Mo/Tc GENERATOR: PRINCIPLES OF OPERATION

1. Prior to shipping the generator to the Nuclear Medicine Department, ⁹⁹Mo sodium molybdate is immobilized on a column of alumina (Al₂O₃; aluminum oxide) due to its very high affinity for alumina. This step must be performed very carefully using remote control equipment to minimize radiation dose to the workers manufacturing the generator.

2. 0.9% saline solution (the eluent) is passed through the column and Na pertechnetate, the daughter of ⁹⁹Mo decay, is eluted from the column with high efficiency due to its almost total lack of affinity for alumina. The driving force is the evacuated vial that creates a very significant pressure differential on the two sides of the generator since the saline side of the generator is always at 1 atm of pressure.

3. The pertechnetate is collected in a shielded, evacuated sterile vial and must undergo quality control testing, then must be calibrated prior to use. It is referred to as the eluate.

4. Quantitative removal of pertechnetate from the alumina column is attributed to the lack of affinity of pertechnetate for alumina, whereas molybdate is essentially completely and irreversibly bound to the alumina (quantitative retention) and cannot be removed, regardless of the volume of saline passing through the column.