Trace determination of nickel (and cobalt) in biological reference materials by radiochemical neutron activation analysis

Summary Very few biological reference materials are certified for nickel below 1 mg · kg^–1. Neutron activation analysis was only rarely considered as a possible approach; reported sensitivities were usually not very good, unless preconcentration was applied.In the present work, the relatively high fast neutron flux of our TRIGA reactor was used to induce the ⁵⁸Ni(n, p)⁵⁸Co reaction, and ⁵⁸Co (E =811 keV) was radiochemically separated from other radionuclides by classical anion-exchange chromatography in hydrochloric acid. ⁵⁷Co was added to the irradiated sample before decomposition as a radioisotopic yield monitor. By concentrating the final sample fraction and measurement in a well-type HP Ge detector, Ni concentrations down to the 10-g · kg^–1 level could be determined for samples irradiated for 1 day. ⁶⁰Co, produced by neutron capture on ⁵⁹Co, is also coseparated and quantified from the gamma spectrum, so that both elements Ni and Co are determined. Results are reported for a series of NBS and other biological reference materials in the concentration range 10 g-10 mg · kg^–1. Possibilities for further increases in sensitivity are discussed.

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Spurenbestimmung von Nickel (und Cobalt) in biologischen Referenzmaterialien durch radiochemische Neutronenaktivierungsanalyse