Optimization for the Synthesis Efficiency of the ¹¹C-Raclopride

The synthesis conditions of the ¹¹C-Raclopride with domestic PET-CM-3H-IT-I synthesis module and ¹¹C-Triflate-CH-3I as methylation agent were studied, which included the alkali equivalent, solvents, temperature, the amount of precursor and elution conditions for the product. The optimum condition was 1.5-3.0 g/L of precursor in acetone (0.2 mL), alkali equivalent (0.30-1.25 eq) and at room temperature (25 ℃) for synthesis of ¹¹C-Raclopride. It could be got with radiochemical yield of (64.82±4.74)% (n=46, EOB of ¹¹C-Triflate-CH₃). The radiochemical purity was over 97% and the specific activity was at (423.61±13.43) GBq/g. It took 23 minutes from ¹¹C-CO₂ to ¹¹C-Raclopride, and the production radioactivity was (6.9±0.87) GBq (n=46). The synthetic process was reliable and reproducible, and the product synthesized by this process was suitable for clinical use.