Measurement of Cadmium Isotopic Composition of Standard Solutions by Multi-collector Inductively Coupled Plasma Mass Spectrometry

A method for precise isotopic analysis was presented in this paper. Measurement of Cd isotopic composition was carried out by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS), using standardsample bracketing technology for mass bias correction. The Cd isotopic data were reported relative to SPEX Cd standard solution and expressed as the δ114/110Cd. Four Cd standard solutions (JMC, SPEX-1, BAM-1012 and Münster) were repeatedly measured and accurate and reproducible Cd isotopic results were obtained in order to assess the accuracy of the measurements. The results showed that the precision for Cd solution measurements was 0.07‰~0.13‰ （δ114/110Cd）. The values of δ114/110Cd measured for the JMC, SPEX-1, BAM-1012 and Münster relative to the SPEX standard solution （δ114/110Cd=0) were 0.55‰, 0.56‰, -0.65‰and 5.14‰ respectively. It indicated that the Cd isotopic composition from different batches of SEPX was different and the variation of δ114/110Cd between SPEX and SPEX-1 was 0.56‰. Considering this difference of Cd standards between SPEX and SPEX-1, the δ114/110Cd of Münster and BAM-1012 relative to SPEX were identical to the values measured in other studies, relative to SPEX-1 solution or JMC solution, when taking into account the uncertainty.