Comparative measurements of zinc-70 enrichment in human plasma samples with neutron activation and mass spectrometry.

Radiochemical neutron activation analysis (RNAA) is compared with isotope ratio mass spectrometry (IRMS) for the measurement of 70Zn isotopic enrichment in human plasma following oral administration of the isotope. It is shown that both techniques are suitable for this purpose, although IRMS yields more precise data. Each method, with its advantages and limitations, can be realistically employed to study kinetics of appearance of 70Zn in plasma obtained during human metabolic studies.