Electrochemical Analysis of Tryptophan using a Nanostructuring Electrode with Multi-walled Carbon Nanotubes and Cetyltrimethylammonium bromide Nanocomposite

Multi-walled carbon nanotubes (MWCNTs) were immobilized on the surface of a glassy carbon electrode (GCE) in the presence of cetyltrimethylammonium bromide (CTAB) to form a MWCNTs-CTAB nanocomposite-modified electrode. The electrocatalytic response of the modified electrode towards tryptophan (Trp) was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The surface morphology of the modified electrode was characterized by scanning electron microscopy. Under the optimized conditions, a significant electrochemical improvement was observed toward the electrooxidation of tryptophan on the modified electrode surface relative to the unmodified electrode. The limit of detection of 1.6 μmol L-1 (S/N = 3) and linear calibration range of 4.9 – 64.1 μmol L-1 was obtained for tryptophan determination using a differential pulse voltammetric method in phosphate buffer (0.1 M, pH 3.0). Real sample studies were carried out in human blood serum, which offered good recovery (94.1-104.08%). The electrode showed excellent reproducibility, selectivity and antifouling effects.