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The characterization and prediction of stationary phase properties used in solid-phase microextraction (SPME) for sampling of volatile organic compounds in air samples and the development of a new type of needle concentrator (INCAT) for sampling of BTEX from aqueous samples
Přikryl, Petr ; Ševčík, Jiří (advisor) ; Feltl, Ladislav (referee) ; Komárek, Karel (referee) ; Leníček, Jan (referee)
UNIVERZITA KARLOVA V PRAZE, PŘÍRODOVĚDECKÁ FAKULTA Katedra analytické chemie CHARLES UNIVERSITY IN PRAGUE, FACULTY OF SCIENCE Department of Analytical Chemistry CHARAKTERIZACE A PREDIKCE VLASTNOSTÍ STACIONÁRNÍCH FÁZÍ POUŽÍVANÝCH PŘI MIKROEXTRAKCI NA TUHOU FÁZI (SPME) PRO VZORKOVÁNÍ TĚKAVÝCH ORGANICKÝCH LÁTEK V OVZDUŠÍ A VÝVOJ NOVÉHO TYPU JEHLOVÉHO KONCENTRÁTORU (INCAT) PRO VZORKOVÁNÍ BTEX Z VODNÝCH VZORKŮ THE CHARACTERIZATION AND PREDICTION OF STATIONARY PHASE PROPERTIES USED IN SOLID-PHASE MICROEXTRACTION (SPME) FOR SAMPLING OF VOLATILE ORGANIC COMPOUNDS IN AIR SAMPLES AND THE DEVELOPMENT OF A NEW TYPE OF NEEDLE CONCENTRATOR (INCAT) FOR SAMPLING OF BTEX FROM AQUEOUS SAMPLES Souhrn doktorské disertační práce Summary of the Ph.D. Thesis Praha 2008 Mgr. Petr Přikryl Disertační práce byla vypracována na Katedře analytické chemie, PřF UK v Praze v letech 2000-2008. Uchazeč/Candidate: Mgr. Petr Přikryl Adres/Address: Katedra analytické chemie Hlavova 2030/8 Praha 2 CZ12843 Email: petr.prikryl@lf1.cuni.cz Obor/Branch: Analytická chemie Školitel/Advisor: Prof. Ing. Jiří Ševčík, DrSc. - 3 - 1. Úvod Analýza mnoha environmentálních polutantů je velmi často obtížná vzhledem ke komplexnosti vzorkovaných matric, a také protože povolené obsahy polutantů v jednotlivých složkách životního prostředí (vzduch, voda, půda)...
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Modern microextraction techniques for gas chromatographic analysis
Bursová, Miroslava ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee) ; Kubinec, Róbert (referee)
The submitted thesis is focused on the development, optimization, testing and practical application of the new microextraction method called Bell Shaped Extraction Device assisted Liquid-Liquid Microextraction (BSED-LLME). The method is based on the application of a miniature bell-shaped extraction tool in which the extraction takes place, so that only minimal solvent losses can occur, and which allows a reproducible dosing and collection of a small volume of the extraction solvent. The BSED- LLME method was used to preconcentrate selected volatile and less volatile analytes from aqueous samples into organic solvents of a density lower than water. After the extraction, the analytes were determined by fast gas chromatography with flame ionization detection and gas chromatography with mass spectrometry. The statistical methods known as Design of Experiment (DOE) were used for determination of the optimal extraction conditions for BSED-LLME procedure. DOE is based on a mathematical description of the system and the prediction of the optimal setting of experimental parameters that may influence extraction efficiency. Factors such as extraction time, volume of extraction solvent, addition of sodium chloride (ionic strength), stirring rate and the diameter of the extraction vessel ect., have been tested....
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Development and optimization of SPE method for preconcentration and determination of fluorotelomeric alcohols in water
Ševčík, Václav ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
New GC-MS method combined with SPE preconcentration step has been developed and optimized for the determination of selected fluorotelomer alcohols in aqueous samples by advanced statistical method in this thesis. 1H,1H,2H,2H-perfluoro-1-octanol (6:2 FTOH) and 1H,1H,2H,2H-perfluoro-1-decanol (8:2 FTOH) have been selected as the analytes. The influence of several factors, such as the sample volume, the carrier gas pressure, the sampling time and the injector temperature on the system response have been studied during the optimization. Utilizing the statistical software Minitab 16 and series of experiments, the optimal values of relevant factors and a suitable type of ionization were found for both analytes. Limits of detection of GC-MS method are 0.24 ng/mL for 6:2 FTOH and 0.42 ng/mL for 8:2 FTOH. Several factors, such as the type and the volume of conditioning agent, the speed of conditioning, the speed of sample flow, the method of column drying, the type and the volume of eluent have been tested for SPE. The optima of these factors were determined using Minitab 16 software. The extraction efficiency dependence on the concentration and volume of the stock solution was used to set the limitation of SPE for the determination of fluorotelomer alcohols. The maximum volume of sample equals to 400 mL...
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Optimization of conditions for derivatization of fatty acids and perfluorinated organic acids with methylchloroformate
Hložek, Tomáš ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
Statistical methods designed for optimization were applied for selection of optimal experimental conditions of derivatization process for perfluorinated acids, PFA (C8, C10 ,C12), fatty acids, FA (C8, C12, C14) and their mixtures. The calibration curves and the extraction efficiences for system acetonitrile/heptane were measured for all studied acids. The Plackett-Burman screening was performed for obtaining the significant experimental parameters from their original series and significant ones were remitted to optimization via central composite design, which takes a second order effects and mutual interactions in between parameters into account. Optimal conditions of derivatization were found for PFA, FA and their mixtures. The principle of the search of optimal selective derivatization conditions for one group of acids in the presence of the other is based on the search of optimum on the response surface where the dependent variable is either sum or difference of acid group responses normalized to common internal standard. It was found that FA influence total response more than PFA and that in the case of demand for selective derivatization of PFA in the presence of FA in the sample, the most significant parameter is the volume of methylchloroformate added. The complete selectivity of...
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Development of analytical methods for determination of phosphorylated components of bacterial cell membranes
Mikulecká, Jana ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
Phospholipids are dominant components of bacterial cell membranes, where they create double layers. Bacteria differ in their phospholipid composition determination of which can help in identification of important groups of microorganisms. Phospholipid composition of bacteria is influenced by many environmental factors, therefore its variation can be observed within one bacterial stem also. Because of its simplicity, thin layer chromatography is usually applied to identification and determination of bacterial phospholipids. Disadvantage of this method are the high demands of time, carefulness and skills of the analytical personnel. The increasing interest in the phospholipid double-layer promotes the detailed investigation of their fatty acid composition because the more detailed analyses allows for more information yield about bacteria. Gas chromatography hyphenated with mass spectrometry seems to be the best choice for these purposes. Fatty acid identity and total fatty acid content in phospholipid molecules could be determined by this method. Additionally, number, position and isomerism of double bonds and presence of other functional groups on hydrocarbon chain could be determined. Whereas a suitable and...
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Characterization of interactions between Rtx-200MS fluorinated stationary phase and analytes by inverse gas chromatography
Vrzal, Tomáš ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
Fluorinated stationary phase in Rtx-200MS column have been characterized by determination of system constants of Abraham equation. Retention on this phase is driven by dispersive and orientation/induction forces. Significant interaction contribution of lone pair electrons or π- electrons provides unique selectivity for analytes with excess of electron density. Unusual behavior of this phase have been determined by study of separation mechanism of polar and nonpolar analytes, in comparison of their separation on polar and nonpolar phases. This behavior is due to medium polarity of the phase (system constant s), which is not so pronounced to cancel separation of nonpolar analytes due to induction forces. In some cases contribution of lone pair electrons or π-electrons can contribute to this separations. Key words fluorinated stationary phase Rtx-200MS, inverse gas chromatography, LFER method, Abraham's equation
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Toxicity of Organic Mixtures
Reitmajer, Josef ; Feltl, Ladislav (advisor) ; Čabala, Radomír (referee) ; Ventura, Karel (referee) ; Mejstřík, Viktor (referee)
6. CONCLUSION The aim of this study was to test additiviý of chemical compounds in distribution process between two phases and to compare distribution coefficients K-;^ for different molar ratio of mixture with acute toxicity index EC50 gained on oligochaeta Tubifex tubifex. Mixtures of organic solvents ethanol, benzene, aniline and nitrobenzene were studied. Deviations from additivity were found for distribution coefficients of all tested mixtures. The most significant deviation exhibited benzene - ethanol mixture. The lowest deviations were observed for mixture ethanol - aniline. The results obtained indicate that the partition coefficient K.;* behave similarly as acute toxiciý. Definitely it is for benzene - ethanol mixture. It is possible to suppose that this parameter might be used for estimation of changes in acute toxicity of mixtures. The aim of the second part of the thesis was to study how distribution of chemicals changes with concentration and composition of mixture. Variations in distribution of mixture components beťween gaseous and aqueous phase were found. The highest deviations were found for benzene - ethanol and benzene - eniline mixtures. No deviation was found for mixture aniline - nitrobenzene. Deviations were not as significant as in first part of study. Dependences of distribution...
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Analysis, separation and physico-chemical characterization of peptide hormones by capillary electrophoresis
Šolínová, Veronika ; Jelínek, Ivan (advisor) ; Feltl, Ladislav (referee) ; Coufal, Pavel (referee) ; Samcová, Eva (referee)
I 11 CoNcr,usroNs The work bas demonstrated that capinary zone elechophoresis and micelrar electokinetic cbromatography are high-perfomrance and high-sensitive methods for qualitative and quantitative anďysis and for physico-chemicď characÚerization ofpeptide hormones. using the strategy for the rational selection of experimental conditions for cE analysis and separations ofpeptides, ionogenic peptides were separated as cations in the classical and isoelectric buffers in the acidic region, pH 2- 2'5, and as anions in amphoteric buffer in weakry arkaline conditions, pH = 8'1. Non-ionogenic peptides were analyzed by miceilar electrokinetic chromatography with micelrar phase consisting of anionic detergent sodium dodecylsulphate in alkaline conditions, pH 8.8. The experimental conditions were selected with the aim to avoid the adsorption of peptides on the capillary wall, which was particularly reached with suppression of dissociation of si'anol gÍoups on the imer capillary wall in the acidic pH region and with electrostatic repursion negatively charged peptides from negatively charged dissociation silanol groups on the inner capillary wall in the alkaline pH region. The pH values of background electrolýes were chosen in the region, where the biggest differences in calculated specific charges of analyzed...
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