Determination of iron in beer using atomic absorption spectroscopy

Obsahem této práce je vývoj a optimalizace metody stanovení obsahu železa v pivu bezplamenovou AAS jako citlivější alternativy k běžně používané plamenové AAS. Zatímco pro vodné roztoky byla vyvinutá metoda plně funkční, u reálných vzorků piva matriční efekty zcela znemožňovaly toto stanovení. Proto byla vyvinuta metoda přípravy vzorku, a to přečištění piva přes kolonku naplněnou adsorbentem Florisilem. Po této úpravě byly rušící látky odstraněny a mez detekce pro tento způsob stanovení byla stanovena šestkrát nižší než pro plamenovou AAS. Vzhledem k tomu, že v reálném vzorku byl naměřen o 30 % nižší obsah železa než pomocí plamenové AAS, je třeba danou metodu dále optimalizovat, což bude předmětem dalších experimentů.This thesis describes the development and optimisation of a method for determination of iron in beer using electrothermal atomic absorption spectroscopy as a more sensitive option to routinely used flame atomic absorption spectroscopy. While a fully functional method has been developed for aqueous solutions, matrix effects in real beer samples made this determination impossible. Therefore, a method of sample preparation has been developed, beer purifying through column with adsorbent Florisil. After this adjustment the interfering substance was eliminated and the detection limit of ETAAS was six times lower than the detection limit of FAAS. The content of iron in the real beer sample using ETAAS was measured as 30 % lower than using FAAS, it is therefore necessary to optimise this method. This will be the subject of further experiments.Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Determination of biologically active compounds in hops by LC/HR-MS method

Obsahem této práce je vývoj a optimalizace metody pro identifikaci polyfenolických látek pocházejících ze chmelu (Humulus lupulus L.) s potencionální antimikrobiální aktivitou. V rámci extrakce látek ze chmelu byly sušené chmelové hlávky aplikovány do růstového media, odkud látky difundovaly do agaru a po naočkování bakteriálním kmenem Streptococcus aureus vytvořily inhibiční zónu. Pro extrakci látek z agaru byla optimalizována metoda kombinující extrakci acetonem s vysolením metodou QuEChERS. Měření probíhalo s použitím LC/HR-MS s hybridním analyzátorem kvadrupól-orbitální pastí. MS metoda byla vyvinuta jako screening s následnou fragmentací látky na základě seznamu hmot. Látky extrahované z inhibiční zóny byly následně identifikovány buď proti databázi, anebo byla jejich struktura objasněna pomocí fragmentačních spekter.This thesis describes development and optimalization of method for identification of polyphenols compounds present in hops (Humulus lupulus L.) that have potential antimicrobial activity. Within extraction of compounds from hop, minced hop cones were applied in a growth medium, where compounds diffused into the medium and created an inhibition zone after inoculated with Streptococcus aureus. The method combining extraction with acetone a salting out using QuEChERS principles was optimized for extraction of compounds from solid growth medium. The analysis was carried out using LC/HR-MS with a quadrupole-orbitrap hybrid mass analyzer. The MS method was developed as a screening method with a subsequent fragmentation of compound of interest on the base of inclusion mass list. The compounds extracted from inhibition zone were identified either by searching against a database or their structures have been elucidated on the basis of their fragmentation spectra.Katedra analytické chemieDepartment of Analytical ChemistryPřírodovědecká fakultaFaculty of Scienc

Methods for verifying the authenticity of hops – an effective tool against falsification

Falsifi cation attempts occur in almost all commodities and hops is no exception. It is therefore necessary to look for ways to verify its authenticity. This review summarizes modern methods for verifying the authenticity of hops and also provides the latest results of the collaboration of the Research Institute of Brewing and Malting, PLC. and the Hop Research Institute, Ltd., in Žatec. Chemotaxonomic and genetic methods are used to verify the authenticity of hops. Chemical analyzes of newly bred hybrids potentially suitable for Czech beer focused on the content and composition of alpha and beta acids, content and composition of hop oils, and content of total polyphenols were performed and molecular genetic analyses of 150 selected hop genotypes including a world-wide range and breeding material were conducted in 2015. These data were used to construct a comprehensive dendrogram from the tested genotypes. The authors also examined the profi ling of Czech hop varieties based on the chemical profi les of proanthocyanidins, and succeeded in using cluster analysis to clearly distinguish the varieties of hops including their genetic relatedness

Determination of biologically active compounds in hops by LC/HR-MS method

This thesis describes development and optimalization of method for identification of polyphenols compounds present in hops (Humulus lupulus L.) that have potential antimicrobial activity. Within extraction of compounds from hop, minced hop cones were applied in a growth medium, where compounds diffused into the medium and created an inhibition zone after inoculated with Streptococcus aureus. The method combining extraction with acetone a salting out using QuEChERS principles was optimized for extraction of compounds from solid growth medium. The analysis was carried out using LC/HR-MS with a quadrupole-orbitrap hybrid mass analyzer. The MS method was developed as a screening method with a subsequent fragmentation of compound of interest on the base of inclusion mass list. The compounds extracted from inhibition zone were identified either by searching against a database or their structures have been elucidated on the basis of their fragmentation spectra

Determination of iron in beer using atomic absorption spectroscopy

This thesis describes the development and optimisation of a method for determination of iron in beer using electrothermal atomic absorption spectroscopy as a more sensitive option to routinely used flame atomic absorption spectroscopy. While a fully functional method has been developed for aqueous solutions, matrix effects in real beer samples made this determination impossible. Therefore, a method of sample preparation has been developed, beer purifying through column with adsorbent Florisil. After this adjustment the interfering substance was eliminated and the detection limit of ETAAS was six times lower than the detection limit of FAAS. The content of iron in the real beer sample using ETAAS was measured as 30 % lower than using FAAS, it is therefore necessary to optimise this method. This will be the subject of further experiments