Abstract: STUDY ON THE RECOVERY OF IODINE AFTER ACID DIGESTION AND ASHING OF BIOLOGICAL SAMPLES USING 131I TRACER AND NEUTRON ACTIVATION ANALYSISHou Xiaolin Feng Xiangqian Li Chunsheng Ding Wenjun Qian Qinfang Chai Zhifang(Institute of High Energy Physics,Laboratory of Nuclear Analysis Techniques, the Chinese Acadmy of Sciences, P.O.Box 2732, Beijing 100080)Yang Yizhe(Monitor Station for Environmental Protection, Agriculture Department of Shanxi Province, Xi'an 710003)ABSTRACTThe recoveries of iodine in the procedure of acid digestion and ashing are studied using 131I tracer and instrumental neutron activation analysis.The results indicate that the recoveries of iodine are different in different acid digestion conditions.Under the optimum condition,more than 95% of iodine remained in the digestion solution.With high temperature ashing,the recovery of iodine is less than 2%.Adding alkaline into the samples can significantly improve the iodine recovery,but the ashing is incomplete in this case.Only 90% of iodine is recovered using alkalic ashing at 650℃.Key words Iodine Acid digestion Ashing 131I tracer Neutron activation analysis