Isolation of high purity ⁷³Se using solid phase extraction after selective 4,5-[⁷³Se]benzopiazselenol formation with aminonaphthalene

A fast and efficient process for the production of the PET radionuclide ⁷³Se was developed using ⁷⁵Se as a surrogate. ⁷⁵Se was separated from proton irradiated arsenic trioxide by reaction with 2,3-diaminonaphthalene to 4,5-[⁷⁵Se]benzopiazelenol. This compound was purified using SPE column chromatography and subsequently decomposed with hydrogen peroxide. For further chemical conversions [⁷⁵Se]selenite was reduced to elemental [⁷⁵Se]selenium by either using thiosulfate or sulfur dioxide. The recovery yield of ⁷⁵Se from the target amounted to 43%. The utility of the isolated ⁷⁵Se for radiosyntheses was demonstrated by the successful preparation of [⁷⁵Se]selenomethionine. The methodology developed using ⁷⁵Se was successfully transformed to ⁷³Se.