A new route for the synthesis of [18F]fluoroaromatic substituted amino acids: no carrier added L-p-[18F]fluorophenylalanine.

L-p-[18F]fluorophenylalanine was designed as a potential marker for probing protein synthesis in the human brain by positron emission tomography. This radiotracer has been synthesized using nucleophilic displacement of the activated nitro group of p-nitrobenzaldehyde by NCA 18F- obtained from the 18O (p, n) reaction on enriched water. The L-form of the [18F]fluoroamino acid can be separated on an analytical scale chiral column. A typical production run of 22.2 GBq (600 mCi) of 18F obtained after a 10 microA.h bombardment of 18 MeV protons on 99.8% 18O-enriched water leads to a batch of 1.11 GBq (30 mCi) of NCA L-p-[18F]fluorophenylalanine after a total synthesis time of 120 min.