High resolution LC-MS characterization of [18F]fluorocholine produced in accordance with GMP at high specific activity

Introduction: Several production-grade methods are available for synthesizing [¹⁸F]fluorocholine in accordance with good manufacturing practice (GMP), producing the radiopharmaceutical in a range of various strengths and molar activities. We sought to characterize the specific activity and purity of an [¹⁸F]fluorocholine product synthesized according to GMP in prepration for a new clinical trial for hepatocellular carcinoma (NCT04965454).

Methods: [¹⁸F]fluoride was produced by bombarding 98% enriched [¹⁸O]water using an 11 MeV cyclotron at 90mA for 30 minutes. [¹⁸F]fluorocholine was synthesized using an automated GMP kit-based synthesis method. Radiopharmaceutical quality control was based on European Pharmacopoeia monograph 2793. Samples of the final product were additionally analyzed using high resolution liquid chromatography-mass spectrometry (LC-MS) with an Orbitrap mass spectrometer to quantify non-added carrier [¹⁹F]fluorocholine and potential impurities not quantified by the other analytical quality control methods.

Results: All synthesized products passed quality control analytical procedures for radionuclide identity, radiochemical identity, radiochemical purity, chemical purity, endotoxin, and sterility. Fluorocholine mass was below the lower limit of quantification of a high performance liquid chromatography analytical procedure based on monograph 2793. Concentrations of [¹⁹F]fluorocholine were confirmed using high resolution LC-MS as ranging from 0.000022% to 0.000037%. Molar activity was found to exceed 450 GBq/umol. The level of dimethylethanolamine was below the 0.001% limit of gas chromatography. Total impurities were estimated at 0.01%.

Conclusions: Radiopharmaceutical-grade [¹⁸F]fluorocholine was produced under GMP conditions and confirmed to have high specific activity and purity.