Analysis of sulfur and carbon isotope ratios in mixed matrices by secondary ion mass spectrometry: Implications for mass bias corrections

摘要

The effects of mixed matrices on mass bias during the measurement of ~(34)S/~(32)S and ~(13)C/~(12)C ratios by secondary ion mass spectrometry were investigated. Four samples consisting of fine-grained mixtures of 50-95 wt ‰ carbonate, 5-50‰ iron sulfide, and 0-5‰ iron oxide were analyzed. The measured δ~(34)S and δ~(13)C values on all four samples were identical within analytical error, and were identical to the values of the pure sulfide and carbonate minerals. These results indicate that, even for materials that are smaller than the primary ion beam contained in a matrix of different composition, it is possible to calibrate mass bias by using coarse-grained mineral standards.