Gilbert E. Janauer, Dorothy 1. Gockel, and Theodore D. Zucconi SUNY at Binghamton B~nghamton,N e w York 13901
A "Self-Sharpening" Separations File for Teaching Separation Methods
T h e choice between either penetrating deeply into subject matter or covering a wide range of interesting topics has to he made in most chemistry courses. This decision seems particularly agonizing in upper level courses on separation methods. A fairly typical course may consist of a thorough treatment of the principles of chromatography with examples from liquid-liquid, ion-exchange, and gel permeation chromatography, together with a few lectures on classical techniques introduced superficially in .earlier courses (precipitation, distillation, and extraction). As a rule, because of time limitations, many important and interesting modern separation methods are never discussed, and a student who wishes to acquire a solid and diversified background in the separations field will have to do extensive outside reading. Unfortunately, students often do not use the literature efficiently. Therefore, to help them discover, absorb, and digest new information the instructor will have t o provide a framework, guidance, incentive, reinforcement, and constant feedback ~ ~ i t hhis i n course. Presented heiore the Division of Chemical Education a t the 162nd National Meeting of the American Chemical Society, Washington, D. C., September 12-17,1971.
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Journal of Chemical Education
While searching for a single mechanism likely to provide all this in a systematic way for a sizeable class the idea of a student-created, gradually improving and growing, "self-sharpening" card file suggested itself to the senior author. It was to be the students' task to start the file, continue to provide new entries, improve existing entries, eliminate duplications, report on new techniques, propose an organization for the file, and to carry through with the indexing, all with a minimum of ''. mstructor interference." Only one third to one half of class time would be spent on conventional lectures, the rest of the time to be spent with student presentations and discussions focused on the contents, organization, and indexing of the file. To acquaint the students rapidly with the separations literature the initial assignment in the course was for each student to prepare a list of general references (monographs) and journals available in the university library which contained "10% or more material directly or indirectly related to separations." A comparison of the products of this assignment in brief discussions was extremely helpful to the class. Assignments of a varying nature were given to promote the acquisition of new entries for the separations
Table 2.
Table 1. Selected Assignments Required During a Graduate Level Course in Separation Methods at SUNY Binghamton 1. The construction of an alphabetical list of all journals which devote, on the average, more than ten percent of their space to separation methods and are available in the libraly. 2. The preparation of asimilar list of loca.lly available books and monogra hs dealing with separation methods by author, title, an$card cstslog number. 3. The selection of fields of interest for making entries to the card file: e.g., destructive separations, electromigration, distillation techniques. 4. A paper on a selected or assigned topic with an outline of the paper made available to all class members two weeks before a "mini-seminar" presentation and class discussion of the material. Topics for thesepapers included the following a) gel permeation chromatography b) gas chromatography c) se~arations through clathrateformation
' ti& methods 1) separationson the basisof interface henomena 5. A critical review of the card file as it stoo$mid-way through the course. 6. A brief critical discussion of a number of assigned file cards, including the revision and improvement of at least one of the cards. 7. A proposal for systematizing and optimizing the use of the file. followed bv resenta at ion of these ideas to the class.
file (see Table 1). The students had to grasp entire areas or concepts and had to boil down to essentials large quantities of material for a 15-min "mini-seminar" presentation. Entries to the file (5 X 8 cards kept in a convenient location of the Science Reading Room) were generated automatically through these papers but students were also allowed and encouraged to make entries on any new separation methods found in the current literature regardless of the field. At mid-semester each student was required to turn in an evaluation and critique of the card file as it stood. Then, the file entries were divided among the class and each student was made responsible for criticizing and improving entries assigned to him. Both assimments and ensuine class discussions led to the emergence of a final format for the separations file. No particular organization or indexing system had been preselected for the file a t its outset so as to ensureunrestrained, organic development toward a truly general system covering the entire field. Thus, the total number of file entries was like Topsy and "just grew," while the final format and contents evolved through an iterative and self-correcting process. Three types of uses were envisioned for this file, and its organization and indexing reflect these proposed uses. (1) A student or teacher might need general information and references on one or more cla~sesof separation methods, such as electromigrations, chelate separations, column chromatography, etc. (2) A chemist or chemical engineer might wish to separate certain specific compounds. He would approach the problem from a consideration of the type of species present, e.g., polar species, ionic species, colloidal species, polymeric species. (3) A separation technique might be sought which would capitalize on differences between particular physical-chemical properties or constants for the species in a mixture, such as differences in their
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A Sample froin the Parameters Used in Indexing Card File Entries
Operational/Mechanistic Parameters hatch operation
oden c d m n packed column gradient convection electromieration
Species Pammeters
ions
inorpanic trace com~onente organic trace eornp6nents colloids polymeric species isotonic s~ecies
Separation Parameters volatility charge size (volume) density isoeleetric point reaction rate diffusion rate
diffusion rates, vapor pressure, solubilities, etc. Considering these uses, three independent categories were selected for indexing: (a) Operational/l\iIechanistic Parameters, referring to the principles involved in either the mechanics or mode of operation; (b) Species Parameters, relating to the nature or type of species to he separated; and (c) Separation Parameters, referring to the physical-chemical properties exploited to produce separation. The use of the category called "Separation Parameters" has contributed-grksatly to the students' understanding of the separations field, since students become aware early that two species can be separated only if they display some significantalbeit small-differences. Differences in 24 such properties were found to be the basis for the more than 70 separation techniques incorporated into the file to this date. Some of the parameters selected to represent the physical-chemical differences which may be utilized to achieve separations are listed in Table 2 along with examples from the other two indexing categories. Some "lateral thinking" h a proved fruitful in conceiving novel separation techniques and in predicting new applications of existing methodology. Each entry to the separations file was typed on a 5 X 8 single-holed library card (Dyna-Slide) and was numerically keyed for indexing by using a differentside of the card for each of the three types of parameters. Ample room for possible future expansion or modification of the indexing system was left on the fourth side of the card. The separations file contains only one entry for each individual method. However, new applications were also entered whenever they illustrated a different principle or a significantly different combination of known principles. Considerable emphasis was placed on a thorough discussion of the physical-chemical basis underlying each separation method. This was found to help the students grasp the essential differencesbetween apparently similar methods within broad areas such as ehrort~:~togmphy or membrnnr srp:~r:~tions.l 1 Further infornlnrion or, the wlsrutions file ir~cluduap: 3 description of the indexing system k i t h examples and a simple computer sorting program will be available from the authors upon request.
Volume 49, Number 7, July 1972
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