Determination of 131I as contaminant in samples of fission 99Mo

A method for 99Mo production from fission products was developed at the Ezeiza Atomic Center 15 years ago. A complete quality control of the product, preceding its use in nuclear medicine, is a basic requirement. One of the main purposes of this work was to improve the resolution of the 364.5 keV and 366.4 keV peaks, from respectively 131I and 99Mo, due to the fact that the former could not be detected in the presence of high activities of the later. A new procedure is described for determination of 131I impurity contents present in the 99Mo samples. A highly specific 131I separation from an alkaline solution has been developed, which utilizes porous metallic silver. Elemental silver was prepared by reduction of Ag+ with ascorbic acid. The isotopes of iodine were fixed as Ag 131 I and then, the iodide ion was eluted from the column with a Na2S solution. Finally, the 131I activity could be quantitatively determined. All the parameters were fitted in order to obtain a suitable statistic in counting times within 2000-5000 seconds, short enough for on-line controls. (author)