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This master thesis is dedicated to the determination of concentration of selenium and mercury in seafood. The theoretical part is devoted to the selenium characteristics, toxicity and occurrence of the biochemical functions of selenium and the relation of selenium and mercury in fish. The practical part deals with the determination of selenium and mercury in fourteen species of fish that have been purchased fresh or vacuumed in chains store in the Czech Republic. Analysis of the selenium content was performed by atomic absorption spectrometry with electrothermal atomization. Determination of the total mercury content was performed with using atomic absorption spektrometer AMA 254. Results of total mercury contents were compared with legislative limits as per Commission Regulation (EC) No. 629/2008. Selenium Health Benefit Values Se-HBV were calculated.

The work deals with the determination of heavy metals (mercury, cadmium and lead) in carp tissues by the use of atomic absorption spectrometry. The theoretical part is focused on the heavy metals and their forms in fishes and in the environment. The anatomy of fishes and the composition of the fish meat are also discussed. The practical part summarized the results of concentrations of studied heavy metals in the carp's tail muscles and in their liver. Carps were fished in two locations - The Pilský reservoir and Domanínský lake situated in Žďár nad Sázavou district. For mercury determination was used one-purpose atomic absorption spectrometer AMA 254. The amounts of cadmium and lead were measured by the electrotermal atomic absorption spectrometry by use of spectrometr ContrAA 700. The obtained results were discussed and evaluated. Obtained concentrations of mercury and lead did not exceed the regulation limits, only concentration of cadmium in liver exceeded these limits in all samples.

Seven heavy metals were determined in nine samples of Pangasius hypophtalmus tissues purchased in Czech markets during the period November 2013 -- February 2014. Fresh samples were lyophilised and subsequently decomposed by 65% HNO3 in microwave oven. Heavy metals were determined by flame atomic absorption spectrometry (Cu, Fe, Zn) and electrothermal atomic absorption spectrometry (Cd, Cr, Ni, Pb). The certified reference material DORM-4 was used for method validation. The content of the studied elements in the samples was: Cd (< 0,18 -- 4,41 ug/kg FW), Cr (< 6,0 -- 26,2 ug/kg FW), Cu (0,32 -- 0,56 mg/kg FW), Fe (0,58 -- 1,74 mg/kg FW), Ni (43,7 -- 228,2 ug/kg FW), Pb (< 3,3 -- 26,4 ug/kg FW) and Zn (3,70 -- 6,33 mg/kg FW). The results were compared with literature and the risk of negative effects on the human body connected with common consumption of meat was evaluated. Studied samples of Pangasius hypophtalmus tissues were found to be harmless for people diet.

The work is focused on the determination of heavy metals - lead and cadmium in smoked fish products which were bought from stores in the Czech Republic during 2014. These were samples of smoked tuna and marlin (Principesca) in which the above limit values of mercury had been found in a previous study within the SVOČ SPŠCH Brno and a bachelor thesis MENDELU (Ventrubová, 2015) . The theoretical part involves the issue of heavy metals (lead and cadmium), their forms as well as their entry into the environment and accumulation in fish organisms. The experimental part is devoted to the determination of lead and cadmium concentrations in the samples, evaluation and comparison of the results with the relevant hygienic limits. Lead concentrations in the samples did not exceed the allowed hygienic limit, however, cadmium concentrations exceeded the allowed hygienic limit in all samples and this was confirmed by SZPI.

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No description available.

This thesis deals with the further development of the technique of generation of volatile compounds as derivatization methods by speciation analysis of selenium compounds. Specifically, this diploma thesis compares technique chemical and electrochemical generation of selected species of selenium (inorganic Se (IV) inorganic Se (VI), selenomethionine (Se- Met), selenocysteine (Se-Cys), methyl-selenocysteine (Met-Se-Cys) and seleno-urea (Se-U)). The achieved basic analytical characteristics are compared of each species in non-column arrangement with atomic fluorescence spectrometry. The effect of pre- reduction/decomposition unit are tested, using the pre-reduction agent KBr and hydrochloric acid at higher temperature and in the presence of UV radiation. Keywords Selenium, speciation analysis, chemical hydride generation, electrochemical hydride generation, atomic fluorescence spectrometry

The thesis deals with determination of selected nutrients (copper, zinc, iron) in nuts. In total, 33 samples, bought in retail chains in Czech Republic, were analysed. The theoretical part of the thesis is focused on characterisation of individual nuts including other fruits, which are consumed as nuts. In the practical part, contents of copper, zinc and iron were measured by the atomic absorption spektrometry method. From the results, it is clear that the highest amount of copper was found in Brazil nuts. The lowest amount of copper was found in macadam nuts. Overall the highest content of zinc within all types of nuts was found in pine nuts and the lowest amount of zinc was determined in coconut and edible chestnuts. Iron was the most contained in alaburks, cashews and pine nuts. The lowest quantitty of this element was measured in edible chestnuts.

This diploma thesis is focused on an analysis of mercury content in eatable mushrooms. Theoretical part describes transmission of mercury from environment to the soil, next to the mushrooms. Practical part was focused on the determination of total mercury content. Determination of mercury content was provided by atomic absorption spectrometer AMA 254. The samples were obtained from forests in the Czech Republic and Slovakia in 2017 and 2018 and from supermarkets in the Czech Republic. This thesis compares mercury concentration among various types of mushrooms obtained from various collection sites. Moreover, the contents were compared within different collection years, country of origin or size of mushroom. Furthermore, average mercury contents in mushrooms obtained from forests and supermarkets were compared. The highest concentration was found in wild-grown Agaricus bisporus and Macrolepiota procera, which have been grown in areas with higher mercury presence. The highest hazard index was calculated in this samples, too. The highest bioconcentration factor was calculated in Boletus reticulatus.