Multivariate technique for optimization of digestion procedure by focussed microwave system for determination of Mn,...

This article describes the development by response surface methodology (RSM) of a procedure for iron, zinc and manganese determination by flame atomic absorption spectrometry (FAAS) in food samples after digestion employing a focussed microwave system. A Doehlert matrix was used to find optimal conditions for the procedure through response surface study. Three variables (irradiation power and time and composition of oxidant solution-HNO(3)+H(2)O(2)) were regarded as factors in the optimization study. The working conditions were established as a compromise between optimum values found for each analyte taking into consideration the robustness of the procedure. These values were 12min, 260W and 42% (v/v) for irradiation time, irradiation power and percent of H(2)O(2) in solution, respectively. The accuracy of the optimized procedure was evaluated by analysis of certified reference materials and by comparison with a well-established closed vessel microwave dissolution methodology.