Microwave-based digestion method for extraction of 127I and 129I from solid material for measurements by AMS and ICP-MS

Abstract

This work presents a microwave-based digestion method followed by a radiochemical extraction procedure to extract iodine from environmental matrices that provides iodine in a form suitable for the measurement of 129I by AMS, with shorter preparation times, small sample sizes and higher automation than previous methods. Samples were digested by a microwave digestion method in closed vessels using HNO3 as oxidizing agent. Following chemical iodine extraction consisted in an organic compound extraction followed by an aqueous solution extraction and iodine precipitation. Prepared samples were used to measure 127I by ICP-MS and 129I by AMS. The method was validated by ICP-MS measuring 127I content in standard reference materials covering a wide variety of biological, soil and sediment matrices: 1547 Peach Leaves, 1537a Tomato Leaves, 1549 Non-Fat Milk Powder, 2704 Buffalo River Sediment, 2711 Montana Soil and 1648 Urban Particulate Matter from the National Institute of Standards and Technology, IAEA-375 Soil and IAEA SL-1 Lake Sediment from the International Atomic Energy Agency and 186 Pig Kidney from Community Bureau of Reference. The recoveries with respect to the reference values were about 90%. Iodine losses during chemical extraction could be due to its volatilization as HI or I2 in acid means. Accurate results for determination in certified materials and good recoveries.