Determination of the first dissociation constant of 6-benzylaminopurine: A comparison of methods Original Research Article

The dissociation constant of 6-benzylaminopurine was measured by three independent methods: capillary zone electrophoresis, ultraviolet spectrometry and differential pulse voltammetry. Titration curves, obtained from electrophoretic and spectral data, were evaluated by standard procedure using Henderson–Haselbalch equation and by nonlinear computer fitting. Significantly lower values of standard deviations were obtained by using of computer fitting. Dissociation constant pKa=4.01±0.03, 4.10±0.07 and 4.24±0.12 have been obtained for 6-benzylaminopurine from electrophoretic, spectral and voltammetric data, respectively.