Abstract: ENAA OF IODINE IN STANDARD REFERENCE MATERIAL LYOPHILIZED HUMAN URINEZhang Yongbao Wang Ke(China Institute of Atomic Energy， Beijing 102413)Wang Ganfeng(China Institute of Occupational Medicine, Beijing 100050)ABSTRACTThe contents of iodine in two kinds of standard reference materials lyophilized human urine are determined by ENAA. The sensitivity of this method is ten times higher than that of TNAA, and the relative standard deviations of ten measurements are 2.9% and 3.3%, respectively. Two certificated reference samples are used for verification of the analysis. The analytical results are in agreement with the recommended values, and the relative error is less than 3%.Key words lyophilized human urine standard reference material iodine epithermal neutron activation analysis(ENAA)