München, Techn. Universiẗat, Diss., 2003.

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This thesis focuses on analysis of reaction products of phthalaldehyde with selected amino acids using the combination of high-performance liquid chromatography with mass spectrometry. Only one product with dihydroisoindole structure is formed in the case of simple amino acids (glycine, glycine ethyl ester, alanine, α-aminobutyric acid, valine, leucine and isoleucine). Reactions of phthalaldehyde with amino acids with two amino groups (lysine, asparagine, glutamine and arginine) yield different types of compounds. Main products are formed by the interaction of both of the amino groups with one molecule of phthalaldehyde. Apart from this type of product, these reactions also result in formation of the expected analogous structures of dihydroisoindoles. Moreover, the formation of products containing one molecule of amino acid and two molecules of phthalaldehyde is not excluded. The products were structurally analysed by the use of high-performance liquid chromatography and tandem mass spectrometry. Reaction products of phthalaldehyde with α-aminobutyric acid, valine, leucine, isoleucine and lysine were isolated and further analyses such as electron ionisation with double focusing sector analyser and nuclear magnetic resonance were performed. Pieces of information resulting from the analysis of...

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 aim of the thesis is to study the relationship between the structure of N-benzylsalicylthioamide derivatives and their retention behavior in high-pressure liquid chromatography. Furthermore, the influence of various substituents on electron absorption spectra in ultraviolet spectral range was studied. All studied derivatives have two absorption maxima in ultraviolet spectral range at 260 nm and 293 nm. The substitution of an auxochrome on the acyl ring leads to bathrochromic shift and hyperchromic shift, especially of the first absorption maxima. The presence of an auxochrome on the amide ring leads to hyperchromic shift as well. HPLC reversed-phase chromatography, using XDB-C18 ZORBAX column and mobile phase with various composition of acetonitrile, was used to obtain retention times of the derivatives. Using this data, the correlation equations between retention factor (mobile phase with no acetonitrile), resp. slope of the dependence of the logarithm of retention factor on the volume fracture of acetonitrile in mobile phase, and partition coefficient octanol-water, resp. hydrophobic substituent constants, were derived. Key words: QSAR, HPLC, spectrometry, benzylsalicylthioamides

This thesis was focused on testing of portable Raman spectrometer for detection of components in model mixtures of five different biomolecules in a gypsum matrix. The main goal was to test the ability of the instrument to detect amino acids glycine, L-proline, L-alanine and nucleobase thymine in samples containing UV protective pigment -carotene. Other measurements were taken using the laboratory inVia Reflex instrument to comapare the results gained from the portable Raman spectrometer. Both instruments were equipped with the excitation laser working at 785 nm wavelength. It was found out that it is possible to detect amino acid in mixtures containing -carotene at the lowest concentration of amino acid 100 g/kg and the maximum concentration of -carotene 1 g/kg. Thymine could be identified at the concentration of 100 g/kg in mixtures with higher concentration of -carotene (10 g/kg). In mixtures of -carotene at the concentration of 1 g/kg and only one of the studied nitrogen containg compounds (at the concentration of 100 g/kg) in the gypsum matrix, it was possible to detect all present components. In mixtures containing two nitrogen compounds with -carotene at the concentration of 1 g/kg in the gypsum matrix, both nitrogenous compounds could be detected. When measuring the samples of the three nitrogen...

Zugl.: Hohenheim, Univ., Diss., 2005

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.