Five treatment procedures evaluated for the elimination of ascorbate interference in the enzymatic determination of urinary oxalate

Abstract

We evaluated the efficacies of five treatment procedures for eliminating ascorbate interference in the enzymatic determination of urinary oxalate. Aliquots of urine samples, containing different amounts of added ascorbate and oxalate, were individually subjected to ferric chloride, sodium nitrite, sodium periodate, charcoal, or ascorbate oxidase treatment to eliminate ascorbate interference. Oxalate contents of the urine samples were then determined by a banana oxalate oxidase-horseradish peroxidase-linked assay with 3-methyl-2-benzothiazolinone hydrazone and 3-(dimethylamino)benzoic acid as chromogens. Only those urine samples treated with ascorbate oxidase or charcoal consistently gave recovery of oxalate close to 100%. Treatment with other reagents, though improving the recovery of oxalate, gave inconsistent results. On the basis of these data, we describe procedures for simply and reliably assaying oxalate by using banana oxalate oxidase.

Determination of Urinary Oxalate with Arylamine Glass-Bound Sorghum Oxalate Oxidase and Horseradish Peroxidase

“…The oxalate value in 24h urine collected from apparently healthy individuals of different age and sex were measured by the present method using immobilized oxalate oxidase and peroxides and were found in the range 11.0-41.5 mg/24 h (mean 19 .0 mg/24 h , n=46) ( Table 5). The mean values of urinary oxalate determinations by our enzyme are comparable to those obtained by barley oxalate oxidase immobilized onto alkylamine glass beads (19.8 mg/24 hr) (Pundir et al, 1993b) and immune complex of banana oxalate oxidase (17.17 mg/24hr) (Inamdar et al, 1991).…”

“…They also compared the efficiencies of five of these ascorbate eliminating methods and found that the pre-treatment with FeCl₃, NaIO₄ or NaNO₂ was 90% effective with low concentrations of ascorbate in the urine, while charcoal and ascorbate oxidase treatments were 100% effective with high concentrations of ascorbate in urine. In the present work, the urine was pretreated with buffered NaNO₂ for elimination of ascorbate interference (Inamdar et al, 1991). Standard assay conditions were used except for the addition of compound indicated at a final concentration of 1.0 mM in the reaction mixture.…”

Silica‐Polyaniline Based Bienzyme Cholesterol Biosensor: Fabrication and Characterization

“…This is due to the fact that AA can either consume a part of the enzymatically generated H 2 O 2 to form dehydroascorbate or reduces the oxidized states of HRP. However, the interference from AA can be eliminated by using Nafion permselective membrane or by surface‐adsorbing ascorbate oxidase onto the electrode 41.…”

Interferência do ácido ascórbico nas determinações de parâmetros bioquímicos séricos: estudos in vivo e in vitro

“…Atualmente, a enzima ascorbato oxidase é comumente utilizada para eliminar a interferência do ácido ascórbico na reação de oxidorredução. Comparando-se com outros tipos de tratamento para eliminar a interferência causada pelo ácido ascórbico, como cloreto férrico, nitrito de sódio, periodato de sódio, ácido bórico e íon férrico, somente a enzima ascorbato oxidase mostrou completa eficiência (11,21,24). No entanto é interessante notar que os níveis de interferência observados nesse estudo para o ácido úrico com o reagente da BioSystems, que utiliza ascorbato oxidase em sua formulação, foram semelhantes aos demais reagentes de outras marcas comerciais (Figura 2).…”