Fabrication of a novel electrochemical sensor for determination of hydrogen peroxide in different fruit juice samples

A new hydrogen peroxide (H₂O₂) sensor is fabricated based on a multiwalled carbon nanotube-modified glassy carbon electrode (MWCNT-GCE) and reactive blue 19 (RB). The charge transfer coefficient, α, and the charge transfer rate constant, k_s, of RB adsorbed on MWCNT-GCE were calculated and found to be 0.44 ± 0.01 Hz and 1.9 ± 0.05 Hz, respectively. The catalysis of the electroreduction of H₂O₂ by RB-MWCNT-GCE is described. The RB-MWCNT-GCE shows a dramatic increase in the peak current and a decrease in the overvoltage of H₂O₂ electroreduction in comparison with that seen at an RB modified GCE, MWCNT modified GCE, and activated GCE. The kinetic parameters such as α and the heterogeneous rate constant, k', for the reduction of H₂O₂ at RB-MWCNT-GCE surface were determined using cyclic voltammetry. The detection limit of 0.27μM and three linear calibration ranges were obtained for H₂O₂ determination at the RB-MWCNT-GCE surface using an amperometry method. In addition, using the newly developed sensor, H₂O₂ was determined in real samples with satisfactory results.