Hydroxamate column-based purification of zirconium-89 (Zr) using an automated fluidic platform.

Zirconium-89 (Zr) is a long-lived (t = 78.4h) positron-emitting isotope that is useful for positron emission tomography (PET) based diagnostic imaging using radiolabeled antibodies. Hydroxamate resin columns are predominantly used for the purification of Zr from cyclotron bombarded Y targets dissolved in strong HCl. Zr is conventionally eluted from the resin in 1M oxalic acid (HCO), a complexant that is conducive to follow-on binding of Zr through a transchelation process to the deferoxamine siderophore. In the present study, we determined that a lower concentration of HCO eluent (0.8M) is adequate to efficiently remove Zr from a column containing 100mg hydroxamate resin. As a result, less buffering agents are needed to be added to the Zr product fraction prior to labeling. A simple automated fluidic system prototype has been developed to perform the steps required for Zr purification using a hydroxamate resin column (column conditioning in HCl, Y target dissolution, dissolved target solution load onto column, column washes using HCl and water, and Zr elution). The system performance was evaluated using several cyclotron bombarded Y targets; Zr product fractions demonstrated excellent chemical recoveries from these targets, with 1.0mL product volumes yielding 89±2% of the column elution peak activity and 84±2% of Zr recovered from the target (at EOB). These results compare favorably with previously published Zr product volumes and yields, despite the lower concentration of HCO eluent employed. Transchelation of resulting Zr product fractions was performed to assess product quality. The effective specific activity (ESA) ranged between 44(7) and 109(22) TBq·mmole, while the bindable metals concentration, a metric introduced for assessing and comparing product purity, ranged between 43(7) and 115(27) nmole·g.