Development of a high-performance liquid chromatography method for rapid radiochemical purity measurement of [¹⁸F]PSMA-1007, a PET radiopharmaceutical for detection of prostate cancer

Since first becoming commercially available in 2018, the PET radiopharmaceutical [¹⁸F]PSMA-1007 has been used widely for the diagnosis and staging of prostate cancer. A pharmacopoeia monograph first became available in 2021, prescribing a radiochemical purity specification of >91%, based on analytical results from both TLC (for [¹⁸F]fluoride impurity alone) and HPLC (for all other ¹⁸F-impurities). Though this monograph has provided clarity for the quality control testing of [¹⁸F]PSMA-1007, it prescribes a HPLC method using phosphate buffer mobile phase that may present a risk of precipitation of phosphate salts in the HPLC system. The method also requires specialised hardware not immediately available to all laboratories. This work describes the development of a simple, rapid reversed-phase HPLC method utilising 0.1 M ammonium formate mobile phase for the accurate assessment of both [¹⁸F]fluoride impurity and overall radiochemical purity in a single test. This method is especially useful for assessment of product stability over time. A more accurate TLC method for [¹⁸F]fluoride impurity is also described.