Method for detection of long-lived radioisotopes in small biochemical samples

A method for detection of long-lived radioisotopes in small biochemical samples, comprising:

• a. selecting a biological host in which selected radioisotopes are present at a concentration equal to or less than the concentration in the ambient biosphere,
• b. preparing a long-lived radioisotope-labeled chemical specie,
• c. administering said chemical specie to said biological host in one or more doses that do not cause either significant damage to the host's biological system or a significant increase in radiological exposure to the host over the ambient radiation environment or from natural internal sources of radiation,
• d. allowing dissemination and reaction of said chemical specie with said biological system of said host,
• e. isolating a reacted fraction of a biological substance from said host in a manner sufficient to avoid contamination of the fraction from extraneous sources of the radioisotope,
• f. converting said fraction of biological substance to a solid, inert, non-volatile, thermally conductive inorganic sample which efficiently produces charged ions in an ion source without introduction of significant isotopic fractionation, and
• g. measuring the radioisotope concentration in the inorganic sample using an accelerator mass spectrometer.