Quality Control of [68Ga]Ga-ORNB

The radiochemical purity of [⁶⁸Ga]Ga-ORNB was evaluated by the RP-radioHPLC gradient method (Dionex UltiMate 3000, Thermo Scientific, Waltham, MA, USA) in combination with a radiometric detector (GABI Star, Raytest, Straubenhardt, Germany). A column (Nucleosil 120-5 C18 250 × 40 mm, WATREX, Prague, Czech Republic) with a flow rate of 1 mL/min, oven temperature of 25 °C, and ultraviolet detection at 225 and 250 nm was used with acetonitrile (ACN)/0.1% trifluoroacetic acid (TFA)/H₂O as the mobile phase with the following gradient: 0–2 min–0% ACN; 2–15 min–0–36% ACN; 15–18 min–36–60% ACN; 18–19.5 min–60% ACN; 19.5–20 min–60–0% ACN; 20–24 min–0% ACN.

Silica-gel-impregnated glass microfiber chromatographic papers (Varian, Lake Forest, CA, USA) were used for radio-iTLC. Chromatographic paper strips containing a sample of the [⁶⁸Ga]Ga-ORNB complex were developed in a chamber saturated with equal parts of ammonium acetate (1 M) and methanol. After development, the stripes were scanned using a radiometric phosphor imager (Cyclone Plus Storage Phosphor System, PerkinElmer, Waltham, MA, USA), and the chromatograms for each strip were evaluated.