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Comparison of methods for inorganic sulfur speciation in a petroleum production effluent
Author(s) -
Witter Amy E.,
Jones A. Daniel
Publication year - 1998
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620171107
Subject(s) - chemistry , sulfur , thiosulfate , sulfide , sulfate , sulfite , derivatization , inorganic chemistry , environmental chemistry , chloride , reagent , chromatography , organic chemistry , mass spectrometry
Abstract Multiple analytical techniques were compared for identification and quantification of inorganic sulfur species present in a sulfidic waste effluent (produced water) generated during offshore oil production. Inorganic sulfur species including sulfide, polysulfides, thiosulfate, sulfite, and sulfate were measured in produced water samples using sampled direct current polarography, differential pulse polarography, iodometry, spectrophotometry after derivatization with Ellman's reagent, high‐performance liquid chromatography after derivatization with 2,2′‐dithiobis(5‐nitropyridine), and barium chloride precipitation of sulfate. Sulfide was determined in seven produced water samples at concentrations of 1 to 8 mM (˜39% of measured inorganic sulfur), as well as sulfate (˜56%), polysulfides (˜3%), and thiosulfate (˜2%); sulfite was detected only occasionally in lower concentrations (≤50 μM). Comparison of four methods used for sulfide measurement demonstrated systematic differences in results generated by various methods. Measurements of inorganic sulfur species in produced water are influenced by coupled equilibria between different chemical forms. Polysulfides exert an important role in coupling reactions between sulfur in intermediate oxidation states, and their presence can affect quantitation of these species when physical separations or standard additions perturb solution equilibria.