Determination of ¹²⁹I in Fukushima Soil Samples by ICP-MS with an Octopole Reaction System

Abstract

A method was developed for the determination of ¹²⁹I in soil samples that uses an ICP-MS equipped with an octopole reaction system. Oxygen was used as the reaction gas for reducing the background intensity of m/z 129, principally by ¹²⁹Xe⁺. The contribution of polyatomic ions, such as ¹²⁷IH₂⁺, could be effectively corrected for by assuming a production ratio (¹²⁷IH₂⁺/¹²⁷I⁺ = 3 × 10⁻⁸). The measured ¹²⁹I/¹²⁷I ratios in a NIST standard solution and Fukushima soil samples are consistent with the expected value within the analytical error. This method provides a powerful tool for investigating radioiodine contamination in Fukushima and elsewhere.