Neutron Activation Analysis of Zinc in Biological Samples
Although zinc in biological samples has been determined previously by neutron activation analysis, the methods have been time consuming and involve post irradiation separations with remote control handling. Banks, et al, has developed a procedure involving 28 hours of reactor time and remote control manipulation of a dithizone extraction. Dithizone is used on a cellulose acetate column for the method devised by Pierce, et al. After elution of zinc from the column, quinaldic acid is used to precipitate the zinc for counting. Another procedure for determining zinc is described by Bowen, and he uses various precipitating agents to remove the interfering ions and precipitate the zinc. Other methods for the determination of zinc by neutron activation analysis are given by Hicks. These involve precipitation technics or precipitation in conjunction with ion exchange separations. All procedures must be carried out after irradiation and the required precautionary protective measures must be provided for the chemists. | However, the sensitivity attained by measuring the Zn69m nuclide after the sample has been irradiated at least twelve hours is little better than that achieved by conventional colorimetric methods. For this reason the method developed in this research does not measure the activity of Zn69m, but rather measures the activity of Cu64 or Cu66. Zinc dithizonate is isolated in an organic phase, excess dithizone removed and copper is exchanged for zinc. The copper dithizonate is then irradiated and counted. The concentration of copper will be directly proportional to the initial concentration of zinc.
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