Methods and Reference Materials for Measuring Iodine Status

The assessment of iodine status, and iodine intake from foods and supplementation in world populations, is currently an area of increasing focus. The Analytical Chemistry Division (ACD) at the National Institute of Standards and Technology (NIST) is providing support to the quality assurance of analytical measurements of iodine in clinical materials, foods and supplements through the development of Standard Reference Materials (SRMs) with certified values for iodine. The availability of such materials provides substantive tools to improve the accuracy and quality of laboratory measurements. A program is underway to add iodine values to several SRMs which include SRM 3280, a multivitamin supplement, and important nutritional SRMs, SRM 3233 (Fortified Breakfast Cereal), SRM 1549a (Whole Milk Powder), SRM 1845a (Whole Egg Powder), SRM 1849a (Infant/Adult Nutritional Formula), SRM 2383a (Baby Food Composite), and SRM 1954 (Fortified Human Milk), as well as two clinical materials, SRM 2670a (Toxic Elements in Urine), and SRM 3668 (Mercury, Perchlorate and Iodide in Frozen Human Urine). The higher-order analytical methods used for value assignment of iodine in these materials, an overview of the SRM certification process, and the role of SRMs in the quality assurance of laboratory measurements will be presented. Acknowledgements: This work was supported with funding from the National Institutes of Health (NIH), Office of Dietary Supplements (ODS) under interagency agreement number Y1-OD-1239–01.