β-Cyclodextrin functionalized ionic liquid as high performance liquid chromatography chiral stationary phase for the enantioseparation of natural products and pharmaceuticals / Nurul Yani Rahim
The demanding for enantiomerically pure (enantiopure) compounds, especially for pharmaceutical field has been attracting great attention during last decades. Direct enantioseparation by chiral stationary phases (CSPs) using high performance liquid chromatography (HPLC) remains as the most importa...
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| Format: | Thesis |
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2017
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| Online Access: | http://studentsrepo.um.edu.my/7310/ http://studentsrepo.um.edu.my/7310/1/All.pdf http://studentsrepo.um.edu.my/7310/9/yani.pdf |
| Summary: | The demanding for enantiomerically pure (enantiopure) compounds, especially for
pharmaceutical field has been attracting great attention during last decades. Direct
enantioseparation by chiral stationary phases (CSPs) using high performance liquid
chromatography (HPLC) remains as the most important technique for enantioseparation.
The development of novel stable and powerful CSPs is therefore important. The first
part of this study involved a facile and reliable preparation of CSPs. Thus, β-
cyclodextrin was functionalized with ionic liquids (ILs) namely 1-benzylimidazole (1-
BzlIm) and 1-decyl-2-methylimidazole (C10MIm) with tosylate as anion produced β-
CD-BIMOTs and β-CD-DIMOTs respectively. β-CD-BIMOTs and β-CD-DIMOTs
were attached to the modified silica to obtain the CSPs. The performances of the
synthesized CSPs were determined by examining the capability of enantioseparation of
selected analytes: flavonoids (flavanone, hesperetin, naringenin and eriodictyol), β-
blockers (atenolol, metoprolol, pindolol and propranolol) and Non-steroidal antiinflammatory
drug (NSAIDs) (ibuprofen, fenoprofen, ketoprofen and indoprofen). The
performance of β-CD-BIMOTs and β-CD-DIMOTs stationary phases was also
compared with native β-CD stationary phase. The results indicated that β-CD-BIMOTs
stationary phase afforded more favorable enantioseparations than β-CD-DIMOTs and
native β-CD based stationary phases. Therefore, the optimization for enantioseparation
of selected analytes (flavonoids, β-blockers and NSAIDs) and evaluation of interactions
was further investigated on β-CD-BIMOTs stationary phase. The selected flavonoids,
flavanone and hesperetin obtained high resolution factor in reverse phase mode.
Meanwhile naringenin and eriodictyol attained partial enantioseparation in polar organic
mode. In order to understand the mechanism of separation, the interaction of selected
flavonoids and β-CD-BIMOTs was studied using spectroscopic methods which are 1H
NMR, NOESY and UV/Vis spectrophotometry. The result for enantioseparation of
selected β-blockers, propranolol and metoprolol showed good enantioresolution
compared to atenolol and pindolol. The results suggested that the lipophilic property
and the structure of propranolol and metoprolol that enable the formation of inclusion
complex contribute to better enantioseparation. This observation was proven by 1H
NMR and NOESY of β-CD-BIMOTs/β-blockers. The effect of the types and variation
of mobile phase composition on enantioseparation of NSAIDs was also studied on β-
CD-BIMOTs CSP. From the result of enantioseparation, ibuprofen and indoprofen
achieved the better resolution than ketoprofen and fenoprofen due to their favorable
orientation to fit into the β-CD-BIMOTs cavity. This orientation was depending on the
structure of NSAIDs. |
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