Chemical Education Today edited by
NSF Highlights
Susan H. Hixson
Projects Supported by the NSF Division of Undergraduate Education
National Science Foundation Arlington, VA 2230
Chromatographic Separation Techniques for Undergraduates
Georgia State University Atlanta, GA 30303
Curtis T. Sears, Jr.
Darwin B. Dahl, John T. Riley, and Thomas K. Green Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101
For the past several years the Chemistry Department at Western Kentucky University ( WKU) has sought to strengthen its undergraduate program by increasing undergraduate participation in research and providing the necessary background for students to enter professional or Ph.D. programs. At the same time, the department wants to provide adequate experiences for those students who choose to enter the work force upon completion of the baccalaureate degree. The initial objective in the department’s development program was to acquire state-of-the-art instrumentation to address classroom research and requirements. Over the past several years departmental acquisition of FT-NMR, fluorescence, electrochemical, thermal analysis, laser Raman, microscale organic, and polymer laboratory instrumentation has enabled the department to build a successful undergraduate program. The lack of “unique” extraction and chromatographic instrumentation prompted us in 1996 to seek NSF-ILI funds allowing the purchase of a BioRad capillary electrophoresis system (CE), a Dionex ion chromatograph (IC), and a LECO supercritical fluid extraction (SFE) system. The acquisition of this instrumentation has allowed us to develop unique laboratory experiments and offer undergraduate students new opportunities in research. Acquisition of the new instruments led to the development of experiments from which several undergraduate courses would benefit. For example, the laboratory component of Quantitative Analysis has been changed so that only four obligatory titrations are performed. The remaining experiments may now employ thermogravimetry, ion chromatography, gas chromatography, spectrophotometric and fluorometric analysis, and near-infrared measurements (a statistical sampling experiment). Our advanced analytical course is now able to provide a considerable section on separation techniques with experiments using SFE, HPLC, GC-MS, IC, and CE, drawing on the complimentary nature of these techniques and illustrating derivatization schemes that are commonly performed to skirt detection or chromatographic limitations of certain compounds. Two examples of the new experiments are described.
Synthesis and Separation of a Diastereomeric Sulfonium Ion
Darwin B. Dahl, John T. Riley, and Thomas K. Green are in the Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101.
Literature Cited
One of the experiments that has been developed is the synthesis of a diastereomeric sulfonium ion and its subsequent chiral separation by capillary zone electrophoresis (1). In this experiment, the student is easily able to prepare and isolate a sulfonium ion (sec-butylmethyl-p-tolylsulfonium tetrafluoroborate) possessing two stereogenic centers. The product is verified by NMR and analyzed by CE. The procedure is rapid and students are able to separate the compound into its four isomers. It has been instructive to have the students vary the operating conditions in the CE analysis to generate conclusions about the optimization of the separation. This experiment requires two 3-hour laboratory periods to complete. Ion Chromatographic Analysis Ion chromatography has become a very valuable tool in the analysis of both anions and cations. One such experiment involves the analysis of elements in fuels that may become environmental pollutants. A sample of a fuel is decomposed in an oxygen bomb and analysis is performed using the IC. Elements (ions) routinely detected include fluoride, chloride, phosphate, and sulfate. NIST SRMs are used for constructing calibration curves to insure accuracy. Conventional “wet techniques” are also compared and contrasted to these instrumental procedures. The new instruments have also benefitted our undergraduate research program, enabling several students annually to be coauthors of publications or student presenters at professional meetings. Acknowledgment This work was partially supported by a grant (DUE 9650340) from the National Science Foundation Division of Undergraduate Education Instrumentation and Laboratory Improvement Program.
1. Valenzuela, F. A.; Green, T. K.; Dahl, D. B. J. Chem. Educ. in press.
JChemEd.chem.wisc.edu • Vol. 75 No. 10 October 1998 • Journal of Chemical Education
1209
