Quality control procedure for 6-[18F]fluoro-L-DOPA: a presynaptic PET imaging ligand for brain dopamine neurons

The goal of the current study was to establish a quality control procedure for clinical use of 6-[18F]fluoro-L-DOPA (6-[18F]-DOPA) as a selective presynaptic positron emission tomographic (PET) imaging ligand for brain dopamine neurons. A high performance liquid chromatographic procedure using a 5-mu C-18 reverse phase column and ion-pairing mobile phase was used for the quantification of 6-[18F]-DOPA. The radiochemical purity of 6-[18F]-DOPA was measured by 18F radioactivity in HPLC fractions while the chemical purity was determined by an amperometric electrochemical detector with a sensitivity of 25 pg. Quality control of eight consecutive batches of highly purified 6-[18F]-DOPA sample used in a pre-clinical trial revealed that the chemical and/or radiochemical purity of the PET imaging ligand, 6-[18F]-DOPA was greater than 97 +/- 0.5% with a specific activity of 365 +/- 31 mCi/mmol. The knowledge and assurance of radiochemical purity of PET ligands are essential for the interpretation of clinical PET imaging results. The assurance of such quality control would enable comparisons of 6-[18F]-DOPA/PET data obtained from various medical centers using different radiopharmaceutical procedures.