APPLICATION OF ο-TOLIDINE AS SUBSTRATE FOR THE ELECTROCHEMICAL DETERMINATION OF HEMOGLOBIN OR HYDROGEN PEROXIDE

Abstract

In this paper hemoglobin (Hb) was used to catalyze the oxidative reaction of ο-tolidine (OT) with H₂O₂. The oxidative product of OT with H₂O₂ was an azo substrate, which was electroactive and had a sensitive linear sweep voltammetric reductive peak at -0.52 V (vs. SCE) on hanging mercury drop working electrode (HMDE) in pH 5.0 Britton-Robinson (B-R) solution. The conditions of Hb catalytic reaction and voltammetric detection were optimized. Under the optimal conditions, the electrochemical behaviour of the oxidative product was carefully investigated and the electrode process of the product on mercury electrode was proposed. Based on the increase of the reductive peak current of the oxidative product with the concentration of the H₂O₂ or Hb, a new electrochemical method for the determination of trace amount of H₂O₂ or Hb was proposed. The calibration graph had a linear range of 6.0 x 10^-8 to 4.0 x 10^-5 M for H₂O₂ and 1.0 x 10^-9 to 7.0 x 10^-7 M for Hb with the detection limit of 1.0 x 10^-8 M H₂O₂ and 5.0 x 10^-10 M Hb (3σ), respectively. This new proposed method was further attempted to determine the content of H₂O₂ in fresh rainwater with satisfactory results.

KEY WORDS: Hemoglobin, Hydrogen peroxide, ο-Tolidine, Linear sweep voltammetry


Bull. Chem. Soc. Ethiop. 2007, 21(2), 179-188.