ABSTRACT
Sulfate ion reacts with barium ion to form insoluble barium sulfate. A colloid stabilizing agent is added to stabilize the suspension of BaSO4. The absorbance of the sample at 500 nm is read before and after the addition of BaCl2 to compensate for any coloration or turbidity present in the sample. This differential absorbance is related to the amount of sulfate present in the sample using a previously constructed calibration plot (1–3). This is a manual procedure requiring no specialized equipment.
