1. The pharmaceutical composition of 1-amino-3- [F] -fluorocyclobutane-1-carboxylic acid ([F] -FACBC), characterized in that: (1) contains 50-100 mm citrate buffer； and (2) has a pH of 4.0-5.0.2. A pharmaceutical composition according to claim 1, containing 60-90 mM citrate buffer. 3. The pharmaceutical composition of claim 1, comprising 75-85 mM citrate buffer. The pharmaceutical composition according to claim 1, having a pH of 4.1-4.5.5. A pharmaceutical composition according to claim 1, having a radioactivity concentration (RAC) at the end of the synthesis (EOS) of at least 1000 MBq / ml. A pharmaceutical composition according to claim 1, having a radioactivity concentration (RAC) at the end of the synthesis (EOS) of at least 1500 MBq / ml. A pharmaceutical composition according to claim 1, containing not more than 150 μg / ml of 1-amino-3-hydroxycyclobutane-1-carboxylic acid (hydroxy-ASBC) .8. The pharmaceutical composition according to claim 1, containing not more than 80 μg / ml of hydroxy-ACB. A pharmaceutical composition according to claim 1, containing not more than 0.15 μg / ml 1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). A pharmaceutical composition according to claim 1, containing not more than 0.10 μg / ml FACBC. 11. A pharmaceutical composition according to claim 1, containing not more than 2.0 μg / ml of 1-amino-3-chlorocyclobutane-1-carboxylic acid (chlorine-ACBC). The pharmaceutical composition according to claim 1, containing not more than 1.0 μg / ml of chlorine-ACBC. The pharmaceutical composition according to any one of paragraphs. 1-12, provided that the composition does not contain a radio stabilizer. 14. The pharmaceutical composition of claim 13, wherein said radiostabilizer is sugar lactone or sugar alcohol. A method for producing a radiopharmaceutical composition, as defined in any one of claims. 1-14, comprising: (1) bringing a precursor compound of formula I: wherein: LG is a leaving group； PG is a carboxy protecting group； and
