Smith, Derek A. and Sessions, Alex L. and Dalleska, Nathan and Orphan, Victoria J. (2017) Rapid Quantification and Isotopic Analysis of Dissolved Sulfur Species. Rapid Communications in Mass Spectrometry, 31 (9). pp. 791-803. ISSN 0951-4198. http://resolver.caltech.edu/CaltechAUTHORS:20170306-080715333
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Rationale: Dissolved sulfur species are of significant interest, both as important substrates for microbial activities and as key intermediaries in biogeochemical cycles. Species of intermediate oxidation state such as sulfite, thiosulfate, and thiols are of particular interest but are notoriously difficult to analyze, because of low concentrations and rapid oxidation during storage and analysis. Methods: Dissolved sulfur species are reacted with monobromobimane which yields a fluorescent bimane derivative that is stable to oxidation. Separation by Ultra-Performance Liquid Chromatography (UPLC) on a C18 column yields baseline resolution of analytes in under 5 minutes. Fluorescence detection (380 nm excitation, 480 nm emission) provides highly selective and sensitive quantitation, and Time of Flight Mass Spectrometry (TOF-MS) is used to quantify isotopic abundance, providing the ability to detect stable isotope tracers (either ^(33)S or ^(34)S). Results: Sulfite, thiosulfate, methanethiol, and bisulfide were quantified with on-column detection limits of picomoles (μM concentrations). Other sulfur species with unshared electrons are also amenable to analysis. TOF-MS detection of ^(34)S enrichment was accurate and precise to within 0.6% (relative) when sample and standard had similar isotope ratios, and was able to detect enrichments as small as 0.01 atom%. Accuracy was validated by comparison to isotope-ratio mass spectrometry. Four example applications are provided to demonstrate the utility of this method. Conclusions: Derivatization of aqueous sulfur species with bromobimane is easily accomplished in the field, and protects analytes from oxidation during storage. UPLC separation with fluorescence detection provides low μM detection limits. Using a high-resolution TOF-MS, accurate detection of as little as 0.01% ^(34)S label incorporation into multiple species is feasible. This provides a useful new analytical window into microbial sulfur cycling.
|Additional Information:||© 2017 John Wiley & Sons, Inc. Accepted manuscript online: 1 March 2017; Manuscript Accepted: 23 February 2017; Manuscript Revised: 6 January 2017; Manuscript Received: 19 September 2016.|
|Subject Keywords:||sulfur; intermediate; isotopic enrichment; time of flight mass spectrometry|
|Official Citation:||Smith, D. A., Sessions, A. L., Dawson, K. S., Dalleska, N., and Orphan, V. J. (2017) Rapid quantification and isotopic analysis of dissolved sulfur species. Rapid Commun. Mass Spectrom., 31: 791–803. doi: 10.1002/rcm.7846|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||06 Mar 2017 17:06|
|Last Modified:||11 Apr 2017 15:56|
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