Sodium trimetaphosphate was investigated as a new elution agent for the cation-exchange separation of some metal ions. Cation-exchange equilibrium distribution coefficients with Dowex 50W-X8, 200-400 mesh, a sulfonated polystyrene resin, are presented for twelve elements in different concentration ranges between 0.01 M and 0.3 M sodium trimetaphosphate. By considering these distribution coefficients, the separation of twelve metal ions has been performed with 0.1 M sodium trimetaphosphate at room temperature. It was applied as a small scale (0.5 mg of each element) and large scale (0.5 mmol of each element). It has been seen that this separation can be used for the determination and preparative separation of the metal ions. As an elution agent sodium trimetaphosphate has the following advantages over the other elution agents. The elution peaks are narrow and nearly symmetrical. The tailing effects are very small and separation time is shorter than those of other known methods. Qualitative and quantitative determination of eluted ions were performed by spectrofluorimetry. (C) 1999 Published by Elsevier Science BN. All rights reserved.