Chemical separation and isotopic variations of Cu and Zn from five geological reference materials

This paper presents an adapted anion exchange column chemistry protocol which allowed separation of high-purity fractions of Cu and Zn from geological materials. isobaric and non-spectral interferences were virtually eliminated for consequent multiple-collector ICP-MS analysis of the isotopic composition of these metals. The procedure achieved similar to 100% recoveries, thus ensuring the absence of column-induced isotopic fractionation. By employing these techniques, we report isotopic analyses for Cu and Zn from five geological reference materials: BCR-027 blende ore (BCR), delta Cu-65 = 0.52 +/- 0.15 parts per thousand (n = 10) and delta Zn-66 = 0.33 +/- 0.07 parts per thousand (n = 8); BCR-030 calcined calamine ore (BCR), delta Zn-66 -0.06 +/- 0.09 parts per thousand (n = 8); BCR-1 basalt (USGS), delta Zn-66 = 0.29 +/- 0.12 parts per thousand (n = 8); NOD-P-1 manganese nodule (USGS), delta Cu-65 = 0.46 +/- 0.08 parts per thousand (n = 10) and delta Zn-66 = 0.78 +/- 0.09 parts per thousand (n = 9); SU-1 Cu-Co ore (CCRMP), delta Cu-65 = -0.018 +/- 0.08 parts per thousand (n = 10) and delta Zn-66 = 0.13 +/- 0.17 parts per thousand (n = 6). All uncertainties are +/- 2s, copper isotope ratios are reported relative to NIST SRM-976, and zinc isotope ratios relative to the Lyon-group Johnson Matthey metal (batch 3-0749 L) solution, JMC Zn. These values agree well with the limited data previously published, and with results reported for similar natural sample types. Samples were measured using a GVi IsoProbe MC-ICP-MS, based at the Natural History Museum, London. Long-term measurement reproducibility has been assessed by repeat analyses of both single element and complex matrix samples, and was commonly better than +/- 0.07 parts per thousand for both delta Zn-66 and delta Cu-65.