Radiolabelling Process

A method to obtain a composition comprising 1-amino-3-[18F]-fluorocyclobutanecarboxylic acid ([18F]-FACBC) wherein said composition comprises acetonitrile (MeCN) at a concentration of no greater than 50 μg/mL wherein said method comprises:

• reacting [18F]fluoride with a precursor compound of Formula I:
• wherein:
• LG is a leaving group;
• PG1 is carboxy protecting group;
• and,
• PG2 is an amine protecting group;
• wherein said reacting step is carried out in acetonitrile;
• to obtain a reaction mixture comprising a compound of Formula II:
• wherein:
• PG1 and PG2 are as defined for Formula I;
• transferring said compound of Formula II out of said reaction vessel to carry out removal of PG1 and thereby obtain a compound of Formula III:
• wherein PG2 is as defined for Formula I;
• simultaneously to step(ii) applying heat to said reaction vessel;
• and
• transferring said compound of Formula III back into said reaction vessel to carry out removal of PG2 and thereby obtain [18F]-FACBC.