Removal of Ascorbic Acid Interference in Horseradish Peroxidase Estimations of Hydrogen Peroxide

Abstract

Ascorbic acid, which depresses the colour and interferes in reactions in colorimetric and fluorometric assay procedures for hydrogen peroxide involving horseradish peroxidase, has been removed from solutions by treatment with an iodine reagent. This reagent strongly interferes with procedures involving scopoletin, 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) and the reaction between 3-dimethylaminobenzoic acid and 3-methyl-2-benzothiazolinone hydrazone. The iodine reagent slightly depressed the fluorescence obtained using hydroxyphenylacetic acid but this was the most suitable electron donor for amounts of hydrogen peroxide between 6 and 60 nmol. Hydroxyphenylacetic acid spontaneously reduces residual iodine.

Key Words:

• Ascorbate
• Hydrogen Peroxide
• Peroxidase
• Iodine treatment
• Hydroxyphenylacetic Acid