Chemical Education Today
NSF Highlights Projects Supported by the NSF Division of Undergraduate Education
Implementation of an Environmental Focus in an Undergraduate Chemistry Curriculum by the Addition of Gas Chromatography-Mass Spectrometry by Cynthia Atterholt, David J. Butcher, J. Roger Bacon, William R. Kwochka, and Royce Woosley
The Department Chemistry and Physics at Western Carolina University has added an environmental focus to its curriculum, with the long-term goal of becoming a major contributor in environmental chemistry education and research. A new Environmental Chemistry course was added to the curriculum, and an environmental focus was added to existing courses, such as Organic Chemistry, Aquatic Chemistry, Quantitative Analysis, and Instrumental Analysis I and II. Also, we have added a concentration in Environmental Chemistry to the B.S. degree. Gas chromatography–mass spectrometry (GC–MS) was identified as an essential tool in environmental analysis. With support from the National Science Foundation, a new gas chromatograph–mass spectrometer (GC–MS) was purchased to enhance the laboratory experience in undergraduate chemistry courses in (i) the identification of synthesized compounds and natural products, (ii) monitoring compounds and their degradation in the environment, and (iii) analytical method development. This has also enabled the department to add a course in mass spectrometry and has allowed the use of GC– MS in undergraduate research projects. The use of the GC–MS has been incorporated into several experiments in our organic chemistry laboratory courses. The GC–MS is used to characterize natural products and the products of an environmentally benign chemical synthesis. In one experiment, students use a microscale steam distillation adapted from Williamson’s procedure for the comparison of three essential oils as sources of carvone (1). The GC– MS is used to characterize components in these mixtures. In advanced organic synthesis, students explore the dye-sensitized irradiative removal of dithioacetal protecting groups to provide the corresponding carbonyl compound and a dithiol (2). The products of this “environmentally benign synthesis” are characterized by GC–MS. In the Environmental Chemistry course, several experiments are conducted using GC–MS to identify compounds of environmental interest. In one experiment, students extract pesticides from soil samples taken from a nearby apple orchard that had been sprayed for many years with organochlorine pesticides. Students have identified DDT and its breakdown products DDD and DDE in soil samples. Standards were prepared for p,p′-DDT, and the GC–MS was used to identify the breakdown products and other organochlorine pesticides present in the soil samples. In another experiment, students identify unknown polycyclic aromatic hydrocarbons (PAHs) from water that has been in contact with creosote-treated railroad ties. Samples of the creosote-treated wood are stirred in water for 24 hours, 1550
and the PAHs are extracted from the water using solid-phase extraction (3). The GC–MS is used to identify PAHs present in the extract. Because of local water quality problems created by the contamination of ground and surface waters from gasoline spills and leaking underground storage tanks, students in Environmental Chemistry also analyze and compare several fuel samples. They compare low- and high-octane gasoline samples from different sources and identify aliphatic and aromatic hydrocarbons in the various fuel samples (3). The GC– MS is used to identify unknown compounds in the gasoline mixtures. In Instrumental Analysis I, students characterize numerous compounds in cigarette smoke using GC–MS. Hundreds of compounds are found in tobacco smoke, some present in very low levels. Many of these are toxic, including nicotine, and others are carcinogenic. Students collect the organic compounds by passing the smoke through methanol and then qualitatively identify a number of them using GC–MS. Instrumental Analysis II is a senior-level course focusing on advanced topics in chemical instrumentation and analysis. The laboratory component has recently been revised to consist entirely of projects designed to simulate analytical method development (4). The students are presented with an analytical chemistry problem for which they research protocols in the literature, collect samples, implement methods, perform the analyses, and work up the data. They conduct about 3–4 projects per semester, which gives them exposure to a variety of techniques while providing the benefits of a project-based laboratory. The GC–MS has been used to identify volatile compounds in a number of mixtures, such as perfumes, fruits, and cigarette smoke. Research in chemistry is a significant part of our curriculum, and numerous undergraduate students have used the GC–MS in their research. For example, students have studied volatile compounds present in Queen Anne’s lace and Fraser fir foliage. Queen Anne’s lace is of interest because of its toxicology and medicinal value in folklore. Undergraduates have characterized the terpene and terpenoid compounds present in the foliage and seeds of the Fraser fir because this species has suffered serious decline in recent years. We are trying to document differences in concentrations of various compounds and relate these differences to susceptibility of the tree to environmental stresses. Another student has used the GC–MS to study the release rate and degradation of various insect pheromones that are used for mating disruption as an alternative to traditional pesticides. The controlled release of insect pheromones shows
Journal of Chemical Education • Vol. 77 No. 12 December 2000 • JChemEd.chem.wisc.edu
Chemical Education Today edited by
Susan H. Hixson National Science Foundation Arlington, VA 22230
Richard F. Jones Sinclair Community College Dayton, OH 45402-1460
promise as an insect pest control technique, but more research is needed to reach a better understanding of field release rates and degradation. Since the pheromones are natural products, they are susceptible to oxidation, hydrolysis, and UV isomerization reactions in the environment. The GC–MS has allowed students to characterize these degradation reactions. The addition of GC–MS has enhanced many of our undergraduate laboratory courses and student-led research projects. The instrument has also been a valuable tool for incorporating an environmental focus in many of our courses. Further information about experiments incorporated into our curriculum can be obtained on our Web site http:// www3.wcu.edu/~butcher/gcms.html.
Education: DUE 9750583 (instrumentation).
Acknowledgment
Cynthia Atterholt, David J. Butcher, J. Roger Bacon, William R. Kwochka, and Royce Woosley are in the Department of Chemistry and Physics, Western Carolina University, Cullowhee, NC 28723;
[email protected].
This work was partially supported by a grant from the National Science Foundation Division of Undergraduate
Literature Cited 1. Williamson, K. L. Macroscale and Microscale Organic Experiments, 3rd ed.; Houghton Mifflin: Boston, 1999. 2. Epling, G. A.; Wang, Q. In Benign by Design: Alternative Synthetic Design for Pollution Prevention; Anastas, P. T.; Farris, C. A., Eds.; American Chemical Society: Washington, DC, 1994. 3. Ondrus, M. G. Environmental Chemistry: Experiments and Demonstrations; Wuerz: Winnipeg, MB, Canada, 1996. 4. Wenzel, T. J. Anal. Chem. 1995, 67, 470A.
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