High Yielding [¹⁸F]Fluorination Method by Fine Control of the Base

Abstract

New [<TEX>$^{18}F$</TEX>]F-fluorination methods using a minimized amount of precursor has been developed by controlling the base concentration. In the first method, pre-conditioning of the anion exchange cartridge with <TEX>$K_2CO_3$</TEX> solution or water was carried out. The trapped [<TEX>$^{18}F$</TEX>]fluoride on the cartridge was then eluted by KOMs or KOTf solution. [<TEX>$^{18}F$</TEX>]F-Fluorination could be performed without additional base. In the second method, the QMA cartridge was preconditioned with KOMs solutions. Trapped [<TEX>$^{18}F$</TEX>]fluoride on the QMA was then eluted with KOMs and additional base, such as KOH, <TEX>$K_2CO_3$</TEX>, and <TEX>$KHCO_3$</TEX>, was added into the reaction vessel. Method 1 showed a [<TEX>$^{18}F$</TEX>]F-incorporation yield of 20.9% for [<TEX>$^{18}F$</TEX>]FLT synthesis with 5 mg of precursor. Unlike method 1, a [<TEX>$^{18}F$</TEX>]F-incorporation yield of 91.4% was achieved from the same amount of precursor in method 2.