@phdthesis{
author = "Tumpa, Anja",
year = "2019",
abstract = "Poslednju deceniju susrećemo se sa brojnim izazovima kada je u pitanju analitika različitih analita primenom tečne hromatografije hidrofilnih interakcija (eng. Hydrophilic Interaction Liquid Chromatography, HILIC). Uprkos stalnom porastu broja publikovanih radova i dalje se sa sigurnošću ne može predvideti ponašanje različitih analita u ovom sistemu hromatografije. Odgovor leži u složenosti retencionih mehanizama, te su i dalje neophodna naučna istraživanja koja omogućavaju da se ovaj hromatografski sistem detaljno prouči. Shodno tome, cilj ove doktorske disertacije bio je da se primene teorijski i empirijski modeli u cilju definisanja retencionog ponašanja strukturno sličnih analita (olanzapina i njegovih srodnih supstanci) u HILIC sistemu, kao i da se stečena znanja primene kroz odgovarajuću primenu nove metode. Ispitivana smeša analita olanzapina i njegovih osam srodnih supstanci po prvi put je ispitivana u HILIC sistemu u ovoj doktorskoj disertaciji. Pored toga, dve srodne supstance (2 i 8) predstavljaju supstance koje se po prvi put hromatografski opisuju i za koje ne postoje literaturni podaci.U okviru preliminarnih ispitivanja ispitane su četiri HILIC stacionarne faze (silika, diolna, cijano i cviterjonska) pod istim hromatografskim uslovima, čime je omogućeno donošenje preliminarnih zaključaka o uticaju fizičko-hemijskih karakteristika stacionarne faze, kao i analita na retenciono ponašanje u HILIC sistemu.U sledećoj fazi istraživanja, pristupilo se ispitivanju uticaja polarnije komponente mobilne faze (vodeni rastvor pufera), kako bi se dobile informacije o mehanizmima koji su uključeni u celokupan proces retencionog ponašanja. Izvršeno je fitovanje dobijenih rezultata retencionih vremena u teorijske (adsorpcioni, particioni, mešoviti i kvadratni model) i eksperimentalne (Neue model) matematičke modele. Za ocenu podobnosti matematičkih modela koristili su se koeficijent determinacije (R2) i unakrsno validiranikoeficijent determinacije (Q2) kao statistički parametri koji opisuju kvalitet matematičkog modela. Kako postojeći matematički modeli nisu dali zadovoljavajuću pogodnost, u sledećem delu doktorske disertacije pristupilo se kreiranju splajn interpolacionog modelačija je primena za modelovanje hromatografskog ponašanja analita prvi put opisana uovoj doktorskoj disertaciji.Izračunate vrednosti za R2i Q2koeficijente pokazali su da splajn dobro opisuje ispitivani hromatografski sistem, kao i da se može koristiti za predviđanje retencionog ponašanja ispitivanih analita u HILIC sistemu.Nakon teorijskih ispitivanja retencionih mehanizama, u sledećem delu doktorske disertacije, za smešu olanzapina i sedam srodnih supstanci, razvijena je HILIC metoda sa UV detekcijom uz gradijentno eluiranje u skladu sa AQbD (eng. Analytical Quality by Design) konceptom. Ovo je prvi put da je u naučnojliteraturi opisana primena AQbD principa za razvoj gradijentne HILIC metode. Prolazeći kroz dobro definisane faze ovog naučnog koncepta uz korišćenje pogodnog eksperimentalnog dizajna, kreiran je jasno definisan Design Space. Konačno, odabrani su optimalni hromatografski uslovi za analizu olanzapina i njegovih srodnih supstanci primenom gradijentne HILIC metode. Na ovaj način razvijena metoda je validirana i primenjena za analizu odgovarajućeg farmaceutskog oblika olanzapina.Jedna od značajnih prednosti HILIC metode jeste korišćenje rastvarača kompatibilnih sa masenim detektorom. Ova prednost je iskorišćena te je u završnoj fazi ove doktorske disertacije urađen prenos metode na sistem sa masenim detektorom. Transfer je urađen uz pomoć kalkulatora koji je preračunao protok mobilne faze, dužinu trajanja analize i uslove gradijenta u sistemu pod visokim pritiskom (UPLC, eng. Ultra Performance Liquid Chromatography). Cilj ovog transfera je bio da se dobije visokoosetljiva metoda kojom je moguće tačno i precizno pratiti promene u stabilnosti olanzapina pod uticajem različitih agenasa. Konačno, kroz postupak validacije metode potvrđena je njena primenljivost za praćenje stabilnosti olanzapina., Over the last decade, we have been facing numerous challenges regarding the analysis of different substances in HILIC (Hydrophilic Interaction Liquid Chromatography) mode. Despite constant increase in the number of published scientific papers, retention mechanisms still cannot be predicted with great certainty. The answer can be found in the complexity of retention mechanisms, which creates the need for further scientific investigations in order to better understand the system. The goal of this doctoral thesis was to apply theoretical and empirical mathematical models in order to define retention behavior of the structurally similar substances (olanzapine and its related substances), which would help us use gained knowledge for the newly created model. This specific mixture of substances was investigated for the first time in HILIC in this doctoral thesis. Furthermore, two of the related substances (2 and 8) have never been investigated in any chromatography system before.Through preliminary investigations, four HILIC columns have been tested (silica, diol, cyano-propyl and zwitterionic) under the same chromatographic conditions, which allowed us to make conclusions about the influence of physicochemical characteristics of the columns and substances on the retention behavior in HILIC.In the next phase, for the purpose of investigating retention mechanisms, the influence of the more polar component of the mobile phase (aqueous buffer solution) on the retention was investigated. Fitting of the obtained results was conducted in the theoretical (adsorption, partition, mixed and quadratic) models and experimental (Neue) models. For the statistical evaluation of the models, coefficient of determination (R2) and coefficient of prediction (Q2) were used.Since the existing mathematical models did not have sufficient level of fit, in the next phase of the study, spline interpolation model was created. Spline model has neverbeen used for the modeling of chromatographic behavior, prior to this study. Calculated R2and Q2values showed a good fit between spline model and complex HILIC system, consequently allowing it to predict retention behavior of the invenstigated substances in HILIC.After the theoretical part of the study, in the next phase, a HILIC method with UV detection and gradient elution was developed in line with AQbD (Analytical Quality by Design) concept, for olanzapine and its seven related substances. This is the first time that the use of AQbD concept has been published in the scientific paper for the development of the HILIC method. Going through the well-established steps of this scientific concept and by using the adequate experimental design, Design Space was defined. At the end, optimal chromatographic conditions for the analysis of olanzapine and its related substances were chosen. This HILIC method with gradient elution was furthermore validated and applied for the analysis of the pharmaceutical dosage form of olanzapine. One of the greatest advantages of HILIC methods is the compatibility of the polar solvents with the massdetector. This advantage was used in the last part of this study, when previously developed HILIC method was transferred to the system coupled with mass detector. Transfer was performed using the calculator which calculated the new mobile phase rate, the duration of the analysis and the gradient conditions for the UPLC system (Ultra Performance Liquid Chromatography). The goal of this transfer was to develop highly sensitive method which could accurately follow stability of olanzapine under different conditions. Finally, after validating the new method, it’s applicability as the stability indicating method was confirmed.",
publisher = "Универзитет у Београду, Фармацеутски факултет",
journal = "Универзитет у Београду",
title = "Teorijsko i empirijsko modelovanje retencionog ponašanja olanzapina u tečnoj hromatografiji hidrofilnih interakcija",
url = "https://hdl.handle.net/21.15107/rcub_nardus_12126"
}
