In this study, sodium trimetaphosphate was investigated as a new elution agent for anion-exchange separations of the rare earth elements and thorium. Distribution coefficients of these elements have been determined regarding four different concentrations of sodium trimetaphosphate (3.10(-3); 5.10(-3); 7.10(-3) and 0.01 M) on the strongly basic anion exchanger Dowex 1-X4, 200-400 mesh. The separation of the rare earths and thorium obtained from an Australian monazite has been studied by means of elution with sodium trimetaphosphate concentration gradient on a Dowex 1-X4 ion-exchange column. It was applied to the 5 and 250 mg samples. In a small scale separation, all rare earths and thorium were separated in 26 min with concentration gradient elution of sodium trimetaphosphate. Qualitative and quantitative determinations were realized by spectrofluorimetry. In this method the elution peaks are narrow, tailing effects are very small, Dy and Y are well separated. (C) 1999 Elsevier Science B.V. All rights reserved.