Abstract: A new method of stepwise dilution was proposed to study the matrix effects in the determination of REEs by ICP-MS. The highest tolerant level of matrix obtained by this method coincided with that obtained by the conventional method. Trace REEs in different samples were determined directly by ICP-MS without the use of internal standard and matrix matching and the determined values are in a good agreement with the certified values. Stepwise dilution method is a potential method in practical analysis with the advantages such as simplicity for operation, low cost, no need for higher purity matrix, without the use of internal standard and suitable to any other samples with complicated matrix.

Key words: Inductively coupled plasma mass spectrometry(ICP-MS), Matrix effect, Rare earth elements