Ascorbic Acid Department Degradation of Hydrogen Peroxide and Termination of Degradation by Use of Chelating Agents

Abstract

Ascorbic acid, a strong reductant in serum or urine, is known to interfere with the determination of hydrogen peroxide (H₂O₂).
This report describes the redox reaction between H₂O₂ and ascorbic acid in various buffer solutions, and the chemical approaches to protect the H₂O₂ from the above reaction.
It was found that H₂O₂ was reduced by ascorbic acid and ascorbic acid was oxidized by H₂O₂ in phosphate (pH 6.0-8.0) or tris-HCl (pH 7.5-8.5) buffer solution, while the redox reaction did not occur in citrate (pH 5.5-6.5) buffer solution. The redox reaction in the phosphate or tris-HCl buffer was shown to proceed more rapidly at an acidic pH than at an alkaline pH.
The degradation of H₂O₂ and ascorbic acid in these buffer solutions was terminated by the addition of chelating agents such as citrate, oxalate or EDTA, or by passing the buffer solutions through a metal chelating adsorbent.
The reaction was found to be accelerated by trace amounts of metals such as Cu²⁺, Fe³⁺or Fe²⁺, contaminants in conventional buffer solutions.