Amrani, Alon and Sessions, Alex L. and Adkins, Jess F. (2009) Compound-Specific δ^(34)S Analysis of Volatile Organics by Coupled GC/Multicollector-ICPMS. Analytical Chemistry, 81 (21). pp. 9027-9034. ISSN 0003-2700 http://resolver.caltech.edu/CaltechAUTHORS:20100614-153741613
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We have developed a highly sensitive and robust method for the analysis of δ^(34)S in individual organic compounds by coupled gas chromatography (GC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The system requires minimal alteration of commercial hardware and is amenable to virtually all sample introduction methods. Isobaric interference from O_2^+ is minimized by employing dry plasma conditions and is cleanly resolved at all masses using medium resolution on the Thermo Neptune MC-ICPMS. Correction for mass bias is accomplished using standard−sample bracketing with peaks of SF6 reference gas. The precision of measured δ^(34)S values approaches 0.1‰ for analytes containing >40 pmol S and is better than 0.5‰ for those containing as little as 6 pmol S. This is within a factor of 2 of theoretical shot-noise limits. External accuracy is better than 0.3‰. Integrating only the center of chromatographic peaks, rather than the entire peak, offers significant gain in precision and chromatographic resolution with minimal effect on accuracy but requires further study for verification as a routine method. Coelution of organic compounds that do not contain S can cause degraded analytical precision. Analyses of crude oil samples show wide variability in δ^(34)S and demonstrate the robustness and precision of the method in complex environmental samples.
|Additional Information:||© 2009 American Chemical Society. Received for review July 24, 2009. Accepted September 21, 2009. Publication Date (Web): October 6, 2009. We thank Nathan Daleska, Alex Gagnon, Seth John, Magdalena Osburn, and Sean Sylva for assistance with instrumentation and experiments; Tim Lyons, Bill Gillooly, Zeev Aizenshtat, and Ward Said Ahamed for S-isotope analyses of organic standards; Yongchun Tang for crude oil samples; Charles Douthitt, Johannes Schweiters, Claudia Bouman, and Shona McSheehy for advice and support in constructing the instrumentation interface and for useful discussions. This work was supported by The Davidow Endowment for Environmental Science and Engineering at Caltech, the Texaco (Prize) postdoctoral fellowship of Caltech to A.A., and NSF Grant OCE- 0852362 to J.F.A.|
|Official Citation:||Compound-Specific δ34S Analysis of Volatile Organics by Coupled GC/Multicollector-ICPMS Alon Amrani, Alex L. Sessions, Jess F. Adkins Analytical Chemistry 2009 81 (21), 9027-9034|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||15 Jul 2010 21:31|
|Last Modified:||26 Dec 2012 12:08|
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