Volumetric Sulfate Determination

Use of Vanadium Pentoxide in Combustion Method for Sulfur in Refactory Materials

“…There are, however, two methods which do not use combustion tube technique. One involves fusion of the refractory sample with sodium peroxide in a metal bomb (2). The other requires * treatment of the material with hydrofluoric and perchloric acids (9), reduction of sulfates to sulfides, and a final iodometric titration.…”

Direct Titration of Sulfate

“…One series depends on the hydrolysis of a salt of a strong base and a weak acid to indicate the end point-for example, a method which adds excess barium chloride and titrates the excess barium with sodium carbonate in the presence of phenolphthalein. When all the barium has been precipitated as barium carbonate, the addition of a slight excess of sodium carbonate will cause the phenolphthalein to turn pink (19,22,101). A number of salts, such as sodium carbonate, potassium chromate (7,14,45,57,104), potassium stearate (5), or potassium palmitate (6,60,120), have been used in this titration.…”