Abstract: ICP-MS was applied to the determination of 24 non-rare-earth elements present as impurities in 15 high-purity rare-earth samples.Matrix effect,taking Sm,Tb and Tm as testing objects,were studied.Non-mass spectrometric interferences induced by matrix effect were compensated by the addition of indium as internal standard.Analysis of samples having MS-interferences was carried out after the separation of the matrix elements.Detection limits,recovery and RSD′s for the method were found in the range 1.8-390 ng·g-1,92%-107% and 2.9%-5.4% respectively.