ELECTROCHEMICAL BEHAVIOR OF THE HEMIN MODIFIED GRAPHITE ELECTRODE FOR H2O2 DETECTION

Aiming to detect amperometrically H2O2, iron (III) protoporphyrin IX (hemin; Hm) was immobilized by simple adsorption on the surface of a graphite (G) electrode. The electrochemical behavior of the G/Hm modified electrode was investigated by using cyclic voltammetry (CV) and square-wave voltammetry (SWV) under different experimental conditions (scan rate or frequency and pH). The catalytic current measured at G/Hm was found to depend linearly on the H2O2 concentration from similar to 0.01 mM up to 0.04 mM H2O2 (R/N = 0.987 / 4) and from similar to 0.01 mM up to 0.08 mM H2O2 (R/N = 0.973/14) for CV and SWV measurements, respectively. For both methods the detection limit was similar to 10 mu M, while the sensitivity was much higher for SWV [(276 +/- 12) mA/M] than for CV [(13.5 +/- 1.6) mA/M].