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A RADIOCHEMISTRY LABORATORY COURSE USING AUTHORIZATION-EXEMPT QUANTITIES OF RADIOISOTOPES ROBERT WEST Lehigh University, Bethlehem, Pennsylvania
IN
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RECENT years, many universities have started ambitious laboratory training programs in ~adiochemistry; several such laboratory courses were described in a symposium a t an American Chemical Society meeting in 1949 and later published in THIS JOURNAL.^ However, some colleges and universities may have hesitated to begin such courses because of the possible hazards to students, or the expense of obtaining radioisotopes and equipment, or the rather elaborate precautions and procedures required for authorization by the Atomic Energy Commission as a user of isotopes. This may be particularly true for colleges which do not have active research programs in nuclear or radiochemistry. At Lehigh University a one-semester radiochemistry laboratory course has been specifically designed to acquaint students in several scientific fields with safe and effective procedures for using tracer radioisotopes. A distinctive feature of this course is that only authorization-exempt quantities of radioisotopes are used, thus minimizing hazards and expense as well as eliminating the necessity for AEC authorization. Recent liberalization of regulations governing the shipment of authorization-exempt quantities of isotopes has made their use in such a course a practical possibility. Amounts up to 50 microcuries of certain isotopes are now available without authorization, and more important, the maximum quantity of several different radioisotopes may be shipped together in the same package. At least one supplier2 has taken advantage of the re' J. CHEM.EDUC.,28, 2 ff. (1951).
'Abbott
Laboratories, Radioisotope Division, Oak Ridge,
Tennessee.
VOLUME 34, NO. 1, JANUARY, 1957
vised regulations to offer for sale kits of up to ten different isotopes, selected from those of most general usefulness and interest. The total cost for isotopes for t.he course a t Lehigh, taken by ten students, was less than $25. To limit expenses for equipment, only one counting assembly was used, consisting of a thin-window GeigerMuller tube, a lead counting shield, and a scaler. Other special equipment included an inexpensive survey meter for monitoring, a calibrated radium D standard, a set of micropipets and syringes, tind counting cups and planchets. Aluminum absorbers for determining @particle range and a large steel tray for the working space were constructed in the shop. The ten students included both seniors and graduate students in chemistry, biology, geology, and chemical engineering. All were taking or had taken a lecture course in nuclear a i d radiochemistry. The students worked in pairs carrying out one set of experiments every two weeks. The experiments mere designed for a working time of about three hours, and were written up individually. Since each pair of students should have exclusive use of the counting equipment during the laboratory period, only one pair of students was scheduled to work on any one afternoon. The experiments are listed in the accompanying table. Most of the experiments were taken from the manual by Schweitzer and Whitneya and adapted for low levels of activity. The selection of exoeriments SCHWEITZER, G. K., AND I. B. WHITNEY,"~adio'activeTracer Techniques," D. Van Nostrand Co., Ino., New York, 1949, pp. 92-9, 10&105, 133-41, and 147-9.
Experiments in the Radiochemistry Laboratory Course Week
Ezperiments
Matmials used
Small counting Instruction in safety procedures Use of monitoring equipment, and standards G-M counter and sealer Study of eeometrv. coincidence. and stitisti& in co&ing Calibration of a shipment of Pa Pa, 20 PC Backscattering of B particles from Dil A --
Construction of a Feather analyzer based on Pa* Separation of Th234 and Paaa4from urmiums Determination of half-life and betadecay energy of Pa284 Rate of exchange of I- ion with an organic iodide Half-life of 1'81 Isotope dilution analysis of a chromite solution Measurement of the solubility of SrSO*. mine SJS Beta de&y energy of SS' Identification of an unknown radioisotope by means of @-decay energy and tracer experiments
UOP(NOa)2.6H90, 50 g.
ILJL, 10 PC. Cr", 50 uc
Zn64 Rhea, Cd0, Cads, Na'P, 1-5 pc. each
"BOOTH. A. H.,J. CAEM.EDUC.,28, 144 (1951).
was governed both by nature of the isotopes and by the instruments available to us; other experiments would have been chosen if a y-ray spectrometer or a neutron source for preparing short-lived activites had been
available. Except for counting, all radiochemical work was carried out in a hood resewed for this purpose. The danger of hazards to the students was slight because of the low levels of activity used. Nevertheless, rigid urecautions against contamination and exposure were taught and used in the laboratory, since these safety precautions are an important part of training in the use of radioactive materials. The students were also required to attend a series of training films on radioisotope use.4 The Lehigh radiochemistry laboratory course in its present form may serve to indicate the sort of course that can now be offered to seniors and graduate students with a minimum outlay for instruments and materials. It is to be hoped that the increased availability of authorization-exempt quantities of radioisotopes will also lead to increasing use of these materials in general and physical chemistry laboratory ~ourses.~
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' "The Radioisotope" film series produced by the Army Signal Corps with the technical aassistrtnce of the Atomic Energy Commission. These excellent films have A m y designations PMF 51458 through 5145f, and 5147~. They can be obtained from the Army Central Film Library in the Army area where the borrower resides. LIBBY,W . F., Address to 129th Meeting of The American Chemical Society, April 10, 1956, Chem. Eng. News, 34, 2125 (1956).
JOURNAL OF CHEMICAL EDUCATION
