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 an Isoprime PrecisION IRMS (Cheadle Hume, Stockport, UK). Samples are combusted at 1000°C in a reactor packed with tungsten oxide and elemental copper. Immediately following combustion, sample gases are reduced with elemental copper at 900°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 ³⁴S delta values are obtained after adjusting the provisional measurements such that correct ³⁴S delta 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.