Sorption Characteristics and Chromatographic Separation of 90 Y 3+ from 90 Sr 2+ from Aqueous Media by Chelex-100 (Anion Ion Exchange) Packed Column.

There is growing demand for separation of 90 Y carrier free from 90 Sr coexisting to produce high purity 90 Y essential for radiopharmaceutical uses. Thus, in this context the sorption profiles of Y 3+ and Sr 2+ 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 Y 3+ from Sr 2+ ions (1.0 × 10 -5  M). Batch experiments displayed relative chemical extraction percentage (98 ± 5.4%) of Y 3+ from aqueous acetic acid solution onto Chelex-100 (anion ion exchanger), whereas Sr 2+ species showed no sorption. Hence, a selective separation of Y 3+ from its parent 90 Sr 2+ has been established based upon percolation of the aqueous solution of Y 3+ and Sr 2+ ions containing acetic acid at pH 1-2 through Chelex-100 sorbent packed column at a 2 mL min -1 flow rate. Y 3+ species were retained quantitatively while Sr 2+ ions were not sorbed and passed through the sorbent packed column without extraction. The sorbed Y 3+ species were then recovered from the sorbent packed column with HNO 3 (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 Y 3+ as (YCl 6 ) 3- and an extra part for "surface adsorption" of Y 3+ by the sorbent is proposed. The established method was validated by measuring the radiochemical (99.2 ± 2 1%), radionuclide purity and retardation factor ( R f  = 10.0 ± 0.1 cm) of 90 Y 3+ 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 Y 3+ uptake and relative chemical recovery. A proposed flow sheet describing the analytical procedures for the separation of 90 Y 3+ from 90 Sr 2+ using chelating Chelex 100 (anion exchange) packed column is also included.