Investigations into sulfur speciation by electrospray mass spectrometry

Abstract

Sulfur is an element that manifests itself in a wide variety of chemical forms in the environment and it is generally not sufficient just to determine the elemental level of sulfur in environmental samples. In this study it is shown that electrospray mass spectrometry (ESMS) has the potential to provide a powerful direct probe for sulfur species in solution samples. The basic electrospray mass spectra to be expected for species such as SO₄^2–, S₂O₈^2– and S₂O₃^2– are presented, and the important role of controlling and varying collision induced dissociation (CID) conditions in order to validate the species identity is illustrated. It is also shown that ESMS can be used to monitor sulfur species such as S₄O₆^2– and S₂O₆^2–, which are products in certain redox reactions and also thiosulfate complexes, such as Ag(S₂O₃)₂^3–. Finally, quantitative results are presented for the determination of sulfate in waste water.