This paper introduces a new type of extractant, sym-dibenzo-16-crown-5-oxyhydroxamic acid (HL). The extraction of UO
, Na+, K+, Sr2+, Ba2+ and Br– were studied with HL in chloroform. The results obtained show that UO
can be quantitatively extracted at pH above 5, whereas the extractions of K+, Na+, Ba2+ and Br– are negligible in the pH range of 2–7. The dependence of the distribution ratio of U(VI) on both the concentration of the HL and pH are linear, and they have the same slope of 2. This suggests that U(VI) appears to form a 12 complex with ligand.Uranium (VI) can be selectively separated and concentrated from interfering elements such Na, K, Sr and Br by solvent extraction with HL under specific conditions. The recovery of uranium is nearly 100% and the radionuclear purity of uranium is greater than 99.99%. Therefore, it has greatly improved the sensitivity and accuracy for the detection of trace uranium from seawater by neutron activation analysis.