In the present work, for the first time, electromembrane extraction (EME) combined with differential pulse voltammetry by multi-wall carbon nanotubes modified screen-printed carbon electrode has been reported for determining sufentanil. EME of sufentanil was carried out by applying a D.C. electrical potential through a thin supported liquid membrane (SLM). Charged drug molecules were extracted from an aqueous sample, through the SLM, into an acidic aqueous acceptor solution (20 mu L) which is placed inside the lumen of a hollow fiber. Then, the acceptor solution was analyzed using differential pulse voltammetry (DPV). A Box-behnken design was used in order to optimize different variables affecting extraction efficiency using following DPV currents as signals. The main parameters which affect the extraction and determination of sufentanil were observed to be: accumulation time, 30s; organic solvent, 2-nitrophenyl octyl ether; pH of the donor phase, 2.5; pH of the acceptor phase, 1.0; extraction time, 28 min; extraction output potential difference, 190V and stirring rate, 1000 rpm. Under the optimal conditions, DPV currents were linear with the concentration of sufentanil within the range of 6.4 x 10(-8)-3.62 x 10(-6) mol dm(-3) with the detection limit (S/N = 3) of 2.0 x 10(-8) mol dm(-3). Finally, the proposed method has been successfully used for the determination of sufentanil in urine and plasma samples. (C) 2013 Elsevier Ltd. All rights reserved.