H₂O, CO₂, F, S, Cl, and P₂O₅ analyses of silicate glasses using SIMS: Report of volatile standard glasses

Abstract

Secondary ion mass spectrometry (SIMS) is a powerful technique for measuring low-concentration volatile elements such as H, C, F, Cl, and S in micrometer-sized samples. The number of studies on volatiles in terrestrial and extraterrestrial materials using SIMS, particularly in volcanic glasses, has been rapidly increasing in the recent decade. Although SIMS has the capability of measuring volatile abundances at the level of parts per million (ppm) in samples, standard materials are required to obtain reliable datasets. We therefore prepared fourteen glass standards, including nine synthetic glasses and five natural glasses (0.02–4.8 wt% for H₂O, 85–9400 ppm for CO₂, 55–2957 ppm for F, 55–2833 ppm for Cl, and 51–1372 ppm for S), which covered the broad ranges of volatile contents in volcanic silicate glasses reported to date. H₂O and CO₂ concentrations of the glasses were determined by Fourier transform infrared spectroscopy (FTIR) and F, Cl, and S concentrations were determined by ion chromatography following pyrohydrolysis. Two SIMS instruments, NanoSIMS 50L and IMS-1280HR, were used to measure the volatile contents including H₂O, CO₂, F, Cl, and S in addition to the P₂O₅ content in a series of volatile standard silicate glasses together with four basaltic glass standards distributed by the United States Geological Survey for the P₂O₅ content. The ³⁰Si-normalized intensities of volatile elements and ³¹P showed good correlations with volatile and P₂O₅ abundances in standard glasses in all ranges with the squared correlation coefficient (R²) > 0.996 except for CO₂, where R² = 0.992. We confirmed that most synthetic and natural glasses are of good quality for volatile standards of silicate glasses.