Determination of cobalt in biological materials by RNAA via induced short-lived 60mCo

Abstract

A procedure is described for the determination of cobalt in biological materials, based on post-irradiation separation radiochemical neutron activation analysis (RNAA) using the short-lived induced radionuclide 60mCo. 60mCo has been rarely used as an indicator radionuclide in NAA due to low concentrations usually found in biological materials and due to its short-half life (t1/2=10.5 min). Using a procedure based on dissolution of the irradiated sample, precipitation of Co with sodium diethyldithiocarbamate, extraction of the complexes formed into toluene, purification and counting by gamma spectrometry, Co was determined in biological materials at ng g−1 levels. For evaluation of gamma spectra, the Hypermet-PC and HyperLab 2002 Gamma Spectroscopy systems were used. Differences between these software programs are discussed. The results of the analyzed biological materials (reference materials), together with the identified uncertainty sources, are presented. The RNAA method allows rapid, robust and simple separation of short-lived 60mCo from neutron irradiated biological samples in high and reproducible yield (83%), with adequate sensitivity for routine use, reducing the time necessary for the irradiation, processing and measurement in comparison to classical NAA using 60Co, thus retaining the important advantage of NAA as a blank free technique.