Ascorbic acid/saline eluant increases 188Re yields after “wet” storage of 188W/188Re generators

We have evaluated several factors in an attempt to minimize the reduced yields observed after “wet” storage of 188W/188Re generators, which include the dispersion of 188W-tungstic acid in the alumina column bed by pre-mixing with silica gel, incorporation of cupric ion as an antioxidant in the adsorbent, and elution of the alumina columns with saline solution containing ascorbic acid. The results demonstrate that dispersion of the 188W-tungstic acid in a silica---alumina bed and the use of cupric ion do not significantly increase 188Re yields after weekend “wet” storage. In contrast, addition of ascorbic acid at concentrations as low as 0.01% in the saline eluant was found to be an effective method of maintaining good 188Re yields after “wet” weekend storage, resulting in Monday elution yields greater than 70%. Use of low concentrations of ascorbic acid is thus an effective alternative to drying the generator columns before storage.