Fully resolved high-precision measurement of 36 S for sulfur reference materials.

Autor: Sun J; Department of Geology, University of Maryland, College Park, Maryland, USA., Farquhar J; Department of Geology, University of Maryland, College Park, Maryland, USA.; Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA.
Jazyk: angličtina
Zdroj: Rapid communications in mass spectrometry : RCM [Rapid Commun Mass Spectrom] 2024 Jul 30; Vol. 38 (14), pp. e9768.
DOI: 10.1002/rcm.9768
Abstrakt: Rationale: Advances in sulfur isotope measurement techniques have led to increased analytical precision. However, accurate measurement of 36 S remains a challenge. This difficulty arises primarily from unresolved isobaric interferences of 36 SF 5 + at m/z = 131 u, 186 WF 4 2+ and 12 C 3 F 5 + , which lead to scale compression. Theoretically, unresolved interference with 2% relative intensity could cause 1‰ underestimation in a sample with real δ 36 S = +60‰.
Methods: Our study develops an interference-free four-sulfur isotope measurement method by using the high-resolution mass spectrometer Panorama. The mass resolving power of Panorama allows the distinction of 186 WF 4 2+ and 12 C 3 F 5 + from 36 SF 5 + .
Results: The 186 WF 4 2+ relative intensity was initially 9.4% that of 36 SF 5 + but reduced to 1.5% through tuning, while 12 C 3 F 5 + relative intensity dropped from 74% to 40% after flushing with air. Three IAEA standards were analyzed with both Panorama and MAT 253. We obtained Δ 36 S IAEA-S-2  = 1.238 ± 0.040‰ and Δ 36 S IAEA-S-3  = -0.882 ± 0.030‰, relative to IAEA-S-1, from Panorama, and Δ 36 S IAEA-S-2  = 0.18 ± 0.02‰ and Δ 36 S IAEA-S-3  = 0.11 ± 0.14‰ from MAT 253, while δ 34 S values from the two instruments are consistent.
Conclusion: The measurement discrepancies on 36 S between Panorama and MAT 253 highlight the impact of scale compression due to unresolved isobaric interferences. Resolving this problem is crucial for accurate 36 S analysis. We recommend replacing the filament material with rhenium, tuning the filament voltage, and avoiding carbon in instruments to eliminate or mitigate interferences. We propose future systematic efforts to calibrate the δ 33 S, δ 34 S, and δ 36 S of IAEA-S-1, IAEA-S-2, and IAEA-S-3 and advise bracketing all three reference materials in the measurement sequences, to enable calibration.
(© 2024 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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