National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Optimization of nontargeted analysis of beer by gas chromatography with mass spectrometry
Růžičková, Hedvika ; Vrzal, Tomáš (advisor) ; Korban, Anton (referee)
A non-targeted analysis of beer samples was carried out using dispersive liquid-liquid microextraction (DLLME) and gas chromatography with mass spectrometric detection (GC-MS). The method was optimized in terms of the composition of the reaction mixture and the type of dispersing agent used. One sample of alcoholic beer was used for the optimization. The processed data showed that the optimal arrangement of DLLME for non-targeted analysis of beer is a reaction mixture consisting of 1 ml of the sample, 300 µl of the extraction agent (chloroform), and 700 µl of the dispersing agent (ethanol).
Mixture toxicity of estrogenic endocrine disruptors in samples from the Czech Republic
Černá, Tereza ; Cajthaml, Tomáš (advisor) ; Klusoň, Petr (referee) ; Šváb, Marek (referee)
The environment is contaminated by countless toxic chemicals of mainly anthropogenic origin; therefore, elucidating the impact of chemical mixtures is one of the biggest challenges of current research. Endocrine disruptors (EDs) acting through the oestrogenic nuclear receptor are typical representatives of the mixture toxicity concept of concentration addition, which can be accurately predicted using the latest mathematical models. Oestrogenic activity and oestrogenic EDs have been detected in many matrices across the globe in biologically relevant concentrations; therefore, they are considered a high risk. The presence of synthetic steroids in the aquatic environment in units of ng/l can disrupt the hormonal pathways of individuals and subsequently cause fatal changes in whole populations. However, if the exposure is terminated, the ecosystem will recover in a few years. Wastewater treatment plants (WWTPs) are able to remove a large number of chemicals, including synthetic and natural oestrogenically active compounds; nevertheless, their occurrence in WWTP effluents and in sewage sludges is frequent. Therefore, WWTPs are considered significant sources of agricultural and water ecosystem pollution. This dissertation thesis focuses on the mixture toxicity of oestrogenic EDs and their occurrence in...

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