Neutron Activation Procedures for Silver Analysis in Precipitation

Abstract

Laboratory techniques have been developed for concentrating and isolating silver from aqueous samples. When these concentrated samples are activated in a thermal neutron flux of 4 ? 1012n cm?2 sec?1, quantitative measurements down to 10?9 gm masses of silver can be made. When 1-liter samples of water are used, the lower limit of detection of silver in the sample is about 3 ? 10?12 gm cm?3 concentration. Typical Ag concentrations being observed in snow collected in the western United States range from this lower limit to 10?8 gm cm?3, the majority being between 10?9 and 10?11. The lower limit does not therefore appear to be a serious factor in silver determinations in snow collected at ground stations. The system described is a non-destructive one, the accuracy of measurement using ?-ray spectrometry being 1, 2, 10 and 80% for masses of silver 10?6, 10?7, 10?8 and 10?9 gm, respectively. By using a 24-sec half-life radioisotope for the Ag determination, the cost of activation and turn-around time on samples is kept to a minimum. Data analysis is computerized and rapid.