Multivariate optimization of a microwave-assisted leaching procedure using dilute acid solutions, for FAAS determination of Cu, Fe, Mn, and Zn in multivitamin/multimineral supplements

摘要

This paper reports the development of a microwave-assisted procedure for leaching of copper, iron, manganese, and zinc from multivitamin/multimineral supplements by use of dilute acid before determination by flame atomic absorption spectrometry (FAAS). A Doehlert design was used to find optimum conditions for the procedure by use of response-surface methodology. Three variables (acid concentration in the leaching solution, irradiation time, and irradiation power) were used as factors in the optimization study for two acids, HCl and HNO3. Final working conditions were established as a compromise between the optimum values for each analyte, taking into consideration the robustness of the procedure. The best leaching results were obtained with HNO3 and the acid concentration, irradiation time, and irradiation power used were 0.70 mol L-1, 15 min and 360 W, respectively. The accuracy of the optimized procedure was evaluated by comparison with a well-established closed-vessel microwave dissolution technique.