Hydrous 18F-fluoroethylation – leaving off the azeotropic drying

The study describes the development of a simple and effective method for [18F]fluoroethylation, called as smart [18F]fluoroethylation without azeotropic drying, by elution of a [18F]fluoride loaded QMA column with a K2CO3/K222/acetonitrile solution containing 2% (v/v) water directly to the 1,2-ethylene glycol-bis-tosylate precursor. The method was exemplified on the radiosynthesis of three COX-2 inhibitors with different core structures. In comparison to conventional [18F]fluoroethylation, the reaction time was generally shortened and the radiochemical yield was improved in each case by factor 4-5 by this approach.