Development of a new electrochemical sensor for verapamil based on multi-walled carbon nanotube immobilized on glassy carbon electrode

• The MWCNTs/GCE was used in the construction a voltammetric sensor for verapamil.
• The behavior of verapamil on the surface of modified electrode was studied.
• The modified electrode has good stability, detection limit and wide linear range.
• The preparation and regeneration of electrode is very easy (no need any polishing).
• These advantages make electrode useful as a voltammetric sensor for verapamil.

A sensitive and selective method is presented for the voltammetric determination of verapamil using a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs/GCE). The oxidation peak current of verapamil at 1.02 V (vs. Ag/AgCl) is remarkably increased on the MWCNTs/GCE. Scanning electron microscopy (SEM) was used for characterization of the modified electrode surface. The electrochemical oxidation of verapamil using the MWCNTs/GCE was investigated by cyclic voltammetry. The experimental parameters including chemical and instrumental variables were investigated and optimized for verapamil determination. Under the optimum conditions voltammetric peak currents showed a linear response for verapamil concentration in the range of 2.5–70.0 μM, for both CV and DPV with detection limits of 2.0 μM and 1.6 μM, respectively. The relative standard deviation of five replicates determinations of 15.0 μM verapamil was 3.92%. The interference effects of frequently encountered excipients, additives and common species on the determination of verapamil were also studied. The sensor was successfully applied for verapamil determination in pharmaceutical and spiked human serum samples.