Multiple elements separation(Fe-Mg-K-Ca) from a single rock digest and their isotope measurements on MC-ICPMS

Here we presented a fast and convenient method to separate Fe, Mg, K and Ca elments one by one via AGMP50 cation exchange resin from a single rock digest. The samples were dissolved in a mixture of concentrated HF-HNO₃ acids and then extracted in 2 M HCl for chemical column. When loading the sample to resin, B and high field strength elements( HFSEs) can be removed by diluted HCl and Al can be leached by a mixture of diluted HCl+HF acid. Following this step, Fe can be collected by another mixure of HCl+HF acid. Then, Li, V and Na were removed by diluted HCl (0.7M HCl) and Mg was cut by 1.3M HCl as eluent. After that, K was collected by 1.5 M HNO3 as eluent and Ca was collected by 3 M HCl. Based on this method, Fe, Mg, K and Ca can be effectively separated from other matrix elements from a single rock digest and recovery of all these elements are close to 100%.

A serious of international rock standard materials were used to test this method. Fe and Mg isotope measurements were carried out on multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS) by mode of standard-sample-standard, respectively. All the results are consisitent with the refered results within alalytical error, indicating this is a robust method to be used in measuring Fe and Mg isotopes. To date, K and Ca isotopes are still not measured yet, both of them will be tested in other labs in following days where can be measured them.