Uranium determination in sea water

Uranium analyses of sea-water samples taken from different locations were carried out by the isotope-dilution method. Uranium was separated by liquid-liquid extraction from 2000 ml of sea water, for each determination. The small residue of uranium resulting from the chemical separation was analyzed by mounting it on a tantalum filament and examining the U0₂⁺ thermal ions in a Nier six-inch radius, 60° sector-type mass spectrometer. The results show a concentration of 3.1 to 3.5 micrograms of uranium per kilogram of sea water, with a uranium/sahnity ratio of 9.0 to 9.8 X 10^minus;8.