Abstract: Verapamil is an electroinactive cationic drug. This paper describes the method for determination of trace verapamil on the Nafion-modified glassy carbon electrode. The peak current of dopamine is decreased when verapamil is added to an electrolyte solution containing electroactive dopamine. A good linear relationship was found between the extent of the decrease in the peak current and the logarithmic concentration of verapamil in the range of 5×10^-7～1×10^-5mol/L. The detection limit of the method was 2.5×10^-7mol/L. The recovery was 96.2～105.7%, and the relative standard deviation was 3.2% (n=10).

Key words: verapamil, Nafion-modified electrode, cathodic stripping voltammetry