Separation of Long-Lived Radionuclides on QMA Light Anion-Exchange Cartridge in Manufacture of Radiopharmaceutical Preparations Based on ¹⁸F

Abstract

Sorption and elution on a QMA light anion-exchange cartridge of long-lived radionuclides formed in [¹⁸O]H₂O under irradiation of a niobium target with Havar alloy input window on a Cyclone 18/9 HC cyclotron have been studied. It was shown that more than 90% of ⁵¹Cr and ⁷Be radionuclides from irradiated [¹⁸O]H₂O is sorbed on the QMA light anion-exchange cartridge. ^{55,56, 57,58}Co, ^52,54Mn, and ⁵⁷Ni radionuclides pass through the cartridge and are delivered into a flask with [¹⁸O]H₂O for subsequent regeneration. It was found that about 30% of cobalt and manganese radioisotopes and also ~7% of chromium are present in the irradiated [¹⁸O]H₂O in solid particles >5 μm in size. It was found that the main dose-providing chromium, manganese, cobalt, and beryllium radionuclides are hardly desorbed from QMA light in the elution of [¹⁸F]fluoride with a K₂CO₃ complex with cryptand [2.2.2] in an acetonitrile–water mixture, which provides a purification of these radionuclide impurities, with their amount reduced by a factor of 30–100. Nb, Ta, Re, and Tc radioisotopes are quantitatively sorbed on the anion-exchange cartridge and are mostly (up to 80% of the total activity) eluted together with [¹⁸F]fluoride into a reactor for synthesis. The observed fundamental aspects of the distribution of long-lived radionuclides are explained with consideration for their chemical forms of existence in aqueous solutions and the properties of the sorbents used.