Chromatographic and Esr Studies of Bonded Reverse-Phases

Kooser, Robert

Abstract

Liquid chromatography and solid phase extractions are extremely important separation techniques for complex biological systems. Most of these techniques rely on a stationary phase composed of straight chain alkane molecules bonding to silica to make what is called a reverse bonded phase. To achieve the best possible separations, it is neceseary to understand how the molecular structure and dynamics of the bonded phase affects the efficiency of the separation or extraction process. This will allow the design and synthesis of stationary phases targeted for specific separation problems (e.g., a mixture of complex sugars). Researchers in this area have begun to use spectroscopic techniques such as nuclear magnetic resonance, and infrared and luminescence spectroscopies to probe the nature of the stationary phase. This project will use the spin label spectroscopic technique to examine how the dynamics and molecular configuration (i.e., microscopic proporties) of model stationary phases relate to the macroscopic properties that determine separation effectiveness, such as solute retention and efficiency. This will be done by examining the changes that occur in the electron spin resonance spectra of spin labeled systems as a function of changing chromatographic conditions and repeating these experiments using well established macroscopic techniques, such; as chromatographic peak broadening. This project will be the first to apply a spectroscopic method to the study of the structure and dynamics of the stationary phase under actual conditions of a separation experiment, including monitoring the bonded phase changes that occur during the passage of the solute. Solutes used in this study will be model compounds of substances of value to the health sciences, such as a series of amino acids or prototype drug mixtures. This study will add substantially to the understanding of the mechanisms of separation processes useful to the health sciences and will aid in the design of more efficient processes.