20.500.12556/DKUM-94271 Določanje polifenolov v vzorcih hmelja (Humulus lupulus L.) s HPLC-DAD magistrsko delo Determination of polyphenols in hop samples (Humulus lupulus L.) by HPLC-DAD Namen magistrskega dela je optimizacija ekstrakcije polifenolnih spojin, optimizacija HPLC metode za določanje polifenolov v hmelju, ter določitev vsebnosti le-teh v različnih sortah hmelja. Hmelj ima izrazite antioksidativne lastnosti, za katere so ključne polifenolne spojine. V magistrskem delu smo se osredotočili na katehin, epikatehin, ferulno kislino, naringin, 4-hidroksikumarin, kvercetin in ksantohumol, ki so običajno prisotne v hmelju. Lastnosti polifenolnih spojin so močno povezane z njihovo kemijsko strukturo, zato je pomembna ustrezna ekstrakcija, ločba ter identifikacija spojin iz naravnih virov. Izbrane polifenole smo analizirali s HPLC-DAD metodo, ki smo jo ustrezno optimizirali ter jo delno validirali. Določili smo njeno linearnost, LOD, LOQ, natančnost in točnost. Z izračunom izkoristkov smo izbrali najbolj optimalno metodo ekstrakcije, pri čemer smo primerjali vpliv koncentracije topila, čas ekstrakcije, način ekstrakcije ter maso vzorca. Ekstrakcijo smo izvajali z uporabo ultrazvočne kopeli (UAE, angl. »ultrasound-assisted extraction«). Z optimizirano metodo smo določili vsebnost posameznih polifenolnih spojin v sortah hmelja Savinjski golding, Celeia, Bobek, Styrian Fox, Styrian Dragon, Dana in Styrian Wolf. The aim of the master thesis is to optimise the HPLC method for the determination of polyphenols in hops, to optimise the extraction of polyphenolic compounds and to determine their content in different hop varieties. Hops exhibit antioxidant properties, which are largely determined by their polyphenolic compounds. In this MSc thesis we focused on catechin, epicatechin, ferulic acid, naringin, 4-hydroxycoumarin, quercetin and qanthohumol, which are commonly present in hops. The properties of polyphenolic compound are strongly linked to their chemical structure, hence the importance of proper extraction, separation and identification of compound from natural sources. The selected polyphenols were analysed by HPLC-DAD method, which was optimised and partially validated. Its linearity, LOD, LOQ, precision and accuracy were determined. By calculating the recoveries, the most optimal extraction method was selected, comparing the influence of solvent concentration, extraction time, extraction method and sample mass. The extraction was carried out using an ultrasound-assisted extraction (UAE). With the optimized method, we determined the content of individual polyphenolic compounds in hop varieties Savinjski golding, Celeia, Bobek, Styrian Fox, Styrian Dragon, Dana and Styrian Wolf. polifenoli hmelj HPLC optimizacija validacija polyphenols hops HPLC optimisation validation true true false [A. Deželak] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2025-08-12 10:07:40 2025-09-03 14:10:16 2026-03-24 07:32:39 0000-00-00 00:00:00 2025 0 Maribor 0 Maribor 1 spletni vir (1 datoteka PDF (XIII, 79 str.)) 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 [543.544.5:547.56]:633.791(043.2) 247867651 MAG_Dezelak_Anja_2025.pdf MAG_Dezelak_Anja_2025.pdf 1 36C67DE8DABF0A908038040410CD2166 0970be64f056b23105c7723024c2005b69b720cd940ea29773dde4d7028c3ed0 76faf3c8-8329-11f0-8e8c-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=196570 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0