Gas-chromatographic determination of urinary oxalate.

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

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 pH of the mobile phase was ke...

Urinary oxalate determination by use of immobilized oxalate oxidase in a continuous-flow system.

In this procedure, oxalate oxidase (EC 1.2.3.4) immobilized in a continuous-flow system is used to determine oxalate in urine. The hydrogen peroxide formed from oxalate is detected by use of a color reaction with peroxidase (EC 1.11.1.7), 3-methyl-2-benzothiazoline hydrazine, and N,N-dimethylalanine. However, urine contains an oxalate oxidase inhibitor, which cannot be removed by heating, ion-e...

Preventing ascorbate interference in ion-chromatographic determinations of urinary oxalate: four methods compared.

In an attempt to decrease ascorbate interference on the ion-chromatographic determination of urinary oxalate, we compared the effectiveness of four different methods for ascorbate elimination by analyzing a representative urine pool supplemented with successive ascorbate additions. Two of the methods--treatment with ferric ions or boric acid--have been described elsewhere; treatments with nitri...

Urinary oxalate by rate analysis compared with gas-chromatographic and centrifugal analyzer methods.

Measurement of urinary oxalate: an enzymatic and an ion chromatographic method compared.

An ion chromatographic and an enzymatic method for determination of oxalic acid in urine were compared on the basis of reliability and practicability. Both methods displayed a within-run imprecision of under 5% and a total imprecision of under 10%. The mean recovery of 0.2 mmol/l sodium oxalate lay close to 100% for both methods. After 80 parallel determinations, both methods produced statistic...