|
|
The issue of alkylderivatives of mercury in biotic matrices
Zajícová, Markéta ; Doležalová Weissmannová, Helena (referee) ; Vávrová, Milada (advisor)
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.
|
|
|
Speciation analysis of selenium in selenized yeast
Motlová, Tereza ; Vitoulová, Eva (referee) ; Diviš, Pavel (advisor)
The aim of the theses was determination of selenium species in yeast Saccharomyces cerevisiae cultivated in medium with added inorganic form of selenium (Sodium Selenite). Concentrations of Sodium Selenite in cultivation medium were 0,1; 1; 10 and 100 mg.l-1. Cultivation was undertaken in fermenting tub for period of 72 hours. Cultivated yeasts were extracted by use of enzymes and subsequently the species of selenium in particular parts of yeasts were determined. In order to determine selenium species, the method of high-performance liquid chromatography in combination with atomic fluorescent spectrometer and technique of hydride generation was used. Having analysed different fractions of the yeasts Saccharomyces cerevisiae it was ascertained that during cultivation the sorption of selenium occurred in form of Se4+ in cell membranes while in cytoplasm no inorganic forms of selenium were found. Furthermore, it was stated that yeasts Saccharomyces cerevisiae are able to metabolically change inorganic forms of selenium to organic forms (selenomethionine), while these forms are present in cytoplasm and they are likely to be bound to proteinic structures of cell membranes. An increase of concentration of Se4+ in cell membranes could be observed as a result of increasing concentration of Sodium Selenite in cultivation medium. In proteinic structures the concentration of organic selenium forms increased only to concentration 10 mg.l-1 of Sodium Selenite in cultivation medium.
|
|
|
Arsenic and arsenic species cycle in environment
Ševčíková, Kateřina ; Sommer, Lumír (referee) ; Dočekalová, Hana (advisor)
This bachelor thesis, based mostly on literature retrieval, deals with monitoring of individual arsenic compounds in the environment and is also reviewing methods used for their analysis. The experimental part is focused on determination of various arsenic in the Oncorhynchus mykiss tissue by HPLC-UV-HG-AFS. Obtained results showed that the arsenic was present in the tissue of the Oncorhynchus mykiss in form of arsenobetaine, which is common for fishes and other aquatic animals and is not toxic even for consuments.
|
|
| |
|
| |
guest ::
