Assay of potassium carbonate and potassium bicarbonate – Reliable, and selective determination of both species

Potassium carbonate and potassium bicarbonate are important raw materials in the pharmaceutical industry. As APIs, both can be used in effervescent tablets and powders as supplements to help patients with low potassium levels in their blood.

For both species, the other species is the most important contamination. For the assay, a selective method is thus required. Separation of both species by ion chromatography is not possible as the eluent changes the ratio of carbonate and bicarbonate falsifying the result. Due to their different pKa values, carbonate and hydrogen carbonate can be selectively determined by titration, which is therefore the method of choice for pharmacopeias, such as the USP and Ph.Eur.

Using potentiometric autotitration instead of manual titration increases the accuracy and reliability of results. Furthermore, the use of an autotitrator ensures that crucial requirements of regulatory compliance guidelines such as data
integrity are met.