As a primary standard for preparing volumetric alkali solutions and as a buffer in pH determinations. Potassium hydrogen phthalate is used as a primary standard for acid- base titrations as well as for calibrating pH meters. It acts as a buffer in pH determination. It finds application as a useful standard for total organic carbon testing.
Crystallise it first from a dilute aqueous solution of K2CO3, then H2O (3mL/g) between 100o and 0o. Before being used as a standard in volumetric analysis, analytical grade potassium hydrogen phthalate should be dried at 120o for 2hours, then allowed to cool in a desiccator. [Beilstein 9 IV 3169.]
