Highly efficient production of [18F]fallypride using small amounts of base concentration

To minimize the base concentration of a phase-transfer catalyst, [18F]fluoride was extracted from 18O-enriched water trapped on an activated ion exchange cartridge (Chromafix® PS-HCO3) using different concentrations of tetrabutylammonium bicarbonate (TBAHCO3) or Kryptofix 2.2.2./K2CO3 in organic solvents such as CH3CN/H2O or MeOH/H2O. The optimal labeling condition for [18F]fallypride with automated synthesis was that 2 mg of tosyl-fallypride in acetonitrile (1 mL) was heated at 100 °C for 10 min using 40% TBAHCO3 (10 μL). [18F]Fallypride was obtained with a high radiochemical yield of approximately 68±1.6% (decay-corrected, n=42) with a total synthesis time of 51±1.2 min, including HPLC purification and solid-phase purification for the final formulation.