Equilibrium and Kinetic Studies of Ligand-Exchange Reaction of Aluminum(III)-5-Sulfoquinoline-8-ol Complex with Phosphate Ion by Reversed-Phase Ion-Pair Liquid Chromatography

Abstract

The reversed-phase ion-pair liquid chromatographic behavior of complexes of alummum(lll) with 5-sulfoquinoline-8-ol (HQS) on a column packed with a polystyrenedivinylbenzene copolymer is investigated with eluents that contain phosphate buffer. The aluminumdll)-HQS complex results in two peaks on the chromatograms; the heights of the peaks strongly depend on the pH of the eluent, the concentrations of HQS and phosphate buffer in the eluent, and the column temperature. The results obtained are interpreted according to the ligand-exchange reaction of aluminum(lll)-HQS with H 2 PO 4 - or HPO 4 2 in the eluent. The compositions of the mixed ligand complexes are determined, and the equilibrium and rate constants for the ligand-exchange reaction are estimated.