Simultaneous Determination of ~(143)Nd/~(144)Nd and ~(147)Sm/~(144)Nd Ratios and Sm-Nd Contents from the Same Filament Loaded with Purified Sm-Nd Aliquot from Geological Samples by Isotope Dilution Thermal Ionization Mass Spectrometry

摘要

Isotope dilution thermal ionization mass spectrometry (ID-TIMS) is the standard technique used to achieve precise ~(143)Nd/~(144)Nd and ~(147)Sm/~(144)Nd isotope ratios and accurate elemental concentrations of Sm-Nd. However, in previous studies, purified Sm and Nd fractions must be individually loaded onto different filaments for their accurate determination using TIMS because of severe isobaric interferences. Thus, the classical ID-TIMS technique is time consuming and laborious. In this study, a new method is proposed, which is able to acquire both ratios of ~(143)Nd/~(144)Nd and ~(147)Sm/~(144)Nd and concentrations of Sm-Nd simultaneously on the same filament arrangement. The measurement time and filament consumption are reduced by 50percent with the current method, and therefore, the operation cost of TIMS is significantly reduced. A mixed ~(152)Sm-~(148)Nd spike was employed to achieve accurate results after spike subtraction and isobaric interference corrections. Results obtained from a series of standard rock samples are in good agreement with recommended values, within +-0.003percent for the ~(143)Nd/~(144)Nd ratio and +-1percent for the ~(147)Sm/~(144)Nd ratio.