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-89(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 mu L, was packed with hydroxamate resin. A condition of inverted selectivity was developed, whereby the Zr-89 eluent solution for the primary column is equivalent to the Zr-89 load solution for the secondary column. The ability to transfer Zr-89 from one column to the next allows two sequential column clean-up methods to be performed prior to the final elution of the Zr-89(IV) oxalate. This approach assures delivery of high purity Zr-89 product and assures a Zr-89 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-89 present in the foils was recovered in the secondary column elution fraction. Furthermore, elution peak analysis of several Zr-89 elution profile radiochromatograms made possible the determination of Zr-89 recovery as a function of volume; a Zr-89 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-89 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-89 product elution volume, titrations of the Zr-89 product with deferoxamine mesylate salt across two preparatory methods resulted in mean effective specific activity (ESA) values of 279 and 340T Bq.mmole(-1) and mean bindable metals concentrations ((M-B]) of 13.5 and 16.7 nmole.g(-1). These ESA and (M-B] values infer that the Zr-89(IV) oxalate product resulting from this tandem column isolation method has the highest purity reported to date. (C) 2018 Elsevier B.V. All rights reserved.