Determination of tissue calcium by nondestructive neutron activation analysis.

A method is described for measuring the concentration of calcium in arterial tissue by neutron activation analysis. The principal advantage is that the method is nondestructive and is ideal for analytical situations in which multiple biochemical measurements are required on a few-milligram sample. Application of the method is illustrated here by a study of aortic calcium metabolism in pigeons and monkeys being used as animal models in experimental atherosclerosis studies. The determination is made on irradiated dry fat-free tissue by using 4Ca (T’/2, 8.8 mm) to measure calcium. The interference of fl5 with the measurement is insignificant. Neutron activation data from one set of tissues were compared with data obtained by atomic absorption spectrophotometry in the same tissues. Good relative agreement was found, although results by atomic absorption were slightly systematically higher than those by neutron activation. Reasons for this are discussed.