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Methods for the Characterization of Electrostatic Interactions on Surface-Confined Ionic Liquid Stationary Phases for High Pressure Liquid Chromatography

Fields, Patrice R.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307044073

Abstract Details

2011, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
This body of work is a continuation of work previously completed in our group that examines the retention properties of surface confined ionic liquid (SCIL) stationary phases under reversed-phase and supercritical fluid chromatographic conditions. SCIL’s have been shown to be useful for separating a variety of both organic and inorganic compounds. However, there has been little work done to elucidate the different retention mechanisms and properties that allow for the wide range of retention modes observed. The first chapter provides a brief history and survey of the properties of ionic liquids. The first chapter also includes an overview of the linear solvation free energy relationship (LSER), which is used to characterize the retention of solute sets containing both neutral and ionizable compounds in under reversed-phase and supercritical conditions. This chapter also provides insight into the evolution and development of molecular solute descriptors. The second chapter discusses several methods that can be employed to modify the LSER model to account for electrostatic interactions between the SCIL stationary ohases and ionizable solutes in reversed-phase chromatography. The P, D and J solute descriptors are evaluated based on their ability to fit the retention of ionizable solutes to the LSER model and to produce coefficient values that are consistent with the underlying molecular interactions and what has been previously reported in reversed-phase studies. The third chapter investigates the use of the LSER model to characterize the retention mechanism of two SCIL stationary phases under supercritical conditions. The LSER coefficients generated via the multiple linear regression of chromatographic retention data are compared and analyzed for statistical difference from one another. The two SCIL phases are further compared to a 2-ethylpyridine (EP) stationary phase, which is more commonly used in chromatography with compressible fluids. This chapter further examines the viability of the P and J solute descriptors to describe the electrostatic interactions between the SCIL stationary phases and ionizable solutes under supercritical conditions. The fourth chapter examines the ion exchange properties of several SCIL stationary phases. A series of small inorganic ions in acetonitrile-water mixtures are used to probe mechanistic differences in the stationary phases due to the substituents attached to the exchange moiety after correcting for loading differences between the phases. Connections have been made between the observed retention properties and the solvation of both the anion analytes and the stationary phase. The fifth chapter summarizes the findings of the previous chapters and offers suggestions for the future directions for this project while the appendix describes a method for estimating the viscosity of binary and ternary supercritical fluids. The estimates are based on a form of Darcy’s law and relates the effect of temperature, pressure and flow rate on the estimates.
Apryll Stalcup, PhD (Committee Chair)
James Mack, PhD (Committee Member)
Thomas Ridgway, PhD (Committee Member)
211 p.
Chemistry
Surface-confined ionic liquid; LSER; Ionization; Electrostatic interactions; Reversed-phase chromatography; Supercritical fluid chromatography

Recommended Citations

Citations

  • Fields, P. R. (2011). Methods for the Characterization of Electrostatic Interactions on Surface-Confined Ionic Liquid Stationary Phases for High Pressure Liquid Chromatography [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307044073

    APA Style (7th edition)

  • Fields, Patrice. Methods for the Characterization of Electrostatic Interactions on Surface-Confined Ionic Liquid Stationary Phases for High Pressure Liquid Chromatography. 2011. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307044073.

    MLA Style (8th edition)

  • Fields, Patrice. "Methods for the Characterization of Electrostatic Interactions on Surface-Confined Ionic Liquid Stationary Phases for High Pressure Liquid Chromatography." Doctoral dissertation, University of Cincinnati, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307044073

    Chicago Manual of Style (17th edition)

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© 2011, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.