This study describes the development by response surface methodology (RSM) of a procedure for copper determination by inductively coupled plasma optical emission spectrometry (ICP-OES) in water and biological samples after extraction by magnetic nanoparticles. Four variables such as, pH of solution, amount of extractant, amount of nanoparticles, and time were regarded as factors in the optimization study. Results of the two-level full factorial design (2(4)) based on an analysis of variance demonstrated that only the pH, amount of extractant (E), and amount of nanoparticles (N) were statistically significant. Optimal conditions for the extraction of copper samples were obtained by using Box-Behnken design. Optimum conditions were 5.1, 7.2 mg, and 9.6 mg, for pH of solution, amount of nanoparticles, and amount of extractant, respectively. Under the optimized experimental conditions, the detection limit of the proposed method followed by ICP-OES was found to be 0.9 microg L(-1). The method was applied to the determination of copper in water and biological samples.