Determination of Cu, Zn, Ga, Ag, Cd, In, Sn and Tl in Geological Reference Materials and Chondrites by Isotope Dilution ICP-MS

Mass fractions of Cu, Zn, Ga, Ag, Cd, In, Sn and Tl were determined via isotope dilution quadrupole ICP-MS in twenty-one geological reference materials (RMs) and the carbonaceous chondrites Orgueil (CI1), Murchison (CM2) and Allende (CV3). The RMs comprise basaltic/mafic (BCR-2, BE-N, BHVO-1, BHVO-2, BIR-1, BRP-1, JB-2, OKUM, W-2, WS-E), intermediate/felsic (AGV-2, G-2, JA-2, RGM-1), ultramafic (DTS-2b, MUH-1, PCC-1, UB-N) and sedimentary (MAG-1, OU-6) rocks. Pressure digestion was applied for nonbasaltic samples to ensure effective sample digestion. For basaltic RMs, hot plate digestion was found to be sufficient for a quantitative recovery of the target elements. To minimise interferences and increase ion beam intensities during isotope ratio analyses by ICP-MS, separation of the target elements was carried out from single sample aliquots using a novel anion exchange procedure. The intermediate precision (2s) estimated from two to four replicate analyses was usually < 4% and results are in agreement with literature data, where available. Especially for Ag and Tl, the intermediate precision was compromised, likely due to low ion beam intensities and, hence, higher background and blank contributions. For ultramafic RMs, nugget effects and incomplete digestion might compromise the intermediate precision. Results for the carbonaceous chondrites Orgueil (CI1), Murchison (CM2) and Allende (CV3) agree well with previously reported data.