Analysis of organosulfur compounds in produced waters using mass spectrometry

Produced water is a complex waste effluent generated during offshore oil production. The recent efforts are aimed at providing information that can be used to assess the effects of produced water discharges into the coastal environment near Gaviota, California. Analysis of dichloromethane extracts of produced water samples revealed that a series of polar organosulfur compounds of intermediate polarity are abundant constituents. A suite of mass spectrometric techniques including electron ionization, chemical ionization, high resolution mass spectrometry, and MS/MS are being used for chemical characterization. These chemicals are present in far greater concentrations than petroleum hydrocarbons in the same waste stream, but the environmental importance and the origins of these compounds remain unclear. Studies are underway using model compounds to test the hypothesis that they arise from reactions of abundant sulfides with other organic compounds. Assessment of the distribution of produced water constituents near the discharge outfall is being performed by sampling seawater, mussels, and sediment at two depths at three sites in the vicinity of the outfall. The authors have developed analytical protocols for determination of organosulfur constituents in each of these matrices. Simultaneous analysis of lipid profiles from the mussels can be carried out without modification of the analytical procedures