Sulfur Isotope Analysis via SF6

All sulfur species - both reduced and oxidized moities - were converted to silver sulfide (Ag₂S) (see Johnston et al., 2007 (link); Leavitt et al., 2014 (link)). Following this, samples were fluorinated under 10X excess of F₂ headspace at 250°C, generating analyte sulfur hexafluoride (SF₆). SF₆ was then purified cryogenically via distillation at −117°C and chromatographically on a 6-foot molecular sieve 5 Å column coupled to a 6-foot HayeSep Q 1/8-inch column, with a TCD for detection and quantification. Purified SF₆ was measured as ${\text{SF}}_5^{+}$ (m/z of 127, 128, 129, and 131) on a Thermo Scientific MAT 253 (1σ: δ³⁴S ± 0.2 ‰, △³³S ± 0.006 ‰, △³⁶S ± 0.2 ‰).