Electrochemical determination of captopril in the presence of acetaminophen, tryptophan, folic acid, and l-cysteine at the surface of modified carbon nanotube paste electrode

Abstract

A novel carbon paste electrode (CPE) modified with 2,2′-[1,7–heptanediylbis(nitrilomethylidene)]-bis(4-hydroxyphenol) (DHB) and carbon nanotubes (CNTs) was prepared. At first, the redox properties of the modified electrode were 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 120 mV at modified electrode than unmodified CPE. Differential pulse voltammetry (DPV) of CAP at the electrochemical sensor exhibited two linear dynamic ranges (7.0–100.0 and 100.0–2,500.0 μM) with a detection limit (3σ) of 2.43 μM. DPV was used for determination of CAP in the presence of acetaminophen (AC) and tryptophan (Trp), CAP in the presence of folic acid (FA), and CAP in the presence of l-cysteine (l-Cys) by the electrochemical sensor. The proposed electrochemical sensor was used for the determination of these substances in real sample.