A potential fused quartz reference material for LA-MC-ICP-MS silicon isotope ratio measurement

Abstract

A new fused quartz glass reference material, NWU-Qtz, has been developed for in-situ Si isotope measurement by femtosecond laser ablation multi-collector inductively coupled plasma-mass spectrometry (fsLA-MC-ICP-MS). Major element characterization suggests the NWU-Qtz glass has no growth rim or zoning, and extensive measurements performed by fsLA-MC-ICP-MS demonstrate its homogeneity in Si isotopes. Traditional bulk Si isotope analyses of NWU-Qtz glass by solution nebuliser (SN)-MC-ICP-MS and gas source-isotope ratio mass spectrometry (GS-IRMS) yielded a mean δ30SiNBS-28 value of 0.12 ± 0.12‰ (2s, n = 6). Randomly selected chips of NWU-Qtz analyzed by fsLA-MC-ICP-MS gave a mean δ30SiNBS-28 value of 0.12 ± 0.17‰ (2s, n = 373). The intermediate measurement precision across five analytical sessions was better than 0.21‰ (2s), suggesting NWU-Qtz glass is suitable as a microanalysis reference material for Si isotope measurements. Six well-characterized reference materials analyzed using fsLA-MC-ICP-MS calibrated against NWU-Qtz yield δ30SiNBS-28 values in agreement with previously published data, further validating the feasibility of NWU-Qtz glass as a proposed reference material. The recommended mean δ30SiNBS-28 value for NWU-Qtz glass is 0.12 ± 0.12‰ (2s, n = 6) as determined by bulk SN-MC-ICP-MS and GS-IRMS analyses.