A nanocomposite film modified electrode was successfully prepared by dispersing titanium dioxide nanoparticles (TiO2), hydroxyapatite nanofibers (HAP) and multi-wall carbon nanotube (MWCNT) into chitosan solution. Based on this modified electrode, a mercury-free and highly sensitive method for the determination of o-phenylenediamine (o-PDA) was established. The prepared electrode was characterized by scanning electron microscope (SEM), cyclic voltammetry (CV) and alternating current impedance (EIS), and the electrochemical behaviors and kinetic properties of o-PDA on the modified electrode wer...