Electrocatalytic oxidation of captopril on a vinylferrocene modified carbon nanotubes paste electrode

The study of electrochemical behavior and determination of captopril, as an angiotensin-converting enzyme inhibitor using a vinylferrocene modified multiwalled carbon nanotubes paste electrode (VFMCNTPE) is reported. The cyclic voltammetric results indicate that the VFMCNTPE system can remarkably enhance electrocatalytic activity toward the oxidation of captopril in aqueous buffer solution pH 8.0. Under the best experimental conditions selected, the calibration curve for captopril was linear in the concentration range from 0.2 to 400 mu mol L-1 and a detection limit of 0.08 mu mol L-1 was obtained. The influence of pH and potential interfering substances on the determination of captopril were studied. Electrochemical impedance spectroscopy was used to study the charge transfer properties at the electrode-solution interface. Finally, the sensor was examined as a selective, simple, and precise new electrochemical sensor for the determination of captopril in real samples, such as drugs and urine. Satisfactory results were obtained.