Sulfur Isotope Analysis of Sulfide and Sulfate Minerals by Continuous Flow-Isotope Ratio Mass Spectrometry

• Published in: Analytical chemistry (Washington) Vol. 73; no. 2; pp. 220 - 225
• Main Authors: Grassineau, N. V, Mattey, D. P, Lowry, D
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15-01-2001
• Subjects: Chemistry; Isotopes; Minerals; Scientific imaging; Sulfur
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac000550f

A continuous flow method (CF-IRMS) for the rapid determination of the sulfur isotope composition of sulfide and sulfate minerals has significant advantages over the classic extraction method in terms of the reduced sample quantity and a rapid analytical cycle of less than 8 min/analysis. For optimum performance, the technique is sensitive to a number of operating parameters, including sample weight and the O2 saturation of the Cu-reduction reactor. Raw data are corrected using a calibration based on five international and internal standards ranging from −17.3 to +20.3‰, which requires monitoring in order to correct the effect of changing δ18O of the sample gas on the measured mass 66 values. Measured sulfur contents are within 1−1.5% of expected values and the reproducibility of δ34S values is ±0.1‰ (1σ). The technique has been used successfully for more than 1000 analyses of geological samples with a wide range of δ34S from −20 to +20‰.