Determination of Trace Amounts of Copper Using the Quantitative Isotope Dilution Method

Abstract

Trace amounts of copper were determined by the quantitative isotope dilution method and the radioactivation analysis based on its principle. A radioisotope of the known specific activity (radioactivity A, carrier content M) is added to the unknown amount M_x, and m which is less than the total amount of the element is separated. By measuring the radioactivity a of the separated fraction, M_x is determined by the following equation: M_x=m⋅A/a-M. In the radioactivation analysis, the irradiated sample is divided into two parts, and M is added to one. An amount m is separated from each part, and then, a and a' are measured. The unknown amount M_x is calculated from M_x=a'M/ (a-a') . The experiment to determine the reaction ratio between copper and dithizone was carried out at various conditions and it was observed that the ratio was constant in the buffer solution of pH 5 containing 0.2-4.7μg of copper. The reproducibility of the results was satisfactory. Then, this method has been applied to the determination of trace amounts of copper in the materials and satisfactory results were obtained.