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 opera- tion. 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 sym- posium deal effectively with the many problems asso- ciated with the glassware and chemicals which are normally supplied by the average chemistry depart- ment stockroom. Furthermore, many of the older types of instruments-including, for example, tensiom- e ter~, 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 instru- ment is to perform-let us say refractive index measure- ment-is known from some specific requirement. Gen- erally 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 undergradu- ate, must be considered. On the other hand, if we de- cide that the instrument is to be used for research pur- poses a t the graduate and staff level only, then its pre- cision and versatility for use in more general applica- tions must be considered.

The cost factor indicated in Table 1 is probably the most important consideration involved in the procure-

TABLE 1 Instrument Classification

OPERATION

I EDUCATION- -RESEARCH

K PRECISION a COrnLEXITY

I

JULY, 1950 389

ment of instruments for university work. In general the precision which we wish to obtain in a given opera- tion 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 iu- strument 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 acquisi- tion of a given instrument. In fact, the several factors listed in Table 1 governing the acquisition of instru- ments 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 pur- poses, 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 consid- ered 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 refractom- eter, one Dipping refractometer, and one Fischer re- fractometer, rather than two Abbe refractometers. In this way three instruments, differing in type of con- struction, cost, complexity, and precision will he avail- able.

Frequently, after all of the factors enumerated in Tahle 1 have been considered, it is discovered that two commercial instruments of similar type and cost are available. The college purchaser under these condi- tioneis faced with several new problems in making his selection. If there is insufficient difference in con- struction 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 instru- ments of rugged construction. These manufacturers should be considered favorably, particularly if the fac-

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 hohe from which the instrument is to be purchased is another problem to be faced by the purchaser. I t seems advisable to pur- chase 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 in- structor 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 impos- sible to construct in a college or in outside shops many precision optical instruments, it is advisable from many standpoints to assemble or construct certain instru- ments. This is particularly true of electrical instru- ments 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 con- ditions. 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 elernen- tary 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 interdepend- ent factors which differ with each college situation. A tentative order of procurement, preferred by the writer for an undergraduate course in instrumentation, is pre- sented 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 avail- able 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 pro- curement of the remainder. Occasionally more com-

390 JOURNAL OF CHEMICAL EDUCATION

TABLE 2 Order of Procurement

Undergraduate level Prima~y Eztension

1. Analytical Balance 1. Semimiom, Micro 2. Spectroscope 2. Spectrometer, Spectrograph 3. Potentiometer 3. Recording Types 4. Conductivity Bridge 4. Electronic Bridges 5. Electrodeposition 5. Controlled Potential 6. pH Meter 6. Recording Type 7. Refractometer 7. Abbe, Precision 8. Calorimeter 8. Turbidirneter, Nephelometer 9. Gas Analyzer 9. Thermal, Vacuum

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 ob- t.ained. I t is inadvisable to operate an undergraduate- level instrumentation course with advanced-type instru-

~ -

ments. The writer's preference for the order of procurement

of instruments for an advanced undergraduate or gradu- ate level course is given in Table 3. Here again, the

Or&. of Procurement

9. Mass Spec&omet& ' 9. Isotope Ratio * 10. Electronic Devices 10. Dielectric I<, VTVM, etc.

* Not available at Lehigh.

list of 10 primary instruments is amplified by extensions for advanced-type instruction or research. I t is to be understood that the order of procurement is not man- datory and may be changed to meet an individual in- structor's desires or conditions prevailing at a given university.

BUDGET ESTIMATES

Assuming that an analytical balance is available, along with the normal supply of chemicals and glass- ware, an elementary course in undergraduate instru- mentation may be started with a nucleus of 10 primary instruments costing approximately $1500, as shown in Table 4. Single extensions of these instruments now in use a t Lehigh University raised the cost of the initial outlay to approximately $5700. Duplicates of most of the primary instruments, as well as duplicates of some of the extensions, have raised our instrument inventory a t Lehigh for undergraduate instruction to approxi- mately $17,000.

In setting up an elementary course of instrumenta-

tion at least $500 should be set aside each year, approxi- mately $150 of which is to be used for servicing and reconditioning, while the remainder should be allowed to accumulate for the acquisition of extensions. The cost of setting up and maintaining primary instruments and their extensions for use in research at the graduate level will vary widely according to the requirements of the institution. At Lehigh, a t least one of the instru- ments listed in Table 3, with the exception of those marked *, is available. Our total inventory for this type of instruction is $34,000.

TABLE 4 Cost of Instruments (Underoraduate)

Minimum Eztension

Spectroscope $110 $800 Potentiometer 125 575 Conductivity Bridge 150 225 Electrodeoosition 150 500 DH Mete; 150 575 Refractometer Colorimeter Gm Andv~er

HOUSING AND RESPONSIBILITY

The problem of housing and responsibility for in- struments of the type discussed in this paper is most vexing to the university instructor. Ordinary stock- room 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 in- terest. A staff member of instructor rank whose major interest is instrumentation is given full charge and responsibility for the housing, maintenance, care, and service for instruments used in the undergraduate course. These instruments are set up in two rooms and available for use at all times by other staff members and graduate students.

Instruments which have been acquired for graduate instruction and research should be housed in several rooms, set aside exclusively for this purpose. They should be set up for use at all times for graduate students in other divisions of the department. Responsibility for the care and maintenance of these instruments should lie with an experienced staff member of profes- sorial rank. At Lehigh, for example, it is advanta- geous to include instruments such as the mass spectrom- eter, the recording infrared spectrometer, and a spec- trometer with its flame photometer attachments under the direct care and supervision of the writer. Electro- metric titration equipment, polarography, and X-ray equipment are housed in other rooms under the super- vision of another interested instructor.

The problem of servicing and maintaining these newer type instruments has not been satisfactorily solved up to this time. Unless the instructor in charge of instru- mentation is capable of making minor repairs on both

JULY, 1950 391

optical and electronic equipment, considerable difficulty will be encountered in maintaining high operating efficiency. The purchase of instruments from a single supply house with a good service department, as pre- viously mentioned, is of paramount importance. Shop facilities in a chemistry department should be extended to include instrument servicing and, if possible, instru- ment construction.

The problem of duplication of primary instruments

colleges where four complete spectrophotometer assem- blies have been purchased, one each by the physical, inorganic, organic, and analytical divisions. Rarely, if ever, are all four of these instruments in use a t any one time. Proper organization, involving the complete responsibility of one staff member for instrument pur- chase and scheduling, mould minimize duplication of this type and would make available funds for the pur- chase of additional equipment. . .

availabie in a chemistry departme& can'frecpently be REFERENCES solved by compromise and planning. A single set of

(1) Grm, T. R. P., "Optical Methods of Chemical Analysis," primary instruments will suffice for the instruction of MeGraw-Hill Book Co., Inc., New York, 1942. approximately 15 students in each course. Duplica- (2) The Laborato~y, 17, NO. 2, 58059, 1947, Fisher Scientific CO., tion of certain of the primary instruments and the 711 Forbes Street, Pittsburgh, Pennsylvania. extensions will increase the student load providing the (3) WEISSBERGER, A., "Physical Methods of ~nalysis ," Vol.

demand and staff are available. Through proper or- 11, Interscience Publishers, Ino., New York, 1949. (4) WILLARD, H. H., L. L. MERITT, AND J. A. DEAN, "Instru-

ganization of instrument purchase unnecessary duplica- mental Methods of Analysis," D. Van Nostrand Co., Inc., tion may he avoided. The writer knows of several New York, 1948.

+