DETERMINATION OF RARE EARTH ELEMENTS URANIUM AND THORIUM IN ROCK SAMPLES BY HIGH RESOLUTION INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY WITH MEMBRANE DESOLVATION

This paper presents a method for determing of 17 elements including rare earth elements uranium and thorium in rock samples by high resolution ICP-MS with membrane desolvation. Samples are dissolved with high pure HNO,-HF-HCIO, digestion and introduced to HR- ICPMS by membrane desolvating microcefltric nebulizer introduction system (MCN-6000). The system can diminish the formation of multi-atom ions that is one of the most interferences in ICP-MS, and increase the nebulization efficiency of sample. the sensitivities of The elements are increased about 10 times compared to common nebulizer. The determination limits and relative standard deviations for solid sample depending on different elements are bewteen 0.07-1.3 ppt and 0.26%-7%, respectively. The national geological reference materials were determined and the accuracy is better than 10% corresponding to the certified values.