Short communication Sulphate measurement in organic-rich solutions: Carbonate fusion pretreatment to remove organic interferences

  • NE Ristow
  • SW Sötemann
  • MC Wentzel
  • RE Loewenthal
  • GA Ekama


Sulphate measurement using a barium sulphate turbidimetric method in solutions with high concentrations of organic material is shown to be problematic. The organics give background colour, which introduces a positive error to the measured absorption, and inhibit the barium sulphate precipitate, which results in a negative error. A carbonate fusion pretreatment of the sample results in the removal of the organic matter and associated interferences. With this pretreatment, excellent sulphate recoveries were obtained (100%). Rigorous testing of the method shows that reproducible and accurate results are obtainable.

Water SA Vol. 31 (2) 2005: pp.267-270

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eISSN: 0378-4738