Jointly published by Elsevier Science S. A., Lausanne and Akad~miai Kiad6, BzMapest J.Radioanal.Nucl.Chem.,Letters 213 (I) 65-70 (1996) DETERMINATION OF MERCURY AND ARSENIC IN FRESH WATER BY NEUTRON ACTIVATION ANALYSIS Nguyen Van Suc, Mai Minh Hung*, Nguyen Van Hung Nuclear Research Institute, Dalat, Vietnam *Taynguyen University, Vietnam Received 16 February 1996 AccePted I March 1996 Neutron activation analysis has been applied for the determination of Hg and As in fresh- water samples. Preconcentration of Hg and As from the samples before irradiation by using active carbon for scavenging the chelate com- plex of Hg with dithizone at pHI and Fe(OH) 3 for co-precipitating arsenic was used. After irradiation, mercury was determined by direct counting of the irradiated active carbon. Ar- senic was separated from Fe(OH) 3 by precipi- tating arsenic in the metal form after remov- ing 122Sb by extraction in 2N HCI with Ni- diethyldithiophosphoric acid in carbon tetra- chloride. The method is simple and reliable. INTRODUCTION The determination of arsenic and mercury at trace levels in water has assumed great importance today be- cause of their high toxicity. The presence of these el- ements in the human body even at low levels may cause detrimental health effects. 0236-573ll90/US $12.0 Copyright C~3 1990 Akad~miai Kiad6, Budapest All r~ghts reserved 65