Tandem column isolation of zirconium-89 from cyclotron bombarded yttrium targets using an automated fluidic platform: Anion exchange to hydroxamate resin columns.

The development of a tandem column purification method for the preparation of high-purity Zr(IV) oxalate is presented. The primary column was a macroporous strongly basic anion exchange resin on styrene divinylbenzene co-polymer. The secondary column, with an internal volume of 33 μL, was packed with hydroxamate resin. A condition of inverted selectivity was developed, whereby the Zr eluent solution for the primary column is equivalent to the Zr load solution for the secondary column. The ability to transfer Zr from one column to the next allows two sequential column clean-up methods to be performed prior to the final elution of the Zr(IV) oxalate. This approach assures delivery of high purity Zr product and assures a Zr product that is eluted in a substantially smaller volume than is possible when using the traditionally-employed single hydroxamate resin column method. The tandem column purification process has been implemented into a prototype automated fluidic system. The system is configured with on-line gamma detection so column effluents can be monitored in near-real time. The automated method was tested using seven cyclotron bombarded Y foil targets. It was found that 95.1 ± 1.3% of the Zr present in the foils was recovered in the secondary column elution fraction. Furthermore, elution peak analysis of several Zr elution profile radiochromatograms made possible the determination of Zr recovery as a function of volume; a Zr product volume that contains 90% of the mean secondary column elution peak can be obtained in 0.29 ± 0.06 mL (representing 86 ± 5% of the Zr activity in the target). This product volume represents a significant improvement in radionuclide product concentration over the predominant method used in the field. In addition to the reduced Zr product elution volume, titrations of the Zr product with deferoxamine mesylate salt across two preparatory methods resulted in mean effective specific activity (ESA) values of 279 and 340 T Bq·mmole and mean bindable metals concentrations ([M]) of 13.5 and 16.7 nmole·g. These ESA and [M] values infer that the Zr(IV) oxalate product resulting from this tandem column isolation method has the highest purity reported to date.