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 with (129)I, 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 the (129)I/(127)I ratio is accomplished by negative thermal ionization mass spectrometry using LaB(6) for ionization enhancement. The application of the method to the certification of trace iodine in two Standard Reference Materials is described.