Characterization of the separation of paclitaxel and related taxanes by reversed phase liquid chromatography on hydrocarbonaceous and fluorinated stationary phases.
Item
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Title
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Characterization of the separation of paclitaxel and related taxanes by reversed phase liquid chromatography on hydrocarbonaceous and fluorinated stationary phases.
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Identifier
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AAI3074647
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identifier
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3074647
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Creator
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Dolfinger, Ralf.
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Contributor
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Adviser: David C. Locke
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Date
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2003
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical | Chemistry, Pharmaceutical
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Abstract
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Fluorinated columns have been reported to exhibit superior selectivity in the separation of taxanes. This study investigates the differences between fluorinated and hydrocarbonaceous stationary phases in the separation of taxanes and in reversed phase liquid chromatography in general. In this context the phenomenon of changes of elution order with variation of mobile phase composition and temperature is considered as well. Propyl-perfluorophenyl, ethyl-perfluorohexyl and ethyl-perfluoro (1-dimethyl-heptyl) phases are characterized in their selectivity to various compounds and compared to a regular hydrocarbonaceous octyl phase.;Using mobile phase and temperature optimization baseline separation of 15 taxanes is achieved on all phases in 9.5 to 23 minutes in aqueous acetonitrile. The fluorinated columns do not show any definite advantage in the separation of taxanes or other model compounds including aromatic and non-aromatic structures with various functional groups.;Xylosyl-taxol compounds exhibit increasing retention with increasing temperature at mobile phase compositions around 50% acetonitrile leading to exchanges of elution order with other taxanes. The effect slowly vanishes with increasing or decreasing concentration of acetonitrile. This aberrant temperature behavior is shown to be the caused by hydroxyl groups bound to non-aromatic backbone structures and is proportionally dependent on molecular size and degree of hydroxylation of the solute.;Taxanes, especially xylosyl taxol compounds, are found to show initially decreasing retention upon addition of water to the mobile phase followed by the usually observed increasing retention. At higher water concentrations the retention of xylosyl taxol compounds increases much more sharply compared to the other taxanes leading to multiple exchanges of elution order. The initial decrease of retention is attributed to hydroxyl group interactions and is independent of the aromatic or non-aromatic nature of the backbone structure. The increase of retention with further increase in the water concentration is shown to depend on the molecular size of the carbon backbone structure.;A model based on the preferential solvation of the solute is proposed to explain the mechanism of the effects stated above. The retention of the solute does not depend on the chemical structure of the solute but on the structure of a solute-solvent complex. The composition of this complex changes with temperature and mobile phase composition affecting retention of the solute.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
