Professor Williamsen's Research Interests

My two main areas of research interest are the characterization of high-performance liquid chromatography (HPLC) stationary phases and the determination of the molecular mechanism of anesthesia.  Research done by students working with me has been contained within the group and also been done in collaboration with professors and students in the Ursinus College Biology Department, in other academic institutions, and with industrial collaborators.  The research projects are of interest to students interested in analytical chemistry and chemometrics but also to students interested in physical chemistry, biochemistry, applied statistics, and organic chemistry.  Depending on the project students may gain experience with instrumental techniques such as HPLC, gas chromatography/mass spectrometry (GC/MS), diffuse reflectance infrared Fourier Transform infrared spectrometry (DRIFT), cross-polarization, magic-angle-spinning nuclear magnetic resonance (CP/MAS NMR), isothermal calorimetry, and atomic force microscopy (AFM) and with techniques, such as statistics and molecular modeling.  Students are encouraged to make oral and poster presentation at national, regional, and local meetings.  Examples of student presentations and honors from these presentations can be found be found on this link.

 

CHARACTERIZATION OF HPLC STATIONARY PHASES

 

Background:

Chromatography is a group of chemical separation techniques where a mixture is transported in a mobile phase past a stationary phase.  If the components of the mixture interact with the stationary phase for different amounts of time, a spatial or temporal separation is attained.  One of the most commonly used chromatographic techniques is HPLC.  Although HPLC is one of the most commonly used separation techniques in chemistry, the chromatographic separation process is still far from being completely understood, and many important chemical mixtures currently can not be satisfactorily separated.  A better understanding of the interactions between compounds and stationary phases at the molecular level will allow faster and more reproducible method development and synthesis of better stationary phases. 

 

Current Stationary Phases Studies:

The two types of stationary phases that we are currently studying are fluorinated and liquid crystalline stationary phases. Both stationary phases are relatively novel, although they are commercially available to a limited extent.  Fluorinated stationary phases may prove advantageous in the separation of compounds of interest in biochemistry, pharmaceuticals, and forensics.  Liquid crystalline stationary phases may prove useful in the separation of structural isomers.  The fluorinated stationary phases are donated, but we have synthesized the liquid crystalline stationary phases in our lab.

 

Characterization Methods:

We characterize stationary phases through chromatographic and spectroscopic means, computer modeling, and the development of multivariate regression models. The chromatographic characterization involves separations executed under carefully controlled experimental conditions on analyte mixtures that emphasize particular chemical, physical, or structural characteristics. The data from these separations are used to develop multivariate regression and van't Hoff relationships.  The multivariate relationships relate the chromatographic data with parameters that can be linked to one or more physical or chemical attribute(s) of the analytes, stationary phase, or mobile phase (often called quantitative structure activity relationships (QSAR)). These relationships will be used to gain a better understanding of the physical and chemical interactions that occur between the analyte, mobile phase, and stationary phase. The van't Hoff relationships are used to calculate the thermodynamics of the interaction of analyte with stationary phases.  The spectroscopic methods employed may include diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), solid-state nuclear magnetic resonance (NMR), isothermal calorimetry, and atomic force microscopy (AFM).

 

Skills Developed:

Students will use HPLC and a number of spectroscopic techniques.  In the analysis of the data students will use univariate and multivariate spectroscopic techniques and molecular modeling.  In determining the molecular mechanisms, students will need to think about physical and chemical interactions that can occur at the molecular level.  For those students who are working with the liquid crystalline stationary phases, synthesis may need to be performed.

 

 

DETERMINATION OF MOLECULAR MECHANISM OF ANESTHESIA

 

Background:

Anesthesia is a commonly used medical procedure, and a large number of chemical moieties with a variety of chemical functionalities can produce this effect.  The difference between dosages that provide useful physiological effects and those that are toxic is smaller than for anesthetics than for most other categories of drugs.  The molecular mechanism of anesthesia is not well understood, and a better understanding may improve anesthetic effect and lessen deleterious effects.  This is a collaborative project between students in my group and Dr. Sidie’s group in the Ursinus College Biology Department.

 

Current Anesthetics Studied:

Alkanols, particularly 1-alkanols, are the current anesthetic agents being studied.  Studies will be expanded to common local anesthetics.

 

Experimental Procedure:

The Sidie research group has performed physiological studies as a function of temperature, time, and alcohol chain-length on the weakly electric fish Eigenmannia virescens.  Previous students in my group have performed physiological measurements as a function of alcohol chain-length on goldfish.  Using gas chromatography/mass spectrometry (GC/MS) students in my group are measuring the amount of alcohol in both fishes’ bloodstreams to determine whether the physiological effects and the amount of alcohol in the bloodstream are correlated.  These measurements are being made as a function of temperature, time, and alcohol chain-length.  Studies are being done with other components of blood, such as serum albumin, to determine their effect on the bloodstream concentration.  These measurements are being done both by GC/MS and HPLC. 

 

Skills Developed:

Students will use GC/MS and/or HPLC.  In the analysis of the data students will use univariate and multivariate spectroscopic techniques and molecular modeling.  Students will also learn the biochemistry behind the possible mechanisms.   


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EJW Last modified 14 July 2003.