Concentration of iodine traces in solution by filtering through activated carbon

The retention of iodine traces (ppb) was investigated in small activated carbon filters (50 mg) from solution at a yielding rate exclusively determined by pH. Retention is approximately 100% at pH values of 4–6, while no retention of iodine traces occurs after filtering them through an activated carbon filter from very acidic and basic solutions (pH values of 1 and 11, respectively) with 0% yielding rate. Since activated carbon is a very pure material, this procedure may be an alternative method of the activation analysis of iodine traces in foodstuffs, because the half-life of ¹²⁸I, formed by (n,g) reaction, is only 25 minutes. It does not allow either the sample to be placed readily in solution or the radioisotope to be separated after irradiation with the purpose of attaining maximal accuracy and sensitivity in this type of analysis.