Gas chromatography-mass spectrometric characterization of SenSm compounds in synthetic melts and sediments.

A gas chromatography-mass spectrometry (GC-MS) method was used to characterize and identify mixed selenium-sulfur compounds with the formula SenSm in synthetic selenium-sulfur melts and selenium-impacted sediments. This method shows strong fragmentation of SenSm compounds in the electron ionization source, which makes conclusive identification of discrete compounds difficult. Despite these limitations, three SenSm compounds (SeS4, SeS5, and SeS6) were identified conclusively in synthetic samples, and several others were shown to be mixed SeS compounds, without being able to determine a molecular formula. Three selenium-impacted sediments from sites containing similar total selenium concentrations (11.0-18.5 ppm) were extracted with carbon disulfide (CS2); each of the three sediments contained at least 12 SenSm compounds, ten of which were common to all three sediments. Two of the compounds identified in the synthetic samples were also found in all three sediments, SeS4 and SeS5, and a third, SeS6 was found in one sediment sample. This is the first time that cyclic SenSm compounds have been confirmed to exist in the environment.