A three-column system consisting of a combination of C 18 reversed phase, Dowex anion-exchange resin and the chelating resin Chelamine is described. This method permits the simultaneous preconcentration and differentiation between neutral hydrophobic organic metal complexes, anionic complexes and the “free ion” concentration of the transition metals in water samples with complex matrices. General operating conditions were established by numerous experiments with model substances. The sample analyses can be made without any previous treatment and hence the pre-established natural equilibria are unadulterated. The method was used in the investigation of several fresh-water and sea-water samples for the determination of Cu 2+, Cd 2+, Pb 2+ and Mn 2+ and showed excellent reproducibility.