Improved Two-Column Cd Chromatographic Separation Procedure and High-Precision Cd Isotope Analysis
Zhong Qiaohui
Peng Bingyu
He Chifeng
Guo Jiakai
Chu Gaobin
Yin Lu
Li Jie
Abstract：Accurate and high-precision analysis of Cd isotope composition in geological and environmental samples is of great significance for the study of marine primary productivity,paleoenvironmental changes,traceability of heavy metal Cd pollution,genesis of sulfide deposits,and marine Cd cycles.However,the low Cd content and complex matrix of environmental and geological samples pose challenges to high-precision Cd isotope analysis.For geological and environmental samples,this study developed an efficient and reliable two-column Cd chromatographic separation procedure and a high-precision Cd isotope determination method.In the first column of AG-MP-1M anion exchange resin,a large amount of the matrix,including≥99%ratio of Sn,was removed first,then Cd and a small amount of Sn were rapidly eluted using 4 mL of 1M HNO3 solution.Unlike the traditional second-column separation of Cd using TRU,Spec,UTVEA and BPHA extraction resins,in addition to Mo,Sn and Zr elements,TOPO resin can further separate other potential residual matrix elements such as Mg,Fe,Pb,Ti,V,Ag,Cu and Zn,etc.,without causing problems with resin-derived organic matter.Cadmium isotope ratio was conducted on Neptune Plus MC-CP-MS,using double spike method(111Cd-113Cd)for instrumental mass discrimination correction.The long-term external reproducibility for two standard solutions(NIST SRM 3108 and Spex Cd)was better than±0.05‰(2SD).Geological and environmental standard samples processed by the presented two-column Cd chromatographic separation procedure and then determined the δ114/110CdNIST 3108 values are consistent with the values reported in the literature within uncertainty,confirming the accuracy,reliability and efficiency of this method.Furthermore,the Cd isotope compositions of the domestic geological standard samples GSR-2 and GSR-3,and soil standard sample GSS-6a are reported for the first time,which are beneficially for evaluating the analytical capabilities between different laboratories and data quality control.Overall,this study will provide efficient and convenient new technique for the accurate and high-precision Cd isotope analysis of geological and environmental samples.
Keywords：Cd isotopeTOPO resinchromatographic separationdouble spike methodgeochemistry
Publication Date：2025-07-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 2511-2524 )