C 18 sep pak light cartridge

A solution of ¹⁸F-fluoride obtained from proton bombardment of ¹⁸O-water in a General Electric PETtrace cyclotron and 2 mg of K₂CO₃ in 0.4 mL of water and 15–20 mg of Kryptofix 222^® in 2 mL acetonitrile were added to a reaction vessel of a GE MicroLab module (Cincinnati, OH). The mixture was evaporated azeotropically at 140°C under a stream of argon after the addition of 2 mL of CH₃CN. A solution of the precursor-FNDP (2 mg) in DMSO (0.8 mL) was added to the reaction vessel with the mixture heated at 160°C for 12 min. The reaction mixture was cooled, diluted with 0.7 mL of water, and injected onto the reverse-phase semi-preparative high performance liquid chromatography (HPLC) column. The radioactive product peak was collected in 50 mL of HPLC grade water. The water solution was transferred through an activated Waters C-18 Sep-Pak light cartridge (Milford, MA). After washing the cartridge with 10 mL saline, the product was eluted with 1 mL of ethanol through a 0.2 µM sterile filter into a sterile, pyrogen-free vial and 10 mL of 0.9% saline was added through the same filter. The final product ¹⁸F-FNDP was then analyzed by analytical HPLC to determine the radiochemical purity and specific radioactivity. The total preparation time including quality control was 75 min.

The C18 Sep-Pak^® method was carried out in tandem with the standard Oasis method. In the Sep-Pak^® method, a single-use solid phase extraction (SPE) C18 SepPak Light Cartridge (Waters, Milford, MA, USA) was pre-hydrated and pre-conditioned manually with 5.0 mL of absolute ethanol followed by 10.0 mL of deionized water. A volume of 0.05 mL [⁶²Cu]Cu-ETS product solution was withdrawn from the quality control sub-lot reaction vial, and diluted with 0.95 mL deionized water. The sample was mixed thoroughly and then loaded into the SPE column. The loading eluate was collected into a test tube (“A”). Next, the C18 Sep-Pak^® Light was eluted with 10.0 mL of water, followed by 10.0 mL of air flush. This aqueous eluate was also collected in tube “A”, and contains ionic impurities (e.g. ⁶²Cu²⁺ and ⁶²Zn²⁺). In order to recover the lipophilic [⁶²Cu]Cu-ETS complex, the Sep-Pak^® was then eluted with 1.0 mL ethanol, followed by 5.0 mL of air flush. The ethanol fraction was collected in tube “B”. The ‘dry’ cartridge was placed in test tube “C”. Finally, the radioactivity of samples A, B, and C was determined using a radionuclide dose calibrator, and the radiochemical purity of the [⁶²Cu]Cu-ETS was calculated as: $$[{}^{62}\mathit{\text{Cu}}]\mathit{\text{Cu-ETS Radiochemical Purity}}=\frac{\mathit{\text{Ethanol Fraction Radioactivity}}}{\mathit{\text{Total Radioactivity}}(A+B+C)}\times 100\%$$