[en] The four reagents tested were N,N-dihexylacetamide (DHA), 2,6-diacetylpyridine bis(furoylhydrazone) (H₂dapf), 1,3-dimethyl-4-acetyl-2-pyrazolin-5-one (DMAP) and N-methylfurohydroxamic acid (NMFHA). DHA and H₂dapf were investigated for their complex formation with uranium, and DMAP and NMFHA were used as chelating agents in high performance liquid chromatography (HPLC). Uranium(VI) is preferentially extracted from nitric acid solutions using DHA in toluene. The extraction characteristics of the U-DHA complex are studied. A 119,000 μgL^-1 U solution is analyzed for twenty-six elements. The U is extracted with DHA, and the trace metal ions are then determined by inductively coupled plasma-mass spectrometry. Uranium must be removed from the sample before analysis to prevent ionization suppression. H₂dapf is synthesized and characterized. Studies of the complexation of metal ions with H₂dapf is described. U(VI) forms a stable complex with H₂dapf, and a procedure for selectively determining trace U by spectrophotometry is presented. DMAP complexes of Cu(II), Fe(III), Ga(III), Th(IV), U(VI), V(V), and Zr(IV) are separated using reversed phase HPLC. NMFHA complex of Al(III), Fe(III), Hf(IV), Nb(V), Sb(III), and Zr(IV) are separated using reversed phase HPLC. NMFHA is also used to separate uranium(VI) from trace lanthanide ions. 266 refs., 46 figs., 24 tabs