Preparation of Reactive-Polyacrylate Capillary Monoliths and Their Use As Stationary Meiıa in Hydropilic Interaction Chromatography
Erkakan, Sedef Damla
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ABSTRACT THE PREPARATION OF REACTIVE-POLYACRYLATE CAPILLARY MONOLITHS AND THEIR USE AS STATIONARY MEDIA IN HYDROPHILIC INTERACTION CHROMATOGRAPHY Sedef Damla Erkakan Master of Science, Department of Chemical Engineering Supervisor: Prof. Dr. Ali TUNCEL September 2015, 66 pages In this study, the synthesis of new polar polymer-based monoliths was performed and their chromatographic performance in hydrophilic interaction chromatography (HILIC) mode was determined. Poly(HPMA-Cl-co-EDMA) monoliths were prepared via thermally initiated block copolymerization into silanized capillary fused silica tubes having 100 µm internal diameter. In the synthesis stage, concentrations of monomer, cross-linking agent and porogen in the polymerization solution and polymerization temperature were changed. The effects of each of these changes on the structure of monolith were investigated. After obtaining appropriate pore size distribution, specific surface area and back pressure values, a chromatographic ligand, triethanolamine (TEA-OH) was covalently attached to monolith via a single step reaction. These newly produced monolithic columns with different pore structures and polarities were used successfully for the separation of nucleotides, nucleosides and benzoic acids. All chromatographic studies were performed by using acetonitrile/aqueous buffer system as the mobile phase. In the chromatographic studies, the lowest plate height was obtained as 20 µm using uracil (nucleotide), 54 µm using thymidine (nucleoside) and 25 µm for benzoic acid derivatives. According to chromatographic results, it was seen that efficient separations of benzoic acid derivatives were mainly based on hydrophilic interaction mechanisms. Under optimized separation conditions, TEA-OH attached monoliths was successfully applied for the rapid, high resolution and without obvious peak tailing separation with lower than 5 % column to column relative standard deviation values for each nucleotides. However, the first time introduced “retention-dependent column efficiency” behavior for the HILIC system ii showed that the plate height raised with increasing retention factor. Its possible reasons were discussed. In this study, the first monolithic column which is capable of separating polar analytes in HILIC mode was synthesized in our country. In the light of these results, better separation efficiencies can be achieved with further studies.