Tellurium interference in 129I activation analysis

Measurement of 129I at low levels is required for effluent control, environmental assessment and tracer studies in the natural environment. Low level 129I analysis has also been used for measurement of natural-fission-produced 129I in minerals and ores as well as meteorites. The most sensitive method for 129I measurements is neutron activation analysis of iodine separated from a suitable sample. Minimum sample processing prior to neutron activation is desirable in order to reduce chances of sample contamination with uranium or 129I. A potential interference in the activation analysis method is the production of 129I (130I) from Te impurities in the irradiated ampoule. Procedures have been developed and applied to measurement of the magnitude of the potential Te interference. One-tenth of a microgram of Te in the irradiated ampoule is sufficient to produce interference in the analysis. This is detectable by either radiochemical Te measurements or by 131I detection in the iodine fraction from the irradiated ampoule. This paper discusses the procedures and results of Te interference studies in 129I activation analysis. The interference was found to be insignificant for most analyses. 5 tables