Separation of Germanium-68 from irradiated targets

Objectives Germanium-68 has a half life of 270 days and decays to gallium-68 with a half life of 1.13 hours which makes the two isotopes ideal for a medical isotope generator. The short half life of gallium-68 allows preparation, purification and imaging of small molecules and peptides and the generator can be eluted multiple times in a day for patient imaging. The germanium-68 produced at Brookhaven Linac Isotope Producer from proton irradiation of liquid gallium metal targets has been purified in the past by liquid-liquid extraction using organic solvents such as carbon tetrachloride or toluene. The FDA has listed these solvents as Q3C - class 1 and 2 solvents in its Guidance for Industry documentation. This FDA classification places the solvents in a category that should not be employed in manufacturing of drugs due to unacceptable toxicity.

Methods A new separation process utilizing a common buffer system and commercially available resin was developed to separate germanium-68 from the irradiated gallium target. The soluble gallium allows a separation time of less than 3 hours.

Results The new process results in 82-99% recovery of germanium-68 with minimal to no zinc-65 and cobalt in the final product. The concentration of gallium in the final product in the new separation process is ~24 ppm which is half the amount of the concentration of gallium in the final product by organic extraction (~40 ppm average).

Conclusions The new process is being adapted for use in hot cells for production and purification of Ci amounts of germanium-68 to meet cGMP requirements.

Research Support U.S. Department of Energy Office of Nuclear Physic