Sorption Characteristics and Chromatographic Separation of 90Y3+ from 90Sr2+ from Aqueous Media by Chelex-100 (Anion Ion Exchange) Packed Column.

Abstract

There is growing demand for separation of 90Y carrier free from 90Sr coexisting to produce high purity 90Y essential for radiopharmaceutical uses. Thus, in this context the sorption profiles of Y3+ and Sr2+ from aqueous solutions containing diethylenetriaminepenta acetic acid (DTPA), ethylenediaminetetra-acetic acid (EDTA), acetic acid, citric acid, or NaCl onto Chelex-100 (anion ion exchange) solid sorbent were critically studied for developing an efficient and low-cost methodology for selective separation of Y3+ from Sr2+ ions (1.0 × 10-5 M). Batch experiments displayed relative chemical extraction percentage (98 ± 5.4%) of Y3+ from aqueous acetic acid solution onto Chelex-100 (anion ion exchanger), whereas Sr2+ species showed no sorption. Hence, a selective separation of Y3+ from its parent 90Sr2+ has been established based upon percolation of the aqueous solution of Y3+ and Sr2+ ions containing acetic acid at pH 1-2 through Chelex-100 sorbent packed column at a 2 mL min-1 flow rate. Y3+ species were retained quantitatively while Sr2+ ions were not sorbed and passed through the sorbent packed column without extraction. The sorbed Y3+ species were then recovered from the sorbent packed column with HNO3 (1.0 M) at a 1.0 mL min-1 flow rate. A dual extraction mechanism comprising absorption associated to "weak-base anion exchanger" and "solvent extraction" of Y3+ as (YCl6)3- and an extra part for "surface adsorption" of Y3+ by the sorbent is proposed. The established method was validated by measuring the radiochemical (99.2 ± 2 1%), radionuclide purity and retardation factor (Rf = 10.0 ± 0.1 cm) of 90Y3+ recovered in the eluate. Ultimately, the sorbent packed column also presented high stability for reusing 2-3 cycles without drop in its efficiency (±5%) towards Y3+ uptake and relative chemical recovery. A proposed flow sheet describing the analytical procedures for the separation of 90Y3+ from 90Sr2+ using chelating Chelex 100 (anion exchange) packed column is also included.