Rapid Aqueous Late-Stage Radiolabelling of [GaF 3 (BnMe 2 -tacn)] by 18 F/ 19 F Isotopic Exchange: Towards New PET Imaging Probes

A simple and rapid method for F radiolabelling of [GaF (BnMe -tacn)] by F/ F isotopic exchange is described. The use of MeCN/H O or EtOH/H O (75:25) and aqueous [ F]F (up to 200 MBq) with heating (80 °C, 10 min) gave 66±4 % F incorporation at a concentration of 268 nm, and 37±5 % F incorporation at even lower concentration (27 nm), without the need for a Lewis acid promoter. A solid-phase extraction method was established to give [Ga F F (BnMe -tacn)] in 99 % radiochemical purity in an EtOH/H O mixture.