DETERMINATION OF TRACE URANIUM IN FIVE SOIL SAMPLES DIGESTED BY MICROWAVE

Three soil samples and two radioactive river sediments are digested by microwave. Uranium in samples is extracted by TOPO and determined by liquid fluorimetry.The uranium isotope distribution in the two radioactive samples is measured by HP-ICP-MS. Compared with Chinese standard method GB11220.2-89, the procedure tried in this work is faster with less reagents. The recovery of uranium is higher and the precision of determination is also better. The determined abundance of)~234)U and)~235)U in GBW08304a is almost as same as the natural uranium. While the lighter isotopes of uranium in GBW08304 are somewhat depleted. The undigestable part of soil sample GBW-07404-GSS-4, explored by scanning electron microscope with EDS, is found to be composed of F,O,Al,Cu,Ti,etc.