Determination of mercury in biological and environmental materials by instrumental neutron activation analysis

Mercury is determined by instrumental neutron activation analysis and Ge(Li) gamma-ray spectroscopy in biological and environmental samples. Samples are sealed in polyethylene vials and irradiated with standards for 8–10 hours in a water cooled assembly at a thermal neutron flux of 8.1012 neutrons/cm2/second. High resolution gamma-ray spectroscopy allows the measurement of the 279 keV gamma ray of203Hg. Corrections are made for203Hg decay and for75Se interference on the 279 keV gamma-ray. No interferences are important in biological or environmental samples and the problem of mercury volatilization and loss is eliminated by cooling during irradiation and the use of a sealed irradiation/counting container. The precision (counting statistics) of a single determination range from 0.4 to 15% (relative standard deviation). The detection limit for mercury varies with sample composition. For human blood the detection limit is 0.0035 ppm Hg.