V O L U M E 19, NO. 9
640 frequency plots. The “SBS analyses” by chemical methods, cited in text and legends of plots, were performed by Shuford Schuhmann. LITERATURE CITED
( 1 ) Natl. Bur. Standards, Misc. P u b . M177 (1947). (2) Natl. Bur. Standards, Research Papers 625 (1933) ; 661 (1934) ; 715 (1934); 962 (1937); 1113 (1938); 1396 (1941). (3)Ibid., 1175 (1939).
(4) I b i d . , 1382 (1941). (5) Shepherd, Martin, ANAL. cHEbr.9 19;77 (1947) (6) Shepherd, Martin, Bur. Standards J . Research, 2, 1145 (1929); Research Paper 75. (7) Shepherd, Martin, J . Research N a t l . Bur. Standards, 36, 313 (1946) ; Research P a p e r 1704. ( 8 ) Shepherd, Martin, J. Research iyatl. Bur. Standards, 38, 19 (1947) ; Research Paper 1759. (9) Shepherd, Martin, J . Research N a t l . Bur. Standards, 38, 491 (1947); Research Paper 1789.
A New Approach to Analytical Chemistry As Taught at Louisiana State University A. R. CHOPPIN, ARTHUR L. LEROSEN, AND PHILIP W. WEST Coates Chemical Laboratories, Louisiana State University, Baton Rouge, La. The paper describes the efforts at Louisiana State University to supplement and extend classical methods and introduce students to the new physical approaches to the field of analytical chemistry.
I
N ORDER to solve any chemical research problem, suitable analytical methods must be available. The nature of these available methods determines the scope of chemical studies, while the development of new procedures and techniques precedes the development of a field wherein the methods can be applied; i t follows then that a thorough training in analytical chemistry is needed by every worker in branches of this science. I n addition, specialists in the field of analytical chemistry are needed to pioneer the discovery and development of new techniques. The success of newer instrumental and microchemical methods has brought about far-reaching changes in the field of analytical chemistry. New laboratories have been equipped with wide assortments of iastruments, many of which were research curiosities before the war. The idea that an analytical laboratpry would contain many instruments costing from $1000 to $20,000 each would have been considered fantastic ten years ago. However, since this is the situation now existing, the problem confronting industry is to find qualified analytical chemists capable of exploiting newly developed instruments and extending special techniques for the benefit of research and control groups. Quite properly the sources for such men are the colleges and universities. However, since a training in the “classical” methods of analysis would seem to fall short of present-day requirements, a new approach to this phase of the chemistry curriculum is indicated. The problem of academic training for analytical chemistry has been very well summarized by Hallett ( 1 ) . Training for instrumentation specialists has been discussed by Muller ( 2 ) who points out present deficiencies of colleges in this field. The present paper describes the efforts made a t Louisiana State University to supplement and extend classical methods and introduce students to the new physical approaches of the field. EDUCATIONAL PHILOSOPHY
Discussions of the academic training for analytical chemistry must take into consideration both undergraduate and graduate curricula. Certainly the undergraduate studies must give the student a thorough training in the fundamentals of chemistry, mathematics, and physics. Furthermore, undergraduate work should provide an education as well as a training. Any specialization, then, must come through graduate studies, since four years of undergraduate study provide scarcely enough time for the basic subjects. Graduate work, on the other hand, should
not be narrowed to such an extent that the field of specialty monopolizes the attention of the .student. Overemphasis of the specialty a t any time is a short-sighted policy which must ultimately result in stagnation. In this regard it is important to note that modern methods of analysis require a thorough training in physics and physical chemistry. The close relationship between inorganic and analytical chemistry seems generally to be appreciated, while a majority of chemists appear to have overlooked the fact that orgainic chemistry is equally important, since practically all new analytical reagents are organic compounds. Furthermore, well over 50% of all analyses now run are made on organic substances. The Undergraduate Level. Training in analytical chemistry rightfully begins with the course in “qualitative” analysis. Certainly this course is among the most important as far as its value in the fundamental training of the student is concerned. On the other hand, as generally taught it seems to be misnamed. More properly i t might be termed “systematic inorganic chemistry” or “analytical separations.” Its qualitative analysis aspects stem from antiquity and are so cumbersome that they find little practical application in a busy commercial laboratory. In this department, therefore, identification of chemicals as such is taught in the courses on microchemistry and spectroscopy, while the socalled “qualitative analysis” is.taught with emphasis on inorganic chemistry and analytical separations. Quantitative analysis is generally considered as the course in which manipulative skills are to be developed. While everyone seems to agree to this, some schools have tended to neglect the theoretical aspects of the subject. Quantitative analysis a t Louisiana State University is aimed to give the student both laboratory practice and a fundamental knowledge of the principles involved. The course is unique in that only one semester of the “classical” methods of analysis is taught a t the sophomore level, after which a semester of instrumental methods of analysis is taught a t the junior level. The basic course consists of a balanced selection of fundamental operations along with a thorough study of chemical calculations and pertinent chemical theory. Substitution of instrumental for traditional methods in the second half of the course permits the practice and acquiring of skills and a t the same time introduces the student to methods consistent with modern industrial practice. Instrumental methods of analysis deal with the application of physical methods to the analysis
SEPTEMBER 1947 of chemical compounds and not to the designing of such instruments themselves. Logically, the operations1 characteristics, basic design, and funct,ioning of integral parts of each instrument, are studied, but it is felt that the field of instrument' design is so highly specialized that it should be considered as a separate and distinct branch. Inclusion of microchemistry as an undergraduate (and graduate) course seems necessary if a balanced program in chemical analysis is to be presented. Certainly, few would argue that practical qualitative analysis is not important, and little doubt, can exist that microchemical methods are the most satisfactory for such investigations. Still speaking from the qualitative analysis standpoint, it is desirable and practicable to include in such a course both polarized light microscopy,and ordinary light microscopy in addition to spot test methods and general microchemical techniques. Lectures on microchemistry can be limited to the theory and applications of complex ions and organic reagents, provided a simplified procedure for polarized light microscopy such as described by West (3) is used. Quantitative microanalysis should ordinarily be offered a t the graduate level. Graduate Study. Graduate study in analytical chemist'ry requires a high degree of specialization. However, it cannot be overlooked that physical chemical principles are involved and t.hat in many instances the difference between a physical chemist and an analytical chemist is merely a difference in attitudes. Likewise, many analyses and much of the development of instrumental methods represent the work of physicists. One of the most significant advances in all analytical chemistry has been the development of organic reagents for inorganic analysis. In light of these facts then, we cannot say that a special course in advanced polarography or chromatography is more important than a course in applied electronics or an extra course in advanced organic chemistry. The graduate program a t Louisana State Univeqsity, therefore, has been designed to survey the modern methods of analysis and, in addition, supplement training in the fundamentals of allied fields. Graduate students entering from schools not having microchemistry or instrumental methods of analysis are expected to register for a t least one of these courses. The next course ordinarily taken is a lecture course in advanced analytical chemistry which is intended to correlate various principles important to analytical chemistry and provide a background for future specialization; all graduate students must ordinarily take this course, regardless of field of specialization. The usefulness of spectroscopic methods is so weil established that is is inconceivable that graduate work in analytical chemistry would be complete without training in these techniques. Most of the principles of qualit,ative and quantitative emission spectroscopy can be adequately covered in a one-semester course, but it is necessary that sufficient equipment be available and individual instruction provided, if the analytical aspects are to be covered within so short a time. A one-semest.ercourse in spectrophotometry can be made to cover the essential laboratory techniques, but if the theoretical possibilities are to be extracted from such data, a complementary course or courses in physical-organic chemistry and/or modern physics covering an introduction to quantum mechanics with emphasis on spectroscopic applications should be included in the curriculum. Although spectrophotometry covering the visual and ultraviolet regions of the spectrum is sufficient to familiarize the student with the general techniques of the method, some work in the infrared should be included if possible. R-ithout question, individual comprehensive courses could profitably be offered in such fields as chemical microscopy, spot tests, organic reagents, chromatography, polarography, electrometric titrations, x-ray diffraction, quantitative microanalysis, colorimetry, automatic instrumental control, etc. Obviously, however, such a list of courses could not be supported, even if instructors were available to teach them: .4 partial ansxer to
641 the problein of offering such a selection of courses is teaching general courses and then permitting those students needing specified courses to take them on an individual basis, such studies being on an informal basis with .the student furnishing the initiative and the department furnishing guidance, counseling, and necessary facilities. Such a system is currently in operation with satisfactory results. A final consideration, but one of extreme importance, is the general curriculum of which analytical chemistry is a part. To begin with, chemistry a t Louisiana State University is a department in the College of Chemistry and Physics. As a consequence, very close cooperation exists among the chemistry, physics, and mathematics departments. Most of the chemistry majors have minors in physics. Besides a year of general physics, all undergraduate students are required to take courses in electricity and magnetism. In addition to traditional courses in physical and organic chemistry, all chemistry majors are required to take a course in qualitative organic chemistry, and practically all majors are required to take a t least one advanced course each in physical chemistry and organic chemistry. A total of 142 credit hours is required for graduation. Master's degree candidates majoring in analytical chemistry take, in addition to the courses in their field of speciality, an average of about two advanced courses each in physical and organic chemist,ry plus one or two courses in physics. Doctorate requirements total slightly over twice those required for the master's degree. Of particular interest in regard to physics courses is applied electronics which is taught with the chemist's needs in mind. The course in x-ray is also recommended for the analytical students. BASIC COURSES
The course in qualitative analysis follows the course in general inorganic chemistry. I t consists of three hours of lecture and six hours of laboratory for an 18-week semester. Lectures are devoted mainly to discussions of chemical equilibria, including oxidation-reduction equilibria. Atomic structure is reviewed and the arrangement of electrons in subgroups is discussed in relation to periodic arrangement and chemical properties. Laboratory work includes the semimicroanal sis of mixtures of cations, and a systematic analysis of anions. gpot tests for the anions are studied as separate experiments. Additional exercises are also included on chromatographic separations (inorganic ions), fractional crystallization, and the preparations of certain inorganic substances considered to be of interest. Quantitative analysis, stressing classical methods, is taught as a one-semester course of three hours of lecture and six hours of laboratory each week. Lectures are devoted to the development of chemical principles as applied to analytical chemistry. Lecture time is also used for discussions of laboratory methods and for appropriate demonstrations of techniques. Special emphasis is given chemical calculations. An auxiliary text is used for this work and the use of titers in titrimetric analyses is taught, The relationship between titers, molarities, and normalities is shown and all students are expected to be able to use the various methods of calculation interchangeably. Because the amount of time allotted to traditional quantitative methods is much less than is customary, particluar attention has been given the choice, order of presentation, and method of teaching the laboratory work. Students are not permitted to work during spare time but instead are required to work under close supervision during the scheduled laboratory periods. A major faculty member is responsible for and is present during each period in every laboratory section. Graduate assistants, in turn, are responsible for designated groups within the section and are required to teach the students to whom they are assigned. The determinations listed in Table I are performed. The determinations are run in the order listed with the exception of the colorimetry and pH exercises, which are performed in available time during the course of the other determinations. A course in instrumental and industrial methods of analysis replaces the usual second-semester of classical uantitive analysis and is required of all chemistrv majors in the Coflege of Chemistry
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642
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V O L U M E 19, NO. 9
and Physics. The course consists of six hours of laboratory and one hour of lecture and is normally taken in the junior year. Spectrophotometry and colorimetry are studied; a transmittancy curve is run with a spectrophotometer and the data are studied. From the transmittancy curve, proper .filters are selected and suitable procedures chosen for use in the colorimetric analysis of the substance being investigated. Both single-cell and doublecell types of filter photometers are studied. Electrometric methods of analysis include electrodeposition, conductometric and potentiometric titrations, and polarography. Particular attention is paid to the applications of polarography to organic and inorganic analyses. Careful measurements of halfwave potentials, diffusion coefficients, and diffusion current constants are made and quantitative analyses are performed, employing methods based on the use of diffusion current const,ants, internal standards, and diffusion current versus concentration working curves. Other methods studied include volumet'ric (gas) analysis, chromatographic separations (with subsequent spectrophotometric study), calorimetry, and turbidimetry as time permits.
Table I. Determiriatioris ii t Quaiititative Analysis Determination $&ate'
Method Gravimetric (precipitation a s RaS04)
Chlorido
1itrimetric (RIohr)
Soda nsh
Titrimetric (gravimetric standardieatton of HCI, indirert standardization of NaOH)
Braes
Gravimetria
Tin Lend
(Weighed as i3n0 (Weighed as PbS&
Copper
(Weighed a s CuSCN)
Zinc
(Weighed a s S-hydroxyquinolate) Titrimetric (ZimmermanReinhardt)
Iron
Copper
Titrimetric (iodometry)
Colorimetry Iron Chromate
Colorimetric (Standard series) (Balanced column)
PH
(Fixed s t s n d 8 r d s electrometric methods are also used)
Remarks t h e student a general orientation. lllustrates many common techniques Illustration of precipitation reactions i n titriiuetric analysis and direct titration methods Illustrates neutralization methods in titrimetric analysis slid use of back-titrations, Gravimetric standardization of HCI introduces a t o o often overlooked method of standardization a s well as teaches principles involved in gravniinietric chloride (and silver) determinations Impresees student with value of proper filtering, washing. Introduces schematic methods of analysis Introduces use of filter aids Provides special solubility problenis. Introduces use of fritteducibles a n d nf drvinn
Gives
Emission Spectroscopy. This course consists of one hour of lecture and six hours of laboratory per week. Special outside work is encouraged. Enrollment is limited to graduate students. Lecture offers a general survey of the fundamental theories of atomic spectra with an aim of correlating specialized courses in atomic physics and quantum theory with the problems of the spectroscopist. Laboratory work covers instrumentation with special emphasis on adjustment and calibration, use of standards, preparation of reference plates, and analytical techniques (both qualitative and quantitative). The use of measuring devices, photography, and densitometric methods is stressed. Spectrophotometry, a companion course to emission spectroscopy. Spectrophotometry applied to the ultraviolet, infrared, and visible partions of the spectrum is studied, from the standpoint of both analytical application and use in structural studies. Advanced analytical chemistry, consisting of three hours per week of lecture and demonstration, is taught a t the graduate level. This course consists of discussions of the underlying principles, instrumentation, fundamental techniques, ranges of application, and typical applications of various instrumental methods. Advanced topics are discussed in the fields of complex ions, organic reagents, schematic analysis, and chromatography. Throughout the course special emphasis is placed on the factors affecting the precision and Bccuracy of the various methods considered. Water Analysis. This course is offered a t the graduate-undergraduate level and consists of one hour of lecture and six hours of laboratory per week. The lecture is devoted to the interpretation of analyses. The laboratory work deals with the complete mineral analysis of water and sanitary chemical and boiler water analyses. Advanced Analytical Chemistry Laboratory. The course consists of six hours per week of special laboratory work, limited to selected students. This course serves to extend an individual field of study beyond that possible in the courses in microchemistry or instrumental and industrial methods of analysis. The work may be of semiresearch type. Analytical Chemistry Seminar. Seminars on current advances in analytical chemistry. Ordinarily only a single development will'be considered per semester. Analytical Techniques in Biochemistry. Special analytical techniques applying t,o biochemical problems are taught in the Department of Agricultural and Biochemistry.
CONCLUSIONS Application of redox reactions to titrimetric analysis. Many theoretical principles are involved such a s catalysis, effect of complex ion formation on equilibria, redox potentials, etc. Exaiiiple of a very iniporLantand vervatile nnalytical method Example of use of Nessler tubes Use of Duboscq colorimeter is introduced generally important determination. Eixed standard comparators, universal indicator papers, and electronic pH I I I P I ~ T S a r e used
Mas!
Microanalysis is required of majors in industrial chemistry and elected by most of the other chemistry majors. I t consists of dix hours of laboratory and one hour of lecture per week for a semester. Additional lecture time is taken from laboratory time when needed. Lectures are devoted to studies of complex ions and their application to analytical problems and to studies of organic reagents as applied to inorganic analysis. Laboratory work includes a study of ordinary light microscopy, polarized light microscopy, and general microtechnique. 'l'he work in polarized light microscopy deals mainly with crushed samples of inorganic substances. However, some time is devoted to recrystallized samples and to organic materials. Spot tests are studied from the standpoints of theory of reactions, theory of interferences, and practical application. A few preliminary cxercises are made studying the effect of foreign substances, temperature, and'concentration changes on crystal habit, after which ordinary light microscopy is used for confirmatory checking. Lxcrcises are included to introduce such microchemical techniques as distillation, sublimation, centrifugation, filtration, micro boil111:. point determinations, etc. ih
ADVANCED COURSES
Acadeinic training in analytical chemistry must be made to conpresent needs of industry. I n general, bhis means that ihe use of instrumental methods of analysis must be taught. Kqually important is the teaching of various microchemical techtiiques which would include the closely allied fields of complex ions and organic reagents. Where possible, special operations such as chromatographic separations should be presented. Such a program must be combined with a thorough foundation in the fundamentals of chemistry, physics, and mathematics. A t the master's and doctorate levels specialization in analytical rhcnhtry, more than in other fields, should include advanced i'ourses in physics (particularly optics and electronics), organic chemistry, and physical chemistry. With the emphasis on 'instrumental and microchemical methods iitiiilytical chemistry becomes an expense item and 89 such prew i t s a number of administrative problems. College authorities I ti general will have to be made to realize that budgets in this divi&ii must be greatly increased. Additions to the faculty will be required in many schools, and the day is past when any graduate chemist can be considered as good enough to teach analytical chemistry. Unfortunately, men having the required training are aliriost impossible to locate, and there is little hope that the situntiiin \vi11 change within the next two or three years. ~ I X I I I with
LITERATURE CITED
(1) Hallett, L. T., IND.ENG.CHEM.,ANAL.ED., 17, 747-8 (1945). (2) MIilller, R.H., I b i d . , 19, No. 1, 24A (1947). (3) West, P. W.. Chemist Analyst, 34, 76-81 (1945); 35, 4-8, 26-35 (1946).
