Sequential Chemical Separation of Cr and Ti from a Single Digest for High Precision Isotope Measurements of Planetary Materials

Yuki Hibiya, Tsuyoshi Iizuka, Katsuyuki Yamashita, Shigekazu Yoneda, Akane Yamakawa

Geostand Geoanal Res. doi:10.1111/ggr.12249
First published: 19 November 2018


“Combined determination of Cr and Ti isotopes of planetary materials offers a means with which to investigate their genetic relationship and the evolution of the protoplanetary disk. Here, we report the new sequential chemical separation procedure for combined Cr and Ti isotope ratio measurements. It comprises three steps: (i) Fe removal using AG1‐X8 anion exchange resin, (ii) Ti separation using TODGA resin, and (iii) Cr separation using AG50W‐X8 cation exchange resin (with one additional step of Ti purification using AG1‐X8 anion exchange resin for samples having high Cr/Ti and Ca/Ti ratios). We applied the proposed procedure to terrestrial and meteorite samples with various compositions. Typical recovery rates of 90–100% were achieved with total procedural Cr and Ti blanks of 3–5 and 2–3 ng, respectively. We measured the Cr and Ti isotope compositions of the separated samples using thermal ionisation mass spectrometry and multiple collector‐inductively coupled plasma‐mass spectrometry, respectively. Our Cr and Ti isotope data were found to be consistent with those of previous studies of individual Cr and Ti isotopic compositions of the meteorites. These results demonstrate the capability of our separation method when applied to combined high‐precision Cr and Ti isotope analyses for single digests of planetary materials.”