JOURNAL OF CHEMICAL EDUCATION
INSTRUMENT PROBLEMS IN A COLLEGE CHEMISTRY DEPARTMENT EARL 1. SERFASS Lehigh University, Bethlehem, Pennsylvania
A sCIEivmnc "instrument" may be defined in a broad sense as any specific contrivance or aid which may be used to carry out any particular physicochemical operation. In accordance with this definition all scientific tools, from test tubes to hydrometers, may he classified as instruments. It is not my purpose to discuss in this paper the problems of procurement, stocking, servicing, etc., of all types of equipment. Other discussions in this symposium deal effectively with the many problems associated with the glassware and chemicals which are normally supplied by the average chemistry department stockroom. Furthermore, many of the older types of instruments-including, for example, tensiome t e r ~ , colorimeters, ovens, and thermostatshave been ~urchased.stocked. inventoried, and serviced in accor&nce with standa*d procedures for many years and present no new problems in chemistry department administration. I propose to consider, therefore, new problems presented by increased use of those optical and electrical instruments which are considered by the instrument engineer to be specific in their operation or application. Problems frequently arise in the procurement of this type of instrument from lack of consideration of one or more interrelated factors. Table 1 consists of a block diagram showing a number of the interrelated factors which should be considered when purchasing a new
instrument. Usually the operation which the instrument is to perform-let us say refractive index measurement-is known from some specific requirement. Generally our first consideration in collegiate work is to determine the application of the device, i. e., are we to use it for strictly educational or research purposes. Should we decide upon educational requirements only, then the level of instruction, graduate or undergraduate, must be considered. On the other hand, if we decide that the instrument is to be used for research purposes a t the graduate and staff level only, then its precision and versatility for use in more general applications must be considered. The cost factor indicated in Table 1 is probably the most important consideration involved in the procureTABLE 1 Instrument Classification OPERATION EDUCATION-
I
-RESEARCH
K PRECISION
a COrnLEXITY
I
JULY, 1950
ment of instruments for university work. In general the precision which we wish to obtain in a given operation will largely govern the cost of the instrument. Furthermore, the cost of an instrument usually is directly proportional to its complexity of construction and operation. Often we find that a certain sum of money will be available for the purchase of instruments. Under these circumstances the cost factor of each iustrument must be considered first, i. e., placed at the top of chart in Table 1. Following the consideration of the aforementioned factors, the university instructor must decide whether it is advantageous to construct the instrument in the school or in outside shops, or to purchase the completed instrument from the manufacturer or supply house. Here again, assembly or direct purchase considerations may he the paramount factors concerning the acquisition of a given instrument. In fact, the several factors listed in Table 1 governing the acquisition of instruments in general are all interrelated, since any one factor may become of primary importance depending upon the specific problem. An example of the use of Table 1 as an aid in the procurement of a specific instrument-let us say a refractometer-may clarify this interrelationship. If the refractometer is to be used for educational purposes, at the lower undergraduate level in analytical chemistry, its precision and cost need be moderate only, and therefore we may limit ourselves to the purchase of a simple Fisher-Jelly student refractometer costing approximately $50. On the other hand, if we should require a higher-precision refractometer for use at the higher undergraduate and graduate levels, a more versatile Abbe, costing $500, will be indicated. If a very versatile, high-precision instmment is required for research purposes, then a Bausch and Lomb precision refractometer costing $1500 must be considered. Less versatile in its general use, but remaining to he considered because of its high sensitivity, is the interferometrr costing $2000 and up. If the consideration of a purchase of refractometry equipment is governed by the availability of $1000, then it may he advisable to purchase one Abbe refractometer, one Dipping refractometer, and one Fischer refractometer, rather than two Abbe refractometers. In this way three instruments, differing in type of construction, cost, complexity, and precision will he available. Frequently, after all of the factors enumerated in Tahle 1have been considered, it is discovered that two commercial instruments of similar type and cost are available. The college purchaser under these conditioneis faced with several new problems in making his selection. If there is insufficient difference in construction and principle of operation to afford a decision between the two instruments, then the manufacturer must be considered. Certain manufacturers have developed a reputation for constructing quality instruments of rugged construction. These manufacturers should be considered favorably, particularly if the fac-
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tors of availability and service are paramount. An Abbe refractometer from a foreign manufacturer is undesirable under the latter considerations. The selection of the supply h o h e from which the instrument is to be purchased is another problem to be faced by the purchaser. I t seems advisable to purchase a large majority of the instruments from a single supplier, particularly if the supply house has developed a reputation for maintaining a large stock of quality products. A supplier should be selected who is capable and willing to give prompt and efficient service in the repair and reconditioning of instruments. The problem of procurement of instruments by the university instructor would be considerably simplified if educational discounts were made available to him through the supplier. In the long run, the supplier would probably bcnefit from this policy, inasmuch as a student would be most likely to purchase after graduation an instrument with which he is familiar. Although it may he impractical and a t times impossible to construct in a college or in outside shops many precision optical instruments, it is advisable from many standpoints to assemble or construct certain instruments. This is particularly true of electrical instruments which may be assembled in the college shops on a "bread board" basis for the undergraduate level of instruction. Electronic amplifiers for electrometric titrations are examples of this type of construction. Student understanding of the principles involved in a given instrument is greatly enhanced under these conditions. A commercial model of the same type of instrument, of the self-contained or "black box" type, may be substituted for advanced instruction after the student has mastered the elementary principles. The low cost of construction of a specialized instrument at a university as compared to a commercial model may be the deciding factor determining the acquisition of a new instrument. The mass spectrometer constructed by the writer a t Lehigh University cost approximately $5000 whereas the installation of a commercial model of the same versatility would have involved the outlay of about $30,000. ORDER OF PROCURFMENT
To set up a course of instrumentation of the elernentary type on the undergraduate level a nucleus of about 10 instruments is required. The order of procurement of these instruments is a function of many interdependent factors which differ with each college situation. A tentative order of procurement, preferred by the writer for an undergraduate course in instrumentation, is presented in Table 2. Ten primary instruments are listed in the order of their procurement. The writer feels that a t least one of these instruments should be available for student use before any of the instruments listed under the extension in Tahle 2 need be obtained. Frequently one or more of the primary instruments are already available, thus tempering the order of procurement of the remainder. Occasionally more com-
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tion at least $500 should be set aside each year, approximately $150 of which is to be used for servicing and reconditioning, while the remainder should be allowed Undergraduate level to accumulate for the acquisition of extensions. The Prima~y Eztension cost of setting up and maintaining primary instruments Analytical Balance 1. Semimiom, Micro Spectroscope 2. Spectrometer, Spectrograph and their extensions for use in research at the graduate Potentiometer 3. Recording Types level will vary widely according to the requirements of Conductivity Bridge 4. Electronic Bridges the institution. At Lehigh, a t least one of the instruElectrodeposition 5. Controlled Potential ments listed in Table 3, with the exception of those pH Meter 6. Recording Type Refractometer 7. Abbe, Precision marked *, is available. Our total inventory for this Calorimeter 8. Turbidirneter, Nephelometer type of instruction is $34,000. Gas Analyzer 9. Thermal, Vacuum TABLE 2 Order of Procurement
1. 2. 3. 4. 5. 6.
7. 8.
9. 10. Microscope
10. Photomicrography
plex type instruments listed in the extension of Table 2 will be found available in a given school despite the fact that their primary counterparts have not been obt.ained. I t is inadvisable to operate an undergraduatelevel instrumentation course with advanced-type instruments. The writer's preference for the order of procurement of instruments for an advanced undergraduate or graduate level course is given in Table 3. Here again, the ~
Or&. of Procurement
TABLE 4 Cost of Instruments (Underoraduate) Spectroscope Potentiometer Conductivity Bridge Electrodeoosition DHMete; Refractometer Colorimeter Gm Andv~er
Minimum $110 125 150 150 150
Eztension
$800 575 225 500 575
HOUSING AND RESPONSIBILITY
The problem of housing and responsibility for instruments of the type discussed in this paper is most vexing to the university instructor. Ordinary stockroom facilities and staff are generally not well suited or competent to take charge of or to service instruments of the type discussed here. A solution to this problem, at which we have arrived, may be of some interest. A staff member of instructor rank whose 9. Mass Spec&omet& ' 9. Isotope Ratio * major interest is instrumentation is given full charge 10. Electronic Devices 10. Dielectric I
