Quantitative Analysis, for Premedical Students ELTON M. BAKER Fresno State College, Fresno, California
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encountered in most quantitative analysis courses, and and a few determinations of organic substances.
HERE appears to be a definite need for a separate . . . course m quantltatwe analysis containing the same general principles of the conventional course but organized in such a manner as to interest the student of medicine. Most colleges offer courses in quantitative analysis to interest the chemist and the chemical engineer without considering the interests of students of other fields. According to a recent article by Van Peurseml 30 per cent of the students enrolled in quantitative analysis were premedical students. Twentynine per cent were chemists and 30 per cent engineers. Saver2proposed changes in the customary laboratory experiments by placing emphasis on the analysis of solutions and volumetric techniques which premedical students needed in their medical course. Special courses are many times criticized as being courses that merely train a student to do a specific laboratory procedure rather than to educate him to apply a principle. This need not be true of the experimental determinations which are chosen to illustrate the basic principles developed. For example, a determination using the iodometric method is considered essential in most courses in quantitative analysis. The chemist may be interested in the analysis of copper ore, while the medical student is probably more interested in the analysis of reducing sugar in urine by the same method. As long as the fundamental principles are the same, a choice of the experiment could be governed by the professional interest of the student. In view of this interest the author has conducted a survey and tabulated data from 45 of the 67 recognized medical schools in the United States who answered his questionnaire. This questionnaire aimed to determine what medical-school authorities thought was the most valuable content for a laboratory course in quantitative analysis for premedical students. The results showed that authorities unanimously agreed on the desirability of a course in quantitative analysis for premedical students. All but one recommended a course in quantitative analysis for such students, and more than half of them thought that premedical students should not be required to take the same course as those majoring in chemistry. This may be due to the desire of medical faculties to have a course which includes illustrative material of medical interest. But the necessity of a knowledge of the same underlying physical-chemical principles, techniques, and attitudes inherent in an application of the scientific method should be stressed. The techniques and determinations which the medical schools - desire are found in Table 1. They are those 'VAN PEURSEM,J. CHEM.EDUC.,21, 252 (1944). S m v m , J. CHEM.Eouc., 7, 365 (1930).
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TABLE 1 D a r e n m r w * ~ ~ oAND ~ s T B C ~ I Q UDESIRABL& BS r~ A Q U A N ~ T A I - AN&LYSIS COURSB POPI PB=UBDIC*L STUD&NIS Dclcminorians
Sulfate Chloride Acid Base Calcium
Iron Phosphate Ammonia (Nessler) Nitrogen (Kjeldahl) Acetone bodieo Reducing sugar Vitamin C Other determinations
Rrsfionsc 24 30 36 36 25 22 22 25 28 13 17 5
Tcrhniqucr Calibrationofpipet Ure of a pipet Calibratiooof a buret Use of meter
a
Response 26 31 25
standard pH
Use of a colarimefer Useofa saecharimeter Use of a balance Use ola spectrometer Use of a refractornetex Use of other insfrunento
26
30 19 9
5 3 9
7
The apparent current interest among chemistry teachers in the use of a standard pH meter and colorimeter is undoubtedly due to a desire for the students to acquire an additional technique. However, i t is obvious that if the student is to make the best use of either instrument, he must know the fundamental principles upon which it is based. With only a few modifications the special course for premedical students may be made to cover the principles found in a conventional course. In practice, the following experimental determinations have proved to be satisfactory. The sulfate can be determined gravimetrically. Most gravimetric techniques are involved in this determination. The chloride may best be determined volnmetrically using one of the adsorption indicators. A solution of almost any weak acid will serve to illustrate the type of acid which a medical student may need to analyze. Experience in further neutralizations may be obtained in an analysis for nitrogen by the Kjeldahl method. Buffer solutions might well be used for pH determinations with indicators or a standard pH meter. Solutions of iron and calcium compounds may be determined by the common method of using either potassium permanganate or ceric sulfate as an oxidizing agent. Reducing sugars may be determined iodometrically by the Shaffer-Hattmann method. The solution of a phosphate is an important determination in which the colorirneter is used. The principles involved in the determinations are fundamental. The determinations themselves are ones that might interest a medical student. In conclusion, a special course in quantitative analysis for premedical students seems desirable. Adherence to the fundamental theory and techniques is imperative. The determinations used as illustrative applications may be those which are of interest to the student of medicine. The quantitative analysis course for premedical students taught by the author has been built upon these three generalizations. 5Ci7
