A novel voltammetric sensor was developed for the determination of N-nitrosopropranolol (as a carcinogenic metabolite of propranolol) based upon a carbon paste electrode, impregnated with molecularly imprinted polymer nanoparticles. The nano-sized imprinted polymer was synthesized via precipitation polymerization. Synthesis of the imprinted polymer for N-nitrosopropranolol was found to be difficult because of instability of the template in polymerization condition. Thus, the propranolol-imprinted polymer was prepared and used as the recognition element of the sensor. By adjusting the extraction pH to acidic condition, N-nitrosopropranolol was selectively adsorbed on the imprinted polymer-modified electrode, even in the presence of propranolol. The analyte was then assayed by differential pulse voltammetry technique. The oxidation current of hydroxy group of N-nitrosopropranolol was utilized in the electrochemical determination stage. Electrochemical impedance spectroscopy was used for the evaluation of N-nitrosopropranolol recognition by the MIP nanoparticles, existing on the electrode surface. The effect of electrode composition, extraction parameters and electrolysis conditions on the performance of the developed method was investigated and the optimum conditions were chosen. The method showed dynamic linear concentration range from 1 x 10(-7) to 1 x 10(-5) mol L-1. The detection limit of the method was calculated equal to 8 x 10(-8) mol L-1 (S/N = 3). Relative standard deviation of three separate determinations by the method was found to be 5.6%. Application of the developed method for the determination of N-nitrosopropranolol in real samples gave satisfactory results. (C) 2013 Elsevier Ltd. All rights reserved.