Table 2 Comparison of the main steps in the preparation of [18F]LBT999 on TRACERlab FXFN and AIO modules and synthetic results compared to the initial work by Dollé’s group (Dolle et al., 2007)
Synthetic results of production of [18F]LBT999 | Dollé’s work (n > 20) | FXFN (n > 16) | AIO (n = 5) |
|---|---|---|---|
1. Azeotropic drying | |||
K2.2.2. | 12–15 mg | 7.2 mg in 715 μL ACN | 7.2 mg in 715 μL ACN |
K2CO3 | 1 mL of a 1.0/mL solution | 3.8 mg in 285 μL H2O | 3.8 mg in 285 μL H2O |
Evaporation/Temperature | 145–150 °C 10 min | 70–100 °C 10 min | 95 °C 10 min |
2. Radiofluorination | |||
Precursor | 3.5–4.5 mg | 3 mg | 5.5–6 mg |
DMSO | 0.6 mL | 1 mL | 0.8 mL |
Reaction time | 10 min | 10 min | 7 min 30 |
Temperature | 165 °C | 165 °C | 155 °C |
3. HPLC Purification | |||
Eluent | H2O/CH3CN/TFA: 72/28/0.1 | AcNH4 (0.1 M)/ CH3CN: 40/60 | AcNH4 (0.1 M)/ CH3CN: 40/60 + Na-Asc (0.5%). |
Flow rate | 5 mL/min | 4 mL/min | 4 mL/min |
Column | Symmetry®C18, Waters (300 × 7.8 mm, 7 μm) | Alltima® C18, Grace (250 X 10 mm, 5 μm) | Agilent Zorbax Eclipse XDB-C18 (250 X 9.4 mm, 5 μm) |
4. Formulation | |||
ETOH | 2.0 mL | 1.5 mL | 2.5 mL |
NaCl (0.9%) | 8.0 mL (volume adjusted bring EtOH concentration below 10%) | 13.5 mL | 22.5 mL + Na-Asc (0.5%). |
Synthetic results | |||
Starting activity (GBq) | 37 | 77.2 ± 2.1 | 102.7 ± 19 |
Radioactivity at EOS (GBq) | 3.7–5.92 | 16.8 ± 1.9 | 23.8 ± 7.1 |
Radiochemical yield at EOS (%) | 17.3–27.7 | 35.3 ± 5.1 | 32.7 ± 5.9 |
Activity yield at EOS (GBq) | 10–16 | 23.3 ± 4.3 | 23.1 ± 4.5 |
Radiochemical purity (EOS) | > 95 | 99.4 ± 0.2 | 98.3 ± 0.5 |
Total synthesis time (min) | 85–90 | 65.8 ± 3.8 | 48 ± 1.9 |
Molar activity at EOS(GBq/μmol) | 37–111 | 158.6 ± 79.8 | 154.3 ± 51.1 |