The identification of selenopolythionates in aqueous solutions by electrospray ionization-Fourier transform-ion cyclotron resonance-mass spectrometry

ABSTRACT Selenosulfate (SeSO32-) has been shown to occur in certain industrial process waters, and selenopolythionates (SenSxO62-) can be suspected to form from SeSO32- via oxidative or addition reactions. We report here the first observation of selenopolythionates in waters by mass spectrometry. The high mass accuracy and ultra-high resolution of Fourier transform-ion cyclotron resonance-mass Spectrometry with electrospray ionization (ESI-FT-ICR-MS) were used to analyze the isotope patterns of selenium (Se), sulphur (S), and oxygen (O) satellites, in order to provide unequivocal determination of the molecular sum formula of three different selenopolythionates. An aged aqueous solution of SeSO32- was shown to contain the sodium adducts of selenotrithionate (NaSeS2O6-), diselenotetrathionate (NaSe2S2O6-), and triselenopentathionate (NaSe3S2O6-). The identity of these ions was confirmed by accurate mass determination (Δ m/z