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