Chemistry Letters, Vol.30, No.1, 14-15, 2001
Equilibrium analysis of acid dissociation reactions of phenolphthalein by using mobility change in capillary zone electrophoresis
An equilibrium analysis method by capillary zone electrophoresis was utilized for the determination of acid dissociation constants of phenolphthalein, which is unstable in an alkaline aqueous solution. Apparent electrophoretic mobility of phenolphthalein increased with increasing pH of a migrating solution. Acid dissociation constants (pK(a)) of phenolphthalein were determined as 8.84 and 9.40 by applying a non-linear least-squares analysis to the mobility change.