Shippensburg State College Shippensburg, Pennsyl.vanio 17257
1
Ancllvsis Course
Most chemistry educators will agree that, with the heavy emphasis on chemical instrumentation both in graduate school and industrial work, today's undergraduate chemistrv maiors - need a broad exposure to instrumental techniques before graduation. ldeaiy, students should feel confident operating all the major instruments in a department even before they begin their senior research projects. In the better equipped educational institutions this would include a familiarity with X-ray analyzers, mass spectrometers, nuclear magnetic resonance equipment, etc. It is possible, of course, to teach students about some instrumental techniques with simpler "teaching model" equipment such as spectrophotometers, etc., but these are rarely used in actual research and chemistry majors are not easily made aware of the much greater capabilities of more of the sophisticated instruments unless they can actually use them. One often hesitates, however, to allow undereraduates the use of maior e a u i ~ m e nfor t fear of disrupting research projects or"of iosiihle damage at the hands of the inexoerienced user. Although this is a legitimate concern, many institutions have service instruments which are not continually tied up in research projects and could be used for teaching purposes as well. The risk of damage can be minimized with careful operation instructions provided with each instrument.
-
Course Description
The one-semester undergraduate instrumental analysis course at Shippensburg State College is designed to provide our juniors and seniors with the maximum theoretiThis paper was presented at the 25th Annual Pittsburgh Conference of Analytical Chemistry and Applied Spectroscopy, March 5, 1974. 'Maloan, D.E., J. CHEM. EDUC., 48, 139, (1971). 2Barnard,W. R., J. CHEM. EDUC., 49,136, (1972).
cal and practical exposure to every available analytical instrument regardless of complexity or cost. Two features of this successful program are lectures which emphasize electronic construction of the instruments, in addition to the theory of their operation, and laboratory work arranged such that each student is allowed to operate all instruments, on his own, with a minimum amount of help from an instructor. Eleven major instrumental techniques are studied. See Tables 1 and 2. The lecture portion of the course meets for two 50-min periods each week. The semester begins with an introduction to electricity and electronics which lasts about four weeks. Electronic components and simple circuits such as rectifiers, transistor amplifiers, and operational amplifiers are discussed. The remaining 11 weeks are devoted to the theory of the instrumental methods. Schematic diagrams of the instruments are introduced and discussed. Exams are given periodically. The laboratory work requires an average of six hours each week. The first four weeks are spent in the electronics laboratory where students assemble and test a variety of simple electronics circuits ranging from rectifiers through twostage transistor amplifiers. Operational amplifiers are also studied. Instruction in the use of meters, signal generators, and oscilloscopes is included. For the remainder of the semester, each student performs an experiment, on his own, with a different instrument each week. This means that up to 11 different experiments are in progress weekly by different students. In larger classes, students may do some work in pairs but every individual is required to operate the equipment and write his own report. Conducting a laboratory course in this manner immediately poses a problem. With this rotating system, students are often asked to operate equipment they have never seen before. Teaching a student to operate an instrument
Voiurne 52. Number 4. April 1975
/
229
Table 1. Instrumental Techniques Studied Instrumental Method Flame Emiseion and Atomic Absorption Polarosraphy Qualitative and Quantitative Gas Chromatopraphr UV-Vis Sptrophotometry (Kinetics) Fluorometry Mass Spectrometry Qualitative and Quantitative X-Ray Powder Analysis Soecifie Ion Potentiometrv
Equipment Weed Perkinzlmer 305 A.A. Beckman D.U. with Flame Attachment P.A.R. Model 170 Electrochemistry System Perkin-Elmer Model 900 Gas Chromstoglaph Beekman DK 2-A and DB-G
Turner Model 110 du Pont Model 490 Mass Spectrometer Siemans-KristalloRex 2 Orion Fluoride Electrode
lannel Analyzer ac-3 VMOS.
Table 2. Titles of ExDeriments ~ p t r o p h o t o ~ e t r determination ic of phosphate in R l o d Serum Introduction to Fluoromelry and Analysis of 2',7'-Dichlomfluore%eii Trace Analysis of Metals by Flame Emission and Atomie Absorption Methods 'Anslysia of Acetic Acid Solutions by NMR " Evnlustion of Specific Ion Electrodes X - ~ s powder y ~iffraetionAnalysis of cvbie Crystal Structvrea " A Study of Some Important Parameters in Gas Chromatography a Msas Speetrometw-Analysis of a Mixture at 70 eV Gamma Ray Counting by Single and Multichannel Methods Polarnzraohv-netermiiitiii of Cadmium bv the Calibration ~eth;ld. Emission Sneetroseoov-A Qualitative Analysis ..
"S-value" measurements onto cards and the comnuter generates a table of cell constant values versus sums of sauered Miller indices for each of the lines observed. Thev are then required to search the table for appropriate matches and report the cubic cell type. The mass spectrometry experiment includes the use of either remote video or Teletype time-sharing terminals. The procedure calls for the quantitative analysis of a mixture of three alcohols and students use a program which performs successive spectral ion abundance subtractions which eventually results in the determination of the relative partial pressures of the components iqthe mixture. Each student is required to hand in a written report of his work each week. Besides presenting data and reporting an analysis of an "unknown" sample, the reports must also include lists of advantages, limitations, and possible sources of error associated with the instrumental technique they used. The reports must also include descriptions of several other applications of the particular instrumental method from the literature as well as some other uses they think possible. Evaluation
li
"Taken from: "Instrumental Analysis Manual; Hsrgis, L. G. Marcel Dekker, Inc., New York, 1970.
Guilbault, G. G.,
such as a mass spectrometer can often be time consuming, particularly if the principles of that technique have not yet been covered in the lecture. This program could require several instructors just to demonstrate proper instrument operation since, as in our case, 11 different experiments may be in progress, simultaneously, in different parts of the science building. However, we have found that one person can effectively teach an entire laboratory section if instrument operation instruction is carried out with the aid of audio cassette recorders. Othersl' have described success using cassette recorded programs to provide experiment instructions to undergraduate classes. However, programs used in our class describe only instrument operation procedures and may be used by faculty and other students as well. Each week students are asked to read some brief introductory information about a particular instrumental method before beginning the laboratory work. When ready, they pick up a recorder and take it to the instrument they will use. The recordings begin with eeneral familiarization of the instrument, including a description of the function of various parts and contr6ls. Following that, step-by-step operation procedures are presented which often include statements of caution regarding particularly sensitive manipulations. Within a short ne&d. students are cautiouslv " nerformina . - exneriments . = with such sophisticated equipment as the mass spectrometer. nmr. or multichannel analyzer. Student confidence see& to 'build quickly. The iu&uctor acts as a roving "trouble shooter" during .this period. After the initial introduction to the instrument, students are free to complete their work on an open schedule during the remainder of the week, either working in pairs or individually. The use of computers is also included in this program. In the X-ray experiment, students punch powder pattern
230
/
Journal of Chemical Education
This course in instrumental analysis has been very successful. The students' written evaluations of the course continue to be favorable. Many have mid that although the work load is large they feel it is worth it considering what they learn in the span of one semester. The use of taped instruction has also been well accepted. Many feel less nervous listening to the tape than having an instructor looking over their shoulder. Several have made suggestions as to how particular recordings could be improved to provide a clearer understanding of some step or operation. The recordings can be improved or expanded a t the will of the instructor. Although this takes some time to do, i t has not been necessary very often because the tapes in our program describe the operation of one particular instrument only and once they have been used successfully there is little need to change them. From an equipment maintenance point of view this program has also been quite successful. In the three years the taped instruction technique has been used, there have been no student accidents which have caused any damage or downtime on any instrument. We have experienced no increase in frequency of repairs, above that expected for any instrument in normal use, since the technique was introduced. It should, of course, be understood that students are not totally competent with instruments after a one-week exposure to them. They do, however, come away with a good working knowledge of all the major equipment in our department and seem eager to use them later in research and other courses. The tapes are always available to those who have comnleted the course and wish to review a nrocedure before using the equipment at a later date. Teaching the course as described here is no easy task. Long hours are spent grading the many laboratory reports, but the time spent seems justified based upon the written and verbal reactions of the students who have taken the course. A similar instrumentation course structure on the eraduate level has also been successful. A new course. ~ioinstrumentalAnalysis for medical technology and pre: medical students, will also be taught this way. Acknowledgment
The author expresses his appreciation to Kenneth Berkich and William Fultz for writing the computer programs used in this course.
