The Direct Determination of Urinary Oxalate by Non-Suppressed Ion Chromatography

Abstract

In this paper we describe a simple ion Chromatographie method for determination of oxalate in urine. Acidified urine was diluted 1 : 2 with 0.03 mol/1 benzidine hydrochloride in 0.3 mol/1 boric acid to precipitate sulphate. The supernatant was passed through a C18-cartridge and 100 μΐ of eluant were injected into an ion Chromatographie system. Oxalate was measured by nonsuppressed conductivity detection. The detection limit for urinary oxalate was 0.05 mmol/1. The recovery for spiked urine samples was 101.5% with a CV of 4.5%. The within- and between-assay coefficients of variation were less than 4.5% and 2.5%, respectively. We found the results obtained by this method to be statistically equivalent to an enzymatic assay and a different ion-chromatographic method.