Neutron activation analysis of biological materials for sub PPM amount of mercury without determining the chemical yield

A simple method for the determination of sub ppm amounts of mercury in various biological materials by neutron activation analysis is described. Irradiated samples were decomposed with H2SO4 - fuming HNO3 mixture and mercury selectively isolated by ion exchange chromatography using Dowex 50X2(H+) and Dowex 1X4(Br-) columns in HBr medium. Finally the activity of 197Hg fixed on an anion exchange resin was measured either with a Ge(Li) or a NaI (Tl) detector. Both the high radiochemical purity of mercury and the practically quantitative recovery were achieved thus eliminating the necessity of determining the chemical yield. The method was used for the determination of mercury in flour, milk, butter, margarine, fish, etc. Total time of analysis (including counting) amounted to 6-7 hrs and several samples could be simultaneously analysed by one technician. (T.G.)