Analysis of geothermal water samples for radioactive iodide tracer

New counting cocktails and vials have been chosen to replace those used for approximately fifteen years in geothermal tracing tests. Supplies of the previous cocktail had become exhausted and the opportunity was taken to replace it with a more modern biodegradable cocktail with improved counting stability. An account is given of the current method of extracting iodide ion from geothermal water, both for the standard (2 litre) and the large (up to 25 litre) sample sizes. Calculation methods for both tracer concentrations and errors are also given. (author)