Chemical Education Today
NSF Highlights Projects Supported by the NSF Division of Undergraduate Education
An Environmental Focus Using Inductively Coupled Plasma–Optical Emission Spectrometry and Ion Chromatography by Arthur Salido, Cynthia Atterholt, J. Roger Bacon, and David J. Butcher*
The chemistry faculty at Western Carolina University (WCU) has incorporated an environmental focus in its curriculum and research programs. We believe that an enhanced understanding of environmental chemistry is important for all chemistry graduates based on the production of large quantities of chemicals on a global scale, the need for responsible management of these chemicals, and the development of new industries in this area. In order to achieve this goal, we have made a commitment to hiring faculty whose teaching and research interests include environmental chemistry; incorporated environmental chemistry into our existing courses; developed an environmental chemistry course; and developed a concentration in Environmental Chemistry to the B.S. degree. Our long-term goal is to become a major contributor in environmental chemical education and research. Inductively coupled plasma–optical emission spectrometry (ICP–OES) and ion chromatography (IC) were identified as suitable tools for determination of elements and ions, respectively. ICP–OES allows rapid, simultaneous, sensitive determination of virtually all elements, and IC allows the determination of cations and anions with good sensitivity. Support from the National Science Foundation (NSF) allowed the addition of ICP–OES and IC instrumentation to our undergraduate laboratories. The ICP–OES and IC instruments have been integrated into the curriculum to promote student learning in •
Monitoring elements and ions in environmental samples.
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Analytical method development.
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Undergraduate research.
Several experiments have been developed in our analytical and environmental chemistry courses. For example, IC has been used in our Aquatic Chemistry, Quantitative Analysis, and Instrumental Analysis I courses for the determination of cations and anions in natural waters and wastewater. WCU is the home of the North Carolina Mountain Aquaculture Center (NCMAC), which has fish hatching and rearing facilities. Commercial rainbow trout (Oncorhynchus mykiss) farming is a significant local industry that has been reported to be harmful to water quality. Environmental concerns focus on metabolic and uneaten food wastes that enter streams (1), including ammonium ion, phosphate, nitrate, nitrite, and sulfate, which cause increased levels of vegetation and eutrophication of waterways. Our students have employed ion chromatography to analyze wastewater from the NCMAC for these ions to evaluate the effects of trout farming on water quality. 22
Pressure-treated wood is treated with a solution of copper, chromium, and arsenic to retard damage by mildew, fungi, insects, bacteria, and mammals. Ondrus described an experiment in which copper and arsenic are determined in pressure-treated wood by atomic absorption spectrometry (AAS) (2). We have modified this experiment to determine these elements and chromium by ICP–OES. ICP–OES has several advantages compared to AAS for these analyses: improved sensitivity, longer linear dynamic range, no chemical interferences, and simultaneous analysis of all three elements. We have found that ICP–OES is significantly easier and faster than AAS, allowing students to focus upon results of the experiments with a reduced emphasis on the mechanical aspects. Fish oil tablets are a nutritional supplement that provide omega-3 fatty acids, which have been reported to reduce the risk of coronary heart disease (3). However, the U.S. Food and Drug Administration has recommended that Americans limit their intake of specific species of fish due to high levels of mercury (4). We were therefore interested to see if measurable levels of mercury were present in fish oil tablets, and consequently developed an experiment for our Instrumental Analysis I course. The tablets consist of the fish oil enclosed in a gelatin capsule. The capsule is difficult to digest, and in order to minimize losses of mercury due to volatilization, a mild sample preparation procedure was developed. One fish oil tablet was digested in 3 mL of nitric acid and 9 mL of hydrochloric acid at room temperature for three hours. The sample was diluted to 50 mL with deionized water. Quantitative analysis was performed by ICP–OES using aqueous calibration standards. This experiment provides practical experience analyzing a pharmaceutical product. Instrumental Analysis II is a senior/graduate-level course focusing on advanced topics in chemical instrumentation and analysis. The laboratory has recently been revised to consist entirely of projects designed to simulate analytical method development (5). The students are presented with an analytical chemistry problem for which they research protocols in the literature, develop methods, collect samples, perform the analyses, and analyze the data. The students currently do two projects in this course. The first project, performed by the entire class, involves the determination of elements by ICP–OES in natural water samples. The students are given some guidance in this introductory project. Each student pair uses the ICP–OES to qualitatively determine 20 elements simultaneously. After this screening study, 1–3 elements are chosen for students to perform quantitative analysis. Calibration graphs are prepared
Journal of Chemical Education • Vol. 80 No. 1 January 2003 • 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
and the students characterize the detection limits and linear dynamic ranges for their elements. The samples are analyzed quantitatively using the standards, and by standard addition, with recovery checks for quality control. This project allows students to develop practical experience in environmentalanalytical analysis. Several students have used ICP–OES for their second project in Instrumental Analysis II. For example, this instrument has been employed for the determination of heavy metals in roadside soil and foliage around the WCU campus. Although lead has been absent in gasoline and hence automobile exhaust for many years, we were interested in metal levels in the soil produced by deposition from fluids, tire degradation, emissions, and other pathways. We were also interested in monitoring the uptake of metals in plants. Using EPA methods as guidelines, methods were developed to acid digest the samples, followed by ICP–OES analysis. In general, the levels of the metals in soils and plants were below the ICP– OES detection limit, indicating that automobiles do not significantly contribute heavy metals to roadside soil. Other recent projects include the determination of mercury in soil and vacuum cleaner dust, lead in candlewick solder, and calcium, iron, and magnesium in paper plant effluent. Research is an integral component of the WCU chemistry curriculum, and ICP–OES and IC have been involved in several projects. For example, a nearby housing development, Barber Orchard, has been declared a Superfund site by the U.S. EPA, primarily because of elevated levels of lead and arsenic employed as a pesticide when the site was an apple orchard. ICP–OES has been employed to quantify lead and arsenic in a variety of samples associated with this site. One student is growing various fruits and vegetables to evaluate the levels of these metals in the edible parts of the plants. Conventional methods to treat contaminated soil involve its removal to a hazardous waste site, which is an expensive and disruptive process. Several WCU students have investigated the use of phytoremediation, the use of green plants to remove contaminants from the soil, as an alternative approach (6). Preliminary experiments demonstrate the effectiveness of phytoremediation at Barber Orchard.
In summary, ICP–OES and IC have been shown to allow the development of innovative experiments for environmental analysis. These techniques are also well suited for students to learn analytical method development, and have proven to be versatile tools for research projects. Further information about our curricular developments are available at our Web site (7). Acknowledgment This work was partially funded by an award from the National Science Foundation Division of Undergraduate Education: NSF Award 9950221 (CCLI-A&I). Literature Cited 1. Loch, D. D.; West, J. L.; Perlmutter, D. G. Aquaculture 1996, 147, 37–55. 2. Ondrus, M. G., Environmental Chemistry: Experiments and Demonstrations, 2nd ed.; Wuerz Publishing Ltd.: Winnipeg, Canada, 1996. 3. FDA Announces Decision on Another Health Claim for Dietary Supplements. U.S. Food and Drug Adminstration: Washington, DC, 2000; http://www.fda.gov/bbs/topics/ANSWERS/ ANS01050.html (accessed Sep 2002). 4. An Important Message for Pregant Women and Women of Child Bearing Years who May Become Pregnant. U.S. Food and Drug Administration: Washington, DC, 2001; http://www.cfsan.fda.gov/ ~dms/admehg.html (accessed Sep 2002). 5. Wenzel, T. J. Anal. Chem. 1995, 67, 470A–475A. 6. Raskin, I.; Ensley, B. D., Eds. Phytoremediation of Toxic Metals: Using Plants to Clean up the Environment; Wiley: New York, 2000. 7. http://sparkychem.wcu.edu/icp-ic/icp-oes_ic.html (accessed Sep 2002).
Arthur Salido, Cynthia Atterholt, J. Roger Bacon, and David J. Butcher are in the Department of Chemistry and Physics, Western Carolina University, Cullowhee, NC 28723;
[email protected].
JChemEd.chem.wisc.edu • Vol. 80 No. 1 January 2003 • Journal of Chemical Education
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