Determination of pKa values of salicyl alcohol and phenol by capillary electrophoresis with amperometric detection.

A simple and rapid method based on capillary electrophoresis with amperometric detection (CE-AD) to calculate the dissociation constant of salicyl alcohol and phenol is described. The effects of several factors, such as the potential applied to the working electrode, injection time, and separation voltage, were investigated to find the optimum conditions for pKa determination. Operating in a wall-jet configuration, a 300-pm carbon disk electrode used as the working electrode exhibited good response at 0.86 V (vs a saturated calomel electrode ISCE]) for salicyl alcohol and phenol. The effective mobilities of salicyl alcohol at different temperatures were determined by monitoring the migration time changes of salicyl alcohol and phenol. The dissociation constants of salicyl alcohol and phenol were calculated to be 9.94 and 9.96, respectively, which are in good agreement with the literature.