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Kyselina kávová jako nový fluorescenční marker kvality nápojů
Vodová, Veronika
The work was focused on the study of the photochemical behaviour of caffeic acid (KK) with focus on the evaluation of quality of beverages. This organic acid is found in various beverages of natural origin, such as grape wines, juices, or teas. KK shows a very interesting photochemical behaviour, which is influenced by the environment in which it is found. If the quality of drinks changes, for example from the point of view of punching, the concentration of KK and the reaction conditions will naturally change as well. If such samples are exposed to UV radiation (starting photochemical reactions) and then is recorded fluorescence, which can be used to distinguish the sample from each other. Due to the complexity of this issue, this work is divided into two parts. The first (overview) part of this work contains important information about KK from different perspectives (occurrence, metabolism, effects etc.). The second (practical) part this work focused on fluorescence monitoring of KK standard under different conditions after UV irradiation (effect of UV exposure time, effect of pH of the environment and effect of phosphate buffer concentration). Based on the results, it was clearly demonstrated that the fluorescence properties of KK (photochemical behaviour) are strictly dependent on the pH, UV radiation time, the concentration of KK used and the chemical composition of the drink. These results suggest that KK can be considered as a fluorescent marker of beverage quality. To test this hypothesis will need to be analysed a larger number of real samples and statistically evaluated.
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Vývoj, optimalizace a validace analytické metody na stanovení kyseliny chikorové a dalších derivátů kyseliny kávové pomocí LC/MS
PAZDERKOVÁ, Nela
This thesis deals with the development, optimization, and validation of an analytical method for the determination of chicoric acid and other caffeic acid derivates using LC/MS. First, the development and optimization of the analytical method was conducted. The following parameters were selected for the optimization: mobile phase composition and flow rate injection volume capillary temperature, voltage S-lens and F-lens voltage, ion injection time, product ion selection, and collision energy. Then, the analytical method was successfully validated and tested for quantitative analysis in a range of Echinacea food matrixes - tea, tablet, and tincture.
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