Analysis of ³⁴S-¹⁸O isotopic clumping in sulfate by high-resolution mass spectrometry of SO₂F₂

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We present a novel technique to analyze δ³⁴S, δ¹⁸O, Δ'³³S, and ³⁴S-^18OO double-substitution (Δ'³⁴S¹⁸O) in sulfate by measuring SO₂F₂ gas with a high-resolution isotope ratio mass spectrometer. The external reproducibility (1 sem) is ± 0.09 ‰ (δ³⁴S), ± 0.2 ‰ (δ¹⁸O), ± 0.02 ‰ (Δ'³³S), and ± 0.08 ‰ (Δ'³⁴S¹⁸O) for repeated analyses of our in-house reference sulfate. Furthermore, accuracy of our analytical approach is demonstrated by the analysis of sulfate with distinct negative Δ'³⁴S¹⁸O, produced by mixing ³⁴S and ^18OO labeled sulfate solutions.Sulfates from laboratory experiments as well as from different natural environments show a total Δ'³⁴S¹⁸O range of approx. 1.5 ‰ and indicate that sulfates that form in low temperature surface environments have distinctively higher Δ'³⁴S¹⁸O than sulfates which form at elevated temperature at hydrothermal conditions.Therefore, Δ'³⁴S¹⁸O may be a promising tracer for sulfate sources.