Dodecanethiol-stabilized platinum nanoparticles (PtNP) were prepared by biphasic method and applied as modifier in a screen-printed electrode. Electrochemical characterization of this material has been evaluated using cyclic voltammetry (CV) and chronopotentiometry. The influence of some experimental conditions (current stability, influence of pH medium and electroactive area) in the electroanalytical behavior of the modified electrodes has been studied in order to achieve the best condition for platinum oxide formation. Under these optimized conditions, the modified electrode was evaluated as an electrochemical sensor for dapsone (DDS) determination and showed a linear response for DDS concentration in the range of 5.0 x 10(-6) to 9.1 x 10(-5) mol L-1 with a detection limit of 7.6 x 10(-7) mol L-1. The precision and accuracy were evaluated as a function of experimental repeatability and reproducibility, which showed standard relative deviation values lower than 3.0% for both. Recovery studies and DDS determination in real pharmaceutical samples were performed demonstrating that the proposed methodology is suitable for determining DDS in human urine and pharmaceutical formulation samples. In comparison to a Pt-bulk electrode, the sensitivity of the proposed sensor was at least three fold larger. (C) 2012 Elsevier Ltd. All rights reserved.