Sorption Characteristics and Chromatographic Separation of [sup.90]Y[sup.3+] from [sup.90]Sr[sup.2+] from Aqueous Media by Chelex-100 Packed Column

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