Characterisation of δ142Ce/140Ce Isotope Ratios in Geological Reference Materials using an SSB+Sm Doping and MC‐ICP‐MS Method

Abstract

We report the δ142/140Ce values for thirty‐three widely available geological reference materials (RMs), including igneous rocks, metamorphic rocks, sediments and soils. The Ce isotope ratios of twenty‐two Chinese RMs are reported for the first time. After chemical purification using TODGA resin (50–100 μm, Eichrom, USA), Ce isotope measurements of these RMs were conducted by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) with a combined standard‐sample bracketing (SSB) and Sm‐doping technique. The data quality of the Ce isotope results was assessed by repeated measurement of pure Ce reference solutions (NIST SRM 3110, JMC304, CDUT‐Ce) and well‐characterised geological RMs (BHVO‐2, BCR‐2, Nod‐A‐1, Nod‐P‐1, etc.). Our results are in excellent agreement with previously reported values within intermediate measurement precision (±0.04‰, 2s). The igneous rock and soil RMs showed limited variations in δ142/140Ce values, which ranged from ‐0.036 ± 0.018‰ to 0.062 ± 0.046‰ and ‐0.015 ± 0.015‰ to 0.029 ± 0.009‰, respectively. The river/marine sediments and Mn nodules displayed variable Ce isotope ratios ranging from ‐0.005 ± 0.018‰ to 0.141 ± 0.023‰, suggesting detectable Ce isotopic fractionation during low‐temperature processes.