet which would subsequently serve for quality control during the production of this drug in the pharmaceutical industry. Separation was performed on the Acquity UPLC BEH C18 column (50 × 2.1 mm, 1.7 µm), the column temperature was set at 40 řC, autosampler temperature was 10 řC, the mobile phase was composed of methanol (B) and distilled water with the addition of 0.1% formic acid (A), sample injection volume was 1 µl and the flow of mobile phase was 0.4 ml·min-1 , gradient elution (time: 0-0.5-1.5-2.5-3-5.5 min, A: 85-85-30-30- 85-85% v/v). UV detection at 275 nm and the total analysis time was 5.5 minutes. The trueness (relative error) was in the range of 0.05 - 2.73 % and the accuracy (relative standard deviation) was in the range of 2.38 - 5.79 %. The LOD values were: 9.25·10- 4 mg·ml-1 for paracetamol, 2.15·10-4 mg·ml-1 for caffeine and 7.93·10- 4 mg·ml-1 for guaifenesin and values for the LOQ were 3.08·10-3 mg·ml-1 for paracetamol, 7.17·10-4...

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