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Application of Separation Techniques Connected with Mass Spectrometry for the Analysis of Environmentally Important Compounds
Mácová, Daniela ; Čelechovská, Olga (referee) ; Márová, Ivana (referee) ; Demnerová, Kateřina (referee) ; Čáslavský, Josef (advisor)
The identification of the hydrolysis and photodegradation products of flexible polyurethane foams (PUFs) with addition of biooriginated and biodegradable additive was the first topic of this dissertation work. Separation of polyurethane foam hydrolysis degradation products, designed for ecotoxicological tests, was managed by high-performance liquid chromatography coupled with mass spectrometry (HPLC/MS). The degradations product structure was elucidated by tandem mass spectrometry (MSn). PUF photodegradation products were obtained by exposure of materials by irradiation at 254 nm. Semi-volatile degradation products were isolated from the exposed polyurethane by n-hexane extraction; volatile compounds were collected by solid phase microextraction (SPME). Gas chromatography with mass spectrometry (GC/MS) and complete orthogonal tandem gas chromatography with mass spectrometry (GCxGC/TOF MS) was used for separation and identification of photodegradation products. The influence of the bio-filler on the character of degradation products and the possible effect of PUF degradation products on the environment was discussed at the end of this section. The determination of isoprostanes – markers of oxidative stress in tissues of beadlet anemone (Actinia equina) was the subject of the second topic. F2-isoprostanes were synthesized from the arachidonic acid. With thereby prepared isoprostanes the method of determination by liquid chromatography with tandem mass spectrometry (HPLC/MS/MS) was developed and optimized. The isoprostane isolation process from the Actinia equina tissues was optimized with solid phase extraction (SPE). The resulting methodology was used to quantify isoprostanes in tissues of anemones, which were exposed to both moderate and high temperature changes. The temperature changes were used to initiate the oxidative stress in organisms. In addition, concentration levels of unknown compounds were also monitored. These unknown compounds were extracted from tissues together with F2-isoprostanes and their identity is discussed in this dissertation work too. The possibility of using isoprostane levels in the Anthozoa tissues for the oxidative stress monitoring is discussed in the conclusion of this work.
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Analysis of degradation mechanisms oligobutadienes
Baťa, David ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with the studies of liquid oligobutadiens properties in AC electric field by dielectric relaxation spectroscopy method. The current issue in the diagnosis of oligomeric and polymeric materials during the activity of various degradation factors and options of their alleviation and suppression was studied. The existing apparatus is modified for monitoring possibilities of polymeric materials during the action of various degradation and operational factors. Effect of climatic factors are experimentally investigated, especially UV radiation and temperature on the course of the frequency dependence of complex permittivity components with respect to the different composition and length of the polymer chain.
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Světlostálost povrchových úprav barevnými laky
Rašovská, Karolína
This bachelor thesis deals with the determination of the light fastness of surface treatments with colored varnishes intended for the exterior. The color change was measured and analyzed on samples with a surface treatment of colored varnishes, namely on massive base materials of spruce and oak. The light fastness of the surface treatments of the verified paints was determined using the BYK spectrophotometer. The gloss change of the paints was assessed thanks to the PICOGLOSS 503 gloss meter. Tests of adhesion, paint thickness and hardness were also performed. To verify the properties of individual paints, the samples were subjected to tests according to ČSN standards. The aim of this work is to compare the properties of the used paints.
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Study of beer photodegradation by optical methods
Tayari, Tomáš ; Gabriel, Petr (advisor) ; Lustig, František (referee)
If beer is exposed to light radiation, it very quickly creates an undesirable unpleasant so- called lightstruck flavor. According to current ideas, 3-methyl-2-butene-1-thiol (MBT) is responsible for the lightstruck flavour in beer. The formation of MBT is associated with non- enzymatic reactions in which isohumulones and sulfuric components of amino acids and their derivatives emerge. Riboflavin (vitamin B2), which absorbs light and reacts with isohumulones in the excited state, acts as a photocatalyst. Light degrades riboflavin into its photoproducts. The aim of this work was to verify the possibilities of optical detection of beer photodegradation. An apparatus for detecting spectrally differentiated fluorescence intensity with a replaceable excitation LED source was constructed. The apparatus allows the excitation emission matrix of fluorescence (EEM) to be measured with selected excitation wavelengths. The fluorescence signal is scanned by a spectrophotometer with 90 ř offset to the excitation beam and corrected by its intensity which was detected in a straight line. The light source and detectors are connected to the measuring chamber via optical fibers. The fluorescence spectra of riboflavin, its photoproduct lumichrome and samples of fresh and defined light-damaged beer were measured on the...
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Study of thermal and photodegradation of beer and other fermented beverages
Škoda, Jakub ; Gabriel, Petr (advisor)
In this thesis the optical changes of beers and model beer solutions during their photodegradation were studied. The optical changes - change of absorbance - were measured on the prototype of apparatus COLORTURB and were correlated with sensory tested intensity of the lightstruck flavour of beer and with riboflavin content in samples. High correlation between the lightstruck flavour intensity, the loss of absorbance at the wavelength of 450 nm and the riboflavin content loss was found. The partial recovery of the absorbance for both beers and model beer solutions was found and was attributed to the riboflavin photoproducts transformation.
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Study of beer photodegradation by optical methods
Tayari, Tomáš ; Gabriel, Petr (advisor) ; Lustig, František (referee)
If beer is exposed to light radiation, it very quickly creates an undesirable unpleasant so- called lightstruck flavor. According to current ideas, 3-methyl-2-butene-1-thiol (MBT) is responsible for the lightstruck flavour in beer. The formation of MBT is associated with non- enzymatic reactions in which isohumulones and sulfuric components of amino acids and their derivatives emerge. Riboflavin (vitamin B2), which absorbs light and reacts with isohumulones in the excited state, acts as a photocatalyst. Light degrades riboflavin into its photoproducts. The aim of this work was to verify the possibilities of optical detection of beer photodegradation. An apparatus for detecting spectrally differentiated fluorescence intensity with a replaceable excitation LED source was constructed. The apparatus allows the excitation emission matrix of fluorescence (EEM) to be measured with selected excitation wavelengths. The fluorescence signal is scanned by a spectrophotometer with 90 ř offset to the excitation beam and corrected by its intensity which was detected in a straight line. The light source and detectors are connected to the measuring chamber via optical fibers. The fluorescence spectra of riboflavin, its photoproduct lumichrome and samples of fresh and defined light-damaged beer were measured on the...
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Study of thermal and photodegradation of beer and other fermented beverages
Škoda, Jakub ; Gabriel, Petr (advisor)
In this thesis the optical changes of beers and model beer solutions during their photodegradation were studied. The optical changes - change of absorbance - were measured on the prototype of apparatus COLORTURB and were correlated with sensory tested intensity of the lightstruck flavour of beer and with riboflavin content in samples. High correlation between the lightstruck flavour intensity, the loss of absorbance at the wavelength of 450 nm and the riboflavin content loss was found. The partial recovery of the absorbance for both beers and model beer solutions was found and was attributed to the riboflavin photoproducts transformation.
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