A novel, single-isomer, 14-sulfated cyclodextrin for use as a chiral resolving agent in capillary electrophoresis /
A novel, single-isomer, 14-sulfated cyclodextrin, the sodium salt of heptakis(2-O-methyl-3,6-di-O-sulfo)-β-cyclodextrin (HMdiSu), was synthesized, analytically characterized, and utilized as a chiral resolving agent for capillary electrophoresis (CE). HMdiSu was synthesized on the 100 gram scale in...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=725921851&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | A novel, single-isomer, 14-sulfated cyclodextrin, the sodium salt of heptakis(2-O-methyl-3,6-di-O-sulfo)-β-cyclodextrin (HMdiSu), was synthesized, analytically characterized, and utilized as a chiral resolving agent for capillary electrophoresis (CE). HMdiSu was synthesized on the 100 gram scale in greater than 97% purity, through heptakis(6-O-tert-butyldimethylsilyl)-β-cyclodextrin, heptakis(2,6-di-O-tert-butyldimethylsilyl)-β-cyclodextrin, heptakis(2-O-methyl-3,6-di-O-tert-butyldimethylsilyl)-β-cyclodextrin, and heptakis(2-O-methyl)-β-cyclodextrin intermediates. The purity of each synthetic intermediate and final product was determined by HPLC and indirect UV-detection CE, respectively. The structural identity of each compound was verified with MALDI-TOF-MS, ¹H and ¹³C NMR spectroscopy, and X-ray crystallography. HMdiSu has been used to separate twenty-four weak base enantiomers in pH 2.5 background electrolytes using CE. For the weakly binding bases, the cationic effective mobilities decreased, approached zero, and then increased again as the concentration of HMdiSu in the background electrolyte (BE) was increased. For the strongly binding bases, the cationic effective mobilities decreased, became anionic at very low concentrations of HMdiSu, passed an anionic mobility maximum, then decreased again as the concentration of HMdiSu was increased. Viscosity corrections according to Walden's rule did not eliminate these unexpected mobility extrema. The mobility extrema were rationalized by extending the charged resolving agent migration model (CHARM model) to include ionic strength effects. HMdiSu was also investigated for use as a protein mobility modulator in CE due to the ion pairing capabilities of its 14 sulfate groups. Myoglobin, with a pI=7.0, was chosen as the model compound because it contains multiple, spatially-distinct, fixed positive charges. The cationic mobility of myoglobin became anionic with increasing HMdiSu concentration at pH 8.0, indicating that HMdiSu interacts with myoglobin and renders its mobility negative. However, HMdiSu also adsorbs on the poly(vinyl alcohol) (PVA)-coated capillary surface and provides ion-pairing sites for myoglobin. This degrades the peak shape and separation efficiency compared with the HMdiSu-free BE, meaning that HMdiSu cannot be used as a mobility modulator for practical protein separations. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xii, 122 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 105-110). |