title: Determination of Trace Level Iodine in Biological and Botanical Reference Materials by Isotope Dilution Mass Spectrometry.
abstract: A method has been developed for the determination of trace level iodine in biological and botanical materials. The method consists of spiking a sample with129I, equilibration of the spike with the natural iodine, wet ashing under carefully controlled conditions, and separation of the iodine by co-precipitation with silver chloride. Measurement of the129I/127I ratio is accomplished by negative thermal ionization mass spectrometry using LaB6for ionization enhancement. The application of the method to the certification of trace iodine in two Standard Reference Materials is described.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: John W
authors.initials: JW
authors.lastname: Gramlich
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Murphy
keywords: Standard Reference Materials; biological material; botanical material; iodine; mass spectrometry; trace analysis