Chemical procedure for Zn purification and double spike method for high precision measurement of Zn isotopes by MC-ICPMS

We have developed a new technique for Zn separation and high precision isotope measurement of geological and cosmochemical samples. The protocol includes sample digestion, chemical separation and purification with ion-exchange chromatography and a double spike isotopic measurement using a MC-ICPMS. An analytical precision of 0.02 parts per thousand (2SD) for Zn-66/Zn-64 was obtained by multiple measurements of a secondary standard (JMC-Lyon). In order to test the accuracy of our method, we analyzed the Zn isotopic composition of the geological reference materials BHVO-2, AGV-2, BIR-1, BCR-2 and JB-2, which are consistent with previous measurements from the literature. The measurements of geological reference standards show an external reproducibility ranging between 0.02 and 0.05 parts per thousand (2SD). This study provides a high precision and accuracy Zn isotope double spike technique for geological and cosmochemical rock samples, while requiring only 28 ng Zn per analysis, and is therefore suitable for the study of high temperature igneous or cosmochemical processes. (C) 2020 Elsevier B.V. All rights reserved.