High-throughput method for simultaneous quantification of N, C and S stable isotopes and contents in organics and soils

Stefania Mambelli; Paul D Brooks; Robin Sutka; Scott Hughes; Kari M Finstad; Joey Pakes Nelson; Todd E Dawson

doi:10.1002/rcm.7605

High-throughput method for simultaneous quantification of N, C and S stable isotopes and contents in organics and soils

Rapid Commun Mass Spectrom. 2016 Aug 15;30(15):1743-53. doi: 10.1002/rcm.7605.

Authors

Stefania Mambelli¹, Paul D Brooks¹, Robin Sutka², Scott Hughes³, Kari M Finstad⁴, Joey Pakes Nelson⁵, Todd E Dawson^{1

4}

Affiliations

¹ Center for Stable Isotope Biogeochemistry, 1140 Valley Life Science Building, University of California at Berkeley, Berkeley, CA, 94720, USA.
² MLS Analytical, 21380 Sea Ray Lane, Wilmington, IL, 60481, USA.
³ EA Consumables, Inc., 5090 Central Hwy, STE 3A, Pennsauken, NJ, 08109, USA.
⁴ Department of Environmental Science, Policy and Management, 130 Mulford Hall, University of California, Berkeley, CA, 94720, USA.
⁵ Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Biological Laboratories 4081, Cambridge, MA, 02138, USA.

PMID: 27426450
DOI: 10.1002/rcm.7605

Abstract

Rationale: Information about the sulfur stable isotope composition (δ(34) S value) of organic materials and sediments, in addition to their nitrogen (δ(15) N value) and carbon (δ(13) C value) stable isotope compositions, can provide insights into mechanisms and processes in different areas of biological and geological research. The quantification of δ(34) S values has traditionally required an additional and often more difficult analytical procedure than NC dual analysis. Here, we report on the development of a high-throughput method that simultaneously measures the elemental and isotopic compositions of N, C and S in a single sample, and over a wide range of sample sizes and C/N and C/S ratios.

Methods: We tested a commercially available CHNOS elemental analyzer in line with an isotope ratio mass spectrometer for the simultaneous quantification of N, C and S stable isotope ratios and contents, and modified the elemental analyzer in order to overcome the interference of (18) O in δ(34) S values, to minimize any water condensation that could also influence S memory, and to achieve the complete reduction of nitrogen oxides to N2 gas for accurate measurement of δ(15) N values. A selection of organic materials and soils was analyzed with a ratio of 1:1.4 standards to unknowns per run.

Results: The modifications allowed high quality measurements for N, C and S isotope ratios simultaneously (1 SD of ±0.13‰ for δ(15) N value, ±0.12‰ for δ(13) C value, and ±0.4‰ for δ(34) S value), with high throughput (>75 unknowns per run) and over a wide range of element amount per capsule (25 to 500 μg N, 200-4000 μg C, and 8-120 μg S).

Conclusions: This method is suitable for widespread use and can significantly enhance the application of δ(34) S measurements in a broad range of soils and organic samples in ecological and biogeochemical research. Copyright © 2016 John Wiley & Sons, Ltd.