Determination of δ44/40Ca and δ56/54Fe in Geological Materials Combined with a Simplified Method for their Separation Using a Single TODGA Resin Column

A measurement procedure has been developed for the determination of delta Ca-44/40 and delta Fe-56/54 in geological samples by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) and thermal ionisation mass spectrometry (TIMS), combined with a single TODGA resin column for their separation. Using the TODGA resin for separation of geological materials, Fe and Ca ions were eluted by using 8 ml of 1.5 mol l(-1)HNO(3)and 8 ml of 2 mol l(-1)HCl, respectively, and their recovery was 99.7 +/- 0.4% (n = 3) for the former and 99.4 +/- 0.6% (n = 3) for the latter after removal of matrix and interfering elements using 12 ml of 6 mol l(-1)HCl. This procedure was validated by the reference materials AGV-2, BCR-2 and BHVO-2. Their Fe and Ca isotope data were comparable to their literature values, confirming a single column containing TODGA resin can be applied to the separation of Fe and Ca in geological samples for determination of their isotope ratios free of measurement bias.