STUDY OF PORE SIZE EFFECT IN CHROMATOGRAPHY BY VIBRATIONAL SPECTROSCOPY AND COLLOIDAL ARRAYS

Persistent Link:
http://hdl.handle.net/10150/196108
Title:
STUDY OF PORE SIZE EFFECT IN CHROMATOGRAPHY BY VIBRATIONAL SPECTROSCOPY AND COLLOIDAL ARRAYS
Author:
Huang, Yuan
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Current study of separation mechanism in chromatography heavily relies on the measurement of macroscopic properties, such as retention time and peak width. This dissertation describes the vibrational spectroscopy characterization of separation processes.Raman Spectroscopic characterization of a silica-based, strong anion exchange stationary phase in concentrated aqueous solutions is presented. Spectral response of stationary phase quaternary amine is closely related to changes in interaction between counter anions and the amine functional groups as the result of anion hydration. The molecular-level information obtained will provide useful guidance for control of stationary phase selectivity.To study the effects of stationary phase pore size on separations processes, monodisperse silica particles in the sub-100 nm range are prepared and self-assembled to well-ordered, three-dimensional colloidal arrays. A modified LaMer model is proposed and demonstrated for optimization of reaction conditions that lead to uniform and spherical silica particles. This approach greatly reduces the number of training experiments required for optimization. Fast Fourier transformation of colloidal array scanning electron microscopy images indicates closely-packed hexagonal packing patterns.Using these arrays, a novel system for the measurement of molecular diffusion coefficients in nanopores is reported. This system consists of an ordered colloidal array with well-defined pore structure deposited onto an internal reflection element for in-sit collection of kinetic information by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). A mathematical model is established to extract diffusion coefficients from these data. A decrease of approximately eight orders of magnitude in molecular diffusion coefficients is observed for molecular transport in nanopores.Finally, by using this colloidal array-ATR-FTIR system and the corresponding mathematical models that describe absorption in the colloidal array, the distribution in the nanopores of the acetonitrile organic modifier in an aqueous mobile phase solvent system is determined. Based on the results of 50 nm colloidal arrays, pore surface properties have a strong effect on the distribution of organic molecules from bulk solution to the pores.
Type:
text; Electronic Dissertation
Keywords:
chromatography; colloidal array; nanopartilce; pore size; silica; vibrational spectroscopy
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Classics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Pemberton, Jeanne E.
Committee Chair:
Pemberton, Jeanne E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleSTUDY OF PORE SIZE EFFECT IN CHROMATOGRAPHY BY VIBRATIONAL SPECTROSCOPY AND COLLOIDAL ARRAYSen_US
dc.creatorHuang, Yuanen_US
dc.contributor.authorHuang, Yuanen_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractCurrent study of separation mechanism in chromatography heavily relies on the measurement of macroscopic properties, such as retention time and peak width. This dissertation describes the vibrational spectroscopy characterization of separation processes.Raman Spectroscopic characterization of a silica-based, strong anion exchange stationary phase in concentrated aqueous solutions is presented. Spectral response of stationary phase quaternary amine is closely related to changes in interaction between counter anions and the amine functional groups as the result of anion hydration. The molecular-level information obtained will provide useful guidance for control of stationary phase selectivity.To study the effects of stationary phase pore size on separations processes, monodisperse silica particles in the sub-100 nm range are prepared and self-assembled to well-ordered, three-dimensional colloidal arrays. A modified LaMer model is proposed and demonstrated for optimization of reaction conditions that lead to uniform and spherical silica particles. This approach greatly reduces the number of training experiments required for optimization. Fast Fourier transformation of colloidal array scanning electron microscopy images indicates closely-packed hexagonal packing patterns.Using these arrays, a novel system for the measurement of molecular diffusion coefficients in nanopores is reported. This system consists of an ordered colloidal array with well-defined pore structure deposited onto an internal reflection element for in-sit collection of kinetic information by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). A mathematical model is established to extract diffusion coefficients from these data. A decrease of approximately eight orders of magnitude in molecular diffusion coefficients is observed for molecular transport in nanopores.Finally, by using this colloidal array-ATR-FTIR system and the corresponding mathematical models that describe absorption in the colloidal array, the distribution in the nanopores of the acetonitrile organic modifier in an aqueous mobile phase solvent system is determined. Based on the results of 50 nm colloidal arrays, pore surface properties have a strong effect on the distribution of organic molecules from bulk solution to the pores.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectchromatographyen_US
dc.subjectcolloidal arrayen_US
dc.subjectnanopartilceen_US
dc.subjectpore sizeen_US
dc.subjectsilicaen_US
dc.subjectvibrational spectroscopyen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineClassicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPemberton, Jeanne E.en_US
dc.contributor.chairPemberton, Jeanne E.en_US
dc.contributor.committeememberArmstrong, Neal R.en_US
dc.contributor.committeememberMash, Eugene A., Jr.en_US
dc.contributor.committeememberSaavedra, Scotten_US
dc.contributor.committeememberZheng, Zhipingen_US
dc.identifier.proquest10158en_US
dc.identifier.oclc659750736en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.