The activation cross-section is 0.53 barns.
If 100 μg of sodium is irradiated for 1 day in a flux of 5.10^12 neutrons cm–^2 s–^1 , what will its activity be
when it has been removed from the reactor and transferred to a laboratory 3 hours' journey time away?
(6) A mixture is being assayed by radioisotope dilution analysis. 10 mg of the labelled analyte (0.51
μCi mg–^1 ) was added. 1.5 mg of the pure analyte was separated and its specific activity measured and
found to be 0.042 μCi mg–^1. What was the amount of analyte in the original sample?
(7) In a radioimmunoassay procedure, 1 pmol of labelled analyte was added to the sample. Antiserum
equivalent to 75 pmol of analyte was then added, and after incubation the bound and free fractions
separated by precipitation with ammonium sulphate solution. The activity ratio, bound: free, was
measured to be 2.88. Calculate the number of moles of analyte in the original sample.
Further Reading
Anon, Sampling and Measurement of Radionucleides in the Environment, HMSO, 1989.
Chapman, D. I., 'Radioimmunoassay', Chemistry in Britain, 15, No. 9, 439, 1979.
Knoll, G. F., Radiation Detection and Measurement (2nd edn), Wiley, New York, 1989.
McKay, H. C., Principles of Radiochemistry, Butterworth, London, 1971.
Malcolme-Lawes, D. J., Introduction to Radiochemistry, Macmillan, London, 1979.
Pasternak, C. A. (ed.), Radioimmunoassay in Clinical Biochemistry, Heyden, London, 1975.
Salmon, L., Instrumental Neutron Activation Analysis in Environmental Studies of Trace Elements,
AERE-R 7859, HMSO, 1975.