Absolute Determination Of Samarium Isotopic Abundance By Multiple-Collector Inductively Coupled Plasma Mass Spectrometry

Standard solutions of different samarium isotope abundance were prepared by blending high concentrated isotope of Sm-152 and Sm-154, which were measured by multiple-collector inductively coupled plasma mass spectrometry(MC-ICPMS) to gain the correction factor. In order to achieve better accuracy, solution concentration, nebulizer gas flow rate, sampling position and collision gas flow rate have been studied. Continuous measurement of standards and samples with constant conditions was needed for correction of results because of the instability of sampling system and ICP source. The same samples were determined using thernal ionized mass spectrometry (TIMS). The measurement results of two methods were compared and the corrected results of main isotopic ratios were almost accordant better than 0.03%. The precision of MC-ICPMS results was comparative with that of TIMS, but the mass bias of latter was approximately an order of magnitude greater than that of MC-ICPMS. By correction of isotopic standards, the absolute measurement method of MC-ICPMS was established.