Should Advanced Instruments Be Used in Introductory Courses

Laboratory instruction in first year college chemistry courses has undergone change in recent years. Among the new emphases at some institutions is in...
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Should Advanced Instruments Be Used in Introductory Courses? by Jack K. Steehler

Recently I attended a national gathering of college/ a majority of the group university chemical educators where the topic of appropriat the recent meeting ate use of instrumentation was under discussion. Based expressing serious on personal experience, I knew doubts about any use that the answer to the title of instrumentation… question was “Yes, of course!” After all, hasn’t this Journal in introductory published a number of articles laboratories. on this very topic (1–5)? To my surprise I heard a majority of the group at the recent meeting expressing serious doubts about any use of instrumentation (beyond the level of pH meters or the simplest visible spectrometer) in introductory laboratories. What a shock! Apparently there is still real resistance to widespread adoption of this practice, necessitating further open discussion of the issues involved. I work at an institution where instruments are used everywhere. Our first-year science majors have hands-on exposure to almost all major instrumentation in the year-long sequence (FT-NMR, HPLC, UV–vis, GC/MS, AA, FTIR). Our large-enrollment liberal arts chemistry course has students doing FT-NMR on aspirin samples they synthesize, crime solving by HPLC, and using AA for water analysis. The disparity between my own experience and the majority viewpoint at the recent gathering caused me to reflect carefully on this question and prompted this essay. The bottom line will be a conclusion that instruments can and should be widely used at the introductory level, but both sides of the question will be explored. First of all, let’s explore the driving forces encouraging use of instrumentation at the introductory level. A brief list of those forces includes: To my surprise I heard

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Introductory courses reach the greatest number of students, increasing the educational impact. Typically the number of students who would eventually be exposed to instrumentation in upper level instrumental analysis courses is only 10% of the number at the introductory level. For many students the introductory course is their only chance to experience an important part of modern laboratory science. Modern science makes extensive use of instrumental methods, and students should be exposed to that reality. Student expectations of science include modern techniques, and student responses are improved when those expectations are met. Today’s students need to see connections to their lives and experiences. Modern instruments match up well with experiments with significant real-world flavor, such as crime scenarios or environmental investigations.

Two statements form the heart of this list. First, we should teach students chemistry that is closely related to how the discipline is currently practiced. Surely no one will argue that students do not need to understand modern instrumental methods! The second core idea is that today’s students respond best to course content that they perceive to be relevant. The standard practice of 20 years ago of expecting students to embrace a set of core concepts simply because they are stated to be core concepts is no longer effective (if it ever was effective for more than the elite students). Beyond this idea of student motivation, we should recognize the benefits of using a variety of teaching methods. Modern instrumentation offers a learning experience that complements both classroom instruction and traditional labo- Instruments offer not ratory experiences. Instruments only exposure to offer not only exposure to technology, but a visual approach to technology, but a understanding data. Graphical visual approach to presentation of recorded data is understanding data. almost instantaneous, allowing close linkage between the lab work generating the data and the interpretation of those data. These ideas describe real benefits of using instruments in the curriculum. However, we also want to define the doubts and concerns that exist about such laboratory programs. Again, a brief listing is appropriate. •

Sufficient instrumentation cannot be provided to serve the number of students at the introductory level. Single copies of instruments cannot serve a full class of students. Use of advanced instruments by introductory students will lead to significant problems with broken equipment. Upkeep and repairs are too expensive. Black box instrumentation distances the student lab experience from the core principles of introductory chemistry courses. The hands-on flavor of chemistry in a beaker is essential.

There are two concerns being expressed here. One concern includes a range of practical concerns—sufficient instrument availability, sufficient durability, sufficient support funds. The second concern is the pedagogical question of whether instrumentation teaches what needs to be taught. One answer to such questions is to point out the success many schools have had with instructional use at introductory levels. In the experience of my own institution, the practical concerns can all be handled successfully. The entry-level problem is acquiring instruments in the first place. Obviously few institutions can purchase a full range of instructional instruments solely with internal funds. External grants are available to assist with such purchases.

Journal of Chemical Education • Vol. 75 No. 3 March 1998 •

Chemical Education Today

However, you must apply in order to be funded!! That initial follows synthesis, analysis follows sample preparation, just as barrier, convincing yourself to apply, is the largest hurdle to in real-life chemical experimentation. In our experience, the overcome. And if initial applications are turned down, get hands-on chemical experience is just as strong in experiments some constructive feedback and try again. Our chemistry using instruments as in other experiments. We aren’t advodepartment has the instruments it has primarily owing to a cating doing away with wet chemistry; we choose instead to willingness to seek external funding. Almost all of our instruintegrate it with the use of instrumental techniques. ments have involved external grants, Some would also argue that with appropriate internal matching instruments are used as black boxes We aren’t advocating doing away with funds. at the introductory level, and that What about the durability wet chemistry; we choose instead to no chemical insight results. I guess question? We have had extremely a poorly designed and executed exlow breakage problems. In our integrate it with the use of instrumental periment might in fact end up that more than ten-year experience techniques. way, (as would any poorly designed with FTIR, GC, HPLC, FTexperiment), but such flaws are not NMR, UV–vis, and AA usage in inherent in the use of instrumenintroductory courses, we have had to deal with only two intation. Good introductory material can provide information jection syringes that needed replacement (one GC and one on what instruments do in a way that reinforces core conHPLC) owing to student misuse, one broken quartz UV cucepts of first-year chemistry (e.g., discuss polarity and solvavette (broken in an advanced course, not first year), and only tion when using chromatographic instruments, atomic and one broken NMR tube in the magnet. Students have caused molecular structure when using spectroscopy). zero problems for the FTIR and AA instruments. We have We should not feel apologetic if first-year use of instrualso found that expenses for both ongoing purchase of conmentation is somewhat simplified. We admit that our firstsumable supplies and for occasional needed instrument reyear students don’t get a full NMR introduction when we pairs have been quite manageable, although buying cryogens for use NMR in lab. In fact, we prefer to start with proton dethe NMR is a large expenditure. coupled 13C NMR because of its simplicity. But that simplicity does give a good introduction, leading to a multiyear, Next, let’s consider the question of work load per instrumultilevel approach to instrumentation, encompassing the ment. Our institution has only one of each major instrument full four-year curriculum. This approach is similar to the way (except GC: we have two GCs and one GC/MS). Yet we have we structure our presentation of concepts over four years. It been able to use these instruments extensively without long is essential that the early stages of that multilevel approach waits in line. Scheduling is the key, along with experimental match the students’ level of sophistication, providing interdesign that rotates students through several activities, reducing esting lab experiences without overwhelming their ability to peak demand on instruments. For example, in our crime lab, comprehend. students rotate through four stations—sample preparation, Modern chemistry uses instrumentation for good reaGC, TLC, and HPLC. Using more instruments actually helps sons. It is powerful and fast. Students need early exposure to ease scheduling problems. We also define instrument conditions instruments for several reasons, including the motivating conto maximize efficiency. For example, a typical IR takes 2–3 nection to real-life chemistry, the complementary nature of minutes, a UV–vis spectrum takes 2–3 minutes, NMR spectra this type of laboratory experience, and the need to start learncan be acquired in 3–4 minutes, and both GC and HPLC ing these powerful methodologies. The practical objections are usually limited to 3-minute experiments. Adequate superto such usage can all be handled if thoughtful attention is vision, typically by student lab assistants, also keeps things paid to the details of experimental design and scheduling. moving and helps teach students good technique. We also Let’s allow our students the power and fun of using modern use advance scheduling to resolve conflicts between courses. instruments at all levels! A master schedule is prepared at the start of the semester. In some cases different courses use the same instruments during the same lab period, in different assigned time blocks. Literature Cited The second major issue regarding first-year usage of 1. Van Ryswyk, H. J. Chem. Educ. 1997, 74, 842–844. instrumentation is a pedagogical concern. First-year students 2. Heuer, E.; Koubek, E. J. Chem. Educ. 1997, 74, 313–315. need to gain hands-on experience with chemicals, with reac3. Walters, C.; Keeney, A.; Wigal, C. T.; Johnston, C. R.; Cornelius, tions, and with laboratory techniques and manipulations. R. D. J. Chem. Educ. 1997, 74, 99–102. There is a certain gut-level understanding that comes from 4. Eichstadt, K. E. J. Chem. Educ. 1992, 69, 48–51. doing chemistry in a beaker, such as seeing PbI2 precipitate 5. Jones, B. T. J. Chem. Educ. 1992, 69, A268–A269. when Pb(NO3)2 and KI solutions are mixed. Does use of instruments preclude sufficient experience with “wet chemistry”? No! Even when extensive use is made of instruments, many Jack K. Steehler teaches in the Department of Chemistry, experiments aren’t instrument based. Furthermore, good experiRoanoke College, Salem, VA 24153-3794; phone: 540/375ments involving instruments use them in context. Spectroscopy 2442; email: [email protected]. • Vol. 75 No. 3 March 1998 • Journal of Chemical Education