Abstract
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Objectives Tentagel® (TG) resins are mainly used for solid phase synthesis of peptides and oligonucleotides. These resins are similar, but with higher PEG loading, to the ABEC® resin which has been extensively used for Tc purification. The aim of this work was to assess if TG resin can efficiently separate pertechnetate (TcO4-) from bulk molybdate (MoO42-).
Methods Resins were packed in columns and conditioned with (NH4)2CO3 (3 M). Load solutions consisted of 1.6 g Mo dissolved in 20 mL H2O2 (30%) and 20 mL (NH4)2CO3 (3 M). Approximately 25 MBq of generator eluted [99mTc]TcO4- in 0.5 mL of 0.9% saline was added to each load solution. Initial separations were performed manually but preliminary studies using an automated synthesis unit (ASU) are also reported. Subsequent to loading, the columns were washed with 5 mL (NH4)2CO3 and eluted using deionized water (DIW). The eluate was then passed through strong cation exchange and alumina A columns. The [99mTc]TcO4- was eluted from the alumina column using saline. The radioactivity was measured using a dose calibrator.
Results Recovery of 99mTc was 61%, 85% and 70% for 288 mg, 510 mg and 743 mg of TG S-OH respectively. Lower resin mass resulted in less adsorption while higher mass resulted in lower elution efficiency. To compare, ABEC2000 (2g) gave 73 % recovery, with lower adsorption and elution efficiency compared to the TG S-OH (510 mg) experiment. Preliminary ASU studies with the TG S-OH media (483 mg and 458 mg) resulted in 88% (30 mL DIW elution) and 77% (20 mL DIW elution) total recovery. Both products had a pH of 7, while Al3+, SO42- , MoO42- , NH4+ and H2O2 tests all showed levels lower than the detection limit of each test.
Conclusions Tentagel S-OH showed good recovery of 99mTc in experiments with conditions simulating those present during processing of cyclotron produced 99mTc using large Mo targets (1.6 g).
Research Support This work was supported by Natural Resources Canada. We acknowledge our ITAP partners, ACSI and CHUS.