EVALUATION OF (GeGa)-Ge-68-Ga-/68 GENERATOR PRE-ELUTION EFFICIENCY ON METALLIC IMPURITIES IN THE COMPOSITION OF(68)GaPSMA-11 RADIOPHARMACEUTICAL IN NUCLEAR MEDICINE PET CHEMISTRY

Abstract

Objective: The presence of metallic impurities can pose a se-rious concern due to their interaction with receptor-specific biomolecules that require the highest possible specific activity, especially in radioactive labeling. There are studies in which Zn and other toxic metal pollution increases if the generator is not used for a long time. In this study the effect of pre-elution on chemical and radiochemical impurities in the synthesis product was investigated. Material and Methods: In the study, 68GaPSMA-11 labeling was performed with the generator eluate that was not used for one month (sample 1). A blank elution was taken 24 hours after using the generator (sample 2). In the next 24 hours, the second 68GaPSMA-11 labeling was performed (sample 3). Six hours after this labeling, another 68GaPSMA-11 synthesis was performed (sample 4). Eluates were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: Results was reported as a table in mu g/ml. 68Ge levels determined at 0.018 ppm, 0.012 ppm and 0.009 ppm levels in the labeled products were determined below the pharmacopoeia limits. Zn(II) impurities were found as 0.625 ppm in the labeling performed without generator pre-elution. In generator pre-eluted labelings; Zn(II) impurities were determined as 0.133 ppm and 0.108 ppm. Conclusion: Pre-elution of the generator prior to synthesis does not seem to be a chemical requirement other than zinc pollution. 68GaPSMA-11 can be pre-eluted for high labeling efficiency, but it is thought that pre-elution is not significant in terms of chemical and radiochemical contamination.