The concentration and separation of trace metal ions chelated with either bis(2-hydroxyethyl)dithiocarbamate (HEDC) or 1,3-dimethyl-4-acetyl-2-pyrazolin-5-one (DMAP) by reversed-phase adsorption chromatography has been studied. Both reagents form water-soluble, neutral metal chelates that can be adsorbed onto a reversed-phase stationary phase;The concentration of metals of the hydrogen sulfide group from very dilute solution by chelation with HEDC and subsequent adsorption on a small column of Amberlite XAD-4 resin is described. Selectivity is achieved by pH adjustment or by the use of masking agents. The metal chelates are eluted from the column with acidic ethanol and determined by AAS;The adsorption properties of five XAD resins and three activated carbons have been studied for removing metal ions chelated with HEDC from industrial wastewater. Amberlite XAD-4 and Nuchar WV-B activated carbon were found to have the highest adsorption capacities. The adsorbents can be regenerated with methanol;The HEDC chelates of Co(III), Cu(II), Ni(II), and Hg(II) have been separated by reversed-phase HPLC. Co(III), Cu(II), and Ni(II) can be determined in the range of 0.005 - 10.0 mg/L, while Hg(II) can be determined in the range of 0.02 - 25 (mu)g/L after an on-line preconcentration step;The synthesis and characterization of DMAP is described. This reagent forms stable chelates with Zr(IV), Th(IV), and U(VI). The UO(,2)(DMAP)(,2) chelate has been prepared and characterized. A procedure for concentrating trace amounts of U(VI) chelated with DMAP onto XAD-4 resin is described.