Development of methodology for the preparation of 90Sr-90Y generators at IPEN/CNEN-SP

1321 Objectives: 90Y has a relatively short half-life (T1/2=64h) decays to a stable daughter (90Zr), emits β-radiation (Max. 2.28MeV) and has no γ-ray, what makes this nuclide very attractive for therapeutic applications. 90Y is produced through a generator system, from the decay of 90Sr (T1/2=29y). In this work, the 90Sr-90Y generator was developed using a cation exchange resin method. 90Sr is strongly adsorbed in the resin and 90Y is eluted in 0.003M EDTA. The generator efficiency and radionuclide control results will be shown using also 85Sr (γ-ray emitter). Methods: The generator was developed, using AG 50WX8 exchange resin converted to the Na+ form and then conditioned with 0.003M EDTA solution (pH=4.8). The loading solution had 20μl of 90Sr (55.5MBq) and 300μL of 85Sr (28.7MBq) and the elution was perfomed with 0,003M EDTA. Activities of 90Y and 90Sr were determined by Liquid Scintillation Counting and 85Sr by γ-ray spectroscopy using a HPGe detector. A paper chromatographic method was performed for the quality control, using Whatman3 paper and 0.9% NaCl as the solvent. In this case, the Rf of 90Y is zero and the Rf of 90Sr is about 1. Results: Weekly elutions were performed for this generator. Between the 1st and 4th elution the 90Y activity remained nearly constant. From the 5th elution on, an increase in the 90Y activity was noticed. The efficiency yield was 95% in the last elution. The breakthrough of 90Sr was less than 0.04%. The quality control showed that 90Y had no 85Sr impurities, inside the detection limits of the detector. Conclusions: The results presented here are very promising, showing that the methodology is able to separate the two nuclides, with low quantities of 90Sr impurity and satisfactory elution yields. Research Support: The research was supported by IAEA and CNPq granted a fellowship.