20.500.12556/DKUM-73381 Sočasno določanje različnih fenolnih spojin v ekstraktih čajev s tekočinsko kromatografijo z UV zaznavo diplomsko delo univerzitetnega študijskega programa I. stopnje Simultaneous determination of phenolic compounds in tea extracts by HPLC-UV Čaj predstavlja eno najbolj priljubljenih pijač na svetu in se po količini zaužitja uvršča takoj za vodo. K temu pripomorejo njegov dober okus, vonj in številne fenolne spojine, ki zaradi svojih antioksidativnih lastnosti pozitivno vplivajo na človekovo zdravje. Da bi določili dejanske vsebnosti fenolnih spojin v ekstraktih čajev, smo razvili analizno metodo z uporabo tekočinske kromatografije visoke ločljivosti z UV zaznavo. Analizirali smo trideset komercialno dostopnih čajev slovenskega proizvajalca in določevali prisotnost desetih fenolnih spojin: rožmarinska kislina, protokatehuična kislina, vanilinska kislina, (+)-katehin, rutin, siringinska kislina, ferulna kislina, p kumarna kislina, klorogenska kislina in kavna kislina. Razvito metodo smo validirali tako, da smo določili ponovljivost, obnovljivost in linearnost metode ter mejo določljivosti in zaznavnosti. Ekstrakte čajev smo pripravili tako, da smo po mletju in sušenju zatehtali ustrezno količino posameznega čaja, ga prelili z vrelo ultra čisto vodo, premešali in pustili 30 min. Sledilo je filtriranje s filter papirjem, redčenje z ultra čisto vodo na določen volumen in filtriranje s PTFE filtri tik pred analizo s HPLC-UV. Spojine smo eluirali gradientno, pri čemer je bila mobilna faza A sestavljena iz 100 % acetonitrila in mobilna faza B iz 1 % ocetne kisline. Separacijo smo dosegli v 40 minutah pri valovni dolžini 280 nm. Ugotovili smo, da je v analiziranih sadnih čajih prisotnih v splošnem manj izbranih fenolnih spojin in v nižjih koncentracijah kot v zeliščnih in pravih čajih. Največkrat so bile v čajih prisotne vanilinska kislina, protokatehuična kislina in kavna kislina, medtem ko smo siringinsko kislino in (+)-katehin določili v najmanjšem številu čajev. Tea is one of the most popular drinks in the world and is the second most consumed drink after water. Reasons for that are its good taste, flavour and many phenolic compounds, which have positive impact on human health due to their antioxidant properties. To determine actual content of phenolic compounds in tea extracts, an analytical method using high performance liquid chromatography with UV detection was developed. Thirty commercial teas from a Slovenian manufacturer were analysed and ten different phenolic compounds (rosmarinic acid, protocatechuic acid, vanillic acid, (+)-catechin, rutin, syringic acid, ferulic acid, p-coumaric acid, chlorogenic acid and caffeic acid) were determined. Developed analytical method was validated by determining repeatability, inter-day reproducibility, linearity, limit of detection and quantification. The first step in preparation of tea extracts was grinding and drying the content of tea bags. After that an appropriate amount of tea was weighed, poured over with boiling ultrapure water, mixed and left for 30 minutes. The mixture was than filtered through filter paper, diluted with ultrapure water to the final volume and filtered through PTFE filter before the HPLC-UV analysis. The elution was gradient and mobile phase A consisted of 100 % acetonitrile and mobile phase B consisted of 1 % acetic acid. The separation was achieved in 40 minutes and the detection wavelength was set at 280 nm. The results have shown that analysed fruit teas in general contain fewer phenolic compounds and in lower concentrations than herbal, green and black teas. Vanillic acid, protocatechuic acid and caffeic acid were present in the greatest number of analysed teas, while the least amount of teas contained syringic acid and (+)-catechin. čaj fenolne spojine tekočinska kromatografija UV zaznava tea phenolic compounds liquid chromatography UV detection true true false [M. Stopinšek] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2019-04-03 00:15:13 2019-04-25 12:46:17 2022-08-02 00:39:52 2019-08-06 03:29:03 2019 0 Maribor 0 Maribor IX, 50 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 543.544.5:547.562.4(043.2) 22336790 URN:SI:UM:DK:0OQ2PNVV UN_Stopinsek_Masa_2019.pdf UN_Stopinsek_Masa_2019.pdf 1 EB915116BBE47BB002DC404B18060C3F 9cdbd609d7d05ab4be4d80a16a6e9188c1fba7bd2b8e2d86bdfea1b898a5ac44 a945ae0e-7c10-11eb-bb7a-00155d0001ca 20.500.12556/dkum/a9f99221-617d-4bb6-8e89-5e8719b5668f https://dk.um.si/Dokument.php?lang=slv&id=133421 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0