Studies on the separation of 99mTc from large excess of molybdenum

Abstract

BACKGROUND: Due to aging and unexpected prolonged shutdown of nuclear reactors producing ⁹⁹Mo for ⁹⁹Mo/ ^99mTc generators it was necessary to explore the alternative methods of technetium-99m production. The first choice were the accelerators. Three years ago IAEA (International Atomic Energy Agency) initiated the Coordinated Research Project “Accelerator-based Alternatives to Non-HEU production of Mo-99 /Tc-99m” aimed at direct production of ^99mTc in proton accelerators using the ¹⁰⁰Mo(p,2n)^99mTc reaction. POLATOM is participating in this enterprise together with the Heavy Ion Laboratory of Warsaw University and the Institute of Nuclear Chemistry and Technology.

MATERIAL AND METHODS: ⁹⁹Mo/^99mTc solutions and pure ^99mTc used for generators production or milked from ready to use generators were used in experiments. Commercial chromatographic and laboratory-prepared columns were used for separation. The peristaltic pumps were used for solutions delivery onto the columns. Radioactivity of eluted ⁹⁹Mo and ^99mTc was measured using high resolution gamma spectrometry or ionisation chamber in case of high radioactivity. For separation, three different chromatographic methods were used, one based on ion exchange and two on extraction.

RESULTS: Synthetic mixtures simulating the real solutions were used. 99mTc is quantitatively bound in the Dowex-1 × 8 column whereas molybdenum is only slightly retained and totally rinsed with 2M NaOH. ^99mTc is eluted with TBAB. The elution yield has been reproducible and amounted to 78%. The AnaLig Tc-02 resin column was used for ^99mTc retention. Residual Mo was removed by rinsing with 2M NaOH and ^99mTc eluted using small volume of water. The recovery was equal to about 85%. Using C-18 column coated with PEG over 80% of ^99mTc was recovered in about 50 mL of water. The reduction of volume was necessary.

CONCLUSIONS: The recovery of ^99mTc was the highest using AnaLig Tc-02 resin. Time of ^99mTc separation is the shortest for AnaLig Tc-02 resin and it is not higher than 100 minutes and it can further be shortened.