mm.
finding the hard-to-find Λ common analytical problem is measuring minute amounts of a compound in a mixline. Ordinary methods of analysis frequently cannot be used because the sought compound is present in such a low concentration or because other substances are present which interfere. Ordinary isotope dilution tech niques* may be impractical because the compound cannot be obtained in radio active form, or because the isolation step is too difficult. For such tough problems the radioisotopic derivative method** is ideal. The chemist simply converts the sought substance into * See Nuclear-Chicago Technical Bulletin No. 1. ** We have prepared a technical description of pro cedures used in the radioisotopic derivative method as applied in quantitative analysis and will be glad to send you a copy. Ask for Technical Bulletin No. 3.
1 . Form a radioactive de rivative of the substance by adding an easily ob tained radioactive reagent to the mixture.
2. Add some non-radio active derivative, chemi cally identical with the desired derivative.
For most radioisotope applications, only a minimum of nuclear instrumen t a t i o n is n e e d e d . Here standard Nuclear-Chicago instruments have been assembled to illustrate the simple, inexpensive equipment required to measure beta and gamma radiation. Complete nuclear laboratories for radioactive sample measurements can be purchased for less than $3,000.
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ANALYTICAL CHEMISTRY
is a job for radioisotopes a radioactive derivative by reaction with a radioactive reagent which either can be purchased or made readily from commercially available radioactive compounds. A relatively large amount of the same derivative, but «0«-radioactive, is added as carrier and a pure sample is isolated. The carrier greatly simplifies the problem of isolating the derivative. Radioactivity in the isolated sample is compared with the radioactivity in the original radioactive reagent. A simple calculation then yields the amount of sought compound in the original sample. Accurate results are possible where even less than 1 microgram of the sought substance is present. The radioisotopic derivative method has been used in clinical analysis for such problems as the measurement of histamine in animal tissues and the adrenal hormones in
3. Isolate the desired derivative. A completely pure state is not required, provided the impurities are not radioactive, and the degree of purity can be assayed by some ordinary means.
blood. It is equally applicable in industrial problems where the amount of a substance in a mixture must be determined. The amount of radioactivity needed is generally so small that no red tape or special precautions are necessary. •
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Designing and manufacturing high quality, dependable instruments for measuring radioactivity has been our business at Nuclear-Chicago for more than twelve years. We are a leading source for Research Quality Radioactive Reagents, too. From a single instrument to a complete radioisotope laboratory, we can offer you the finest and most practical equipment for your needs. We would be pleased to have you consult us on equipment needed for a progressive program in this field.
4. Measure the radioactivity in the isolated sample and compare with the radioactivity of original reagent.
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nuclear-chicago
CORPORATION
251 WiST ERIE STREET · CHICAGO 10. ILLINOIS Circle No. 67 on Readers' Service Card VOL. 3 1 , NO. 2, FEBRUARY 1959
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