The Voltammetric Determination of Phenolphthalein on Multi-walled Carbon Nanotube-DHP Composite Film-modified Glassy Carbon Electrode

A sensitive electrochemical method was developed for the linear sweep voltammetric (LSV) determination of phenolphthalein (PPL) at a glassy carbon electrode (GCE) modified with a carbon nanotube composite film. In the present paper, multi-walled carbon nanotube (MWNT) was dispersed into dihexadecyl phosphate (DHP) to give a homogeneous suspension. After the solvent evaporation, a uniform film of MWNT-DHP composite film was obtained on the GCE surface. The MWNT-DHP composite film-modified GCE exhibited excellent electrocatalytic behavior toward the oxidation of PPL. Compared with the small reduction current of PPL at the bare GCE, the oxidation current was enhanced greatly at the MWNT-DHP composite film-modified GCE. Based on electrocatalytic effect of MWNT-DHP film electrode, linear sweep voltammetry (LSV) was applied for the determination of PPL. The experimental parameters, which influence the current of PPL, were optimized. Under optimal conditions, high sensitive measurements of DPL were performed in situ. A linear response was obtained in the range from 1.0 10-8 to 5.0 10-6molL-1 DPL and with a limit of detect (LOD) of 5.0 10-9molL-1. The proposed MWNT-DHP film electrode was successfully applied to assay PPL in real samples with satisfactory results.