The use of ICP-OES to determinate ”Rare Earth Elements“ in different matrices often fails because of high spectral interferences. To achieve an correct result the use of a sample preparation is advisable. In this work Extractionchromatography is used as sample preparartion. Three different substances were used as stationary phase. These are Triazaheptan-1,4,7,7-tetraaceticacid (DETATA), Tetraphenylmethylendiphosphineoxide. (TPMDPO) und Tri-n-octylphosphineoxide (TOPO). If DETATA is used as staionaric phase the recovery of REE in the final solution is reduced to 40-60% when bivalent ions such as Ni2+ and Fe2+ are present in the sample. So this substance is not reliable in the use as stationaric phase if the sample is a steelmatrix. In highly concentrated KCl-solution as matrix the recovery of REE’s increases to 98%. In the second part the results of the experiments with TPMDPO are presented. In the presence of Cr3+, Ni2+ oder Mn2+ the recovery decrease significantly. So this substance is also unusable if the matrix is steel. The third examined organic substance is TOPO. If NH4NO3 is added as salting-out material and after reducing the solution with hydrazine the recovery of REE’s is qunatitative. The improvement of the detection limit exceeds the factor of 10 if ICP-OES is the used analysing method.