In this research, an iteration approximation algorithm based on the data of potentiometric titration andthe least squares method to determine equilibrium constants of (5,6-dioxo-3-sulfoquinoline-7-yloxyl)acetic acid in aqueous solution is described. The ionic strength of all solutions were maintainedby 1.0 M of KCl solution. The value of equilibrium constants of (5,6-dioxo-3-sulfoquinoline-7-yloxyl)acetic acid, which have been calculated by this method, are pKa1 = 1.841 was assigned forammonium group (of quinoline ring) and the pKa2 = 3.391 for carboxyl group. The programme hasbeen written with the Matlab language.Keywords: (5,6-dioxo-3-sulfoquinoline-7-yloxyl)acetic acid
equilibrium constant
iterationapproximation algorithm.