Education:

BS (Chemistry): Furman University, Greenville, SC; 1998; Research Advisor: John F. Wheeler

Ph.D. (Chemistry): The University of Kansas, Lawrence, KS; 2003; Dissertation Advisor: A. S. Borovik

Post-Doc: The University of Michigan, Ann Arbor, MI; 2003-2005; Advisor: Mark E. Meyerhoff

Fall 2007 Courses:

CH 123A: Chemistry I
CH 124 A & C: Chemistry I Laboratory
CH 506: Environmental Chemistry
CH 500C: Atomic Absorption Spectroscopy

Spring 2008 Courses:

CH 124 B: Chemistry I Laboratory
CH 376/377: Quantitative Analysis & Laboratory
CH 578: Water Analysis
CH 777: Instrumental Analysis & Laboratory

• Ionophore-based Ion Selective Electrodes (ISE): Potentiometric ion selective electrodes are simple and inexpensive devices for the quantification of several ionic species.  A polymer membrane gives the electrode its selectivity and is mounted on the end of the electrode body.  In a traditional ion-exchange membrane, the selectivity is governed by how well the ions partition into the hydrophobic polymer (called the Hofmeister Series in anions).  Adding an ionophore to the membrane induces a change in the selectivity pattern.   While methods for determining cations are well established, several challenges remain in the analysis of anions.  Our research in this area includes the design and synthesis of metal-ligand complexes that selectively bind anions.  Upon adding these complexes to the polymer membranes, we observe non-Hofmeister response patterns.  Anions of particular interest include fluoride, nitrate, nitrite and bromide.  The ultimate goal of this work is to fabricate useful sensor devices for simple environmental field analysis.
  

• Optical Anion Detection: Another mode of transduction for the detection of important ions is change in a material's optical properties.  Polymer membranes similar to those fabricated for potentiometric measurements can be cast onto glass slides and their UV/Vis absorbance properties monitored with a spectrophotometer.  Transition metal complexes are often highly colored, and binding of a target analyte can modulate the absorbance of this ionophore.  However, it is also common to see little or no change in absorbance of the metal complex upon binding of analyte.  In these cases, a pH sensitive co-ionophore is incorporated into the sensing film so that the binding event can be measured.  When an anion is selectively extracted from the aqueous sample solution into the polymer membrane, a positively charged proton is co-extracted to maintain charge neutrality.  The co-ionophore's absorbance properties are sensitive to its protonation state and thus, upon binding the extracted proton, a color change is observed and this change can be quantified.  Initial experiments involve bathing the film within a cuvette and we will then fabricate a flow-through system in order to quickly measure environmental samples using this detection scheme.
  

• Molecularly Imprinted Polymer (MIP) Modified Electrodes as Selective Sensors: Biomolecules such as enzymes and antibodies are useful in different analytical methods because of their outstanding selectivity for a given target.  However, these molecules are sensitive to environmental conditions and cannot be used or stored under non-physiological temperature, pH or solvent.  These limitations have led researchers to develop synthetic analogs of enzymes and antibodies.  One approach in this area includes  molecularly imprinted polymers (MIP).  As described in the figure, the template is complexed by functional monomers.  This template complex is then copolymerized in the prescence of excess crosslinker.  Template removal yields an imprinted site containing reactive groups with the capability to rebind the template selectively in mixtures of structurally similar molecules.  This is a promising strategy, but one difficulty in using these materials as sensors is the measurement of a binding event.  The vast majority of MIP research has focused on utilizing the materials as selective stationary phases for chromatography and less work has been done in MIP sensor technology.  In this work we aim to create polymer membranes on the surface of electrodes by electropolymerization techniques with a solution of monomers containing functional monomers and template molecules.  We will then attempt to selectively measure the template using cyclic voltammetry as a means of measurement.  Analytes of interest in this study include a variety of pesticides and herbicides.