Simultaneous determination of captopril, acetaminophen and tryptophan at a modified electrode based on carbon nanotubes

A novel modified carbon paste electrode (CPE) based on a new synthesized compound of (E)-3-((2-(2,4-dinitrophenyl)hydrazono)methyl)benzene-1,2-diol (DHB) and carbon nanotubes (CNTs) was prepared. At first the redox properties of the modified electrode was studied by cyclic voltammetry (CV). Then the modified electrode was used as an electrochemical sensor for oxidation of captopril (CAP). Under the optimum pH of 7.0, the overpotential of CAP oxidation decreases about 500 mV at modified electrode than unmodified CPE. Differential pulse voltammetry (DPV) of CAP at the electrochemical sensor exhibited two linear dynamic ranges with a detection limit (3σ) of 70 nM. Also DPV was used for selective and simultaneous determination of CAP, acetaminophen (AC) and tryptophan (Trp) by the electrochemical sensor. The proposed electrochemical sensor was used for determination of these substances in real sample.