Optimization of the extraction process in the synthesis of high specific activity Molybdenum-99 by Szilard Chalmers reaction

Abstract

Molybdenum-99 (99Mo) is a parent radioisotope of technetium-99m (99mTc) which is widely used as diagnostic radiopharmaceutical because of its short half-life and ideal gamma-ray energy of 140 keV. Separation of 99mTc and 99Mo is mainly carried out using a radioisotope generator of 99Mo / 99mTc. Alumina column inside the generator has a low absorbency capacity of Mo (20 mg Mo / g alumina). Low alumina capacity requires 99Mo with high specific activity in order to minimize the amount of alumina so that the generator size could be kept as small and simple. High specific activity 99Mo alternatively can be obtained by Szilard Chalmers’s reaction in irradiated molybdenum phthalocyanine (MoPc) target material. The purpose of this study was to optimize the extraction condition of 99Mo from irradiated MoPc. The study was conducted with stages consisting of the determination of the number of solvents, the effect of extraction time, and Physico-chemical characterization of 99Mo solution. 5-gram MoPc was irradiated in TRIGA Reactor Bandung for 3 days with 5.1012 n.s−1.cm−2 neutron flux. Extraction optimization was carried out using THF, DMSO and NaOH 3M solvents with a ratio of solvent : MoPc (v(ml):w(mg)) were 1: 5, 1:10, 1:25, 1:50, and 1:75. Extraction time was varied for 1, 2, 3, 4, and 5 hours. 3M NaOH with a volume ratio of 1: 5 with an extraction time of 1 hour was considered as an optimum condition to extract 99Mo from MoPc. This condition produced an extraction yield of 54.21% and an enrichment factor of 322.53 times with 95% radiochemical purity as (99MoO4)2-.