Radiometric determination of sulfate

A radiometric procedure for the determination of sulfate based upon the precipitation of barium sulfate is described with a sensitivity of about 0.01 μg/ml. Carrier-free³⁵SO₄ is added to the sample to measure the chemical recovery. The sulfate is precipitated with an excess of barium having a known specific activity of¹³³Ba. The amount of¹³³Ba determined by gamma counting is directly related by stoichiometry to the amount of sulfate in the precipitate.