This article describes the development of a procedure for zinc determination in water and biological samples after extraction by magnetic nanoparticles by inductively coupled plasma optical emission spectrometry (ICP-OES). The optimization strategy was carried out by using two level full factorial designs. Results of the two level full factorial design (2(4)) based on an analysis of variance demonstrated that only the pH, amount of extractant and amount of nanoparticles were statistically significant. Optimal conditions for three variables: pH of solution, amount of extractant (E), and amount of nanoparticles (N) for the extraction of zinc samples were obtained by using Box-Behnken design. These values were 3.8, 3.1 and 3.3 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 0.8 mu g L-1. The method was applied to the determination of zinc in water and biological samples. (C) 2009 Elsevier B.V. All rights reserved.