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 AE 0.074‰ (2s) 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.

Precise/small sample size determination of stable Cd isotope ratios of geological samples with double spike MC-ICP-MS

“…Elemental doping experiments suggest that the measured Cd isotope data were not signicantly affected when the measured solution has Pd/Cd < 10 2 , Fe/Cd < 10 −2 , In/Cd < 10 −3 , Sn/Cd < 10 −1 , Zr/Cd < 10 −2 , Nb/Cd < 10 −1 , Mo/Cd < 10 −2 , Ru/Cd < 10 −2 , Ga/Cd < 10 −2 , Ge/Cd < 10 −2 , Se/Cd < 10 −1 , and As/Cd < 10 −1 . The measured d 114/110 Cd values for rock and soil reference materials and one manganese nodule reference material covering a relatively wide range of Zn/Cd ratios all agree with the 23,25,27,28,33,43,48,51 Note that the data presented here were processed with the chemical purification method without using HBr, i.e., Zn was not separated from Cd. The lower panel denotes the absolute d 114/110 Cd values of these reference materials and the upper panel demonstrates the difference between the data measured in this study and the data reported previously.…”

“…Fig. 7 d 114/110 Cd values of six reference materials with varying Zn/Cd ratios compared to the data reported in previous studies 23,25,27,28,33,43,48,51. Note that the data presented here were processed with the chemical purification method without using HBr, i.e., Zn was not separated from Cd.…”

Double Spike-Standard Addition Technique and Its Application in Measuring Isotopes

“…(a) NIST 2711a was mixed with Cd-Sp26 solution in different fractions. The gray bar denotes the recommended value (0.557 ± 0.032‰) from Lu et al (b) JSd-2 was mixed with Cd-Mu10 solution in different fractions. The gray bar denotes the recommended value (−0.373 ± 0.057‰) from Lu et al…”

“…The δ 114/110 Cd values were 0.552 ± 0.013‰ (2SD, n = 5) for NIST 2711a and −0.351 ± 0.025‰ (2SD, n = 4) for JSd-2, and the δ 98/95 Mo values were −0.654 ± 0.039‰ (2SD, n = 6) for NOD-A-1and −0.030 ± 0.039‰ (2SD, n = 3) for BCR-2. These values are in good agreement with reported data ,,− and will be utilized to compare with other data in the following sections.…”

“…These were done, and the precision and accuracy of DSSA-derived results were evaluated. As shown in Figure , when f spl varies from 13.38 to 76.71%, δ 114/110 Cd values of NIST 2711a and JSd-2 calculated by DSSA agree well with the correspondingly published results, , and the precision is better than 0.079‰. Even if sample Cd is as low as 4.63 ng (NIST 2711a) or 4.31 ng (JSd-2), the δ 114/110 Cd values of NIST 2711a (0.540 ± 0.049‰) and JSd-2 (−0.347 ± 0.026‰) acquired by DSSA (Table S4) still match reported data , and the above results obtained by normal DS using higher amounts of analyte.…”