Abstract
A method of the radioactivation analysis based on the quantitative isotope dilution principle was developed for the determination of trace of cadmium.
The experiments about the reaction between cadmium and dithizone were carried out at various conditions and it was shown that the reaction ratio was constant in the solution of 1 N sodium hydroxide containing more than 200 μg of cadmium carrier. It was also shown that the radioactivity of the extract was proportional to the amount of cadmium isotope.
The method has been applied to the determination of cadmium in aluminium and in zinc. After neutron irradiation, a large amount of cadmium carrier was added and separated by the two dithizone extraction steps. The second extraction was carried out with dithizone in a smaller amount than that required to react with cadmium present and the radioactivity of the extract (a) was measured. A cadmium standard (Ms) was treated in exactly the same way as a test sample and the radioactivity (as) was measured. The unknown amount of cadmium (Mx) was calculated from Mx=Ms a/as. 0.3 ppm of cadmium was analyzed in zinc sample.
