δ^114/110Cd Values of a Suite of Different Reference Materials

Abstract

The δ 114/110 Cd values of thirty‐four environmental and geological reference materials, including rocks, sediments, soils and biological samples, were determined on a Neptune Plus MC‐ICP‐MS instrument using a 111 Cd‐ 113 Cd double spike technique. An intermediate measurement precision of better than ± 0.074‰ (2 s ) was achieved with different reference materials (RMs) of highly variable matrices and Cd contents. The uncertainty of δ 114/110 Cd values was assessed by calculating the 95% confidence interval of the results from this study and the literature using Student's t ‐test. Our measurements of nine previously analysed RMs yielded δ 114/110 Cd values that were indistinguishable from previous results. New reference values for the thirty‐four geological and biological RMs are reported here. The comprehensive data set for these RMs provides guidelines for quality assurance and inter‐laboratory comparison for Cd isotope determination. The large range of δ 114/110 Cd values in rock (−0.001 to +0.287‰) and biological RMs (−0.806 to +0.142‰) suggests that Cd isotope ratio measurement results are a useful tool to study biogeochemical processes.