INSTRUMENTATION BY RALPH H. MÜLLER
The N-Dimensional Nature of Analytical Chemistry With
T H I S TITLE, we m a k e what we
hope is n o t a n unwarranted extrapolation of the title of a recent p a per, "A Third Dimension in the Teaching of Analytical Chemistry" b y our good friend Professor Sidney Siggia of the University of Massachusetts a t Amherst [J. Chem. Educ, 44, 545 (1967)]. His third dimension is "analytical thinking," something which he says cannot be taught b u t can be fostered a n d encouraged b y exposing the student to real analytical problems. These range from the analysis of commercial products, a t t h e undergraduate level, t o solutions of problems of an analytical nature for other departments of t h e University a t the graduate level. Siggia's approach t o the subject must be read to be appreciated a n d enjoyed. He has attained an extraordinary goal which no one can dispute. T h e courses are popular, are received with enthusiasm b y the students and are respected and encouraged b y his scientific colleagues. The invited Special R e p o r t on U n dergraduate Analytical Chemistry b y Professor James W . Pobinson, here at Louisiana State University, is a bold and persuasive discussion of the current s t a t u s of t h e subject
[ANAL. C H E M . ,
40, 33A (1968)]. I n no uncertain terms, D r . Robinson emphasizes t h e continuing and increasing importance of analytical chemistry b u t also explains w h y m a n y students avoid t h e subject like the plague. H e notes t h a t the subject will not disappear from industry or from the university, b u t t h e academic analytical chemist may. Both authors are actively engaged in research, have wide industrial experience, a n d have brought these talents before their students. They know what modern analytical chemistry is a n d can maintain interest and enthusiasm on the part of their students. When they speak of solving problems, they do n o t mean the endless plugging of numbers into formulas or theorems developed 80 years ago b y Wilhelm Ostwald a t Leipzig or b y Walthor Nernst a t Gôttingen - Circle No. 147 on Readers' Service Card
and Berlin. They refer t o important problems arising in industry a n d academic and institutional research centers. W h a t is still more important is the fact t h a t this approach is appreciated b y the students in related fields and disciplines, because they can see a p plications to their own problems. J i m Robinson has also given a n effective answer to t h e usual plea from t h e small institutions—"we don't have the equipment to teach mass spectrometry, infrared, or N M R . " As he says, " I t is always better to teach these subjects from sheets of spectra than not to teach them a t all." Currently, it is our privilege to have a hand in some of these things a t L.S.U. a t both the graduate a n d undergraduate levels, particularly in instrumental analysis. I t is exciting, b u t also confusing because so many questions arise which, a t times, make one wonder whether the subject can be taught satisfactorily a t all. One thing is certain, there is little room or time for a discussion of instrumentation. Almost any modern technique requires for its adequate description, a knowledge on the p a r t of the student of inorganic, organic, a n d physical chemistry. If t h e student has n o knowledge of physics (the practical variety), he m a y still be able to appreciate a n d possibly use the analytical information b u t n o t have the slightest notion of how it was obtained. ' If, despite statements on prerequisites for the course, one third of the students who show u p have n o t h a d organic chemistry, an a t t e m p t to interpret infrared, mass spectra, or nuclear magnetic resonance patterns for them is a challenge, t o say t h e least. This must be the experience of many others, because m a n y have recommended that analytical chemistry be given as late in the undergraduate's career as possible. Conversely, this has the drawback t h a t , having no analytical chemistry, their comprehension of other chemical subjects will b e hampered and much of what they learn will have t o be taken on faith.
Perhaps, in analysis, as well as other chemical disciplines, we need carefully graded approaches to t h e subject. Much has been said about treatment "in depth." We submit that, in any continuum, there is length, breadth, and depth. A beginning swimmer hopes to conquer t h e first two a n d avoid the third. If the third predominates and he goes down for the third time, he has no further use for the other two. There is, of course, the need for a sensible balance between the three variables. F o r beginners, in analysis, we think the breadth factor is the most important. After all, the customer has a right to see all the merchandise. If the professor has a captive audience (required course), his troubles are over. If the course is an elective, he must change his tactics, convince his audience of the importance of the subject and emphasize its utility and place in the general scheme of things. I n the broad approach, length and depth have to be considered, t h e former being determined b y the available time a n d t h e latter, as in the case of the poor swimmer, somewrhere between mere d a m p ness and total (possibly irreversible) submersion. This approach is particularly important in a first course or in a detailed analytical course for advanced students who do not intend t o major in analytical chemistry. If we do n o t realize t h a t this will be their last formal contact with the subject a n d we fail to acquaint them with t h e vast resources of the subject, by giving undue emphasis to one or t w o aspects, they may well be the very people who later propose that analytical chemistry be abolished in their department or institution. I t has already happened. We predict that some day a most unusual and unconventional book on analytical chemistry will be written. I t will be profusely illustrated with real examples of all analytical techniques. I n brief, condensed form, i t will indicate t h e principle involved, range of applicability, available equip-
VOL. 40, NO. 13, NOVEMBER 1968
·
109 A
New toploading balance is fast, accurate...yet RUGGED! New Torbal ET-1 toploader (160g capacity, 1 mg accuracy) makes accurate weighing easier and more foolproof than ever before. N E W EASE thanks to complete digital display without the use of optical projections or verniers to read, no estimating. NEW EASE because the one piece construction of the exclusive Torsion weighing mechanism has no knife edges to chip, wear or collect dust —hence there's no loss in accuracy. NEW EASE —thanks to the electronic null readout feature, the ET-1 is not affected by sensitivity changes — from temperature or humidity variations or enects ot toreign matter or wear. As long as you can see the null needle move for a 1.0 mg weight change, then a difference of 1.0 mg in weight-reading means 1.0 mg — today, tomorrow, next month, next year. NEW EASE because the ET-l's Torsion mechanism is far less affected by vibration than optical balances. You can use an ET-1 in conditions other balances can't take. NEW EASE thanks to out-of-level accuracy. For minor changes in level of the ET-1, zero point does not change.
WRITE FOR FREE BROCHURE.
T H E T O R S I O N B A L A N C E C O M P A N Y Department A. Main Office and Factory: Clifton, N. J.; Sales Offices: Birmingham, Ala., Chicago, 111.; Richardson, Tex.; San Mateo, Cal.; Pittsburgh, Pa.; Plants and Offices in Montreal, Quebec, London, England and Waterford, Ireland Circle No. 144 on Readers' Service Card
Delmar-Brown2 unit for rapid, automatic microdetermination of unsaturation T h e Del m a r - B r o w n 2 Micro H y d r o Analyzer* is a specialized unit for determ i n i n g u n s a t u r a t i o n of m i c r o a n d ultramicro samples by means of catalytic hydrogénation. Each hydrogénation reaction is carried to completion automatically. As many as five separate determinations can b e completed within an hour. T h e simple, compact unit permits rapid and convenient determination of unsaturation at the 5 χ Ι Ο 5 mole level with an accuracy of ± 1 % . It provides useful results at the 5 χ Ι Ο 6 level. Sodium borohydride is used both for in situ generation of the highly-active catalysts and also as the source of hydrogen for the hydrogénation reaction. Thus, the unit requires n o standard solutions, n o hydrogen cylinders, n o thermostated gas burets, and n o purification trains as required by ordinary microhydrogenation methods. Other Delmar-Brown 2 hydrogénation units are available for synthesis of 1 t o 1,000 grams of material and for analysis t o the 0.0002 mole level. *Patented in U.S. Ask for Delmar Bulletin A-24Write to Coleman Instruments Division of The Perkin-Elmer Corporation, 42 Madison Street, Maywood, Illinois 60153.
PERKIN-ELMER
Circle No. 107 on Readers' Service Card 110 A
·
ANALYTICAL CHEMISTRY
INSTRUMENTATION ment, particular advantages a n d o b vious limitations, precision, accuracy, reliability, comparison with alternative methods and, above all, cost, time involved, and competence required of the operator. References will n o t be exhaustive and t o obscure journals b u t t o carefully selected articles which emphasize t h e proper significance of t h e method. I t m a y come as a surprise, and n o t without interest to note t h a t a criminologist can identify and establish the geographical origin of a dust or soil sample b y simple sedimentation tests and without N M R . T h e " h e a l t h " of a car b a t t e r y is checked with a h y drometer a n d not. b y precipitation of the sulfuric acid as barium sulfate or b y an acid-base titration with a p o tentiometrie a u t o t i t r a t o r . M,ilk is routinely checked, as required b y numerous statutes, with a hydrometer (lactometer) even though elaborate teste, in special cases, require a determination of total solids, b u t t e r fat, enzymes, vitamins and presence or absence of pathogenic organisms. T h e book would remind us, as we have to be told repeatedly, t h a t t h e microscope can yield an amazing amount of information, y e t its possibilities are usually ignored. Frequenth 7 , we are guilty of t h e heresy of telling our students t h a t it is almost impossible to define analytical chemistry and, in making an inquiry, one can't really trust anyone's opinion. (We hasten to a d d t h a t t h a t includes their professor.) Tt all depends upon what business he's in. T h e m a n in petrochemicals h a s a firm answer, t h e important things are infrared, mass spectrometry, a n d N M R period. H e will concede some interest in emission spectroscopy or atomic absorption spectroscopy if h e is having catalyst troubles ( N i a n d V ) . T h e instances could be recited a t great length. I n this respect, the modern physician cann o t afford t o be ignorant of even one aspect of medical science. As a diagnostician, he would be helpless if his courses included bacteriology b u t n o t parisitology. As a good internist, he invariably seeks t h e advice a n d confirmation of a specialist, b u t his true forte is command of an extremely b r o a d spectrum of all aspects of t h e profession. We are thoroughly convinced t h a t instrumental analysis faces one p r o b lem t h a t has been with u s for a long time. Somehow a n d somewhere we have t o find a means for explaining general instrumental principles. Students do n o t come t o us with enough background in practical physics t o u n derstand t h e equipment we already have. How a r e they t o suggest i m provements or new approaches?
