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

Abstract

We report the δ^142/140Ce 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 δ^142/140Ce 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.