Rapid Elution of (226)Th from a Two-Column (230)U/(226)Th Generator with Diluted and Buffer Solutions

A radionuclide generator of the short-lived alpha emitter (226)Th was proposed. An original scheme consisting of two in-series chromatographic columns was developed for rapidly producing a neutral citric-buffered eluate of high purity (226)Th. The first column filled with TEVA resin retained the parent (230)U, while (226)Th was eluted with 7 M HCl solution to be immediately adsorbed on the second column containing DGA resin or UTEVA resin. Having substituted the strongly acidic medium of second column with neutral salt solution, (226)Th was desorbed with diluted citric buffer solution. One cycle of generator milking took 5–7 min and produced >90% of (226)Th in 1.5 mL of eluate (pH 4.5–5.0) appropriate for direct use in radiopharmaceutical synthesis. The (230)U impurity in (226)Th eluate was less than 0.01%. The proposed two-column (230)U/(226)Th generator was tested over 2 months including a second loading of (230)U additionally accumulated from (230)Pa.