The acid dissociation constant is an important physicochemical parameter of a substance, and knowledge of it is of fundamental importance in a wide range of applications and research areas. We present a critical review of published methods and approaches for the determination of acid dissociation constants, with a special emphasis on the pKa values of active pharmaceutical ingredients. a 2007 E...

Dissociation kinetic analysis of a complex of Ce(3+) with a polyaminocarboxylic ligand, 8-amino-2-[(2-amino-5-methylphenoxyl)methyl]-6-methoxyquinoline-N,N,N',N',-tetraacetic acid (Quin2), was studied by microchip capillary electrophoretic reactor. Dissociation rate constants, k(d), of Ce(3+)-Quin2 complex in alkaline conditions at pH 8.3 - 9.8 were determined. The linear relationship of k(d) w...

In this study, the direct determination of cefixime as an anti-bacterial agent, in pharmaceutical formulations, urine and human blood plasma was conducted based on spectrophotometric measurements using parallel factor analysis (PARAFAC) and partial least squares (PLS). The calibration set was composed of fourteen solutions in the range of 0.50- 9.00 µg mL-1. PLS models were calculated at each p...

The time course of the soybean lipoxygenase-catalyzed oxygenation of linoleic acid has been analyzed using a kinetic scheme based on two binding sites, compulsory product activation and competitive inhibition by substrate and by product. The dissociation constant (Kp) of the product from the free enzyme is much smaller than 10(-5) M, the dissociation constant of the substrate from the enzyme-su...

A PDP-II online computer method for the titration of mixtures or 3 strong and a weak acid is described. The method is based on multiparametric curve-fitting. One of the parameters found from the calculations is the dissociation constant of the weak acid, hence the method can be applied even when this constant is unknown. Accurate results (relative error * 1%) were obtained for weak acids with p...