analytical chemistry courses for chemistry majors

7
ome MY TOPIC is a general one: ana- lytical chemistry as part of the education of chemists. This topic is of interest today-,beyond the nor- mal reevaluation and rerision that should occur in the teaching of any discipline, because some chemists are questioning whether analysis has any place in academic chemistry and many others see only a minor role for it in comparison with the past. I must admit that I have sorne- what limited experience in the teaching of analytical chemistry. In my five years at Seton Hall I have had the opportunity to teach both graduate and undergraduate courses in analytical chemistry. I have taught the basic courses taken by all chemistry majors at both levels and have been able to make changes in these courses and ob- serve the results. I have concluded that analytical chemistry as presently taught, and as presented in its textbooks, does not reflect the true state or nature of the field. hIy discussion today will try to focus on the essential as- pects of analytical chemistry, for I believe it does have a contribution to chemical education if its real principles are considered. To present my conclusions, this paper has been organized into three parts: first, the reasons for the current low standing of analytical Course S for Chemistry Majors ROLAND F. HIRSCH Chemistry Department, Seton Hall University, South Orange, N. J. 07079 chemistry in academic circles, in ternis of the wrong premises which we as analytical chemists have adopted as the bases for our courses : secondly, my views of what the fundamental objectives of ana- lytical chemistry courses should be, and, finally, the outline of a basic course in modern analytical priii- ciples. These reinarks are intended to refer to a junior,’senior level un- dergraduate course for chemistry majors, but there vi11 be iniplica- tions for the basic graduate-level course as well. It is not my inten- tion to infer anything about the specialized courses in analytical chemistry. I must also admit that what I hare to say does not give a balanced picture of the situation. Each vieTT- point has its supporters. and though I may not give the others their due because of limitations of time, I can conceive of valid reasons for disagreeing with what I have to say. What is Wrong? It is, first of all, a matter of def- initions. We can define analytical chemistry as the study of materials to determine their coniposition, usually in chemical, occasionally in physical, terms. Vhat then does one teach as “analytical chem- istry?” Well, analytical chemists do certain things in their work. They use certain principles in de- signing their methodologies. These principles are built on the basic laws and theories of chemistry and re- lated fields. It is my belief that in analytical chemistry courses, too much emphasis is placed on --what analytical chemists do -a specific methodology, namely interpretation of spectra -those principles which can be presented in a rigorous manner Let me now explain my objections to each of these in turn. Why shouldn’t analytical chem- istry courses for all cheniistry stu- dents emphasize “what analytical cheinists do?” Why isn’t it appro- priate to deyote most of the arail- able lecture time to describing the techniques and methods of our field, and why isn’t it sufficient to use the laboratory to train the students in the skills me use as analytical chemists today? Kell, perhaps the most important objection, as far as I am concerned, is that this is not teaching the fu- ture in lyhich our students will be \Torking. but rather the past and present. Looking back 20 years, just half a professional lifetime ago, can we say that what analytical chemists did then corresponds to what they are doing today? To be sure. some training for the immedi- 42A a ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970

Upload: roland-f

Post on 07-Feb-2017

217 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Analytical chemistry courses for chemistry majors

ome

MY TOPIC is a general one: ana- lytical chemistry as part of the

education of chemists. This topic is of interest today-, beyond the nor- mal reevaluation and rerision that should occur in the teaching of any discipline, because some chemists are questioning whether analysis has any place in academic chemistry and many others see only a minor role for it in comparison with the past.

I must admit tha t I have sorne- what limited experience in the teaching of analytical chemistry. In my five years a t Seton Hall I have had the opportunity to teach both graduate and undergraduate courses in analytical chemistry. I have taught the basic courses taken by all chemistry majors a t both levels and have been able to make changes in these courses and ob- serve the results.

I have concluded tha t analytical chemistry as presently taught, and as presented in its textbooks, does not reflect the true state or nature of the field. hIy discussion today will t ry to focus on the essential as- pects of analytical chemistry, for I believe it does have a contribution to chemical education if its real principles are considered.

To present my conclusions, this paper has been organized into three parts: first, the reasons for the current low standing of analytical

Course S

for Chemistry Majors

ROLAND F. HIRSCH Chemistry Department, Seton Hall University, South Orange, N. J . 07079

chemistry in academic circles, in ternis of the wrong premises which we as analytical chemists have adopted as the bases for our courses : secondly, my views of what the fundamental objectives of ana- lytical chemistry courses should be, and, finally, the outline of a basic course in modern analytical priii- ciples. These reinarks are intended to refer to a junior,’senior level un- dergraduate course for chemistry majors, but there vi11 be iniplica- tions for the basic graduate-level course as well. It is not my inten- tion to infer anything about the specialized courses in analytical chemistry.

I must also admit that what I hare to say does not give a balanced picture of the situation. Each vieTT- point has its supporters. and though I may not give the others their due because of limitations of time, I can conceive of valid reasons for disagreeing with what I have to say.

What is Wrong?

It is, first of all, a matter of def- initions. We can define analytical chemistry as the study of materials to determine their coniposition, usually in chemical, occasionally in physical, terms. V h a t then does one teach as “analytical chem- istry?” Well, analytical chemists do certain things in their work.

They use certain principles in de- signing their methodologies. These principles are built on the basic laws and theories of chemistry and re- lated fields. It is my belief that in analytical chemistry courses, too much emphasis is placed on

--what analytical chemists do -a specific methodology, namely

interpretation of spectra -those principles which can be

presented in a rigorous manner

Let me now explain my objections to each of these in turn.

Why shouldn’t analytical chem- istry courses for all cheniistry stu- dents emphasize “what analytical cheinists do?” Why isn’t it appro- priate to deyote most of the arail- able lecture time to describing the techniques and methods of our field, and why isn’t it sufficient to use the laboratory to train the students in the skills me use as analytical chemists today?

Kel l , perhaps the most important objection, as far as I am concerned, is that this is not teaching the fu- ture in lyhich our students will be \Torking. but rather the past and present. Looking back 20 years, just half a professional lifetime ago, can we say that what analytical chemists did then corresponds to what they are doing today? To be sure. some training for the immedi-

42A a ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970

Page 2: Analytical chemistry courses for chemistry majors

Special ReDort

ate future is necessary, but remem- ber that we are not training the future analytical chemists alone, but all types of chemists.

The second objection I have is that what analytical chemists do represents an almost bewildering variety of methods and techniques applied to a tremendous range of types of samples. There isn’t enough time in a college course to cover all aspects of methodology and applications or even a signifi- cant fraction of them, Further- more, the methods shouldn’t be learned as such anyway, for most of them will be quickly forgotten and can be easily looked up if necessary.

This is not to say tha t “what analytical chemists do” should be excluded from the basic analytical chemistry courses. Techniques will be covered to some extent, es- pecially in the laboratory. Meth- ods and applications should be used throughout the course as examples, carefully chosen to illustrate prin- ciples. Also, the students should be thoroughly acquainted with the sources of reliable methods, such as the AST?vf, APHA. the Treatise on Analytical Chemistry, and the im- portant journals.

Lately, courses dealing primarily in the interpretation of the spectra of organic conipounds have become popular. Many institutions offer courses of this type in conjunction with organic and biochemistry courses, usually a t the sophomore level. There is nothing wrong with this type of course-provided it does not represent the main or the only exposure of the chemistry ma- jor to analytical chemistry. It is my feeling that this kind of course is going to serve as an excuse for eliminating the independent ana- lytical chemistry course from those required of all chemistry majors a t many institutions.

The fact is that the interpreta- tion of spectra type of course misses many key principles of analytical chemistry. It is presented early in the curriculum and has a very limited goal-to teach students how to use an admittedly valuable tool. Being tied to the organic chemistry course, i t cannot include a balanced presentation of analytical chem-

istry, even if a few chapters and experiments on titrations and chromatography are thrown in.

Another danger I see is that the interpretation of spectra of or- ganic compounds is something tha t many nonanalytical chemists can do better than most analytical chemists, because it is a tool that they as organic or inorganic chem- ists make use of constantly regard- less of what their specialty may be. To teach interpretation of spectra best, a t most colleges and univer- sities, it therefore should not be the responsibility of an analytical chemist, but rather of someone else who probably isn’t that familiar with current thinking in analytical chemistry. Therefore, if it is con- ceded that this kind of course is all that every chemistry student need see of analytical chemistry, then the other types of chemists will get the impression that the real anaytical chemist is superfluous since they can teach this better than he can.

This is. I feel, a real danger. Academic chemists in general may lose sight of what of analytical chemistry is really fundamental to all chemistry. There must be a dis- tinctive purpose to academic an- alytical chemistry if i t is to fluorish -indeed, to survive-in colleges and universities.

The analytical chemistry course based on a rigorous development of a limited number of principles is a tradition carried over, in my view, from the earliest days of quantita- t i re chemistry, when close attention to exactness was necessary for ad- vances to occur in the science. At one time the weight and yolume re- lationships were the only important chemical laws or generalizations, and they were therefore the most essential part of a chemist’s train- ing.

Looking a t the currently arail- able analytical chemistry texts, I believe that a disproportionately large amount of space is devoted to gravimetric and rolumetric analy- ses, usually with but a few chapters on other aspects of the subject added on toward the end of the book. IYow I will agree that the pedagogic value of precision drill in

lecture and laboratory is undeni- able, but is it time well spent, con- sidered in light of the overall nature of analytical chemistry? Is it healthy for our discipline to offer upperclass, sophisticated chemistry majors a whole semester consisting of a mixture of principles and ideas which were developed at least 30 years ago, as being the most signifi- cant ideas they can learn from us for their future work?

The fact is that many if not most analytical problems today are, and tomorrow will be, of a low-precision, ball-park answer, rather than a high-precision type. In clinical analysis, for instance, it is not a question of finding to the nearest tenth of a percent relative the glu- cose or calcium or albumin content of a patient’s blood. not even to the nearest 1 %.

Furthermore, many of the most useful analytical principles resist precise quantitation. Even acid- base equilibrium calculations are meaningless beyond two significant figures (maybe even only one sig- nificant figure is justified) in prac- tical cases because of activity ef- fects. Putting it another way, we don’t have enough control over our environment-the analytical sys- tem-to calculate very many useful things with good precision.

Therefore, let’s not emphasize precise calculations and methods (volumetric and gravimetric) in our courses. The students will be in- troduced to these concepts in the general chemistry course, where they are naturally a part of the de- velopment of atomic and molecular theory. The details of the ad- vanced calculations and methods can be found in reference books and handbooks. The results, say of a complex p H calculation, are best found anyway by experimental measurement, such as by using a p H meter.

What Should Be Done?

Having described what I feel is wrong with the teaching of analyti- cal chemistry today, I would like now to offer a prescription for re- storing the vitality of our field as an academic subject. First I will discuss my list of the most impor-

ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970 43A

Page 3: Analytical chemistry courses for chemistry majors

Suecia! ReDort

tant principles of analytical chein- istry; then I xi11 present an outline for a course which covers them.

I beliere that each of the ideas to be enumerated is essential in the education of a cheniist-any kind of chemist. It is niy view, furthermore, that each of these ideas is best presented in the con- text of the an a ly t i c a 1 ch em is t ry course. In other n-ords, it is through these ideas and concepts that I believe x e as analytical chemists can have an essential role in chemical education.

Let me carry this point a little further. Organic and inorganic and biochemists are limited in the types of chemicals and reactions they have to treat and by the theories that are popular today and hence “must be covered.” Physical cheni- ists today emphasize the niathe- matical formalisms so that they can keep up Iyith what their peers are doing. General chemistry courses. if they are general, are taught at a point a t which most students have limited kiion.ledge of chemistry.

I beliere that the analytical chemist has an opportunity not open to the teachers of the other courses in chemistry. It is an op- portunity t o be a generalist, to get to the heart of things chemical, unencumbered by any of the bur- dens just alloted, perhaps unfairly, to the others.

I recently came across an article that impressed me very much in this regard. I t is called “Strong Inference,’’ by J. R. Platt , and it appeared in Science ill 1964 ( 1 ) . Every chemist, surely every an- alytical chemist, should read and ponder what Plat t has to say about the kind of reasoning mhich leads quickly to important conclusions through the choice of the key ex- periments. We can teach our sub- ject in a way that will encourage sound reasoning and intuition, rather than the learning of the for- malisms, details. theories. and niatliematics which are unnecessary to understanding.

Fundamentals of Analytical Chemistry

The first fundamental of analyti- cal chemistry I will call the concept of a signal. There are two types of

signals, analog and digital, and we should develop an understanding of the characteristics of each. Here I might note that there is some con- fusion betveen the nature of the signal and of the readout, as is evidenced by the appearence of so- called digital p H meters. I n anal- ysis, the signal must be defined in relation t o two other factors, the background and the noise, and here also I feel tha t the distinction is not aln-ays made clear in analytical courses. The concept of limit of detection is also part of the idea of a signal.

Closely allied with these con- cepts are the ideas of accuracy and precision, particuIarly the statisti- cal basis for handling experiniental data. I n this regard, I think i t is unfortunate that less than half of the currently available analytical texts distinguish bettveen the stan- dard deviation of a method ithat is, of a single result 1 and the standard deviation of the mean, even though most books do define confidence limits, usually as t.s/.\/z> rather than t . s , . The square root law s , ,~ = s I.\/; is such an important concept in discussing precision of analyses that it should be brought out in analytical chemistry courses right from the start. By the \yay, it has been said that the iiuniber of good scientists is also proportional to the square root of the total num- ber of scientists (2) . An impor- tant point regarding precision is that something is wrong if the ex- perimental precision is much better than that predicted by propagation of errors, as e ell as the more ob- vious fault in the reverse case. The use of statistical tools as aids to coimmon sense should be stressed in the analytical course.

The second fundamental princi- ple of analytical chemistry is tha t of experimental design. It is true that this is implicit in the discus- sion of organic synthesis, for ex- ample, but the analytical chemistry course is the place where it is de- veloped best in more general terms. There are t v o aspects to experi- mental design we should cover. First there is the strategj- of re- search and method development, a

kind of orerall design to original Iyork. This can be taught with ref- erence to the many instructire anecdotes in the book by Beveridge, “The Art of Scientific Investiga- tion” 13), which avoids a dry recita- tion of the stages of the so-called scientific method. A more specific example tha t I use in discussing experiment design is the Simplex method of optimization of condi- Lions. The article on this topic by Long ( 4 ) is very helpful.

The other kind of experiment de- sign we need to concern ourselves with might better be called method design. Here I refer to the tactics that are employed to be sure that a procedure will actually work when applied to real samples. One should discuss the various types of stan- dardization and perhaps also the use of control charts to check for faulty behavior of a method.

L ’

The third group of fundaniental concepts of analytical chemistry comes under the heading of instru- ment design. Here the discussion should center on the electronic, op- tical, and mechanical components and operations d i i c h can be used to ( a , generate a result, and (b) extract this inforniation from the accompanj-ing noise.

Some understanding of electronic circuitry and optics is necessary, but I believe a modular approach to instrumentation should be used as much as possible ( 6 ) . Opera- tional amplifiers, for example, can bc discussed in this fashion. The tdl i i iques of signal-to-noise ratio enhancement, such as modulation and time-averaging, should be de- veloped as concepts (6) .

Xcxt on my list are the principles of the phenomena of nature which can be quaiitified and hence vhich can be used for analysis. Any property which is descriptive of a chemical system-which aids in specifying a particular system-is appropriately discussed in the ana- lytical course. The treatment should be qualitative for the most part , with a minimum amount of theory and derivation$. The em- phasis should be on an understand- ing of v h a t is going on and how it might be useful in analysis-in

4 4 A e ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970

Page 4: Analytical chemistry courses for chemistry majors
Page 5: Analytical chemistry courses for chemistry majors

Special Report

other words, a practical approach. The theoretical aspect should in the main be presented in the form of useful generalizations such as the Xernst and van Deeniter equations -namely, the theories that really work. Frank ( 7 ) recently noted with regard to the structure of water, “after many years of specu- lating about what water might be like in order that i t display cer- tain properties, we can now begin to ask what water must be like if cer- tain pieces of data are , . . re- liable.” K e in analytical chemistry should be sure tha t we are teach- ing the latter type of theory or model.

I particularly emphasize the con- ditional conception of equilibria as developed by Ringbom (8). From the point of view of analytical methods, the idea of side reaction coefficients is a most important con- cept. All kinds of equilibria can be presented using this approach. The arithmetical similarities among the different equilibrium systems, homogeneous and heterogeneous, can be brought out in this way, avoiding misunderstandings and al- lon-ing more time to be spent on the actual chemistry.

I place the ideas of stoichiometry and quantitative relationships last on my list of fundamentals of ana- lytical chemistry not because they are least important. but for the reasons discussed earlier: They are already introduced in general cheni- istry courses and they have been o.\-erst-orked in analytical courses.

Before presenting the outline of a course which tries to follow these “guidelines,” I would like to make one final generalization. I think it very important that the analytical course emphasize the interrelation- ships and similarities betvi-een rar i - ous phenomena. I just mentioned this as an approach to discussing equilibria; let me no\y give a few other examples of how this can be clone. One good case is that of the steady state. This principle ap- pears over and over in the analyti- cal course, such as in discussing secular, transient, and activation equilibria in nuclear chemistry, chain reactions involving enzymes

and other catalysts, precipitation from homogeneous solution, and stopped-flow measurements. If a student can understand the kinetics in one of these cases he will have much less trouble Understanding the others if the conceptual similarities are pointed out to him. LikeJTise the electrical plasmas involved in arc and spark spectroscopy, radio- isotope decay detectors, and sev- eral gas chromatography detectors are based on similar phenomena. The fact tha t diffusion coefficients increase with temperature has an effect-not the same alst-ays-on both line widths in atomic spectros- copy and peak widths in chroma- t ography.

A Course Outline for Analytical Chemistry

M y course assumes tha t the stu- dents are juniors or seniors, with a good general chemistry course and some background in organic cheni- istry, but no additional physical or inorganic chemistry is necessary as preparation. Probably it would re- quire two semesters to cover all this material, h single semester would be sufficient if the main goal were to introduce the students to the subject of analytical chemistry with the expectation that they will later go out and learn on their own whatever details they need to know in their work.

The first section of the course is devoted to the general features of experimentation-types of errors, statistical tools, experiment design, standardization, presentation of re- sults in the form of tables, graphs and equations, and sampling. There it-ould follow a r e v i m of quantitative concept,s,* volumetric calculations. and equilibria, if nec- essary.

The second section of the course is devoted to equilibrium principles. Perhaps this should come later in the course, after a discussion of instrumentation, but the laboratory <tarts out with wet chemistry and separations so equilibria come early in the lectures. I emphasize again the importance Qf applying the conditional equilibrium con- stant approach to all types of equilibria. Solutions are discussed

first, v i t h a section on titrations in which the elements of instru- mental techniques are brought in in connection with the development of end-point detection methods. EDTA titrations are discussed in some detail because of their practi- cal utility, as well as Kasl Fischer titrations and other types of iodim- etry, and functional group analysis by titration. I adniit to a some- what personal choice of examples here.

Konaqueous and molten salt equilibria come next, followed by all types of heterogeneous equi- libria. Kext I treat flame and electrical plasma equilibria, m-ith frequent mention of applications of the principles to problems in spec- trometry. Finally, nuclear reac- tions are discussed from the thermo- dynamic viewpoint. The impor- tance of the niass difference in a nuclear reaction is emphasized.

The third section of my course is on kinetic principles in analyti- cal chemistry. It begins with a dis- cussion of nuclear reactions with the exact decay and activation equations being explained. Since these can be verified in the lab with little dificulty, they are a good start toward the discussion of kinetics. The next portions of the course are devoted to chemical kinetics, al- ways from the viewpoint of what can be done with these phenomena and not what theories can be in- vented to explain them. Diffusional phenomena are developed, since thcy will figure prominently in the later treatment of chromatography. Convection, mixing, and sedimenta- tion are also covered. The treat- ment of solution reaction kinetics includes a review of organic and redox reactions useful in analysis, followed by a discussion of co- ordination chain reactions. Here the concepts of a catalyst and an inhibitor can be explained using chemical species with simple struc- tures, which makes it easier for the qtudents to understand enzyme re- actions, vhich come next. At least half an hour, perhaps a whole lec- ture, should be devoted to exploring the possibilities of enzyme-con- trolled reactions, especially if no biochemistry course is offered to the Ttudents. Of course, examples

4 6 A 0 ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970

Page 6: Analytical chemistry courses for chemistry majors

You don’t have to recalibrate it t o change flow rates, or after clean- ing, or for use after a long idle period. You don’t have t o replace peristaltic tubing or worry about corrosion of metal parts. The new ISCO Model 310 Metering Pump has a Teflon diaphragm driven by a solid state servo mechanism. Exact f low rates are read directly from dials on the face of the pump without referring to calibration tables. Accuracy and reproduc- ibil i tyare maintained a t flow rates from 1.5 to 2,500 ml/hr at pres- sures to 50 psi. All parts con- t a c t i n g t h e pumped l i qu id a re cons t ruc ted o f Te f lon , Kel-F, glass, or similar chemically resis- tant materials.

Wr i te fo r b rochure M P 3 1 fo r complete details.

4 7 0 0 SUPERIOR LINCOLN, NEBRASKA 6 8 5 0 4 PHONE (402) 434 -0231 CABLE: ISCOLAB LINCOLN

Circle No. 76 on Readers’ ServiLe Card

Special Report

of methods are brought in, such as those based on differential reac- tion rates. Finally, heterogeneous kinetics are treated, with most of the attention to precipitation and electrode reactions.

The fourth main division of my course is on the principles of in- strumental techniques and instru- mentation. I will say little about this section because I hare few in- novations to offer. It should be emphasized tha t I do not spend time on spectral interpretation- this is covered by the organic cheni- istry courses-but rather emphasize how the instruments work, sources of error, and so on. The instru- mentation section will include some basic electronics if the lack of back- ground of the students requires it.

The final section of my course is devoted to separatiolls. Some ele- mentary techniques are covered first, such as extraction, precipita- tion, and distillation/volatiliza- tion, with examples iiicluding the Kjeldahl and Pregl methods. Next comes a discussion of chromatog- raphy. After a brief iiitroductioll t o the types of chromatography, the theory is developed. M y treat- ment is a condensation of the first three chapters of Giddings’ book (9 ) with emphasis on how each aspect of the theory relates to the operating conditions and results in one kind of chromatography or another. The techniques of liquid and gas chromatography are then discussed further as such and finally there is a section on separa- tions based on kinetics, including electrophoresis and dialysis.

The Laboratory

The laboratory in aiialytical cheniistry should not contain repeti- tious determinations. Each exer- cise should have the purpose of il- lustrating a principle, a technique, and, if possible, an application as !yell, and there should be a mini- mum of duplication of purposes. I won’t t ry to list everything that we do in our lab-or tha t I would like to see done-but just some of the things I feel are most important. It hasn’t proved possible yet to come up with a really ideal group of experiments illustrating all-im-

MP-1027 Chart Recorder 10‘’ potentiometric strip chart recorder with 6 switch-selected speeds and all solid-state electronics. 7 calibrated full scale ranges: 10, 20, 50,100,200, 500 and 1000mv. Variable range permits full scale io be set anywhere from 10mv to lv . Tuned twin-tee reject .Filter prevents any response to line frequency hum in the input signal. Chart can be manually advanced or reversed. Chart speeds : 2 , 1 , 0.5, 0,4, 0.2, or 0.1 in/min. Other sets of speeds available. $542.

BOX 322 DANVILLE, CALIF. 94526 Cirsle NP. 96 on Readers’ Service Gird

Potentiostat/Regulated Power Supply The MP-1026 is an all silicon solid-state unit. 50w operational amplifier with programming selected by mode switch. Voltage ranges from -10 to -f 1Ov. Current ranges from - 5 to .L 5amps. Anodic or cathodic potentials can be controlled from -5 to + 5v. As an operational amplifier the unit has open loop gain of 100,000. Rise time is faster than lv/,u,sec. Can be operated as constant voltage source, constant current source, potentiostat, or operational amplifier. For general laboratory work. $445.

Mc N I BOX 322 DANVILLE, CALIF. 94526

Circle No. 97 on Readers Service Card

ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970 e 4 7 A

Page 7: Analytical chemistry courses for chemistry majors

Special Report

portant principles ; more develop- ment of effective analytical chem- istry experiments is necessary, I be- lieve.

We start with a short group of volumetric determinations : a chloride using the Faj an’s indicator to check the student’s precision, a nonaqueous acid-base titration which ties in with the lecture dis- cussion of this topic, and EDTA titrations of calcium in CaC03 un- knowns and in dried milk. The procedure in the latter is an old one ( I O ) , hyhich, however, is very effective in showing a multistage separation procedure that is clear- cut, quick, and reliable. I just wish I could get some powdered milk unknowns with distinctly different calcium contents.

I n the second group of experi- ments, the students separate and determine a lanthanide-thorium- uranium mixture by anion exchange on a sulfate resin-again something which is being deyeloped in the Iecture. GIucose is determined using the enyzme-catalyzed method. The students determine the effect of pH on the polarography of an or- ganic compound and choose the op- timum pH for quantitative analysis for the substance (a different one for each student preserves the novelty of what might be repetitious and dull if all were getting the same data on the same compound). A glc column is made and tested. The students have used gc in the organic course, hence this type of experiment in the analytical course. Each group of students uses a dif- ferent type of stationary phase so that in the end interest is generated in comparing the properties of dif- f erent columns,

Finally in the first semester we have a group of experiments in which the student is more or less on his own as far as the amount of instructions he is giyen. One ex- periment is a straightforward quali- tative-quantitative analysis of an organic unknown. The nmr and mass spectra are run for the stu- dent, while he or she obtains ir, uv, and gc data himself. The second experiment in this group is an atomic absorption determination of the trace metals in ores and alloys

taken from our stock assembled some 20 years ago and no longer used as unknowns for the major constituents. The students each get six or seven samples of varied com- position (iron, zinc, nickel, chro- mium ores, steel, brass, bronze). They must find a method of dis- sol-cring each sample, prepare a set of standards, and determine the six elements on our chromium-to- copper multielement lamp. The final outcome is interesting to ana- lyze, since we give out three or four portions from each sample, and can therefore compare results between students and even for the same stu- dent doing duplicates without knowing it.

The final exercise is a miniature research project which requires a minimum of equipment and chemi- cals. The student is given a mix- ture of compounds of three metals. The identity of the metals is known to him. H e must devise a method for determining the first metal in the presence of the other two by some kind of EDTA-type titration using masking and/or separations. He finds a possible procedure in the literature or perhaps works one out himself from literature data (8). He tests his procedure on a known, revises the procedure if necessary -sometimes discarding i t com- pletely and starting out fresh with a new one-and usually makes an attempt a t the unknown within the time limit of four 4-hr laboratory sessions. A report is required in journal format, in which the stu- dent describes and discusses his work. An important point is that while each student has a different combination of metals, they are all using the same kind of chemistry. This seems to encourage discussion and generates enthusiasm even on the part of the students who had lacked interest otherwise in the lab- ora tory work.

The second semester of the lab- oratory is devoted primarily to in- strumentation. I have not been in charge of this part of the course, and hence my comments on i t will he brief. The properties of elec- tronic circuitry, especially opera- tional amplifiers, are investigated. Applications to various techniques

are then brought in as illustrations. An experiment which is instructive and interesting has the students study the effect of changing various parameters (slit width, gain, scan speed) on infrared spectra.

Conclusions

I believe that a case can be made for analytical chemistry as an in- dependent part of the undergradu- ate chemistry curriculum. To do this, however, the present goals and contents of the basic analytical courses must be changed. A pic- ture of analytical chemistry must be presented to chemistry students which emphasizes our subject’s gen- eral contributions. The specific de- tails should be saved for students majoring or specializing in analyti- cal chemistry.

I have outlined the analytical principles I feel are most impor- tant. Although some of these con- cepts are relatively sophisticated they can be mastered-even by the average student-if presented properly. The student gains an un- derstanding of the phenomena of chemistry which he could not get outside the analytical chemistry course. I n short. I believe our students will be clearer thinking chemists and more productive ex- perimental chemists for having had a modern analytical chemistry course.

References

(1) J. R. Platt, Science 146,347 (1964). (2) D. J. deSolla Price, qroted in S.

Klaw, “The Xew Brahmins,” Apollo Eds., New York,,N. Y., p 266, 1969.

(3) VI;. I. B. Beveridge, “The Art of Sci- entific Investigation,” Modern Library, New York, N. Y., undated.

(4) D. E. Long, Anal. Chim. Acta 46, 193 (1969).

(5) G. W. Ewing, “Analytical Instrumen- tation-A Laboratory Guide for Chem- ical Analysis,” Plenum Press, New York, N. Y., 1966.

(6) T. Coor, J . Chem. Ed. 45, A533, 9583 (1968).

(7) H. S. Frank, Science 169,635 (1970). ( 8 ) A. Ringbom, “Complexation in Ana-

lytical Chemistry,” Inter~cience-X~iley, New Pork, N. Y., 1963.

(9) J. C. Giddings, “Dynamics of Chro- matography,” Part I, Marcel Dekker, Inc., New York, N. Y., 1965.

(10) R. Jenness, ANAL. CHEM. 25, 966 (1953).

4 8 A ANALYTICAL CHEMISTRY, VOL. 42, NO. 14, DECEMBER 1970