Establishing the Oxidation Degree of 99Tc Sorbed on Pt Using X-ray Photoelectron Spectroscopy

Abstract

An electrochemical method has been proposed for concentrating the technetium ^99mTc ions formed during irradiation of a molybdenum target with neutrons and used for visualization of internal organs in radiopharmaceutical diagnostics. Technetium was isolated by the electrochemical method. An X-ray photoelectron spectroscopy study showed that technetium is released on the cathode in the form of TcO₂⋅xH₂O due to the electrochemical reduction of pertechnetate ions. As a result of the oxidation of the surface layers by atmospheric oxygen, a certain amount of Tc(VII) is formed in them: the ratio of the amounts of Tc(IV) : Tc(VII) is 3 : 7. Under the optimum process conditions, the efficiency of technetium extraction from a solution containing excess molybdate ions reached 90% within 0.5 h. Since the concentration of molybdenum compounds is low, the reduction of pertechnetate ions occurs with diffusion limitations. The diffusion coefficient of \({\text{TcO}}_{4}^{ - }\) ions, determined by the rotating disk electrode method, was 2.14 × 10^–5 cm² s^–1.