CAPILLARY ZONE ELECTROPHORESIS FOR THE DETERMINATION OF DISSOCIATION-CONSTANTS

Automated capillary electrophoresis is an effective method for the determination of pK(a) values. Advantages include having high sensitivity for poorly soluble solutes, not having to know the concentration of the solutes, and the simplicity of the method. The procedure, further investigated in this work, yielded determined pK(a) values to within 0.07 units of literature values from the IUPAC database for 18 solutes having pK(a) values of less than 9. The range evaluated was 2.43 to 9.99. Bases with pK(a) values above 9 had significant differences with the literature values. Wall adsorption and concentration effects were not potential contributors to these differences. Spectroscopic pK(a) determinations for three solutes showing large differences with the literature values agree with the capillary electrophoresis determinations.