Preparation and characterization of the double potassium salt of sulfosalicyclic acid as a standard substance in alkalimetry

Summary The utility of the double potassium acid salt of sulfosalicylic acid as an alkalimetric standard substance has been studied. To this end an appropriate preparative procedure has been elaborated. This procedure includes partial neutralization of sulfosalicylic acid with potassium carbonate in a hot water-ethanol solution followed by four crystallizations of a crude product from a water-ethanol mixture, 11 by volume. The preparations of the salt prepared according to this procedure are well reproducible and homogeneous. The average content of the pure compound in 6 preparations assayed, based on 36 independent precise titrations was found to be equal to 100.008%±0.030%. The salt proved to be stable up to 280°C, and well soluble in water.These results allow to recommend the double potassium acid salt of sulfosalicylic acid as a primary standard in alkalimetry.Presented at Euroanalysis V, Kraków, August, 26–31, 1984.