Precise measurements of d???????88/86Sr for twenty geological reference materials by double-spike MC-ICP-MS

Analytical method using double-spike and MC-ICP-MS can provide high efficiency of measurement for stable Sr isotopic compositions (delta Sr-88/86). Here we report a method for high precision measurement of delta Sr-88/86 using MC-ICP-MS. A(84)Sr-Sr-87 double-spike was used to correct instrumental mass bias of stable Sr isotopes. Strontium was purified by a cation exchange resin (AG50W-X12, 200-400 mesh), and for samples with high Er, Yb, Lu, and Hf contents, an additional chromatographic purification procedure was applied. The potential effects of doubly charged ion isobaric inferences and different measurement conditions were rigorously evaluated to improve the analytical precision. Data quality was monitored by measuring three USGS reference materials (BHVO-2, AGV-2, and G-2) and two in-house reference materials, giving the long-term precision of 0.03%o (2SD) for delta Sr-88/86. Twenty reference materials, including nine igneous rocks, four sedimentary rocks, two sediments, and five soils, have delta Sr-88/86 values range from-0.06%o to 0.35%o, showing resolvable isotope fractionation during magmatic and supergene processes. This study provides a useful standard dataset for inter-laboratory comparison of stable Sr isotope studies. (C) 2022 Elsevier B.V. All rights reserved.