topics in chemical instrumentation
HOWARD STROEBEL edited by Duke University Durham. NC 27706
Instrumental Analysis Courses Part I. The Current Experimental Practice Harold H. Harris and James J. O'Brien
University of Missouri-St. Louis, St. Louis, MO 63121 Perhaps no other section of the undergraduate chemistry curriculum has undergone such marked change as the course that addresses the use of instrumentation in chemical analysis, that is, the course frequently called instrumental analysis. Remarkable and recent improvements in electronics, minicomputers, data collection and processing methods, as well as the development of new techniques, have created a much greater array of powerful, versatile, and user-friendly instrumentation for routine use in chemical analysis. Arecent article in this Journal (1)illustrated how the content of instrumental analysis courses has evolved by tracing how the material in one perennial textbook in the field has changed over the years.
Atomk Emission
Debating the Course Content
Enhanced instrumental capabilities means that there is now greater opportunity for students to perform meaningful analyses of real-life samples (2).However, this presents instructors and departments with a greater problem in deciding which topics should be covered and which instruments should be used in an instrumental analysis course. In our department, discussing the proper focus for instrumental analysis lecture and laboratory classes has catalyzed discussions on what is currently done versus what should be done in that course. This has lead to discussing what should be done in our whole advanced laboratory sequence of courses and in all courses with a significant analytical chemistry component. To some extent, the choice of topics and the nature of their treatment in instrumental analysis courses should be determined by the clientele being served. Most chemistry majors, after completing undergraduate BS and BA degrees, find themselves working in analytical laboratories using instrumental methods such as atomic absorption spectrometry (AAS) visible and ultraviolet spectrometry (W-Vis) Fourier-transforminfrared spectrometry (FTIR) -gas chromatomaehv - . . (GC) high-performanceliquid chromatography .HPLC) 'gar ehmrnatugraphy mass spectrometry GCIMS,
.
These have come to be viewed as "essential" weapons in the arsenal of the analytical chemist. While employers in chemical industry generally understand the difference between the education of a chemist and the training of a technician, they expect a recent chemistry graduate to be familiar with the major instrumental techniques that are key to the operation of a modem industrial laboratory The challenge for the modern college chemistry department is to fmd enough time in a crowded curriculum and A266
Journal of Chemical Education
The 13 techniques that appeared most frequently in the survey of methods included in the laboratory portion of instrumental analysis courses. Entries are weighted by the number of laboratory hours devoted to the topic. enough money in a limited budget to provide students with two types of background: the theoretical principles that underlie the methods, and some practical experience with the techniques. The latter entails not only the acquisition of the instruments, but also maintaining them and furnishing the requisite consumable supplies. Our Survey of Chemistry Departments
Examining the problem of what to cover in our instrumental analysis course began with an exercise that may be of interest to others. We surveyed some of the leading chemistrv de~artmentsacross the countrv to learn how they weri dea'ling with the same question. ~~ecifically, we wanted to know which instrumental techniaues thev had decided to include in their instrumental analysis co&e or in the closest thing to it. Information was solicited from over 70 chemistry departments (32responded), including those identified in Chemical and Engineering News (3) as having the most BA and BS chemistry graduates. We also obtained information about credit hours allotted to lecture and laboratory portion and information about other analytical courses in their curricula. The Rankings
The figure depicts the relative emphasis that the departments have placed on the topics that appear most frequently in their instrumental analysis courses. AAS and
UV-vis spectroscopic methods tie for greatest popularity. GC, HPLC, and infrared spectroswpy (IR and FTIR were not differentiated) are also included in many curricula. A recent analysis of the "hottest" topics in global analytical chemistry research fmm 1981 to 1990 showed chromatography, especially HPLC, LC, and GC, to be a t the top of the list (4). Some categories would have changed ranks had they been defined a little differently. For example, we could have created a generalized "electrochemistry" category to include polarography, coulometry, conductivity, and spectroelectrochemistry. Then electrochemistry would have been included among the techniques most frequently cited. Likewise, mass spectrometry (MS) and GCiMS combined would have been included in the figure. Extended responses to our survey showed that individual departments chose topics other than the most popular ones for sound pedagogical and economic reasons. These are discussed to some extent in the accompanying article by Bradley T. Jones (Part I1 of this feature). These topics included crystallography, computer interfacing, flow-injection analysis, and thermal analysis, a s well as the electrochemical techniques and mass spectral topics mentioned earlier.
Our Survey of Industry We asked some of the members of our Industrial Advisory Board (University of Missouri-St. Louis) for input concerning the preferred content of analytical chemistry courses. We found that, for the most part, they did not expect BS majors in chemistry to have been "trained" to operate the instruments in industrial laboratories. Instead, they looked for students with various basic skills. They would prefer that we help students do the following.
develop g o d quantitative work habits master report writing .understand analysis assessment g r a s p the principles of the techniques acquire some experience with the more important methods The methods experience they wanted most in baccalaureate chemists involved HPLC, GC, and IR and UV-vis spectrophotometrv. None of them expected newly hired chemisis, even those with previous experience, to bperate any particular GC/MS, FTIR, or other complex instrument without additional training. Results Perhaps the most useful effect of the survey was to reinforce the arrmment in favor of enhanced treatment of in-
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(Continued on Dwe A268)
topics in chemical instrumentation stmmental methods in our chemistry curriculum. We have decided to reorganize our course and to expand it slightly from a three-credit 1ectureAaboratory course to two individual lecture and laboratory courses, each representing two credits. The lecture course will be a prerequisite for the laboratory. We also plan to improve coordination among our other advanced offerings, to assure that our of instmental are exposed to a wide methods, whether in the instrumental analysis course or in one of our other advanced laboratories.
committee, Professors Joyce Corey and James Cbickos, for their participation in the curriculum evaluation described here. This analysis was presented in part a t the Central1Great Lakes meeting of the American Chemical Society, Indianapolis, Indiana, May 29-30, 1991. Literature Cited 1.RaWiff~.A.;Mottola. H.A. J. Cham. Educ. 1991,68,643. 2. Sherren, A. T.J Chpm Educ. 1881,68,598;Bidl~lnsmyer,B. A ; S~hmitz,S.J Chpm. ~du= 1991.66, ~ 1 9 5~inreh, : R.F J c k m ~ d u c 1987.64.438. . 3. ~ k ~ i m ~ ~ ~ d ~ Nn ~gW i1990,69 S ~ ~ e (~~ pi rni30). l g 29. 4. Bra"*, T.;Sch"bert,A.ne"d~A".i. Chem 1991.10. 1.
Acknowledgment The authors express their appreciation to the other two members of our department's analytical chemistry review
Part II. The Choice and Use of Instrumentation Bradley T. Jones Wake Forest University, WinstonSalem, NC 27109 The proper choice and use of instrumentation in the universitv curriculum is an im~ortantfactor in the education of st&euts in chemistry because analytical instmmentation has become invaluable to today's chemist ( I ) . To evaluate the current state of equipment in instrumental analysis laboratories around t h e country, a survey was conducted on the status of spectroscopic equipment, a type of instrumentation widely used in such laboratories. A questionnaire was mailed to 200 randomly selected colleges and universities having graduate programs in chemistry. As of the date of submission of this text, 95 responses had been received. Courses in Instrumental Analysis are offered by 93% of the schools responding. The average enrollment for the course is 24 students per year. The table lists t h e spectrochemical analysis techniques most commonly offered in the laboratory, the percentage of schools offering that technique currently and in 1983, and the average age of the commercial instruments currently employed. Perhaps the most enlightening information obtained from the questionnaire comes from the written responses from the participants. Each laboratory director was asked to describe the most difficult challenge to be faced in the immediate future. The resulting list of problems is described below. Problem 1: Acquisition of Modern Equipment (Cited by 79% of those responding). In recent years instmmentation costs have increased, while funding to support the acquisition of new equipment has become more scarce. Because each piece of equipment is designed for only one type of measurement, many types of specialized experiments may never be available to the student because the purchase of an expensive commercial instrument could not be justified. An excellent illustration of this problem is given in the following quote from one of the questionnaire respondents. It is becoming increasingly difficult to present experimental exercises to undermaduates on modern eaui~mentbecause of the high rwt and rapid drvrlopmrnt ofinrtrumentatiun. Weno longcr attempt to perform walysea in our inatr~lmrntallahc-
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Journal of Chemical Education
ratory relevant to the needs of current research laboratories. Neither techniques that employ the most expensive commercial instruments (e.g., Raman spectrometry, atomic fluorescence spectrometry, and atomic emission spectrometry) nor new techniques are often employed in undergraduate laboratories due to the cost restrictions mentioned above. Furthermore, many currently available instmments are woefully out of date (see table). Those instmments typically the most up-to-date are the WNisible absorption spectrometer and the infrared absorption spectrometer, with average instrument ages of 7.2 and 9.1 years, respective13 It is interesting to note that these two Spedrochemical Analysis Techniques Most Commonly Offered Technique
% Schools
% Schools
Using Technique (1991)
Using Technique (1983)'
Atomic 93 Absorption Atomic 43 Emission Atomic 3 Fluorescence UVIVisible 97 Absorption Molecular 73 Fluorescence Molecular 6 Phosphorescence Raman 9 Scaltering Infrared 84 Absorption 1983data taken from Pickral ( I ) .
Average Age of Instrument (years)
78
10.5
44
12.7
-
10.3
78
7.2
36
11.4
-
9.4
3
9.5
62
9.1
