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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Sledování obsahu sulfonamidů v odpadních vodách z čistíren odpadních vod s různými technologiemi čištění / Monitoring of sulfonamides in wastewater from sewage treatment plants with different treatment technologies

Chaloupková, Petra January 2015 (has links)
The aim of this thesis is to determine the presence of pharmaceuticals in wastewater from several wastewater treatment plants (WWTPs) with different number of equivalent persons and different treatment technologies. Five sulfonamides were chosen for a determination due to their wide usage in human and veterinary medicine practice. The specific compounds are sulfamerazine, sulfamethazine, sulfapyridine, sulfathiazole a sulfamethoxazole. For the determination of those sulfonamides, an UHPLC/DAD analytical method was chosen and optimized. There was also a need for optimization of SPE extraction method, especially a sample volume optimization. 250 mL was chosen as an ideal volume of wastewater sample for SPE. The optimized method was used for determination of sulfonamides in real wastewater samples from WWTP in Podivín, Pohořelice, Hustopeče, Valtice, Lednice and Mikulov. Average concentrations of pharmaceuticals in influent and effluent wastewater samples were in a range of 0,1 – 1 µg/l. The concentration of sulfonamides was mostly found higher in influent samples and lower in effluent samples. It can be said that a partial recovery of sulfonamides on WWTPs was observed.
132

Stanovení tenzidů ve vodách pomocí separačních metod / Determination of tensides in waters by separation methods

Brestovská, Marta January 2015 (has links)
Surfactants are synthetically made surface-active agents contained in washing and cleaning products. They decrease the surface tension and remove dirt. Surfactants can be divided into three basic classes: anionic, cationic and non-ionic. Thanks to the massive use they penetrate into waste water and can disturb the environment. This diploma thesis deals with the occurrence of surfactants in water and their determination by separation methods, especially LC / MS.
133

Stanovení polyaromatických uhlovodíků v pevných matricích hydrosféry metodou QuEChERS - porovnání se stávajícími metodami / Determination of polycyclic aromatic hydrocarbons in hydrosphere solid matrices by QuWChERS - comparision with present methods

Sudová, Petra January 2012 (has links)
Thesis are aimed to the optimization and validation of the QuEChERS method for determination of polycyclic aromatic hydrocarbons in solid matrices of hydrosphere. The QuEChERS method was also used for determination of polycyclic aromatic hydrocarbons in real samples and for comparison of measured results, time and material costs of the method with currently employed methods: (1) accelerated solvent extraction connected with gel permeation chromatography (ASE/GPC), and (2) ultrasonic extraction connected with solid phase extraction (UZ/SPE). According to the validation criteria, the QuEChERS method is suitable for the determination of polycyclic aromatic hydrocarbons in solid matrices of hydrosphere. The QuEChERS technique provides comparable results to ASE/GPC and UZ/SPE. In terms of price and time for sample preparation, the QuEChERS method allows (unlike the methods ASE/GPC and UZ/SPE) fast and inexpensive determination of polycyclic aromatic hydrocarbons in solid samples of hydrosphere.
134

Studium kinetiky trypsinového štěpení peptidů a chirálních separací biologicky aktivních látek metodou HPLC / Study of peptide digestion kinetics by trypsin and chiral separations of biologically active compounds by HPLC

Šlechtová, Tereza January 2016 (has links)
This dissertation thesis composes of two parts; the first part focus on the characterization of trypsin, enzyme frequently used in proteomic research for the investigation and identification of protein sequences, and its peptide digestion kinetics. The second part is aimed to the enantioseparations of biologically active compounds. First part of this project focus on tryptic digestion of synthetic peptides and the development of HPLC method for the identification of synthetic peptides and their fragments. Using the in-solution digestion and HPLC method, relative kinetic constants were determined for problematic sequences. Amino acids responsible for the decrease in trypsin catalytic activity and their location towards the cleavage site were studied. Certain slight exopeptidase activity of trypsin was noted, especially at the end of peptide chain. Furthermore, three columns with immobilized trypsin used in HPLC were compared concerning their catalytic activity. The immobilization of enzymes on solid support is used to elevate the amount of enzyme present during digestion and to assure better repeatability and reproducibility of obtained results. Activity of a new trypsin column synthesized at the University of North Carolina at Chapel Hill was compared to two commercially available trypsin columns....
135

Speciační analýza arzénu s využitím hydridového generování - kryogenního záchytu - plynové chromatografie - atomové absorpční spektrometrie / Arsenic speciation analysis by hydride generation - cryotrapping - gas chromatography - atomic absorption spectrometry

Petreňová, Štěpánka January 2018 (has links)
EN The thesis is focused on a speciation analysis of arsenic with use of the hydride generation - cryotrapping - gas chromatography - atomic absorption spectrometry. The aim of this project was the development of a method and instrumentation of the speciation analysis of arsenic based on combination of selective generation of substituted hydrides with a detection by atomic absorption spectrometry and with use of the cryotrapping of generated arsenic species and their separation by the gas chromatography. In the first part of this work the effects of individual parameters which influence the separation in the gas chromatograph were studied. Especially, time of injection from the cryotrap into GC, temperature program, carrier gas flow and carrier gas flow through a "deanswitch". Optimization of these parameters is an attempt to achieve a satisfactory resolution of the individual peaks of arsenic species separated by gas chromatography. Furthermore, an adequate sensitivity of this method is required to be achieved in comparison to other methods that use AAS detection such as a combination of hydride generation with cryotrapping. For this reason, the detection limits and the quantification of arsenic species were important to be determined as well. A sampling coil was replaced by a sampling tip...
136

Vývoj miniaturizované extrakční metody pro screening netěkavých nitrososloučenin ve sladu pomocí GC-NCD / Development of miniaturized extraction method used for GC-NCD screening of non-volatile nitroso compounds in malt

Malečková, Michaela January 2018 (has links)
The aim of this diploma thesis was to develop a miniaturized extraction method for a fast screening of non-volatile nitroso compounds using gas chromatography with a nitroso specific chemiluminescence detection. According to a final methodology, the samples were prepared by extraction of grinded malt using a mixture of pyridine and acetonitrile in ratio 60:40 (v/v). To enhance volatility of the determined analytes, the two-step derivatization using hexamethyldisalazane and N,O-bis(trimethyl)-trifluoroacetamide was used. The total volume of the sample was 200 l and the preparation time after optimization was in total 80 min. The extraction method was connected to a classification method, which can divide chromatographic peaks into the groups of N-nitroso and C-nitroso compounds, and interfering substances. After application of the methods mentioned above to real malt samples, the specific chromatographic peaks of C-nitroso and N-nitroso compounds were selected. Description of their properties and structure suggestion will be a subject of the following study. Keywords Nitroso compounds, malt, extraction, derivatization, gas chromatography, chemiluminescence detector
137

Separace a identifikace lipopeptidů pomocí chromatografie a hmotnostní spektrometrie / Separation and identification of lipopeptides by chromatography and mass spectrometry

Pravdová, Adéla January 2019 (has links)
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...
138

Analýza esterů kyseliny ftalové v zemědělských půdách ČR

Grossová, Lucie January 2019 (has links)
The thesis on the topic "The analysis of phthalic acid esters in agricultural soils in the Czech Republic" describes the properties of phthalic acid esters, the occurrence and the negative effects related to the environment and human health. The aim of this diploma thesis was to monitor phthalic acid esters, especially di-2- (ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) in agricultural soil samples. Monitoring of phthalates was carried out in cooperation with the Central Control and Testing Institute of Agriculture in Brno as part of their annual monitoring of phthalates and other organic contaminants in soils. During March 2018, a total of 40 soil samples were collected in 12 regions of the Czech republic. Before phthalate analysis, samples were extracted with a mixture of acetone-hexane (1:1). Using ultrasound was performed using high performance liquid chromatography with UV detection. Determined concentrations for DBP were from 0.13 to 1.07 mg.kg-1 dry weight and for DEHP from 0.13 to 1.02 mg.kg-1 dry weight.
139

Využití separačních technik ve fytochemické analýze / The use of separation techniques in phytochemical analysis

Víchová, Simona January 2021 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department: Department of Pharmaceutical Botany Candidate: Simona Víchová Supervisor: RNDr. Jaroslav Jenčo, Ph.D. Title of dissertation thesis: The use of separation techniques in phytochemical analysis The alkaloid extract obtained from stems with immature capsules from Papaver rhoeas L. was subjected to a phytochemical study. The summary extract was separated into individual fractions by Flash chromatography. After performing biological tests for inhibitory activities of acetylcholinesterase and butyrylcholinesterase, the fraction PPR-11 and PPR-12 was selected. The fraction showed the highest activity against butyrylcholinesterase (95.55 ± 0.96 and 97.03 ± 0.79% inhibition of butyrylcholinesterase at 50 /g / ml). The combined PPR 11-12 fractions were purified by preparative chromatography to individual subfractions, which were purified by preparative thin layer chromatography. A monocomponent crystalline substance of alkaloid origin was obtained from the subfraction named PPR 11-12Fr # 8-A. Based on instrumental analysis, the analyte was identified as an alkaloid of the aporphine type (+)-caaverine. The inhibitory activities against acetylcholinesterase and butyrylcholinesterase for (+)-caaverine, were determined and compared with...
140

Problematika alkylderivátů rtuti v biotických matricích / The issue of alkylderivatives of mercury in biotic matrices

Zajícová, Markéta January 2011 (has links)
Alkyl derivatives of mercury, especially methylmercury, bring a significant risk to the environment and the human population. Methylmercury is highly toxic compound, which have the potential to bioaccumulate and biomagnify in tissues of aquatic organisms. This diploma thesis deals with issues of alkyl derivatives of mercury in biotic matrices. The goal of this thesis was to analyze fish tissues. Fish were caught from the river Svratka at the inflow and at the outflow of wastewater treatment plant. Methylmercury was determined in fish muscles and skin. Total mercury was determined in fish muscles. The extraction based on acidic digestion in hydrochloric acid and subsequent extraction with toluene was used for isolation of methylmercury from fish tissues. There was used gas chromatography with electron capture microdetector for determination of methylmercury. Total mercury was determined by special analyzer AMA 254.

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