Determination of Unbiased δ 34 S and Δ 33 S Values by MC‐ICP‐MS Using Down to 30 nmol of Sulfur

International audience ; The multi‐collector inductively coupled plasma‐mass spectrometer is an instrument suited to measuring sulfur isotopes in all types of samples, from ice cores and river waters to carbonates and Archaean rocks. Its main advantage is the more convenient method of sample preparation, as sulfate does not need to be reduced but purified from the sample through ion exchange. This method allows the measurement of unbiased and precise δ 34 S values from samples as small as 10‐nmol with a typical intermediate precision of 0.15‰ (2 s ) at 95% confidence. So far, no attempt has been made to understand at which levels of analytical precision and bias MC‐ICP‐MS could provide ∆ 33 S values. Here, the first standard addition experiment undertaken for ∆ 33 S evaluation shows that measurement results on a Neptune Plus MC‐ICP‐MS allows us to calculate ∆ 33 S values identical to those established by other measurement principles, for samples down to 30 nmol S, with an intermediate precision as good as 0.05‰ (2 s ). Though this precision is not as good as the analytical precision of data acquired by the SF 6 method, the advantages of small sample size and straightforward sample handling make it a very useful tool for investigating past and modern aspects of the sulfur cycle.