Browsing by Subject "garlic"

Literature review of the thesis introduces the characteristics of selenium and its importance in human diet. It also gives an overview on different analytical methods used in speciation of selenoamino acids. The aim of this study was to develop a simple and rapid mass spectrometric method which could be used to detect and specify low molecular weight selenoamino acids from different food materials in order to find and quantify probable cancer protective species. Total selenium content was determined by GFAAS from garlic and Brazil nut samples. The selenium concentration in garlic was 0.1 µg/g and 4.4 µg/g in Brazil nuts. Also, the precipitates and supernatants from the sample extractions (hot water, diluted HCl and proteinase K) were analyzed. There were only about 10% of the total selenium in the supernatants (which were further used in analysis). Samples were derivatized by AccQ·Tag reagent (AQC) and analyzed with UHPLC-ESI-MS method. Even though the method was easy and fast to use, it was applicable only for selenoamino acid standards (MeSeCys and SeMet). No results were obtained from the real samples. Therefore, a more sensitive piece of equipment, HPLC-ICP-MS was applied with Hamilton PRP-X100 column and 5 mmol/l ammonium citrate buffer (pH 5.2). Hot water and diluted HCl extracted samples showed no signs of selenium. At last, proteinase K digested Brazil nut sample showed a small peak of SeMet which was identified by retention time matching with the standard and quantified semi quantitatively from standard curve (0,06 µg SeMet /g Brazil nut). This study showed that the sensitivity of the UHPLC-ESI-MS method was not sufficient to detect such low concentrations of selenoamino acids in garlic and Brazil nut samples. However, the AQC derivatization together with UHPLC-ESI-MS offers a fast, linear and repeatable method for future amino acid analysis.