Karakterizacija nepokretnih faza u kromatografiji reverznih faza ultravisoke djelotvornosti

master's thesis

• Title (english): Characterization of stationary phases in reversed-phase ultra-high-performance liquid chromatograph
• Author: Tea Škrinjar
• Mentor: Tomislav Bolanča (mentor)
• Committee member: Tomislav Bolanča (predsjednik povjerenstva)
• Committee member: Šime Ukić (član povjerenstva)
• Committee member: Dajana Milovac (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2015-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry; Analytic Chemistry

Abstract

Tema diplomskog rada sastojala se od proučavanja eksces adsorpcijskih izotermi organskih otapala acetonitrila i metanola iz vode, Korišteno je pet komercijalno dostupnih kemijski vezanih stacionarnih faza tj. pet kromatografskih kolona (Kinetex™ kolone, Phenyl-Hexyl, Biphenyl, C18, XB C18 i PFP tvrtke Phenomenex®). Te kolone karakteriziraju različite funkcionalne skupine. Eksces adsorpcijske izoterme mjerene su metodom malih poremećaja pod UPLC uvjetima. Dobivene izoterme pružaju korisnu informaciju o strukturi stacionarnih faza. Mjereni parametri pikova otapala su baza za izradu eksces izotermi. Prema tome, injektirana je eksces količina organskog otapala ili vode. Količina "adsorbiranog otapala" može pokazati tip distribucijskog mehanizma. Također je mjeren utjecaj temperature na adsorpciju na koloni fenil-heksil. Bazirajući se na rezultantnim eksces adsorpcijskim izotermama, potvrđeno je da molekule acetonitrila imaju veći afinitet prema promatranim stacionarnim fazama i da reagiraju pomoću π-π veza. Metanol i voda stvaraju vodikove veze sa polarnim i rezidualnim silanolnim grupama na stacionarnoj fazi. Uspoređujući eksces adsorpcijske izoterme za acetonitril i metanol opaža se da je adsorpcija acetonitila oko 3 puta veća od adsorpcije metanola i negativni dio adsorpcije vode u sistemu acetonitril-voda je oko 5 puta veći od onog u sistemu metanol-voda. Adsorpcija acetonitrila se smanjuje s povećanjem temperature i optimalna temperature za adsorpciju je 20 °C.

Abstract (english)

The aim of this master-degree work was studying excess adsorption isotherms of organic solvents: acetonitrile and methanol, from water. Five commercially available chemically-bonded stationary phases, i.e. five chromatographic colums (Kinetex™ columns: Phenyl-Hexyl, Biphenyl, C18, XB C18 and PFP, made by Phenomenex®), were used. These columns were characterized by different functional groups. Excess adsorption isotherms were measured using the minor disturbance method under UPLC conditions. These isotherms provided useful information about structure of the stationary phases. Measured parameters of the solvent peaks were the basis for making excess isotherms. Therefore, excess of organic solvent or water was injected. The amount of "adsorbed solvent" can indicate the type of distribution mechanism. Also, the influence of temperature on the preferential adsorption was measured on Phenyl-Hexyl columns. Based on the resulting excess adsorption isotherms, it was confirmed that molecules of acetonitrile had more affinity for observed stationary phases and they interacted by π-π interactions. Methanol and water formed hydrogen bonds with polar and residual silanol groups on stationary phases. By comparing excess adsorption isotherms for acetonitrile and methanol, one can observe that the adsorption of acetonitrile is approximately 3 times higher than adsorption of methanol, and negative part for adsorption of water in the system of acetonitrile–water is about 5 times above the one in methanol–water system. The adsorption of acetonitrile decreases with the increase of temperature and the optimal temperature for adsorption is 20 °C.

• Keywords: UPLC; RP-LC; adsorpcija; stacionarna faza; eksces izoterma; acetonitril; metanol; voda; otapala; temperatura
• Keywords (english): UPLC; RP-LC; adsorption; stationary phases; excess isotherm; acetonitrile; methanol; water; solvents; temperature
• Language: croatian
• URN:NBN: urn:nbn:hr:149:058362
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-03-07 11:22:45