George M. Pickral
Virginia Military Institute Lexington. 24450
I
I
Analytical Chemistry for Premedical Students
I
Views of college teachers and medical school teachers
The purpose of this project was to study the course content of one-semester analvtical chemistrv courses with suecia1 attention to the needs of premedicaiand health science students. Opinions of both college teachers and medical school teachers on what topics should he included in analytical chemistry were obtained. Survey of College Teachers
In order to determine what topics are currently being taught in analytical chemistry a questionnaire was sent to the "Professor of Analytical Chemistry" a t 214 four-year colleges. The questionnaire was similar to the one used by Donald E. Jones and David F. Roswell in studying the course content of General Chemistry ( I ) . I t consisted of 112 topics selected from the table of contents of analytical chemistry textbooks. The topics were more specific than Presented at the 27th SoutheastlSlst Southwest Regional meeting o f the ACS in Memphis, Tennessee, October 29-31, 1975. Table 1.
T o p i c s as R a t e d by
L?Medicai Teacher Revision I. G E N E R A L
Ill. SEPARATIONS
IV. V O L U M E T R I C A. Acid-Base Equilibria iV. V O L U M E T R I C 6. P r e c i p i t a t i o n and c o m p l e x Formation IV. V O L U M E T R I C C. O x i d a t i o n Reduction
V. I N S T R U M E N T A L METHODS
those published by the Analytical Chemistry Suhcommittee of the Curriculum Committee of the Division of Chemical Education (2). The respondent was asked to rate the topics on a scale from A through D where A was defined as "essential," B as "desirable," C as "include if time permits," and D as "omit." There was an excellent response with 121 of the 214 colleges (56.5%) returning the completed questionnaire. Using the A equal 4.0 system a grade was calculated for each topic. The topics were arranged in three catergories according to the grade received: very important (grade 3.0-4.0), important (grade 2.5-2.9), and less important (grade 1.0-2.4). The results are shown in Table 1. Survey of Medical School Teachers
A second questionnaire was prepared and sent to the Dean of 67 of the 114 medical schools, 38 of the 58 dental schools, and all 9 of the osteopathic colleges of medicine in the United States. The medical and dental schools sur-
College Teachers W i t h Revisions by M e d i c a l School Teachers
VERY IMPORTANT (College Teachers)
3.0-4.0 A c c u r a c y a n d precision Significant figurer Errors ~ a tb echnique Safety Standardization Moiarity Preparation o f r o i u t i o n r Analysis BacU t i t r a t i o n s Balancing equations Weight percent Equivalent weights Giavimetric
Bufferr w a t e r and p~ H~drolyli6 T i t l a t i o n curves Indicators SOiUbility p r o d u c t E D T A titration Indicators S t a b i i i t v constants ~ l t r a t i a ncurves Nernrt equation Eiectlodel Equivalence p o i n t potential Gaivamc celir T i t r a t i o n curves O H meter G l a r l electrode I o n seiective electrode Ultraviolet a n d visible rpectrophotametry Beer's L a w
Medical Teacher ~evision
IMPORTANT (College Teachers1 2.5-2.9
Medical Teacher Revision
LESS I M P O R T A N T ICollege Teacherrl
1.0-2.4
sampling Sample d i s s o l u t i o n
Literature small computers
Formality weight o f rampie Gmvimetlic factors V o l u m e o f reagent
Specific g r a v i t y Mole fraction Titer M i x t u r e s o f barer M i x t u r e s o f halides
Gas c h r o m a t o g r a p h y Column chromatography
lon-exchange Paper c h r o m a t o g r a p n y Thin-layer c h i a m . Gel c h r o m a t o g r a p h y Electrophoreris Solvent e x t r a c t i o n P n y r ~ o i o g i c a lb u f f e r K j e i d a h l analysis
S t r u c t u r e o f complexes CoDreCiDitation Particle size Ad5olption indicator
Mohr method Voihard m e t h o d Separations SolUblilty Itudies
indicators Feasibility o f t i t r a t i o n KMnO, titration
Iodine method5 ceric titration L i Q U i dj u n c t i o n p o t .
Metallic electroder Electrodepaition i n f r a r e d rpect. Atomic abrorption
Palarography CoulometrY Amperametric titration Flame e m i r l i o n FiuoieScence Phorphorercence K i n e t i c studies Radiocnemirtry Minicomputer Clinical ana1yrir Gar analysis w a t e r analysis A i l anaivsir
0 K e y t o medical teacher revirion: D = downgraded. U = UDgraded, n u m b e r s are oercentages. E x a m p l e : D 20-8 Indicators. 28% downgraded t h e topic-20% t o i m p o r t a n t a n d 8% t o lerr i m o o r t a n t . U 4 3 - 3 3 E i e c t r o o h o r e r i r . 76% u ~ g r a d e dt n e t o p i c - - 4 3 % t o v e r y i m p o r t a n t a n d 3 3 % t o important.
182 / Journal of Chemical Education
veyed were those east of the Mississippi River. The questionnaire was based on the survey of college teachers and designed so that i t would be easy for the medical school teachers to agree or disagree with the college teachers. In addition to the list of topics as arranged in Tahle 1 the questionnaire included questions on courses taken by premedical students, qualitative analysis, gravimetric analysis, method of volumetric calculations, and special courses. Completed questionnaires were returned by 40 of 67 (59.7%) medical schools, 23 of 38 (60.5%) dental schools, and 7 of 9 (77.8%) osteopathic colleges. The overall return was 70 of 114 (61.4%). of the responses came from professors of Eighty biochemistrv. 13% from course coordinators, and 7% from members of'the admission committee. Comparison of Surveys
Analytical Chemistry Topics Tahle 1 shows the list of analytical topics as rated by the chemistry teachers with desirable revisions noted by the medical school teachers. There was good agreement between the two on General topics and topics on Stoichiometry. However, under Separations the medical school teachers felt strongly that all types of chromatography should be upgraded and that gravimetric separations are no longer needed. The medical schools rated electrophoresis as the most important method of separation. This reflects their interest in the separation of moteins and amino acids. Volumetric topics upgraded by the medical schools were the Bronsted Theory, polyprotic acids, physiological huffers, and structure of complexes where a lower rating was preferred for indicators, EDTA titrations, and redox titrations. For Instrumental Methods: flame emission, fluorescence, kinetic studies, radiochemistry, and clinical analysis were advanced in importance and ion selective electrodes, metallic electrodes, and electrodeposition were downgraded. There was a divided opinion on infrared and atomic ahsorption. Many chemistry departments have an advanced course in instrumental analysis which covers many of the methods which they gave a low rating with respect to a basic analvtical course. Also. some instrumentation is prominent in organic chemistry and physical chemistry. A low ratine for a articular instrumental method is with respect to &e hasic analytical course and does not contradict Part I1 of the Second Report of the Analytical Chemistry Subcommittee in which areas of instrumentation are listed Table 2.
Chemistry
Counes Suggested b y Medical Schools Usually T a k e n in College 1%)
Suggested b y Medical Schools
(%I
Analyfical lnrfrumenfal Analysis Biochemirfry Organic ladvancedl Phvrical Chemirtry NO additional chemirrry
3.
T i m e Devoted t o Qualitative Analvrir Colleges tactual)
Time None Less tnan 4 w e e k r
4-6 w e e k r 7-9 W e e k s 10-12 weeks Separate course NO opinion
Chemistry Courses Almost all medical schools require a year of general (inorganic) chemistry and a year of organic chemistry as a minimum for entrance (4). Colleges were asked to indicate additional chemistry courses usually taken by premedical students, and medical schools were asked to indicate the courses which would best prepare their prospective students. The results are shown in Table 2. Analytical chemistry in the colleges is by far the most popular course, but in the opinion of the medical schools it is a poor third following biochemistry and physical chemistry. The premedical students may better he served by an integrated laboratory sequence (5-8). The value of the classical quantitative analysis has declined because most medical schools no longer have a laboratory with the biochemistry course. Qualitative Analysis Table 3 shows that there is good agreement between the colleges and medical schools as to the amount of time that should be devoted to qualitative analysis. All colleges surveyed cover qualitative analysis in the freshman course only. Gravimetric Analysis Because of the time-consumine nature of eravimetric determinations and the availability of faster instrumental methods. drastic reductions have been made in this area of analysis.However, as shown in Tahle 4 both the colleges and medical schools see the need for retaining some experimental work in this area. About half of the colleges which include 1-2 experiments in their program accomplish this work in the freshman year. I t is interesting to note that both the Medical College Admission Test and the American Chemical Society Analytical Examination include questions on basic gravimetric topics such as solubility products, properties of precipitates, and gravimetric factors. On the most recent (1974) ACS examination 10 of the 50 questions were in this area. Volumetric Calculations There has been a recent trend among general chemistry authors and younger analytical chemists to base volumetric calculations on the concept of mole ratios and to omit the concept of equivalents. The survey showed that 29.9% of the college teachers favored mole ratios, 57.7% voted for equivalents, and 12.4%used both methods. Ninety percent of the medical . ~ e o.n l enrefer eauivalents while 10%stated it makes no difference. I t appears that the student is going to have to be e x ~ o s e dto both methods. Aeain the MCAT and ACS examinations expect a thorough k:owledge of equivalents.
.~
~~
~
Special Analytical Courses Ninety-three percent of the colleges surveyed teach the same analytical course to both chemistry majors and premedical students.
Co"r6eB
Table
on which instruction should he included somewhere in the curriculum (3).
I%\
Table
Medical Schools (ruggeefed) 1%)
4. T i m e Devoted t o Gravimetric Analysis Colleges (actual)
Time
(%I
~ e d i c a schools i (suggested) 1%)
~ e c t u r e ronly (no
26.8 13.4
18 18
1-2 experiments More tnan 2 exper-
54.6 5.2
52
iments NO opinion
. ..
6
None lab)
6
Volume 53, Number 3, March 1976
/ 183
T a b l e 5.
In the 21 to 50 enrollment range 28 of 31 schools had one lecture section, 24 of 31 had two lah sections, and 4 of 31 had three lab sections. For larger enrollments the trend was lecture sections of 50 to 100 students and lab sections from 15 on up to 75 students.
Analvtical Chernistrv E n r o l l m e n t
umber of S t u d e n f s
Percent
T a b l e 6. C l o c k Hourr of L e c t u r e and L a b o r a t o r y per Week far A n a l v t i c a l C h e m i r t r v Leclure~Lab C l o c k Hours
Percent
2-6 3-6 3-4 2-4
25.8 22.4 12.4
3-3
9.0
10.1
Lecture~Lab C l o c k Hours
2-8 2-3 3-8 Other Combinationr (all d i f f e r e n t )
Percent
4.5 4.5 3.4 7.9
Five colleges have adopted a four-semester sequence of integrated lah which include general, organic, physical, and analvtical chemistw. Five colleges teach classical analytical chemistry in the freshman lab and a semester of instrumental analvsis is required later in the curriculum. There is a divided opinion as to the success of thisscheme (9-10). The medical schools replied 58% "no" and 42% "yes" when asked if premeds should he given a different course geared, for example, to clinical chemistry methods. Both "yes" and "no" repliers commented that the course should he vigorous, demanding, and stress hasic quantitative principles and techniques. "Yes" repliers commented that relevant material is more interesting and easier to learn. Logistics of Analytical Chemistry
Enrollment and Section Size The enrollment of the analvtical chemistrv course is listed in Table 5. In the
