A simple, rapid and sensitive cyclic voltammetry method is described for the determination of the antihypertensive drug captopril in aqueous solution using a graphite paste electrode with rutin as mediator. The catalytic role of rutin in the oxidation of captopril was confirmed by the increase observed in anodic peak current at+0.44 V vs. SCE in the presence of the mediator. Anodic peak current varied linearly with the concentration of captopril in the dynamic range 0.2 to 1.0 mmol L−1. The method exhibited a limit of detection of 89.4 μmol L−1 and a reproducibility of 1 %, values that are comparable with those exhibited by other methodologies employing electrodes without any modification. The recovery rate for the determination of captopril in a pharmaceutical sample was good (91.21 %) suggesting that the described analytical technique would be effective in industrial applications whilst offering a number of advantages over published cyclic voltammetric methods.

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.

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