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Preconcentration and determination of organic perfluorinated acids by gas chromatography
Maradová, Doubravka ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
A rapid and simple derivatization procedure has been developed for gas chromatographic determination for of perfluorinated acids (C6-C12), using isobutyl chloroformate to convert the acids into more volatile isobutylesters, under catalysis by pyridine. The procedure was optimized in an acetonitrile medium and applied to GC techniques with electron-capture detection (GC-ECD) and mass spectrometry with electron-impact ionization (GC-EI-MS), for the sake of comparison, HPLC with electrospray-ionization MS (HPLC-ESI-MS) was also tested. The LOD and LOQ values obtained for these three techniques were compared, and the lowest LODs were obtained with GC-ECD (0,1-1,8 µg/ml). By comparing the sensitivity of analytical separation method utilizing the same derivatization technique for the analysis of PFA, GC-ECD proves to be more appropriate and sensitive than GC-MS. In addition, an evaluation of the various derivatization techniques for GC-ECD, GC-MS and HPLC-MS method without derivatization, shows that GC-ECD method is superior to GC-MS or HPLC- MS.
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Development of Method for Determination of Endocrine Disruptors in Environmental Samples
Novotná, Veronika ; Bosáková, Zuzana (advisor) ; Čabala, Radomír (referee)
There are many substances of natural and anthropogenic origin at present called endocrine disruptors which may influence endocrine system of animals and humans. A complex analysis of endocrine disruptors in environmental samples is important for knowledge of their behaviour in living environment and for their risk estimation. A complex method has been developed in this thesis for an analysis of bisphenol A, 17α-ethinylestradiol, irgasan and 4-nonylphenol in activated sludge and soil involving ASE extraction, sludge extract cleaning with silicagel and GPC and subsequent GC/MS and HPLC/UV samples quantification. These final extraction conditions of ASE have been settled: extraction mixture DCM:acetone (3:1 v/v), temperature 60 řC, pressure 1700 psi, 3 extraction cycles. ASE yield during soil extraction has been settled in range of 93,0-116,3 % with RSD 2,7-5,7% by HPLC/UV analysis and 93,3-106,0 % with RSD 9,3-15,6 % by GC/MS analysis. The whole method yield including the cleaning steps has been settled in range of 78,2-111,2 % with RSD 4,1-10,6 % in HPLC/UV quantification and 74,6-88,9 % with RSD 3,7-18,2 % in GC/MS quantification. The method application on the artificially contaminated sludge and soil samples analyzed after five months of storage has provided the yield of all analysts in range of...
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New pharmacological interventions influencing food intake regulation
Špolcová, Andrea ; Čabala, Radomír (advisor) ; Podlipná, Radka (referee)
NEW PHARMACOLOGICAL INTERVENTIONS INFLUENCING FOOD INTAKE REGULATION Author: Bc. Andrea Špolcová ABSTRACT Prolactin-releasing peptide (PrRP) identified as an endogenous ligand of the orphan receptor GPR10 was originally found to stimulate the secretion of prolactin (PRL) both in vitro and in vivo. PrRP-mediated PRL secretion was later questioned and is not currently considered to be the primary function of PrRP. The fact that both PrRP and GPR10 knock-out mice are hyperphagic and develop late-onset obesity proves the unique anorexigenic properties of PrRP. Designing and evaluation of PrRP analog(s) with selective anorexigenic properties and searching for PrRP antagonists would contribute to finding the mechanism and possible treatment of obesity and metabolic syndrome. In our recent published study (Maixnerová et al., Peptides (2011)), the PrRP receptor was immunodetected and characterized by saturation binding in three rodent tumor pituitary cell lines. Two naturally occurring analogs, PrRP31 and PrRP20, showed comparable potency in binding, cell signaling and prolactin release in pituitary RC-4B/C cells, as well as caused food intake decrease after intracerebroventricular administration in fasted mice. In the present study, analogs of PrRP20 with C-terminal Phe amide derivatives with modified aromatic...
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Analysis and characterization of antimicrobial peptides by capillary electrophoresis
Hlavsová, Tereza ; Coufal, Pavel (advisor) ; Čabala, Radomír (referee)
Capillary zone electrophoresis (CZE) with UV-photometric detection at 206 nm was used for the determination of degree of chemical purity, limit of detection and limit of quantitation of antimicrobial cationic peptide halictine and its 25 analogs. Halictine and its analogs were chracterized by their effective electrophoretic mobilities corrected to reference temperature 25 řC in several acidic background electrolytes. Separations of mixtures of structurally related analogs of halictine were performed by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). The highest values of separation effeciency, up to 2.36∙105 theoretical plates per meter, were achieved by CZE in the background elektrolyte containing 30 mM phosphoric acid, 25 mM Tris and additive of cationic surfactant 0.4 mM didodecyldimethylammonium bromide (DDAB), pH 2.85. The highest values of resolution of CZE separations of peptides were found in background electrolyte composed of 30 mM phosphoric acid, 25 mM Tris, 0.4 mM DDAB and 0.1 % (m/v) hydroxyethylcellulose, pH 2.84.
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Application of monosubstituted cyclodextrins in chiral separation of omeprazole by capillary electrophoresis
Dvořák, Aleš ; Coufal, Pavel (referee) ; Čabala, Radomír (advisor)
Chiral separation of omeprazole was the subject of this work. Five diferent monosubstituted derivatives of α- and β-cyclodextrins, two of them cationic and three anionics, were used as chiral selectors in various buffers of different pH. The influence of CD and buffer concentrations on chiral separation was studied. Voltage of 25 kV, UV detection in the range from 202 to 303 nm and constant temperature of 20 řC was used for all measurements. Concentration of CDs between 0 and 7 mmol.l-1 was used. Fused silica capillary of 50 µm ID and 375 µm OD, 48,5 cm total and 40 cm effective lenght was used as separation capillary. Dimethylformamide was used in stock solution of omeprazole as solvent, and was simultaneously applied as EOF marker. Succesfull chiral separation of omeprazole was achieved under the application of 2'-O-carboxymethyl-β-cyclodextrin (2'-CM-β-CD) and mono-6-deoxy-6-N,N,N',N',N'-pentamethylethylendiammonio- cyclomaltoheptaose dichloride (PEMEDA-β-CD) where the resolution of 1,42 (pH = 5,1) and 4,29 (pH = 11,1) was measured, respectively.
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