Abstract
Ion exchange on Al2O3 columns has been used to quantitatively measure As, Sb, Mo, Th and W in silicate rocks. This procedure requires hour long thermal neutron irradiations, rapid ion exchange after the rocks are brought into solution by peroxide fusion, and short γ-ray counts on a Ge(Li) detector. Detection limits of 10 ppb have been achieved for As, Sb, Th and W. The best detection limit observed for Mo is 3 ppm.