Electrochemical separation and purification of yttrium-86

Abstract

Summary For quantitative determination of in vivo dosimetry of 90Y-labeled radiotherapeuticals by means of PET, the positron emitting analogue yttrium-86 was produced at a low energy (“medical”) cyclotron via the known 86Sr(p, n)86Y reaction. Using 200 mg of 86SrCO3 (enrichment 95.6%) and protons of 15.1 MeV energy, average yields of 86Y of 48 ± 8 MBq/µA h were produced. After dissolution of 86SrCO3 in 3 ml of 0.6 N HNO3, 86Y was deposited in a simple and highly efficient electrochemical two-step procedure onto a platinum cathode at 450 mA (= 20 mA/cm2). The isotope was finally removed from the electrode by 100–300 µl of 0.5–1.0 N HCl or 0.3–0.6 N HNO3 resulting in an overall recovery of 88 ± 6% (corrected for decay). Up to 1 GBq of 86Y with high radionuclidic and radiochemical purity were obtained after a 2.5 h irradiation and a radiochemical separation time of 2 h. An ICP/AES analysis of the separated fraction showed a very small amount of strontium (< 0.1 ppm). The chemical purity of 86Y, essential for efficient labeling, was successfully demonstrated by means of complex formation with DOTA and a DOTA-conjugated peptide, exhibiting labeling yields higher than 98%.