Estimation of expanded uncertainties for Iodine measurement In biological reference materials by epithermal INAA and anticoincidence gamma-ray

摘要

The determination of low levels of iodine in biological materials is generally difficult by instrumental neutron activation analysis (INAA) and sometimes even by epithermal INAA (EINAA) using cadmium filters due to high dead times and Compton background from the y-rays of interfering nuclides in the region of the 443-keV photopeak of ~(128)I. Both conventional and pseudo-cyclic EINAA in conjunction with anticoincidence gamma-ray spectrometry (EINAA-AC) methods using Cd+B filters were developed for the determination of ppb levels of iodine in selected biological standard reference materials (SRMs) issued by NIST. The NIST SRMs analyzed by EINAA-AC for their iodine contents were 1575 (Pine Needles), 1577b (Bovine Liver), 1515 (Apple Leaves), 1547 (Peach Leaves) and 1573a (Tomato Leaves).