20.500.12556/RUL-171833 Določanje vsebnosti askorbinske kisline v izbranih kozmetičnih izdelkih z metodo tekočinske kromatografije Determination of ascorbic acid content in selected cosmetic products by liquid chromatography method Askorbinska kislina je ena izmed ključnih učinkovin v sodobni kozmetiki, saj deluje kot močan antioksidant, posvetli kožo in upočasnuje znake staranja. Kljub temu je kemijsko zelo nestabilna spojina in občutljiva na številne dejavnike. Zato se v kozmetičnih izdelkih pogosteje uporabljajo bolj stabilni derivati askorbinske kisline, vendar pa študije še vedno potrjujejo, da ima prav askorbinska kislina najmočnejši biološki učinek. Iz tega razloga smo se v okviru diplomske naloge osredotočili na vrednotenje vsebnosti in stabilnosti askorbinske kisline v izbranih kozmetičnih izdelkih. Analize smo izvedli z uporabo metode tekočinske kromatografije visoke ločljivosti, ki smo jo naprej ustrezno ovrednotili v skladu s smernicami ICH. Osrednji cilj naloge je bil ovrednotiti vsebnost in stabilnost askorbinske kisline v izbranih kozmetičnih izdelkih in tako pridobiti vpogled v kakovost kozmetičnih izdelkov na našem trgu. Pri tem smo se osredotočili na kozmetične izdelke v obliki serumov, ki so na ovojnini kvantitativno navajali vsebnost askorbinske kisline. Po pregledu trga smo izbrali nabor 12 serumov različnih proizvajalcev v različnih cenovnih območjih (od 6,95 do 88,98 €/30 mL). Pri analizi izbranih izdelkov smo pri osmih izdelkih potrdili prisotnost navedene askorbinske kisline. Pri preostalih štirih izdelkih navedene askorbinske kisline nismo zaznali. Kvantitativna vsebnost asorbinske kisline se je v šestih izdelkih dobro ujemala z navedeno koncentracijo (100 ± 20 %), pri ostalih 2 izdelkih pa so bile vrednosti nižje. V okviru raziskave nismo ugotovili neposredne povezave med ceno in kakovostjo izdelkov, pri čemer smo kot merilo uporabili razliko med navedenim in eksperimentalno določenim deležem askorbinske kisline. Ker smo preverili, ali je razlog za odstopanja vsebnosti askorbinske kisline v izdelkih njena nestabilnost, smo izdelke izpostavili dolgoročnim in pospešenim pogojem testiranja stabilnosti (25 in 40 ℃). Vsebnost askorbinske kisline se pri 25 ℃ praktično ni spremenila, medtem ko smo pri 40 ℃ zaznali znaten padec (50-100 %). Na ovojnini dveh izdelkov smo zasledili priporočilo o shranjevanju izdelka v hladilniku. V obeh izdelkih smo potrdili temperaturno odvisnost razgradnje askorbinske kisline, ki jo lahko omejimo s shranjevanjem pri nižji temperaturi. Zato je priporočilo proizvajalca pri obeh izdelkih smiselno. Zaključimo lahko, da rezultati naloge nakazujejo na potrebo po doslednejšem nadzoru kozmetičnih izdelkov na trgu. Ascorbic acid is one of the key active ingredients in modern cosmetics, acting as a powerful antioxidant, brightening the skin and slowing down signs of aging. However, it is chemically very unstable and sensitive to external factors. Therefore, more stable derivatives of ascorbic acid are commonly used in cosmetic products, although studies continue to confirm that ascorbic acid has the strongest biological effect. For this reason, the focus on this diploma thesis was to evaluate the content and stability of ascorbic acid in selected cosmetic products, using high-performance liquid chromatography, which was first appropriately validated in accordance with ICH guidelines. The main aim of this thesis was to assess the content and stability of ascorbic acid in selected cosmetic products and thereby gain insight into the quality of cosmetic products available on our market. The research focused on cosmetic products in the form of serums that listed a quantitative content of ascorbic acid on their packaging. Following a market review, a selection of 12 serums from various manufacturers in different price ranges (from 6,95 to 88,98 €/30 mL) was made. In the analysis of the selected products, the presence of declared ascorbic acid was confirmed in eight of them. In the remaining four products, the declared ascorbic acid was not detected. The quantitative content of ascorbic acid in six products corresponded well with the declared concentration (100 ± 20 %), while in the other two, the measured values were lower. No direct correlation was observed between product price and quality, as assessed by the difference between the declared and experimentally determined content of ascorbic acid. To determine whether the observed deviations were due to instability of ascorbic acid, we also subjected the products to both long-term and accelerated stability tests (25 and 40 ℃). At 25 ℃, the ascorbic acid content remained practically unchanged, whereas a significant decrease (50-100 %) was observed at 40 ℃. On the packaging of two products, a recommendation to store the product in the refrigerator was noted. In both products, the temperature dependence of ascorbic acid degradation was confirmed, showing better stability at lower temperatures. Therefore, the manufacturer's recommendation is justified in both cases. The results of our study indicate the need for more consistent monitoring of cosmetic products available on the market. Askorbinska kislina kozmetični izdelki stabilnost tekočinska kromatografija visoke ločljivosti vsebnost Ascorbic acid cosmetic products stability high-performance liquid chromatography content true false false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2025-09-03 08:45:15 2025-09-03 08:45:18 2025-09-22 03:44:10 0000-00-00 00:00:00 2025 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 117122 28127.pdf 28127.pdf 1 4DF2AE1B36BFF6BEA674A49860818065 31378cd89c3b49c4008979086152f070dcc38ffca75046157809111af3d51d72 68be11b5-8891-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=215326 Fakulteta za farmacijo 0 0 0