A rapid and precise method for determining sulfate seawater, estuarine waters, and sediment pore waters1

Sulfate can be rapidly and accurately measured by means of an indirect titration. Barium sulfate is precipitated in acid EDTA solution, the precipitate filtered and dissolved in an excess of EDTA at high pH, and the excess EDTA titrated with MgCl2. Interferences from chloride, iron, or phosphate are negligible. Sulfides may interfere, but there is a procedure to remove this interference. The method determines the sulfate concentration in 1.0 ml of seawater with a standard deviation consistently <0.5% of the mean determination of three replicates.