Differential pulse voltammetric determination of metformin using copper-loaded activated charcoal modified electrode

A simple and sensitive carbon paste electrode has been developed for the electrochemical trace determination of metformin (MET). This sensor was designed by Copper(II)-loaded activated charcoal (Cu–AC) in the carbon paste electrode (CPE), which provides remarkably improved sensitivity and selectivity for the electrochemical stripping assay of MET. The drug was accumulated on the surface of the electrode through formation of a coordination complex with copper ions, which enhanced the sensitivity of the method. The effects of various copper(II) salts and oxidation states of copper (within the carbon paste electrode) on MET oxidation behavior were also investigated. The calibration graph was linear over the concentration range of 50 nM to 60 μM MET, and the detection limit was calculated as 9 nM. The proposed electrode was used successfully for MET determination in real matrices.