Voltammetric Detection of Captopril in a Commercial Drug Using a Gold‐Copper Metal‐organic Framework Nanocomposite Modified Electrode

We report the application of an electrochemical sensor based on gold‐copper metal‐organic framework immobilized on the surface of a glassy carbon electrode to the detection of captopril (CAP), an angiotensin‐converting enzyme inhibitor. Cyclic voltammetric studies showed that the joint action of gold nanoparticles and copper‐1,3,5‐benzenetricarboxylate (Cu−BTC) enhanced the electrochemical response to the Cu‐captopril complex that is adsorbed onto the surface of the electrode. Release of gold nanoparticles from Au@Cu−BTC not only increased the conductivity of the electrode but also provided a more favorable environment for the deposition of reduced Cu that is catalytically renewed on the electrode surface. The anodic current of the Cu (II) −CAP oxidation peak varied linearly within two concentration ranges, namely 0.5 to 7.0 μmol L −1 and 10 to 2500 μmol L −1 , with a limit of detection of 0.047 μmol L −1 . The mean recovery for the determination of captopril in commercial tablets was 100.3 % suggesting that the method has considerable potential for future industrial applications.