Voltammetric Determination of Captopril on a Glassy Carbon Electrode Modified with Copper Metal-organic Framework

We report in this work, a new method for the determination of captopril by differential pulse voltammetry using a glassy carbon electrode modified with a copper metal-organic framework (H-Kust-1 or Cu-3(BTC)(2) or Cu-BTC), immobilized on the surface by a copolymer of acrylamide and sodium acrylate. This compound is detected by the formation of a copper(II)-captopril complex that is observed in an oxidation potential at ca. +0.28 V vs. Ag/AgCl. A linear dynamic range is obtained for a captopril concentration of 0.5 mu M to 7.0 mu M and the voltammetric response is highly reproducible within 3.52% error. The sensitivity of 9.71 +/- 0.37 nA mu M-1 and the limit of detection of 0.20 +/- 0.01 mu M make this methodology highly applicable for practical applications. The determination of captopril in a commercial pharmaceutical sample showed a recovery of 93.3%.