Standard Operating Procedure

Gallium - 67

Primary emissions: Gamma ray: 93 KeV (39% abundance), followed by 185 KeV (21% abundance) and 300 KeV (17% abundance)

Decay: By electron capture to stable Zn-67

Shielding: Half value layer (HVL) for X and gamma rays 6 mm lead, Tenth value layer (TVL) for X and gamma rays 17 mm lead

t½: 78.3 h

Conversion of 67Ga citrate to 67Ga chloride

1. Mix gallium citrate solution with two thirds of its volume of chelexed water
2. Wash the 100 mg Sep-Pak® Vac 1 cc (100 mg) silica cartridge with 2ml water
3. Filter the gallium citrate solution manually over a 100 mg Sep-Pak® Vac 1 cc

(100 mg) silica cartridge with a plastic syringe

4. Wash the cartridge twice with 5 mL chelexed water to remove citrate ions
5. Elute the retained radioactivity with 1 mL of 0.1 M hydrochloric acid solution
6. Collect the elute in 100 μL fractions and use the fractions with maximum

radioactivity

Radiolabeling protocol

1. Prepare 1mM ligand solution in water
2. Pipette out 100µL of ligand in a microcentrifuge tube, add appropriate concentration of activity to ligand
3. Adjust the pH of the solution by adding HEPES buffer (pH= 7.4)
4. Check the pH of the solution using a universal pH paper
5. Check labeling efficiency by radio HPLC (mobile phase 10mM NaOAc- pH 4.5 and neat acetonitrile)

Reference

1. Ben Azzouna et al. EJNMMI Radiopharmacy and Chemistry (2017) 2:3