Determination of Urinary Oxalate With Disposable Oxalate Oxidase Hembrane Strips

Abstract

We describe in this paper a simple and easy method of entrapping oxalate oxidase and peroxidase in acrylamide membrane and demonstrate the use of such enzyme membrane strips in the rapid determination of urinary oxalate. A crude preparation of 45-60% acetone cut obtained from banana fruit peel (Musa paradisiaca; French plantain) homogenate serves as a source of oxalate oxidase, which decomposes oxalate into CO₂ and H₂O₂. the oxalate content of a given urine sample is determined by introducing a small enzyme membrane strip (1 × 1 cm) into an aliquot of buffered urine containing a suitable chromogen for peroxidase and then measuring the colour developed due to the interaction of peroxidase with the newly formed H₂O₂ and the chromogen. Urine samples are pretreated with sodium nitrite to eliminate the interference of ascorbic acid in the assay. the enzyme membrane assay compares well with that of wet enzyme assay of oxalate in sensitivity and reliability.

Key Words:

• Oxalate oxidase
• Enzyme membrane
• Urinary oxalate