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

Abstract

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