HPLC methods for the purification of [11C]‐labelled radiopharmaceuticals: reversal of the retention order of products and precursors

Preparative HPLC methods have been developed for a number of [¹¹C]‐methylated PET tracers, which enable elution of the labelled compounds prior to their precursors, thus reducing the overall synthesis time and avoiding contamination of the final product with precusor. This reversal of retention order has been achieved for [¹¹C]DASB, [¹¹C]raclopride, [¹¹C]FLB 457, [¹¹C]carfentanil, and 2‐fluoro‐[N‐methyl‐¹¹C]apomorphine, enabling collection of the purified radiopharmaceuticals from the HPLC system after 5–7 min. Furthermore, by using ethanol as the organic modifier, residual solvent analysis prior to human injection could be avoided and three of the radiopharmaceuticals could be injected directly following simple dilution and sterile filtration. Copyright © 2009 John Wiley & Sons, Ltd.