Solid phase extraction - An alternative to the use of rotary evaporators for solvent removal in the rapid formulation of PET radiopharmaceuticals

Solid phase extraction (SPE) was used for the formulation of several radiop harmaceuticals. The method involves dilution of the previously purified HPL C compound with water, trapping of the activity on an SPE bed, washing off the support, elution of the radiopharmaceutical with a small volume of etha nol (< 1 mL) and dilution with sterile isotonic saline solution. Recovery o f the radiopharmaceuticals was always higher than 97%. Two different method s of automation were developed for the formulation of [C-11] and [F-18]radi opharmaceuticals. In all cases, organic solvent levels in the injectable so lution were below the recommended limits. This fast (3-6 min.) and easy to automate process can be considered as an alternative to the conventional me thods (rotary evaporators).