Preconcentration and determination of cadmium in water by reversed-phase column chromatography and atomic absorption

Studies were made of the solvent extraction of cadmium(II) from hydrochloric acid into a tri-n-octylamine—cyclohexene mixture. Distribution ratios, as a function of amine and acid concentration, were determined and this information was used to establish optimum extraction conditions and the probable nature of the extracted species. This system was used as the basis for the development of a reversed-phase column chromatographic technique for preconcentrating Cd(II). The amine—cyclohexene phase was coated on an inert macroreticular resin (XAD-2) to provide a stable column. With this system, Cd(II) in acidified water samples as large as 31. may be concentrated to 10 ml and determined by conventional atomic absorption. Interferences were studied, and the method was applied to the analysis of fresh-water streams for Cd(II).