Research: Science and Education
Topics in Chemical Instrumentation
Instrumental Analysis Lecture and Laboratory: A Survey James E. Girard* Department of Chemistry, American University, Washington, DC 200815-8014;
[email protected] Constance T. Diamant Mary Washington College, Fredericksburg, VA 22401-5358
Instructors of instrumental analysis lecture and laboratories are faced with a dilemma. Which topics should be covered in lecture and which techniques should be used in the instrumental laboratory? This question has been asked before (1–3) and others have surveyed the instruments used in instrumental analysis laboratory courses (4, 5). Harris and O’Brien polled instructors of these courses at schools graduating the most undergraduate chemistry graduates about their practices in both the lecture and the laboratory (6, 7 ). The purpose of our study was to understand what topics are being taught in instrumental lecture and which instrumental techniques are being performed in the laboratory. A questionnaire based on one used by Sherren in 1981 (8) was sent to instructors teaching at schools that were randomly selected from the ACS’s College Chemistry Faculties 1996 publication and the 1995 Directory of Graduate Research. The sample group was diverse enough to allow us to see if large schools or schools with graduate chemistry programs or engineering schools were teaching the course in ways that differed from the methods used at smaller schools without graduate or engineering programs. We also compared our 1998 responses with those obtained in 1981 by Sherren to see if any long-term trends could be seen. The results of our survey indicate that the instrumental laboratory has changed more than the instrumental lecture course. The Surveys In 1981, Sherren sent out 100 questionnaires to faculty in four-year colleges and universities in all parts of the country. She received 58 responses, and of these, 52 schools had a separate course in Instrumental Analysis. Our questionnaire was based on that of Sherren. It was modified by adding five modern techniques that were not generally in use in 1981: capillary electrophoresis, GC–MS, Table 1. Number and Types of School Sur veyed Type of School
Number of Schools Surveyed
Responding
Public
124
42
Private
103
32
With an engineering program
102
34
Without an engineering program
125
40
With a chemistry graduate program
119
42
Without a chemistry graduate program
108
32
With more than 10,000 students
99
23
With fewer than 10,000 students
128
51
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ICP–AES, FTIR, and supercritical fluids. In addition, five categories that were redundant were removed. We sent 227 questionnaires to faculty at four-year colleges and universities and as Table 1 shows, we chose a diverse sample. We received 74 responses, a 32.6% response rate, and as can be seen in Table 1, the numbers of responses for each category of school were balanced. We correlated the individual responses with the type of school responding, and compared our 1998 results to Sherren’s 1981 responses. A comparison of the 1981 and 1998 percentage of responses regarding topics taught in lecture and laboratory can be seen in Table 2. Summary of the Responses Received The first question asked “How many credit hours do you give for Instrumental Analysis and Laboratory?” The responses we received are not significantly different from those obtained by Sherren in 1981. They indicate that the majority of schools, 54%, give four credits for instrumental lecture and laboratory; 15% give five credits and 16% give three. The next question was “What textbook are you currently using (or do you intend to use next time you teach the course?” We asked for separate answers for the lecture and the laboratory and we found that the overwhelming majority of instructors, 64 of the 74 respondents (86%), use one of the books by Skoog et al. from Saunders for the instrumental lecture. The majority of those teaching instrumental laboratory use no book. Forty-five of the 74 respondents, 54%, use individually designed handouts; another 10, 13%, use Chemistry Experiments For Instrumental Methods by Sawyer, Heineman, and Beebe, published by Wiley in 1984. Thirteen percent did not specify what materials they use. Five schools, 7%, do not offer instrumental laboratory. These findings perhaps indicate that instructors prefer to use their own handouts and as a result, the demand for lab manuals is so small that publishers are reluctant to invest in publishing such materials.
Lecture Topics Responses to our questionnaire indicate that as in 1981, each of the 37 lecture topics listed was being taught by at least one school. However, no school indicated that all 37 topics were taught in one term. Comparison of the 1998 results to the 1981 survey showed a significant change in the frequency of inclusion of some lecture topics. For example, in 1981, optical rotary dispersion, circular dichroism, and polarimetry were taught by a large percentage of instructors. Today almost no one teaches these topics. Although most instructors include gas chromatography and proton NMR in their courses, these topics were taught
Journal of Chemical Education • Vol. 77 No. 5 May 2000 • JChemEd.chem.wisc.edu
Research: Science and Education Table 4. Instrumental Techniques Offered at Undergraduate Schools and Schools with a Graduate Program
Table 2. Topics Taught in Instrumental Analysis, 1981 and 1998 Topic
Lecture
Laboratory
1981 1998
1981 1998 ∆
Experiment
Respondents Including This Experiment (%)
Visible spectrophotometry–absorption
86
97
81
84
Ultraviolet spectrophotometry–absorption
88
91
81
78
Undergraduate
Graduate
Atomic absorption spectroscopy
84
89
62
77
+
UV–vis
88
81
HPLC
62
86
34
74
+
Fluorescence
45
58
Infrared absorption spectrophotometry
81
82
66
55
HPLC
70
76
GC–MS
—
78
—
69
AA
70
79
Liquid chromatography
64
77
28
24
Gas–liquid chromatography
79
77
78
64
–
GC–MS
45
84
FTIR
—
76
—
61
+
FTIR
45
72
Atomic emission spectroscopy
78
76
36
32
ICP–AES
9
26
Mass spectrometry
72
74
19
24
CE
6
28
Molecular fluorescence spectroscopy
64
72
38
54
+
39
12
Electrochemical cells, electrode potentials
86
65
45
31
–
Potentiometric methods
72
65
59
34
–
Inductively coupled plasma–AES
34
65
2
19
+
Cyclic voltammetry
33
57
16
38
+
Proton NMR
59
55
48
33
–
Polarography
78
49
60
35
–
Raman spectroscopy
45
47
3
7
Capillary electrophoresis
—
46
—
18
+
Atomic fluorescence spectroscopy
34
42
2
54
+
X-ray methods
43
39
7
8
31
38
2
20
+
Electric circuits
28
35
7
18
+
Supercritical fluids
—
32
—
3
Controlled potential coulometry
60
28
7
11
Controlled current coulometry
59
23
29
7
–
Electrogravimetric methods
55
22
33
11
–
Amperometric methods
62
22
28
8
–
Chemical analysis of surfaces: ESCA, SIMS
21
19
0
1
Radiochemical methods
28
19
10
3
Thermal methods
33
18
5
7
Conductance methods
55
14
40
14
Electron spin resonance spectroscopy
33
7
3
1
Opical rotatory dispersion
16
5
3
0
Refractometry
26
4
17
3
–
Polarimetry
21
4
21
0
–
Computerized analysis
31
30
21
22
13
C NMR
+
–
Table 3. Most Commonly Offered Instrumental Techniques Respondents Including This Experiment (%)
Experiment UV–visible spectrophotometry
84
Atomic absorption spectroscopy
77
High-pressure liquid chromatography
74
Gas chromatography–mass spectroscopy
69
Gas chromatography
64
Fourier transform–infrared spectroscopy
61
Molecular fluorescence
54
Electrochemical cells
31
Proton nuclear magnetic resonance
33
Electronics
18
Computerized analysis
22
Computerized analysis
by fewer instructors in 1998 than in 1981. As Organic Chemistry II has become more a spectroscopy course, these techniques are generally being taught in the sophomore year. Except for cyclic voltammetry, few instructors now include electrochemistry topics. The instrumentation for cyclic voltammetry has improved considerably since 1981, which probably explains why more instructors are teaching this technique. Other techniques, such as atomic spectroscopy, are replacing electrochemical techniques in the curriculum. The lecture topics most often included are UV–vis spectrophotometry, infrared spectrophotometry, molecular fluorescence spectroscopy, atomic absorption spectroscopy, NMR, GC–MS, mass spectrometry, electrochemical cells, cyclic voltammetry, HPLC, and GC. Results for lecture topics that were not included in the 1981 questionnaire, but added in 1998 were as follows: GC– MS, 78%; ICP–AES, 65%; capillary electrophoresis, 46%; and supercritical fluids, 32%. Except for GC–MS, few of these topics were included in the laboratory at most schools, which is not surprising considering the difficulty of obtaining expensive modern instrumentation for teaching laboratories. GC–MS is the one instrument in this group whose price has fallen significantly, and 69% of schools responding indicated that they included a GC–MS experiment.
Changes in Laboratory Topics The instrumental laboratory has changed more than the instrumental lecture. Four techniques that were often used in 1981, infrared, NMR, electrochemical methods, and gas chromatography, have declined in usage. Six instrumental techniques are increasing in usage: molecular fluorescence, atomic absorption spectroscopy, GC–MS, cyclic voltammetry, HPLC, and elementary electronics. It appears that there is a consensus about which experimental techniques the instrumental course should offer to undergraduates. The 11 most offered instrumental experiments are listed in Table 3 with the frequency of their offering. A comparison was made of the experiments offered by the different types of institution and it was found there were no differences between public and private institutions, between those with more than 10,000 students and those with less than 10,000, or between schools with and without engineering
JChemEd.chem.wisc.edu • Vol. 77 No. 5 May 2000 • Journal of Chemical Education
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Research: Science and Education
departments. However, we did find a difference in lab offerings when we compared departments with and without a graduate program in chemistry. A comparison of the frequency of offering of 9 experiments in departments with and without a graduate program is shown in Table 4. As can be seen in this table, undergraduate and graduate departments offer UV–vis, HPLC, AA, and molecular fluorescence laboratories with roughly equal frequency. However, GC–MS is offered almost twice as frequently by graduate departments, and other expensive modern techniques such as FTIR, capillary electrophoresis, and ICP–AES are all more commonly offered by graduate departments than by undergraduate departments. Undergraduate departments, on the other hand, offer computerized analysis more often, probably because they rely on computer simulations of analytical instruments. Expensive modern instrumentation for instrumental laboratory appears to be less available to undergraduate departments than in graduate departments.
the limited amount of laboratory time that is available, or it may be caused by limitations in instrumentation. The results from the questionnaire we describe may help instructors choose which topics to include. As expected, departments with graduate programs have better equipment available for the instrumental laboratory and consequently undergraduates get a more comprehensive laboratory experience in these departments.
Conclusion
Literature Cited
The content of the analytical curriculum and the instrumental analysis course is constantly evolving, and not surprisingly, the curriculum reflects the sophistication of society. Subjects once taught at the graduate level are now offered at the junior or senior level, and subjects that were once juniorlevel topics are now offered at the sophomore level, mirroring technological advances. The instructor of the instrumental analysis course will always have to weigh which topics are fundamental and necessary and which have to be left out of the syllabus. Responses to our questionnaire indicate that more than twice as many topics are covered in instrumental lecture than in the laboratory. This may simply be a function of
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Acknowledgments We thank Anne Sherren for permission to use her 1981 survey and data. We acknowledge the assistance of Julia Elmer and Ramya Mahadevanijaya in the preparation of the survey and the tabulation of the data. The results of this survey were presented at the 1998 Middle Atlantic Regional Academic Analytical Conference, Georgetown University, Washington, DC.
1. Strobel, H. A. J. Chem. Educ. 1954, 31, 159. 2. Laitinen, H. A. J. Chem. Educ. 1956, 33, 422. 3. Ewing, G. W.; van Swaay, M. Anal. Chem. 1985, 57, 385A– 392A. 4. Leggett, D. J. Anal. Chem. 1981, 53, 385A–392A. 5. Instrumentation Needs of Academic Departments of Chemistry; Anal. Chem. 1984, 56, 1225A–1231A. 6. Harris, H. H.; O’Brien, J. J. J. Chem. Educ. 1992, 69, A266. 7. Jones, B. T. J. Chem. Educ. 1992, 69, A268. 8. Sherren, A. T. Instrumental Analysis: Who is doing what in lecture and lab in the 1980’s. Presented at the Great Lakes Regional ACS Meeting, June 1982, Chicago.
Journal of Chemical Education • Vol. 77 No. 5 May 2000 • JChemEd.chem.wisc.edu
