Review of the development in determination of ¹²⁹I amount and the isotope ratio of ¹²⁹I/¹²⁷I using mass spectrometric measurements

A long-lived radioisotope of iodine, ¹²⁹I, is a fission product and is released into our environment by spent nuclear fuel reprocessing plants or nuclear accidents. The measurements pertaining to ¹²⁹I are focused on evaluating the effects of using human-made nuclear fission products as environmental tracers and for monitoring samples from various types of matrices for regulating radioactive contaminants or radioactive waste repository safety. Thermal ionization mass spectrometry (TIMS), accelerator mass spectrometry (AMS), and inductively coupled plasma mass spectrometry (ICP-MS) have been applied to analyze ¹²⁹I and the isotope ratio ¹²⁹I/¹²⁷I from the environment and food samples. The advantages of these techniques in determination of iodine are high sensitivity, reasonable analysis time, relatively simple sample preparation process, and applicability to a large number of samples. This review describes the technical strategies for quantifying ¹²⁹I with the considerations of reducing the interference and matrix effect, decreasing the limit of detection, and availability of standard materials when using TIMS, AMS, and ICP-MS.