Model 5050

Analytical radio-HPLC was used to identify the product of each synthesis (via co-injection with reference standard) and to isolate pure products to confirm the R_f value of the product bands in radio-TLC. The radio-HPLC system setup comprised a Smartline HPLC system (Knauer, Berlin, Germany) equipped with a degasser (Model 5050), pump (Model 1000), UV detector (254 nm; Eckert & Ziegler, Berlin, Germany) and gamma-radiation detector, and counter (B-FC- 4100 and BFC-1000; Bioscan, Inc., Poway, CA, USA). All HPLC separations used a C₁₈ Gemini column (Kinetex, 250 × 4.6 mm, 5 µm, Phenomenex, Torrance, CA, USA). Using a mobile phase of 3:1 H₂O:MeCN with 0.1% TFA (v/v) and a flow rate of 1.0 mL/min, the retention time of [¹⁸F]Flumazenil was 11 min. For [¹⁸F]PBR06, the retention time was 8 min using a mobile phase of 60:40 (v/v) MeCN:20 mM sodium phosphate buffer (pH = 5.8) with a flow rate of 1.5 mL/min. [¹⁸F]Fallypride samples were separated with a mobile phase of 60% MeCN in 25 mM HN₄HCO₂ with 1% TEA (v/v) and a flow rate of 1.5 mL/min resulting in a retention time of 4.5 min. [¹⁸F]FEPPA samples were separated with a mobile phase of 70:30 v/v H₂O:EtOH with 0.1% H₃PO₄ at 0.8 mL/min, giving a retention time of 15.5 min.

Radio-HPLC was used to analyze crude radiopharmaceuticals and to perform tests for radiochemical and chemical purity and radiochemical identity of TLC-purified batches of radiopharmaceuticals. The radio-HPLC system setup comprised a Smartline HPLC system (Knauer, Berlin, Germany) equipped with a degasser (Model 5050), pump (Model 1000), UV detector (254 nm; Eckert & Ziegler, Berlin, Germany), gamma-radiation detector (BFC-4100, Bioscan, Inc., Poway, CA, USA), and counter (BFC-1000; Bioscan, Inc., Poway, CA, USA). A C18 Gemini column was used for separations (250 × 4.6 mm, 5 µm, Phenomenex, Torrance, CA, USA). [¹⁸F]PBR-06 samples were separated with a mobile phase of 60:40 (v/v) MeCN:20 mM sodium phosphate buffer (pH = 5.8) at a flow rate of 1.5 mL/min resulting in a retention time for [¹⁸F]PBR-06 of 6.5 min. [¹⁸F]Fallypride samples were separated with a mobile phase of 60% MeCN in 25 mM NH₄HCO₂ with 1% TEA (v/v) at a flow rate of 1.5 mL/min resulting in a retention time for [¹⁸F]Fallypride of 5.8 min.