Symmetry prep c18

Tz-PEG₄-NH₂ (25.4 µmol) and DOTA-NHS ester (24.0 µmol) were diluted to 2 mL dimethylformamide (DMF) and 100 µL TEA (716.0 µmol) was added to the reaction mixture and the mixture was stirred overnight at room temperature. Reaction was monitored by TLC (silica, DCM:MeOH, 10:1, R_f(1) = 0.75). The product was purified by semi-preparative HPLC (Waters Symmetry Prep™ C18, eluent: 0.1% TFA in water/ACN, ACN gradient 10% to 80%, 3 mL/min, UV detection at 270 nm, R_t(1) = 9.26 min), and evaporated to dryness, yielding a red oil. Final compound was analyzed with ¹H-NMR (Varian Mercury 300 MHz, CD₃OD): δ 10.33 (s, 1H), 8.57 (d, 2H), 7.60 (d, 2H), 4.54 (s, 2H), 3.92 (br, 3H), 3.80 (m, 12H), 3.64 (s, 6H), 3.60 (m, 18H), 3.35 (s, 2H) and 2.58 (t, 4H) and TOF-ESI-MS mass spectrometry (Bruker Daltonics micrOTOF). Negative ionization mode used in measurement, m/z calc. 819.4079 for C₃₆H₅₄N₁₀O₁₂⁻, found 819.3996.

Synthesis of [¹⁸F]F13640 and quality controls pathways were previously described (Vidal et al., 2018a (link)). Briefly, after production of fluoride preparation ¹⁸O(p,n)¹⁸F cyclotron reaction, 5 mg of F13640 nitro precursor are introduced. After nucleophile substitution, [¹⁸F]F13640 is obtained by separation on a preparative HPLC column (SymmetryPrepC18, 7 μm, 7.80 mm × 300 mm, Waters). The radiotracer is formulated via solid phase extraction techniques using a Sep-Pak Light C18 cartridge (Waters). The final product is eluted with 1 mL of ethanol, diluted with saline and finally sterilized by filtration (sterile filter Millex-GS, 0.22 μm; Millipore).