In the Classroom
Capillary Electrophoresis and High-Performance Liquid Chromatography Experiments throughout the Undergraduate Curriculum Assessment of a Multi-Year, Multi-Course Project Michelle M. Bushey Department of Chemistry, Trinity University, San Antonio, TX 78212-7200;
[email protected] In a typical undergraduate chemistry program, students may encounter sophisticated instrumentation only once or twice in their college careers. When this happens, they may be left with a narrow impression of the capabilities and limitations of these methods. The Trinity University Chemistry Department recently completed the assessment phase of a curricular project where students encountered both capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) instrumentation multiple times, in a variety of chemistry courses, throughout their undergraduate career. Each encounter with the instruments was designed to address the most critical aspects of the techniques at appropriate levels while building from previous student experience. The hypothesis of this project was that students would gain a deeper and more complete understanding of sophisticated techniques if they had the opportunity to work with instruments multiple times throughout the undergraduate chemistry curriculum rather than the case where they would use each instrument only once in an upper-division course. The challenge is to develop experiments that address the most important and appropriate curricular aspects for any given course, while at the same time developing the experience with advanced instrumentation that only can come from performing multiple and in-depth experiments. We have developed labs utilizing HPLC and CE that are appropriate for use in general chemistry, both semesters of organic, analytical, and instrumental courses. Experiments in lower-division courses, in addition to addressing concepts specific to these courses, stressed key features of each instrument, and student input into the experiment design was limited. We relied on autosamplers to address the throughput of heavily enrolled classes. Lower-division students were able to gain an introductory knowledge of key analysis techniques they otherwise might never encounter. These early exposures were incomplete with respect to the particular instrumental method and only designed to teach the most critical aspects of CE or HPLC at that particular time. The primary foci of the labs in the lower division was to convey other topics of importance of the class, such as statistical data analysis or electron donation characteristics of substituents. With this incomplete view of the instrument, students were then in a stronger position in the upper-division courses to delve more deeply into the techniques since they could build off the earlier exposures. With subsequent encounters, the complexity of the experiments increased, the opportunity for hands-on instrument access increased, the amount of student input into the design of the experiments increased, and the concepts were deepened and broadened. By using the instrumentation in a wide variety of applications, students who
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completed the program gained a richer understanding of the capabilities and limitations of these techniques than they would have after a single, albeit advanced lab experiment. Students did not graduate thinking that HPLC means only reversed phase analysis of analgesics, but rather that it can be used to exploit an array of analyte properties for application to a wide range of different sample types. A similar approach could be implemented for a variety of other instruments usually encountered by students only in upper-division chemistry labs. An assessment phase of the project involved tracking students’ perceptions and understanding as they moved through the curriculum through the use of questionnaires that students completed each time they used either the HPLC or CE instruments in a lab. Student responses were then compiled for those who took the entire course sequence. The compiled responses were then reviewed both in-house and by a group of outside experts. The responses have now been evaluated and they indicate that student understanding and appreciation deepen through multiple exposures to the same instrument or technique. We believe that the project goals were met. Not only did students who completed all the courses have a deeper and more sophisticated understanding of these two techniques, but students leaving the course sequence early were exposed to the two separation methods and left with a reasonable understanding of the most important features of each technique. A more complete description of the philosophy, experiments, assessment results, and compiled outside reviewer comments are provided in the online material. Acknowledgments This program was funded by the National Science Foundation CCLI A&I program as project DUE-995227. Additional support was provided by Beckman Coulter and Trinity University. The outside review team consisted of Stuart Bush of Rohm & Haas, Dave Rothman of the Dow Chemical Company, Kevin Bennett and Sharron Smith of Hood College, and Gyula Vigh of The Texas A & M University. Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2009/Mar/abs332.html Abstract and keywords Full text (PDF) Supplement A complete description of the philosophy, experiments, assessment results, and compiled outside reviewer comments
Journal of Chemical Education • Vol. 86 No. 3 March 2009 • www.JCE.DivCHED.org • © Division of Chemical Education
