Most of the current data now available on the determination of calcium, chlorine, magnesium, and sodium in biological materials have been obtained by spectrographic or by calorimetric methods. Neutron activation, the technique whereby a stable isotope is irradiated by neutrons to produce a radioactive nuclide, has also been used for the determination of these elements, but most of these earlier assays involved time-consuming radiochemical separations of the irradiated materials (l-5).
The aim of the present study was to develop a rapid and simple quantitative method for the simultaneous determination of these elements in single bone samples without radiochemical separation. The neutroninduced radionuclides of the elemental species, that is, *Ca (8.8 min), 38C1 (37.3 min) , 27Mg (9.5 min) , and 24Na (15 hr) , are gamma emitting radioisotopes. Each has diverse gamma radiation energies that can be analyzed by means of a gamma ray spectrometer (1,6). No serious problems were experienced in resolving the gamma energies of these species.
The method has been applied routinely to the determination of these