general theory of each type of analysis must he understood before actual procedures are perfected to avoid student cook hook readers and button pushers. Second, all analytical procedures discussed and practiced should he related to actual situations and should use known samples for standardization and verification. The course is roughly two-thirds "wet" chemical methods of both gravimetric and volumetric analysis and one-third instrumental methods with an emphasi; on visible spectral techniques. The &st unit intro&ces elementary quantitative skills with mavimetric analvsis and statistics as the foundation. Lecture on theory of haiance operation and calibration is complemented by a lahoratory exercise in popping popcorn utilizing both double pan and electronic analytical balances? Students make the statistical study by hand calculation and verify it with a previously prepared statistical program on our college computer. Because the second semester freshman course a t ARC has a strone on eauilibrium theorv. - emphasis . .. we can concentrate on techniques for maximization of accuracy and orecision in eravimetric analvsis. In the laboratory the transition from gra\,imetric to volumetric analysis is made by 11 rhluride determinatiun both on a standard chloride sample and on wiener seasonings frum a local seasoning producer. The additional use of a gravimetric buret2 here demonstrates the relation of precision and ease of operation to equipmrnt rosts. Calil)raticm of all vdumctrir equipment is also emphasized. Because students commonly believe that every number displayed by any instrument is valid., thev.are ureed to evaluate constantlv the realistic orecision of the equipment or instrumentation they are using. Volumetric analvsis lectures azain build upon student knowledge of acid-base equilibria hut emphasLe use of the titration and aloha curves for end ooint determination and selection of experimental conditions. In the lahoratory the students try a variety of indicators for a titration of carhonate in soda ash and water hardness with EDTA. In addition to unknown hardness samples, the students, using previously discussed EPA sampling techniques,3 bring in water samples to analyze. In the area of electrochemistry, the phosphate content of baking powder is determined using a potentiometric end-point determination.4 The use of pH meters and ion-selective electrodes introduce the instrumental portion of the course. Instrumental theorv is develooed with emohasis on ouestioning usages and liktations oi the technique, dependagility of the results, and calibration of the instrumentation. Centering upon the Nernst equation, we discuss the techniques of ootentiometric titration, electrodeposition,. . polaromaphv. - . .. and voltammetry. Spectroscopic methods taught, including fluorometry and atomic absorption spectroscopy, involve consideration of the four basic components of light source, wavelength selection, sample containment, and light detection. We start with a Klett calorimeter and work up through Spectronic-20 to an automated Beckman-25 spectrophotometer. Infrared and nuclear magnetic resonance spectroscopy are covered lightly since they are used in organic classes a t ARC. The last two experiments, which tie the course together, demonstrate the total analytical procedure of sampling, separation, technique selection, calibration, actual analysis, and result interpretation. In one experiment, the students are
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Macomber, R. S., J. CHEM. EDUC., 49,714 (1972). 2Butler, E. A., and Swift, E. H., J. CHEM. EDUC., 49, 425 114771 LA".",.
"Manual of Methods for Chemical Analysis of Water and Wastes," U.S.E.P.A. Methods Development and Quality Assurance Research Laboratory, National Environmental Research Center, Cincinnati, OH 45268.1974. ' Walton. H. F.nnd Reye%..J."Modern Chemical Analy-isand I n strumenrnr~on."MnrcelIJrkkrr. Inc.. New Yurk. 1973,p.11. ;'A mure derailed nurse outline and lahnrotmy Pxpmment hst with
references may be obtained upon request.
eiven a brass sample from which they are to separate and analyze tin as tin oxide; analyze copper by elertrodelx)sition, photometric titratim with EUI'A, and atomlc ahsorption: and analyze lead by electrodeposition, atomic absorption, and ion-selective electrode analysis. The final experiment of the semester directs simulv: "ouantitativelv measure somethine." Experiments performed hive ranged fiom the determinatLn of the copper in crayfish blood to the amount of calcium in egg shells. Students also report the toxicity of any chemicals used and the approximate costs of the chemicals involved. Concludiug with a visit to a local independent analytical lahoratorv. we feel that the student has a mod start on heina able to lolk'at an analytical problem and deal with it, whether i t be in chemistry, biology, or g e ~ l o g y . ~
The Sophomore Level Analytical Laboratory Richard A. Pacer Indiana Uniuersity-Purdue Uniuersity a t Fort Wayne Fort Wayne, 46805 What obiectives should euide an instructor in shaoine an analytical fahoratory course? In selecting a balanced set of experiments, it is helpful to implement a variety of learning ohjectives and to consider the objectives met in other courses (e.g., ir work in organic lab). First and foremost, there should he a balance between the classical (gravimetric and volumetric) methods and the instrumental methods. Some of the lahoratory work should involve analytical separations. Statistical treatment of data should he presented early in the course. The burden of reporting a single "best value" for each determination should he placed on the student, so that these statistical concepts are put into practice quite early. Rigorous standards for accuracy must be reinforced by the grading svstem. The following set of lahoratory experiments has been used by the author in such a course: (1)gravimetric sulfate; (2) sodium carhonate in soda ash (volumetric acid-base); (3) phosphate in a rock sample; (4) Mohr chloride; (5)calcium1 EDTA (water hardness); (6) iron by redox titration with dichromate; (7) mixture of aromatic species by gas chromatography; (8) copper by electrodeposition; (9) colorimetric manganese in steel; (10) calcium by atomic absorption; (11) APC tablets by ultraviolet spectrophotometry; (12) nickel by polarography. Illustration of the incorporation of a variety of learning ohjectives in four of these specific determinations follows. 3) Phomhate rock-use
of ion exhanee resins. DH curves of
7) Aromatic species by gas chromatography-selection of analytical response (peak heights or areas?) and compensation for differences in extent of response (use of relative response factors). 10) Calcium by atomic absorption-the role of EDTA in preventing formation of refractom oxides. comoensation for drift of instrument resoonse with time. a d orobleks at ihe trace level (suchas adsorotion
separation by solvent extraction, simultaneous speetrophatometrie determination and technique for selection of optimum wavelengths, and solvent cutoff. In order to reflect some of the trends in the development of analytical chemistry, analytical courses in the future will need to devote meater attention to problems of analvsis a t the trace level; the many applications td clinical chemist&; greater emphasis on samplinz, particularlv with respect to environmehtal samples; ihe rapidly grow& area OF chemical separations; combinations of established techniques, such as gclmass spec.; newly emerging techniques related to surface Volume 56, Number 2, Februav 1979 / 97
analvsis: comnuter interfacing and other comnuter-related appiuittiuns; i n d the analSti&l mrthod itself',in which students arr taught how to define a prohlem hefore beginning the actual analys& itself. Experiments should he redesigned and developed to incorporate new learning objectives related to these trends. New experiments need to be developed in which the student can become involved in the proper sampling of environmental and biological samples. Several questions arise. Will it still he possihle to grade students rigorously on the basis of accuracy, so careful analvtical techniaue will not become lost in the interest of relevancy? Will new types of commercial "unknowns" become available to assist with the transition to greater work with clinical and environmental samples? How can the practice of practical "hands-on" student instrumentation experience he continued as instruments become more sophisticated and costlv? What role can educational technologies (videotapes, slidejtape cassettes, films, etc.) play in impro&g the student's understanding of increasingly sophisticated instruments, so they are not merely used as "black boxes"? The future of the analytical laboratory course will hinge on the answers to these questions.
T h e Analytical T e x t b o o k Situation: Can a T e x t b o o k Present Analytical C h e m i s t r y as It Really IS?
T. R. Williams a n d R. H. Bromund The College of W m t e r Wooster, Ohio 44691 A recent resurgence of interest in analytical chemistry is caused in part by the increasing demand for industrial analysis. A new generation of introductory and instrumental methods texts should now be written to reflect the chanees in the discipline. Our comments are directed specifically toward introductory texts but can be applied to hoth advanced and instrumental analysis text8. Historical perspective suggests the directions that such new analytical texts might t a k e 3 n our opinion, the early text by Kolthoff and Sandell1 reflected strongly what analvtical chemists did, and were expected to do, f&a living. he fundamental concepts, the bases for the analyses performed by the student, were rigorously treated. Two other texts did a great deal to train analytical chemists: Laitinen's "Chemical A n a l y ~ i s "for ~ theoretical concepts and Reilley and Sawyer's text for the instrumental analysis laboratory." student who had snent a vear with the Kolthoff and Sandell text. and did the work well, was certainly prepared to perform most of the analyses of the chemistry profession. Today we simply cannot make this claim. Since Kolthoff and Sandell, there has been verv little change in format except for an increased emnhasis on statistical work and the intrdduction of instrument'al and chrwnatogrnphic suhjects. CIcwls, thr discipline of analytical chemistry has chan& irom that rcprtwnted hy the Kolthoffand Sandell text, hut most of t he cmremporarv hwks do not rrflect these changes. Somr of the concepts which the earlier npprourhes do not cover follow:
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1) Treatment of hoth qualitative and quantitative aspects of
analysis. Recognition of the broad, interdisciplinarynature of analytical chemistrv. 31 Inorpwari,m of tmrh simple teat9 nnd rornplrx instrumcntal trrhnqur to s d \ c prd~lems. 4 1 l'rnltning ~>imalvtical chemists in rhousinp. I ~ hest P method of analysis from a wider range than were available even ten years ago. 2)
98 I Journal of Chemical Education
If it is possible for a text to give an introductory analytical chemistrv student an annreciation of the diversitv and nower of analytical methodoioiy and also reveal the analytical approaches to problem solving, then the initial education of the undergraduate would take on a new dimension and would, in effect, redirect the thinking of students and teachers alike. There are two notable examples which indicate that the goal may be attained. The text by Roberts and Caserio4 has had a profound influence on the teaching and practice of organic chemistry and chemists' approaches to the subject. With the advent of that book, spectral techniques became an integral part of the organic chemist's thinking, and mechanisms were made the companion of equation memorization. Samuelson'ss introductory economics text had a similar impact in that quantitative concepts were introduced and used immediately. In order to produce a comnarahle change in analvtical chemistry throigh textbooks, radical restrkturing will he required with the adoption of a new attitude toward the teaching of analytical chemistry. An author of a textbook of the new generation should concentrate on the broad, imoortant fvature.; in a unified presentation. A clear, integrated vicw is necessary at first wtth fine dt.t;~ilikft for more specialized study, especially in such suhjects as spectroscopymd chromatography. A new text should include material to familiarize students with the problem solving approach to analytical chemistry similar to Siggia'sQarlier text, "An Introduction to Modern Organic Analysis." Texts should introduce solved and unsolved problems which require the student to take a broad view of analysis. These problems could serve as an introduction to the literature and could helo to disnel the student's idea that a given prohlem can be solved in only one way. Examples might be uroduced hv a cooperative effort of industrial and academic chemists. The continuing development of modern instrumentation and its increasing complexity make it essential that procedures for calibration and performance checks he incorporated in current textbooks as the modern counterparts of balance and volumetric glassware calihration. A new text must help to make students aware of the interdisciplinary nature of analytical chemistry. Biochemical, organic, and geochemical examples might he utilized in the treatment of such areas as solubility product or pH. Laboratory experiments should seek to have students employ a wide range of tools to solve prohlems. Other touics to be included in a new analvtical text are proper met hods fur wmplv preparation and &rage, updated %tatisticalmethods reflecting thv u a . d hand.held cnlculntors. and theoretical and practical methods for assessing reagent
a
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Some traditimal matt:rial will have to he deleted. Treatments of rirrations and reagcnts muld he generaliled and ihortcned. Equilihria could bealsotreaiml hroadlyand with fewer examples. It is clear that no one text can do the whole job we suggest. Indeed, several stages may he required. New texts face two main harriers. First, publishers must he willing to invest in new ideas. Second, academic people must he willing to give
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Kolthoff, I. M., and Sarldell, E. B., "Textbook of Quantitative Inorganic Analysis," MacMillan Co., New York, 1936. Laitinen, H. A., "Chemical Analysis-An Advanced Teat and Reference." MeGraw-Hill. New York. 1960. ~eiile;, C. N., and sawyer, D., "~xperimentsfor Instrumental Methods," McGraw-Hill,New York, 1961. Roberts, J. D., and Caserio, M. C., "Basic Principles of Organic Chemistry," W. A. Benjamin, New York, 1964. 5Samuelson, P. A., "Economics." McGraw-Hill, New York. 1948. fi Siggia, S., and Stalten, H., "An Introduction to Modern Organic Analysis," Interscience, New York, 19.56.
