Stresno testiranje stabilnosti hidrofilnih vitaminov

Temov, Dejan (avtor), Roškar, Robert (mentor)

Posamezni hidrofilni vitamini veljajo za nestabilne molekule. Na hitrost njihove razgradnje poleg zunanjih dejavnikov vplivajo tudi njihove medsebojne interakcije, ki so še vedno dokaj neraziskane. Zaradi kompleksnosti dejavnikov, ki lahko vplivajo na njihovo stabilnost, in pomanjkanja ustreznih analiznih metod najdemo v literaturi neenotne rezultate stabilnostnih študij, ki so po večini le kvalitativni. Ker pa je poznavanje problematike stabilnosti vitaminov in njihovih interakcij nujno za zagotavljanje kakovosti vitaminskih izdelkov, katerih uporaba je dandanes izjemno široka, je potreba po zanesljivih stabilnostnih študijah zelo velika. Zatorej je bil osrednji cilj magistrske naloge kvantitativno ovrednotiti stabilnost vseh posameznih hidrofilnih vitaminov v oblikah, ki jih najdemo v vitaminskih izdelkih in njihovih zmeseh v raztopinah pri različnih stresnih pogojih. V ta namen smo sprva ovrednotili predhodno razvito stabilnostno indikativno analizno metodo po smernici ICH ter ugotovili, da le-ta dosega zastavljene kriterije v smislu specifičnosti, linearnosti, točnosti, natančnosti, meje zaznave, meje določitve in stabilnosti kontrolnih vzorcev. Stabilnostno študijo smo pričeli s stresnim testiranjem pri ostrejših pogojih (svetloba, povišana temperatura, oksidacija, kislinska in bazična hidroliza). Tako smo pridobili vpogled v reakcije nestabilnosti posameznih vitaminov ter opredelili vitamin C in 5-metiltetrahidrofolno kislino (aktivna oblika folatov) kot najmanj stabilna vitamina. Ugotovili smo tudi različno dovzetnost za razgradnjo vitaminov v raztopinah posameznih vitaminov in zmeseh. V zmeseh je bila najbolj opazna povečana oksidativna stabilnost vitaminov B1, B2, B5, B6, B9 in B12 ter zmanjšana fotostabilnost vitaminov B3, B5, B6, B7, B9 in B12. Stresno testiranje smo nadgradili s poglobljenim vrednotenjem stabilnosti posameznih vitaminov in izbranih zmesi pri različnih pH medija, temperaturah shranjevanja ter koncentracijah oksidanta (vodikovega peroksida). Za kvantitativno vrednotenje stabilnosti vitaminov smo uporabili kinetiko 1. reda, ki je najbolje opisovala njihovo razgradnjo, in opredelili pogoje, ki odločilno vplivajo na stabilnosti vitaminov ter proučevali interakcije med vitamini v zmeseh. Za večino vitaminov smo potrdili pričakovano pospešeno razgradnjo pri višji temperaturi, medtem ko je pH medija različno vplival na stabilnost posameznih vitaminov. Pri vrednotenju oksidativne stabilnosti vitaminov v zmeseh smo zaznali kompleksne interakcije, pri katerih smo prepoznali ključno vlogo vitamina C.

• Jezik: Slovenski jezik
• Ključne besede: Hidrofilni vitamini, UHPLC-DAD, validacija, testiranje stabilnosti, stresni testi, oksidacija, hidroliza.
• Vrsta gradiva: Magistrsko delo/naloga
• Organizacija: FFA - Fakulteta za farmacijo
• Leto izida: 2022
• PID: 20.500.12556/RUL-143375
• Datum objave v RUL: 17.12.2022

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Stress testing of the stability of hydrophilic vitamins

Izvleček

Individual hydrophilic vitamins are considered unstable molecules. In addition to external factors, their degradation rate is also influenced by their mutual interactions, which are still relatively unexplored. Due to the complexity of the factors that may affect their stability and the lack of appropriate analytical methods, stability studies in the literature provide inconsistent results that are mostly qualitative. However, with the growing use of vitamin products, there is also an increasing need for reliable stability studies, as knowledge on vitamins stability and their interactions is necessary to ensure the quality of such products. Therefore, the central goal of this master's thesis was to quantitatively evaluate the stability of all individual hydrophilic vitamins in their commonly used forms in vitamin products as well as their mixtures in solutions under different stress conditions. For this purpose, we initially validated the previously developed stability-indicating analytical method following the ICH guidelines and found that it meets the set criteria in terms of specificity, linearity, accuracy, precision, detection limit, quantitation limit and stability of control samples. Stress testing under extreme conditions (light, elevated temperature, oxidation, acidic and alkaline hydrolysis) gained insight into the instability reactions of individual vitamins and identified vitamin C and 5-methyltetrahydrofolic acid (the active form of folates) as the least stable vitamins. We also found different susceptibility to degradation of the tested vitamins in solutions of individual vitamins and their mixtures. The most notable was the increased oxidative stability of vitamins B1, B2, B5, B6, B9 and B12 and the decreased photostability of vitamins B3, B5, B6, B7, B9 and B12 in the mixtures. The stress testing was upgraded with an in-depth evaluation of the stability of individual vitamins and selected mixtures at different pH values, storage temperatures and oxidant (hydrogen peroxide) concentrations. First order kinetics best described their degradation and was used for the quantitative stability evaluation. We defined the conditions with decisive effect on the stability of the studied vitamins and investigated the interactions between the vitamins in the mixtures. For most vitamins, we confirmed the expected accelerated degradation at higher temperature, while the pH of the medium had a different effect on the stability of the individual vitamins. When evaluating the oxidative stability of vitamins in the mixtures, we found complex interactions in which we recognized the role of vitamin C as key.

• Ključne besede: Hydrophilic vitamins, UHPLC-DAD, validation, stability testing, stress testing, oxidation, hydrolysis.