EFFECTS OF ORGANIC SULFUR-COMPOUNDS ON EXTRACTION AND DETERMINATION OF INORGANIC SULFATE

The common methods for determining inorganic soil sulfate may be affec ted by the extraction of sulfate from organic sulfur compounds such as ester sulfates. In order to test this, various synthetic organic sulf ur compounds (ranging from ester sulfates to sulfonates and C-bonded s ulfur) were extracted with deionized water or with two common sulfate extractors (0.5 M NaHCO3 and 0.02 M NaH2PO4). Similar amounts of disso lved sulfate were detected in all extracts of the aromatic ester sulfa te hydroxyquinoline sulfate. Sulfate was not released from aliphatic e ster sulfates or C-bonded sulfur. Ion chromatography was compared to a turbidimetric method for the determination of sulfate. The latter met hod, based on BaSO4-precipitation, appeared to be unsuitable for deter mining sulfate in organically influenced solutions .Barium precipitate d sulfate as well as ester sulfates. Furthermore, the photometry of Ba SO4 was influenced by specific absorption of dissolved organic compoun ds, leading to a misinterpretation of the sulfate concentration in the solution.