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UC Davis Plant Sciences


Sulfur (34S) Analysis of Solid Samples

The SIF provides 34S isotope analysis of organic solid materials using an elemental analyzer and pre-concentration unit interfaced with a continuous-flow isotope-ratio mass spectrometer.

Analysis

Stable isotope ratios of 34S in solid samples are measured using an Elementar vario ISOTOPE cube interfaced to a SerCon 20-22 IRMS (Sercon Ltd., Cheshire, UK). Samples are combusted at 1150°C in a reactor packed with tungsten oxide. Immediately following combustion, sample gases are reduced with elemental copper at 880°C and subsequently pass through a buffering reactor filled with quartz chips held at 900°C. SO2 and CO2 are then separated by purge and trap, allowing for full separation and peak focusing. Following separation, the SO2 adsorption trap is heated and the sample SO2 passes directly to the IRMS for measurement.

 

During analysis, samples are interspersed with replicates of several laboratory reference materials to monitor and allow for correction of any potential variation in drift and linearity. Final δ34S values are obtained after adjusting the provisional measurements such that correct δ34S values for laboratory quality assurance materials are obtained. Laboratory reference materials have been calibrated directly against IAEA S-1, S-2, and S-3, as well as NBS-127, SO-5, and SO-6. The long-term reproducibility of this method is ± 0.4 ‰.


The SIF does not currently offer 34S analysis of soils or sediments.  GF/F filter material cannot be run on the sulfur instrument, please avoid/remove all particles of filter prior to sample encapsulation.









 
e-mail: sif@ucdavis.edu | phone: 530-752-8100 | fax: 530-752-4361
UC Davis Stable Isotope Facility | Department of Plant Sciences
One Shields Avenue | Davis, California, 95616 | USA