Figure 3: HPLC analysis the stability of [18F]FP-D-Lys6-GnRH: (a) [18F]FP-D-Lys6-GnRH incubation in PBS and bovine serum for 2 h compared to [18F]FP-D-Lys6-GnRH from the quality control and its reference standard FP-D-Lys6-GnRH; (b) representative HPLC profiles displaying unchanged [18F]FP-D-Lys6-GnRH (peak 3) and its metabolites (peak 1, peak 2, and peak 4) in PC-3 tumors at 1 h after intravenous injection in the blocking group. ret. = retention time in min.