Determination of urinary oxalate by reversed-phase ion-pair 'high-performance' liquid chromatography

Abstract

In this liquid-chromatographic method for determination of urinary oxalate, interfering compounds in the urinary samples were eliminated before chromatography by passage through a preparative C18 mini-column (Sep-pak cartridge, Waters Associates). In the reversed-phase system tetrabutyl ammonium was included as a counter ion to enhance the retention of oxalate. The H of the mobile phase was kept low (2.00) to avoid precipitation of calcium oxalate. This method is faster and significantly more precise than the colorimetric method we currently use.