Separation of Phthalic Acids and Related Impurities

Phthalic acid, phthalic acid isomers, and related products present in the production of phthalic acid were separated on the Primesep D column, based on reversed-phase and in-exchange mechanisms. Neutral, hydrophobic compounds of the phthalic acid production are retained by a reversed-phase mechanism, and phthalic acid and other acidic compounds are retained by a combination of reversed-phase and anion-exchange mechanisms. Resolution and selectivity of this separation can be modified by varying the amount of acetonitrile, buffer concentrations, and buffer pH. This method can be used for monitoring the production cycle of phthalic acid and related impurities.