Multivariate optimization of microwave-assisted digestion of copper and zinc from powder milk

Abstract

In the present study, an easy and fast microwave-assisted digestion method combined with flame atomic absorption spectrometry (FAAS) was developed for zinc and copper determinations in milk samples. The irradiation power, volume of nitric acid, temperature and digestion time were selected for optimization in this work study. The results of 2-level full factorial (24) design based on analysis of variance (ANOVA) and Pareto chart showed that all of factors were statistically significant. The optimal conditions for the analytes extraction in milk samples were obtained by response surface methodology (RSM) based on Box-Behnken experimental design. The conditions of work were accepted as an agreement between optimal values that were found for the analytes. These values were 110 °C, 450 W, 4.0 mL and 21.0 min for temperature, irradiation power, volume of nitric acid and digestion time, respectively. This procedure was applied to the zinc and copper determinations in milk samples. © 2012 Sociedade Brasileira de Química.